# need more fuel? try this little trick. worked for me and only takes 2seconds.



## NTRabbit (Mar 28, 2001)

*problem* 
I did a lot of work on my car (84 rabbitGTI, CIS) this summer learning about the fuel injection system, and trying to make it run like it was new. In the end I got every problem sorted out but one. I couldn't get enough fuel at full throttle, and it would lean at about 3000rpms at full throttle. I found this after I bought an autometer air/fuel gauge. I have a 2.0L engine with a P&P on the head, grind, and race headers, so I assume my fuel just couldn't keep up with all the air going in under full load. 
*solution* 
among many things that needed replacing in the system (ie: fuel injector, WUR, and fuel filter), my final solution was so remove my warm up regulator (WUR) from the engine block and place it in a cool place. Disconnect the electrical plug from it as well to keep the electrical heating element from warming it. If the WUR stays cool, it lets more fuel return to your gas tank, which releaves control pressure on the fuel plunger within your fuel dizzy. The less pressure on top of the plunger, the higher it can rise, and more fuel is able to flow into your injector lines. You can see where it is here, behind my fuel filter:








I had always heard about this technique, but I never knew why it worked, or if it would work for me. It worked like a charm! I run perfectly stoich at all times now, and rich when I mash the gas all the way to the redline. I noticed an immediate power increase in the topend. after doing some comparisons with my gtechPro-competition, I found about a 3 or 4 HP increase, but the real gains were in the topend power, which you could see on HP vs. RPM graphs. 




_Modified by NTRabbit at 12:55 PM 11-16-2003_


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

And one more thing, I read a book called _Bosch Fuel Injection & Engine Management_ by Charles O. Probst. This book was excellent, and I would recommend it to anyone interested in this stuff. 
-Nick


----------



## WackyWabbitRacer (Apr 24, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

Here is a pic of my WUR and its location:








The WUR was converted to a manual adjustable unit so I can set the Control Pressure to any value via the CIS Pressure Tester. Currently the WUR is set to about 42 to 44 psi which makes starting a little difficult but WOT is great. Regards, WWR.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (WackyWabbitRacer)*

that high of a pressure gives you good fuel? I have never tested my control pressure after they car had been warmed up with the WUR out of the way like that, but I always assumed it was around ambient temperatures, maybe a little higher. I just figured it would be in the lower psi range, maybe around 20-25psi, but I could be wrong. Mine still starts like a dream, and then warms up just enough to keep me from going really rich. Thats an interesting technique though, it would be nice to have something like that while doing dyno runs. 
about your engine.....I'm gonna go out on a limb here and guess. Are those cooling coils for your intake below the air box? And I am trying to figure out what is over on the passenger side wall, but it looks like heat exchanger and duct to direct cool air under the intake manifold, haha. You use water to do all the cooling? just curious. 
-Nick


_Modified by NTRabbit at 6:29 PM 11-16-2003_


----------



## WackyWabbitRacer (Apr 24, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*


_Quote, originally posted by *NTRabbit* »_that high of a pressure gives you good fuel? ...about your engine..... Are those cooling coils for your intake below the air box? And I am trying to figure out what is over on the passenger side wall, but it looks like heat exchanger and duct to direct cool air under the intake manifold, haha. You use water to do all the cooling? 

Nick, the WUR (aka Control Pressure Regulator - CPR) normally has a pressure of about 26 psi for initial starting of a totally cold engine, depending on the ambient temperature of the outdoors. 
As the engine warms up and the bimetallic strip in the WUR changes, due to the electrical heater and engine heat, the WUR's pressure will increase to about 52 psi which leans the fuel/air mixture back to a stoichiometric ratio of about 14:1.
The "cooling coils" under the air box is actually a three (3) inch hose from the left headlight bucket to the air box. The "heat exchanger" is actually an Oberg oil filter with a microscreen element. The other hose from the right headlight bucket directs cooler air across the intake manifold. There a heat shield between the intake manifold and the exhaust header, and the cooling hose is an attempt to provide cooler air across the manifold runners. The only water is in the radiator. By the way, the car is a SCCA road race Wabbit. Regards, WWR.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (WackyWabbitRacer)*

