# Enrichment problems? CIS K-Jet guys: Try this mod!



## gearhead455 (Oct 30, 2001)

Having troubles with enrichment? Hey try this out, it may or may not work for you...
I was browsing through my Bosch fuel injection book and stumbled upon a section that talked about the different styles of warm up regulators. Some of the regulators have an atmospheric compensation port; this port can be used to convert your CIS/lambda or Basic warm up to act as a load sensitive enrichment device. So I popped the little black cap off the port and ran a vacuum hose from the port to intake manifold vacuum. This jacks control pressure up to 70 PSI at idle, when under WOT it drops to 50 PSI. Re-calibrate the fuel mixture so it runs at 50% dwell with the 70 PSI control pressure. The next time the vacuum drops it will drive the warm up to reduce control pressure in synchronization with the engine load! While I was driving I was monitoring the O2 and at WOT it responded with a perfect slightly rich .70V-.75V under a heavy load. 
I’m ditching the throttle-activated enrichment; it sucks compared to this!


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

So you're saying your warm-up regulator has this port available? My understanding was that only "high end" model cars had this type of regulator, like the Audi 5000 Turbo (which does have this). I quickly scanned mine for this port last month but wasn't appearent to me it existed...where abouts is this cap you speak of? Is it possible you have an Audi 5000 Turbo or Mercedes warm up regulator?
Jason

[Modified by ONLY 8V, 7:00 PM 4-11-2002]


[Modified by ONLY 8V, 7:01 PM 4-11-2002]


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

Some CIS warm up regulators have this port for "high altitude compensation" according to the bently. I got a reman unit from "The parts place" for $60 and it had this port on it ..... so did the one I turned in I got off of a junked 85 Jetta GL. I'll take a picture of it friday.


[Modified by gearhead455, 3:08 AM 4-12-2002]


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Okay, that makes sence...didn't realise they offer them from the factory on VWs...was this standard on a certain year or is it for high altitude markets (like Denver)?
Jason


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## AdidasCU (Jul 24, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

I don't think he is talking about the side ports from the Audi Unit (boost sesitive) but the top port next to the electronic connector on the top of the WUR...
I wanna see pics of how this is set up..
James


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

BTW which bentley did you read that in?? Can you specify page number too?
Thanks!
Jason


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

Actually the side port on the Audi version isn't really for boost....one is for altitude compinsation (reads atmosphereic pressure) and the top reads full load enrichment (vaccum)...this is just a little more advanced than the single unit, but neither is a "boost" reader...the full load acts as this. The one gear is refering too is actually a full load enrichment unit or a combo FLE and altitude compensation. Got this info from the Bosch Fuel Injection and Engine Management book and the Bosch CIS Technical Book (Bosch yellow book). 
Jason


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

I don't have the book with me now ( I left it with the car at my other garage). It's in the blue Bosch book with the hot wire MAF on the cover. Inside there is a picture of all of the different types of pressure regulators side-by-side. If you ever see a warm up with a black cap on the front next to the electrical connector, pull it off, you will see a port.
I found a picture on the net that looks like the regulator I have, except mine has a plastic cap covering that port sticking out next to the connector.


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Can you provide the part number for the rebuilt WUR you bought...can you provide both the Bosch Part number and the VW/Audi part number as well? Also, where abouts is this "Parts Place" where you bought yours? 
Thanks...Jason


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## agropena (Nov 5, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

where in the engine compartment is locate the warmupregulator?


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Gearhead....couple more ?s....what were your control pressure reading prior to making this change. Also, at WOT what were the O2 senor readings prior to making this change (i.e. with the WOT switch enrichment). Basically just wanting to see if this actually make for improvment for the 83-84 GTI K-Lamda with the WOT enrichment switch. If you didn't do these tests prior to connecting the WUR to vacum, would I be asking for to much to have you run thru the same test both with and without(but with the WOT switch) the vacum line to the WUR....proper comparisions would need to be done on the same day in the same location/altitude.
Thanks!
Jason 
PS: could you give me a brief run down of the motor that you're running this on?