Did you ever find out how much HP CIS is good for unmodified? People used to always tell me that my CIS "should be good for up to 165HP" without modification, but I don't think that is possible without tweaking it. 
I really like the cooling duct going to the intake manifold. I had a friend here in Harrisonburg who raced (SCCA I "think") and had his cars built by some company down in Florida. From the testing they did, he claimed that they saw a 3HP improvement with the heat shield between the intake and exhaust manifolds. It all adds up in the end. 
-Nick


----------



## WackyWabbitRacer (Apr 24, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*


_Quote, originally posted by *NTRabbit* »_Did you ever find out how much HP CIS is good for unmodified? People used to always tell me that my CIS "should be good for up to 165HP" without modification, but I don't think that is possible without tweaking it. 

Nick, I am using the VW MotorSports CIS Metering Unit which is evidently designed for a 16V engine in terms of fuel delivery. With my 1.6L in its SCCA trim, I get about 120 to 125 HP due to restrictions in camshaft lift (max of 0.450 inches) and the induction system (no porting or polishing).
Consequently I have not had any problems with a lean condition, using the VWMS CIS unit. I have heard that a VW CIS should be good for 160 HP but I have nothing to confirm this. I suspect that a stock CIS unit (not the VWMS unit) would probably lean out at about 130 to 140 HP.
I use a Exhaust Temp Gauge (EGT) to monitor the fuel mixture and my EGT readings are normally about 1300 to 1350 degrees (F) which indicates a slightly rich mixture. Regards, WWR.


----------



## Peter Tong (Jun 17, 1999)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

Nick,
The best way to tell on your car is to test flow it... On my Lysholm Cabby I always test flow after injection mods just to visually verify gains in flow...
If any of you folks want more fuel out of your stock CIS setups, and need to replace old and worn out CIS injectors anyways, let me know and I'll have a set of high flow injectors made up for you.
On my Volvo 240t setup I've tested flow to 340cc per minute per injector... I think there is definitely more to be had, I'm looking forward to seeing mid 370's to 380 cc/min soon...or just over 1.5 litres per minute total flow...


----------



## Butcher (Jan 31, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

I hate to burst your bubble but CIS works great when everthing is working properly. By moving your WUR to the fender and 'everthing' runs great sounds suspicious to me. Sounds like you have problems with your WUR or your full throttle switch is not working properly. If you do not have a way to adjust your fuel pressures how can you say by doing this trick it will make every engine run better? Race cars are different than street cars, thats why you will not see chokes on carbs on race engines. Stick with Peters suggestions and do some testing.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Butcher)*


_Quote, originally posted by *Butcher* »_ If you do not have a way to adjust your fuel pressures how can you say by doing this trick it will make every engine run better? Race cars are different than street cars...

I wasn't trying to say it would make every engine run better, I meant that people who have modified cars like mine, and are experiencing the same problem as I am, could possibly benefit from this. 
I have done just about all the testing I can except for a fuel flow rate from the fuel pump or injectors. All four injectors are new, WUR is new, O2 sensor new, fuel filter is new, and all control pressure and system pressure tests are perfect, with perfect leakdown tests as well. My air/fuel gauge shows that the CO is tuned correctly and everything runs great now. 
If there was a problem somewhere, I would have to guess that it comes from the fuel flow rate, due to the pump. But you're right, I should do some testing like peter said. 
-Nick


_Modified by NTRabbit at 8:07 AM 11-17-2003_


----------



## fast84gti (Mar 2, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

Hmmm. I have moved battery, so maybe I should try that. Right now I only have one bolt on my FPR. The other one fell off it hangs a little loose...







And, it is from an AUDI, so none of the parts I have laying around fit, because they are all VW parts







I even have another FPR laying around. I don't care about starting issues, as I live in So Cal, and even on these cold days it starts. I started my car with lots of vacuum leaks, and loose intake manifold in 35 degree weather in MN... Thanks for the info, guys.. tODD


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (fast84gti)*

I should look into doing this on my engine. I'm having trouble finding computers that work right now though. http://****************.com/smile/emthdown.gif And the engine's gutless without the computer, and the mixture manually set.
I better get a computer that works before Friday, since that's the next meet/cruise for our local VW club.


----------



## Evilclown (Mar 12, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*


_Quote, originally posted by *NTRabbit* »_Did you ever find out how much HP CIS is good for unmodified? People used to always tell me that my CIS "should be good for up to 165HP" without modification, but I don't think that is possible without tweaking it. 

Well, a good example of a stock CIS application is the turbo Audis from the 80s. The UrQuattro and 5000 turbo both were around 165hp, and both ran CIS-E. Also, the 1991 200 turbo developed 217hp running a later version of CIS.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Evilclown)*

Were those audi versions of CIS exactly the same at the ones that came on mk1 VW's? That's an interesting tidbit though


----------



## fast84gti (Mar 2, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

But who wants to put a5 cylinder in thier car.....







*wasn't the '91 a one year only, being a 20v turbo (precursor to s4). 92's had the v6.... So that is not really fair to compare to a 4 cyl 8v CIS turbo car..... tODD




_Modified by fast84gti at 5:23 PM 11-18-2003_


----------



## fast84gti (Mar 2, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (fast84gti)*

Here is a little info on Audi 200 fueling.... NOT even close to CIS







"Bosch Motronic electronic multi-port injection, dual knock sensors, computer control of timing and boost pressure" http://members.aol.com/c1j1miller/200-specs.html


----------



## Evilclown (Mar 12, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (fast84gti)*

hmm. my source on the 200 said CIS.
http://www.audiworld.com/model...shtml
Regardless, though, be it 4 or 5 cylinder, CIS-E will support a good amount of hp.


----------



## Peter Tong (Jun 17, 1999)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Butcher)*

Have to agree with Mark here. I've seen CIS dynos posted (911 turbo's specifically) with whp values in the low 400's...the a/f curves were just fine.
CIS has and can be made to fuel boosted cars just fine.
PS: I do have a buddy with an Audi 200 turbo - yes it uses CIS...at least his example does...


_Modified by Peter Tong at 9:05 PM 11-18-2003_


----------



## ABA Scirocco (May 30, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Peter Tong)*

Peter, based on your response in this and others threads, it seems to me that you know more about performance tuning CIS system than just about anybody else here on the 'tex. I have a pretty good grasp of the basics but I'd like to learn more. Can you suggest any resources that would help me out?


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (ABA Scirocco)*

yeah, I hope I'm not giving the impression that I think I know everything with this stuff. I just wanted to tell everyone what worked for me. 

_Quote, originally posted by *ABA Scirocco* »_Peter, based on your response in this and others threads, it seems to me that you know more about performance tuning CIS system than just about anybody else here on the 'tex. I have a pretty good grasp of the basics but I'd like to learn more. Can you suggest any resources that would help me out? 

Peter, have you read "Bosch Fuel Injection & Engine Management"? ABA Scirocco, I thought that book was great. It explained SOOO many things to me I could never figure out. I'd definitly recommend it. I think it covers all bosch injection from the early 70's up till 1990 (?).


----------



## Andrew Stauffer (Oct 2, 2000)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (ABA Scirocco)*

Peter is "the source"! Miller Fuel Injection might be worth looking at as well, they use CIS on sand rails and are apparently quite good at modifying the system to feed 200hp without issue. 
FWIW, I ran a "euro" CIS basic injection set up on my 2.0 8v and dyno'd at 128whp and 138wtq. This would be in the area of 145-150crank hp and 160ish wheel tq. The air fuel gauge never left "rich" once above 4500rpms, there was more in her. Plenty o fuel...........


----------



## Peter Tong (Jun 17, 1999)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (ABA Scirocco)*

One factor that motivates me - I don't want my motor to blow up for lack of fuel under boost. As such I'm willing to go the extra mile and spend $$$ on experimentation to try different things to see what works and what doesn't to increase the flow rates. 
Naturally aspirated you'll likely not get close to the limit of a properly running CIS-Lambda's fuel flow wise, but once you go boosted you have powerful incentive for extra experimentation. There are a few others that have the same motivation I think - Stephen Webb comes to mind. Those folks are very knowledgeable, but don't seem to post as much these days unfortunately...I've been playing with CIS since back in '93 when I did my Audi 80 swap so that doesn't hurt either. Still remember swapping out CIS flow plates with that motor (I tried, thin lip, thick lip, and the smaller sensor plates back then).
just my $.02 worth...,
Peter


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Peter Tong)*

The bowl shape of the air metering unit is very important too. It's basically your fuel vs air map! For CIS, there should be 3 angles to it (idle, light load, full load), and their angle and placement determines how much fuel you get at certain airflow levels.
btw: I just found a computer that works in my CIS-Lambda system, so I'm back to spinning tires in 2nd!