[Modified by ONLY 8V, 10:58 PM 4-11-2002]


[Modified by ONLY 8V, 10:59 PM 4-11-2002]


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Was just thinking of a third test....vacium line connected to the WUR AND the Full Throttle enrichment swtich hooked up....this should give even more fuel, one would think....not that it would necessarly be needed for most apps, but it would be nice to see what O2 sensor numbers come up in this situation for those really high HP motors....like the ones you and I are most interested in








Jason


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

Very interesting info, Gearhead. I've long wondered if that would work. I recall standing in front of my motor , wondering "if the environment is pushing into the WUR and properly leaning it for altitude, why wouldn't a vacuum pulling in the opposite direction of the atmosphere, fatten things up? "
I just kept forgetting to investigate further. Come to think of it, I should have just thrown my vacuum pump on the WUR and see what happened on the A/F meter. Anyway...
ONLY8V, both of my Rabbit GTI's have had this type of WUR(don't have the pn in front of me), so I don't think we're dealing with anything exotic or rare. 
I'm headed to the dyno on the 28th. We'll have a wbO2 sensor to track fueling, so ........hmmmm. I could do some tests to see what's happening to quantify stock enrichment, the adj trim pot fuel inrichment I have hooked up on my 83 GTI, and the added vacuum line fuel enrichment.


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*



> Gearhead....couple more ?s....what were your control pressure reading prior to making this change. Also, at WOT what were the O2 senor readings prior to making this change (i.e. with the WOT switch enrichment). Basically just wanting to see if this actually make for improvment for the 83-84 GTI K-Lamda with the WOT enrichment switch. If you didn't do these tests prior to connecting the WUR to vacum, would I be asking for to much to have you run thru the same test both with and without(but with the WOT switch) the vacum line to the WUR....proper comparisions would need to be done on the same day in the same location/altitude.
> Thanks!
> Jason
> PS: could you give me a brief run down of the motor that you're running this on?
> ...


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## davela72 (Jun 7, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Boy oh boy, you guys like confusing my train of thought on this topic. I'm currently running the euro/CIS basic injection on my car and my trip to the dyno proved that the car was running lean up top. I tried hooking up an Audi 5K WUR to the car but it actually ran worse, way worse. I was a little confused as to where to hook the vacuum line at first. The first time I hooked it to the port on the throttle body and when I fired it up it smoked like crazy, running super rich. After taking it for a drive, I then moved the vacuum hose to a connection on the front of the intake, where I have my knock sensor vacuum hose connected. It idled much better but after another drive, the feeling at WOT was still worse than with the CIS basic WUR connected.
So, I guess I'm still wondering where exactly do you run the vacuum hose to on the intake? 

Thanks!


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (davela72)*

quote:[HR][/HR]Boy oh boy, you guys like confusing my train of thought on this topic. I'm currently running the euro/CIS basic injection on my car and my trip to the dyno proved that the car was running lean up top. I tried hooking up an Audi 5K WUR to the car but it actually ran worse, way worse. I was a little confused as to where to hook the vacuum line at first. The first time I hooked it to the port on the throttle body and when I fired it up it smoked like crazy, running super rich. After taking it for a drive, I then moved the vacuum hose to a connection on the front of the intake, where I have my knock sensor vacuum hose connected. It idled much better but after another drive, the feeling at WOT was still worse than with the CIS basic WUR connected.
So, I guess I'm still wondering where exactly do you run the vacuum hose to on the intake? 

Thanks![HR][/HR]​Did the CIS basic have this port like in the picture above? Audi 5000 WUR's have 2 ports, one for barometric compensation and the other for boost. If you are using the boost port, I don't think it will work with vacuum. 

Otherwise you have everything hooked up right if you are using the port in the picture, the warm up connected to intake manifold vacuum like it's supposed to. But you missed one VERY important aspect of this mod. With the engine at idle, you MUST reset the fuel mixture to be compatible with the new WUR base (at idle) pressure of 70PSI instead of 50PSI. If you don't your car will respond like you described. 

[Modified by gearhead455, 5:51 PM 4-12-2002]


[Modified by gearhead455, 5:57 PM 4-12-2002]


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## davela72 (Jun 7, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

gearhead, I was using the smaller, boost, outlet on the WUR for the vacuum. I just assumed that would be the one to use, guess I was wrong. Now, for a dumb question, how in the world do you get a vacuum hose over that big port on the WUR?
It looks like I might have to give it another try. I could just put the WUR that was on the car back on, i.e., '84 GTi w/ the atmospheric port on it. I guess I could then try to run a vacuum hose from that port to the intake.
Please let me know how you squeezed a hose over that port though.
Thanks!


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (davela72)*

I had to use a fairly large diameter vacuum hose i got from the hardware store.


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## 84_GLI_coupe (Apr 3, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (agropena)*

quote:[HR][/HR]where in the engine compartment is locate the warmupregulator?







[HR][/HR]​It's located on the engine block. Just above where the oilpan is, about halfway along the front of the block. There'll be two braided fuel lines going to it and an electrical connector. It shouldn't be too hard to find.