I have to rewire the power connection for my DIY A/F guage so I can see a stable signal to tell if I'm leaning out at high rpm's. The WUR relocation might help.
Does relocating the WUR change the warmup characteristics of the engine??


----------



## Spinyfrog (Jan 29, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (fast84gti)*


_Quote, originally posted by *fast84gti* »_But who wants to put a5 cylinder in thier car.....









Have you ever heard of Dubweiser? its a company? run by some British lunatic with an Audi 2.2 20v Turbo 5-cyl engine in a mk1 golf with a full sycnro drivetrain.
the car is STOOPID fast!!








I for one would love a 5-cyl in my car! http://****************.com/smile/emthup.gif


----------



## WackyWabbitRacer (Apr 24, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_Does relocating the WUR change the warmup characteristics of the engine?? 

Inside the Control Pressure Regulator (CPR) (aka WUR), there is a diaphragm, a coil spring, and a bimetallic strip or spring. 
The coil spring puts pressure on the diaphragm to counter the fuel pressure. When an engine is totally cold, the bimetallic strip works in conjunction with the fuel pressure to compress the coil spring. With a cold engine, this mechanical situation creates a lower Control Pressure, resulting in a richer, initial fuel mixture.
As the engine begins to warm up, the bimetallic strip begins to deflect, putting less force on the coil spring. The coil spring then puts greater pressure on the diaphragm, resulting in a higher Control Pressure and a leaner fuel mixture.
The bimetallic strip has a heater element around it to prevent the fuel pressure from remaining high for a long time in colder weather. 
Between the engine heat and the electrically heated bimetallic strip, the CPR causes the Control Pressure to increase to about 49 to 55 psi, thus leaning the fuel mixture for less emissions and fuel economy.
If the CPR is relocated from the engine block and its heat, the bimetallic strip is subjected to less heat, thus keeping the fuel mixture in a richer range (ie a lower Control Pressure). Regards, WWR.


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (WackyWabbitRacer)*

On the CIS-Lambda system, the Lambda control unit operates once the thermal switch is open (25C for the black switch on the coolant flange on the front of the head). So I guess that takes care of the warmup. And the lower control pressure would allow the frequency valve to keep the system running rich at higher RPMs, right? More fuel allowed through the valve?
So how is the control pressure regulator going to change the fuel pressure if it's kept away from the engine's heat? Isn't it necessary? Or is it one of those stupid emissions things that kills power.


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*

I'll have to try it out before friday night, since that's when our local VW club is having a cruise.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_I'll have to try it out before friday night, since that's when our local VW club is having a cruise.









Just make sure you know what you're doing first. I wouldn't do this unless you know that you are running lean like I was. I think the first think to do would be to buy an air/fuel gauge if you think you're having problems. Thats what told me I was going lean.


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

I made myself an A/F guage a while ago. And I do know what I'm doing.







I have a full shop at my disposal, with anything I need. If anything goes wrong, it's no sweat to fix. My dad's been tuning/fixing VW's for 30 years, and taught me a lot about modifying engines, as well as how certain injection systems work.
Seeing as how I built my GLI from the ground up, with help from my dad for some of the bodywork, I'm sure I can handle most anything that comes along in this beast.
I thought it was commonly accepted that CIS goes lean at high RPM's with the stock setup. All it takes is one highway run to see if there's any difference. The Lambda system should keep the ratio in check better, since it will be "allowed" to use more fuel when it needs to.
But yeah, I agree with the whole knowing what you're doing thing. A n00b with no experience shouldn't mess with things too much, otherwise they might not know how to get the settings back.


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_ A n00b with no experience shouldn't mess with things too much, otherwise they might not know how to get the settings back.

haha, been there and done that. I remember the first time I tried to hand tune my CO to make my car "run better". I had no idea what I was doing, and screwed everything up. But hey, none of us would be where we are now if we hadn't broken a few lawn mowers, or broken things when trying to make them work better. Its the nature of a gearhead. 

_Quote, originally posted by *84_GLI_coupe* »_ And the lower control pressure would allow the frequency valve to keep the system running rich at higher RPMs, right? More fuel allowed through the valve?
So how is the control pressure regulator going to change the fuel pressure if it's kept away from the engine's heat? Isn't it necessary? Or is it one of those stupid emissions things that kills power.

I'm not 100% sure how to answer that, but refer to what WWR said earlier. Its hard to explain, I just think of it as a diagram in my head. But the warm up regulator is meant to have a low pressure when it is cold. That way, you get more fuel flowing to the engine before your O2 sensor activates, which helps the car wam up. Cold engines like rich mixtures. 
When the pressure in the warm up regulator is low, it lets a little plunger lift up inside of your fuel dizzy. that plunger lets more fuel flow into your injector lines when the plunger is up. I don't think it increases your fuel pressure, just increases the fuel flow rate. Hope that makes a little sense, its hard to understand. I'll try to find a picture and post. 

-Nick


_Modified by NTRabbit at 3:24 PM 11-20-2003_


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*









I hope I am not violating any copywrite laws by posting these pictures, but I put a citation anyways. Again, this book is excellent and explains things VERY well. 
The top image shows how your control pressure regulator (warm up regulator) returns fuel back to the gas tank. When temperature rises, less fuel goes back to tank, and control pressure increases. The control pressure increases on top of the control plunger. 
You can see in the second image how a higher control plunger lets more fuel in, while a lower control plunger lets less fuel in. When control plunger is high (engine and warm up regulator cold), more fuel flows into the upper chamber of the differential valve and out to your injector. 
I'm not going to tell you how the differential pressure valves work, because I am not confident that I totally understand them. They help regulate pressure differences between the metering slits on the control plunger though by deflection though. Don't ask me, its tough to understand. 
-Nick


----------



## NTRabbit (Mar 28, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*









here is a warm up regulator too. refer to what WWR wrote about it.


----------



## IndyCorrado (Dec 27, 2000)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

With all this talk about fueling issues and such on this thread, there should be someone in here who might be able to help me solve the cold and hot start problems i've been experiencing. Just can't seem to figure it out.
Car is an '84 Rabbit GTI. Having trouble with cold starts where the car will stumble for about 4-5 seconds after initial start-up before it hits idle and is fine. With start fine then after it is warmed up. Leave it for an hour or so, come back and it doesn't want to start. Have succeeded in starting it at that point by jumping the fuel pump relay and letting the fuel pump run for about 15-20 seconds and then it will start very rough.
Any ideas? 
Fuel accumulator is not leaking so i ruled that out. 
Tested all fuel pressures (system, control, residual) and they are fine.
Could it be a leaky injector?


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (IndyCorrado)*

Thanks NTRabbit!
Indy: Is the cold-start injector spraying correctly?


----------



## be158 (Apr 4, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (IndyCorrado)*

kinda sounds like the fuel pump relay.. see if you turn your key if the pump pumps pressure up.... that was the prob with mine.. had water leak in on the fusebox .. killed the relay... check it to see if it works..


----------



## be158 (Apr 4, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*

see my car was doing the same thing lean top end.. so i adjusted my fuel mixture to be sorta rich at idle.. and it pulls alot harder up top.. .. should i turn it back and move the control pressure regulator? which is more affective???


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*


_Quote, originally posted by *be158* »_see my car was doing the same thing lean top end.. so i adjusted my fuel mixture to be sorta rich at idle.. and it pulls alot harder up top.. .. should i turn it back and move the control pressure regulator? which is more affective???

Do you have CIS-Lambda? Or just CIS-basic. This kinda makes a difference.
If you have Lambda, then you want your duty cycle at 50% to have full adjustabity from the computer. When the WOT switch is tripped, the computer will default to 65%, which gives you a bit more fuel if you're running less than 65%. If you just richened the mixture, then the computer would have compensated. Move the mixture back to where the duty is 50% and then move the regulator.


----------



## IndyCorrado (Dec 27, 2000)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_Thanks NTRabbit!
Indy: Is the cold-start injector spraying correctly?