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## Rabbid Rabbit (May 1, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (84_GLI_coupe)*

So then this WUR can be used with CIS turbo setup to enrich under boost?


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Rabbid Rabbit)*

quote:[HR][/HR]So then this WUR can be used with CIS turbo setup to enrich under boost?[HR][/HR]​I supose, but I think it would be best to use the audi 5000 turbo WUR.


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

So I go to add this vacuum line yesterday, only to find the WUR on my 83 GTI does NOT have the "atmospheric pressure nipple". Which I find odd, as I would have sworn that it did. I dug out the WUR from my 84 GTI(rip) and it DOES have the atm press nipple, but sadly, that WUR is in pieces. Ah well. I'll have to stick with my grounded freq valve with an adj trim pot for now.


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## Rabbid Rabbit (May 1, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

Well, mine is from an Audi 5000 Turbo, and it looks exactly like the one pictured above. A couple of weeks ago there were a bunch of people saying that the WUR's with the nipple on the front only weren't the enrichment under boost type. I guess they were wrong.


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Rabbid Rabbit)*

Okay, I finished taking apart the WUR that i have that came off my 84 GTI. This particular version has the nipple and cap in question. I was curious to see what's on the other end of that nipple and how vacuum might effect fuel enrichment. The classic "how's that work?" and tear it apart to find out. Turns out, there's nothing at the other end of that nipple. It is literally just a port into the interior, no "mechanism" of anysort at the other end. The two half of the WUR are infact sealed with a rubber gasket, so they are airtight except for this port. 
If the diaphram that effects control pressure is sensitive enough to feel the changes in atmospheric pressure due to elevation change, I'd guesstimate that the vacuum of a high rpm motor will have a considerable effect on things. And gearhead seems to have demonstrated this. That makes additional fueling alot more reachable for those that truly need it. 


[Modified by Andrew Stauffer, 8:56 AM 4-16-2002]


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## eurotrashrabbit (Oct 25, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

I did this mod about 3 years ago. If you have enrichment problems use Audi 5K WUR. THe VW Motorsport infection works well too. But in some cases might be too much fuel.


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## redGTI8v (Apr 15, 2002)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

quote:[HR][/HR]
Sometimes the when I was at full throttle under a heavy load it could only muster up .45V on the O2. Sometimes when I was at a lighter load at WOT the O2 would read too rich well into the .85V range. Now when I am into the throttle medium it NEVER reads under .55V-.60V. Before the O2 used to swing all over the place. WOT is a rock solid .70V - .75V under any load. Also I noticed that the car seems to idle smoother after a real hard WOT acceleration, I think this is because when I decelerate from WOT the intake manifold vacuum increases to 22 inches of vacuum and drives the warm up lean. (cutting off fuel on deceleration) 
The results on the O2 sensor and my "a$$ accelerometer reading" are [HR][/HR]​Now I am fairly new to vw but from my knowledge of most f/i cars I know factory o2 sensors are considered to be highly inaccurate at anything but stoich. I am not trying to dis your results they seem good but it seems that I wouldn't put too much fath in a stock o2 sensor. If you have a wideband then maybe I would have more confidence. just my caveat
later
b


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (redGTI8v)*

If the O2 was not accurate than what is the point of the ECU controlling the mixture with it








Wide-band O2? Someone is pulling your leg. O2 signal feedback works one way and one way only since 1979.


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

redgti8v is correct in that the factory O2 sensors only measure *very accurately* right around stoich. They will indicate rich and lean as a trend, but as you move away from stoich, the accuracy dramatically decreases. Remember, the factory had no intentions for the sensor to measure anything but a nice lean, powerful mixture, so they don't chose a sensor that is capable of everything we're after. 
Wide band, while I don't know what is truly different about them vs the stock sensors(other than $$$), DO measure with the same accuracy across the entire range, thereby making them invaluable if you're trying to accurately set a rich or lean mixutre.


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

I dunno man, I'm not sure what you want from a O2 sensor. 
.5 = stoich 
.6-.8 = Rich
.4-.2 = Lean
What else are you really going to determine with a "wide band" and why do you need to know. I'm looking for something rich at WOT, something lean on deceleration and something stoich during cruse, that’s about all you can hope for.