As far as I know it is........I checked it per the Bentley and it seemed to be fine........just to be on the safe side I swapped it with the one out of my other rabbit GTI and it did improve the cold starts significantly (no longer needing to start the car with my foot on the gas for about 10-12 seconds to keep car going), but it still stumbles upon cold starting for about 3-4 seconds before catching idle
As for the fuel pump relay idea........pump doesn't run when i turn the key to the "on" position..........swapped that out too from the other car and no change........pump still won't run when the key is turned "on"
Should I try to cold start the car with a jumper across the fuel pump relay terminals to see if that works, or is there another connection that the relay bridges other than the power to the pump that would affect the starting?


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (IndyCorrado)*

The pump should turn on for about 1 second, then turn off when you turn the ignition on. It SHOULD NOT pump when the engine has no spark. That's why it takes a signal from the coil. It's there in case you crash, keeps everyone safer. If you flip, the flow plate opens all the way, and your cylinders fill with fuel, and then out any open valves = KABOOM!!
I moved the regulator tonight, and when it wasn't trying to die, I got a HUGE power increase at above 4000 rpm. I gotta figure out why it was doing that. I put it back on the block so I could drive it. Maybe the computer was acting up again.








I got my A/F guage hooked up to a better power supply, so it's stable now. http://****************.com/smile/emthup.gif 4 bars = stoich. 3 bars = what I was getting when it was running bad after I put the reg back on the block. 0 bars = what I was getting when I had no power with the reg relocated.
Time to solve this...


----------



## be158 (Apr 4, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (NTRabbit)*

so i should go back and let my car warm up change back my mixture. to normal which is about 40 dwell cycles.. then remove the control pressure regulator and move it off the block....
so how does this affect gas mileage???
ill have to try this.. next week!!!..


----------



## Peter Tong (Jun 17, 1999)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*

Thought I'd post up a CIS dyno chart that I recently ran into...








and yet another - yes - thats almost 460 whp...on CIS...











_Modified by Peter Tong at 9:54 PM 11-22-2003_


----------



## junkyardjockey (Nov 11, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (Peter Tong)*

how would this work with a 86 cis-e??? i know they dont have a WUR,but maybe there is some thing else


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*


_Quote, originally posted by *be158* »_so i should go back and let my car warm up change back my mixture. to normal which is about 40 dwell cycles.. then remove the control pressure regulator and move it off the block....
so how does this affect gas mileage???
ill have to try this.. next week!!!.. 

You should be getting 50% duty, measured at the plug on the passenger-side strut tower.
Try moving the reg first, then adjusting your mixture. I was in a rush and didn't adjust after I moved it. I doubt that's what caused the problem with mine though.


----------



## be158 (Apr 4, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*

yeah i set the dwell back at 45-50.. which is about 50 duty cycles... on the passenger side... test connector...
then i moved the CPR and unpluged it...
then i drove...i hit 4k rpm.. and wham.!!! it boggs down bad. like hitting a walll.. !!!
so i tried a few more runs from a dead stop... and i think its when the full throttle enrichment kicks in stumbles bad... but if i flutter the throttle then once it gets to 5k it screams up to 6250rpm....
so i think i may be getting to much fuel when it kicks .. when i got back i looked at my dwell meter it was now at 32 or so... 
so what should i do???
adjust the mixture with it CPR moved?
any ideas would be cool!!!


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*

Yes, you SHOULD adjust mixture with the CPR moved. If you don't, then you're probably gonna run too rich, and your computer won't be able to keep up.
I found the gremlin in my fuel system.







My header wasn't grounded very well. I put a thick wire between one of the collector bolts to one of the steering rack mount studs. My injection is now stable. I'm going to move my CPR sometime in the next few days, once I make sure that the gremlin has been killed. http://****************.com/smile/emthup.gif


----------



## ABA Scirocco (May 30, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_I found the gremlin in my fuel system.







My header wasn't grounded very well. 

That's exactly why VW and most other manufacturers went to the 4-wire O2 sensor.


----------



## 84_GLI_coupe (Apr 3, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_
That's exactly why VW and most other manufacturers went to the 4-wire O2 sensor.

Good to know! 1 wire for O2 signal, 1 for the heating element, 2 for ground?


----------



## ABA Scirocco (May 30, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (84_GLI_coupe)*


_Quote, originally posted by *84_GLI_coupe* »_
Good to know! 1 wire for O2 signal, 1 for the heating element, 2 for ground?

That's right, usually there are 3 different coloured wires. Two wires will be the same colour, they'll be for the heater, and they're interchangeable just connect one to ground and the other to an ignition switched power source. The remaining two are the actual sensor wires, one's signal voltage and the other's signal ground, to figure out which is which, put a voltmeter on them and heat it up with a propane torch.


----------



## be158 (Apr 4, 2003)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (ABA Scirocco)*

ok.. i thought moving the CPR would be a good idea.. but i realized its not after i moved it....heres why!
ok.. say i move the CPR and then adjust the mixture.... it should be right shouldnt it?
well did that.. then it got really cold here.... so even tho its not that much change (30) degrees it was enough to screw my mixture all up running way rich since its colder...!!!
so this mod of moving the CPR might work if you weather is the same all the time.. but i watched my dwell meter as drove...in the city under the hood gets hotter.. so the mixture gets leaner... then onthe highway its cooler.. so the mixture richens up!!.. on the highway coming home i was reading 10-11 dwell cycles!!! runing way rich!!...
so at least i learned something you cant fool the mecanical temp sensor in the CPR its way more accurate than we thought!... http://****************.com/smile/emthdown.gif 
one way would be get a manual CPR to replace the factory one.. then at all temps you can have the same pressure..


----------



## WackyWabbitRacer (Apr 24, 2001)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*


_Quote, originally posted by *be158* »_one way would be get a manual CPR to replace the factory one.. then at all temps you can have the same pressure.. 

For racing purpose only on my basic CIS, I converted the electrical-mechanical VW CPR to a totally mechancial CPR and remove the electrical heater around the bimetallic strip, relocating the CPR to a cooler location near the left headlight bucket.
By using the CIS pressure tester, I can adjust the Control Pressure to the desired value. Currently the Control Pressure on my basic CIS system is set to about 42 to 44 psi which creates a richer fuel mixture. 
However for the street, I would not advice the usage of a mechanical CPR. Regards, WWR. 


_Modified by WackyWabbitRacer at 9:47 PM 11-24-2003_


----------



## Peter Tong (Jun 17, 1999)

*Re: need more fuel? try this little trick. worked for me and only takes 2seconds. (be158)*

Hi Folks,
I haven't been following this thread too closely, but I'm not sure what the point of moving the CPR off the block would be with the CIS lambda system. The lambda is going to try to compensate via the frequency valve and it will swing the mixture back to stoichiometric if its within the adjustment range (which is actually quite large). 
If you want to enrichen then your best best would be to wire up an RPM switch to trigger the stock WOT switch only when it passes 4k. If you want very fine control you can plumb a relay to disconnect the lambda (to set it back to 50% duty cycle), then plumb a secondary frequency valve fuel circuit around the stock circuit with an EIC capable of controlling a low impedance injector (the stock VW ones are about 2.7 ohms). Then you'll need a MAP sensor for the EIC and you'll be able to enrich at all the different load points. 
With boost, you want the extra fuel, just plumb in the Audi 5kt, or Volvo 240t warm up regulators, leave the stock Lambda connected, then plumb the secondary FV bypass and have it mapped to progressively start bleeding lower chamber pressure off. Doing things this way - the pressure sensitive WUR is going to drop control pressure as the engine revs through, and the lambda valve will swing in response towards zero duty cycle in response in an attempt to lean out the mixture. Since the Lambda will be pulling out fuel at the top end you'll need to start adding duty cycles to the secondary FV gradually until you hit 100% on it (max flow). This is how its setup on my Cabby...the less expensive option is to use an rpm switch to trigger 80% at the cross over point where things start going lean.
I'm currently using a stock VW FV for the secondary bypass, but have a custom injector holder. I plan on cycling the 2nd FV up to 100% and measure flow, then replacing it with a somewhat larger low imp. pulsed injector to drop lower chamber pressure more than is possible with the stock FV to gain more fuel flow....goal is 380+ cc/min per injector...
hope this info is helpful to some folks,
Peter T.


----------