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

If you're really pushing a motor, you need better resolution. You're indicating a general trend with the stock sensor, but the diff in richness btw .6 and .8 is huge, maybe enough to toast a motor under alot of boost. 
Especially when you consider what's being said here, that .8 is too far away from stoich to be accurately measured. The sensor may read .8, but what is it really? A wide band will tell you. 
Granted, for a normally aspirated CIS motor, the stock sensor is probably fine. But for very accurate and precise measurements, wide band is the ticket. Granted, the $500-1000 htat they cost makes them relatively uncommon, but if you need a specific mixture to ensure motor life, it can be a huge advantage. I think the folks that benefit the most from this is the high boost crowd.


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

$500 - $1000 bucks eh, No thanks I'll stick to my $30 sensor and a dyno run.
Remeber, I own a *A1 Rabbit*, we are known to be very cheap.


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Believe me, I'm right there with you. Cheap rules, and it works quite well thus far. But if you were running high boost or trying to set up a programmable EFI from scratch, it would be invaluable(if not cheap). 
Interestingly, the diy-efi website has a write up on building your own wideband set up using the factory sensor from a lean burn honda civic from the early 90s, IIRC. Total materials cost is rumored to be ~$200.


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

What about monitoring exhaust gas temperature? Wouldn’t that be accurate and cheaper?


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

I would think that monitoring EGTs offers rather accurate info, but I really have no experience with it. Like you, I'm pretty pleased with the set up capabilities offered my the $30 single wire O2 sensor. 
I've heard it said by some members of the turbo crew that the EGT gauges are more valueable than the AF gauge for determining mixture, but I don't know why, specifcally. I suspect that it has to do with the decreasing accuracy as you move away from stoich, as well as the fact that the Bosch o2 sensor signal tends to bounce alot during normal, proper function and the EGT may smooth this out. I'm sure the temps don't bounce as much or as rapidly. 
To revisit your initial post for a moment, how much vacuum do you think that a motor creates under WOT? It would be interesting to apply a the ole MityVac hand vacuum pump that I often use to bleed brakes to the WUR and monitor the changing fuel conditions that way. IE apply vacuum equivalent to WOT



[Modified by Andrew Stauffer, 9:25 AM 4-18-2002]


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*



> To revisit your initial post for a moment, how much vacuum do you think that a motor creates under WOT? It would be interesting to apply a the ole MityVac hand vacuum pump that I often use to bleed brakes to the WUR and monitor the changing fuel conditions that way. IE apply vacuum equivalent to WOT
> QUOTE]
> Hopefully the engine will be producing zero intake manifold vacuum at WOT. All the vacuum should be present at idle... about 17 inches...


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## Andrew Stauffer (Oct 2, 2000)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Can't be zero as your brake booster wouldn't work, and the ignition advance wouldn't be working. And your enrichment trick wouldn't work, either.








No?


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

The enrichment trick works because the mixture is set at idle with 17 inches of vacuum acting on the WUR boosting it's pressure to 70PSI. The vacuum drops in proportion to the throttle opening, the drop in vacuum drops the WUR control pressure (rich). The Vacuum booster has a check valve and it was never intended to be active at WOT (what's the use of trying to brake at WOT







)
The distributor works off PORTED vacuum not manifold vacuum. Ported vacuum is in front of the throttle plate and has the greatest vacuum at WOT.



[Modified by gearhead455, 6:54 PM 4-18-2002]


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## redGTI8v (Apr 15, 2002)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (Andrew Stauffer)*

Egt is fairly accurate and much cheaper but you must know what your car should have because every make of motor has a little variation.
A dyno and a factory o2 wouldn't be too bad. My point isn't that our O2 suck. It was that factory o2 are designed to give f/i ecu a simple rich/lean signal not a fine tuned spot on the spectrum. Wide band's give you mor accuracy. The slope of a factory o2 is very narrow.
I am not trying to down play your results, as long as your not going lean and you are putting down more power than it must be working.
Just don't expect .6 to be any better that .8 because o2 just aren't that accurate. I do give you much props on finding a solution for lean conditions very cool, I am just trying to remind everyone that f/i are a science and that you must have accuracay and validity as a science. 
B


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## ONLY 8V (Mar 4, 1999)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (redGTI8v)*

We tune our Drag Rabbit with EGT's in each runner of the header to monitor each cylander....works just fine for us...BTW the car has never seen a DYNO either....just the EGTs and the true test bed, i.e. the track.








Jason
PS: one thing to keep in mind, Progamable EFIs (SRS, Electromotive, etc) all use regular O2 sensors....seeing that you can set your a/f ratios via these EFI systems tells me the O2 sensors work just fine at either end of the stoich/lamda marker. I'd use the $30 O2 sensor to set what is right and then pull the plugs after a run to verify correctness....you can tell a lot from looking at a plug.

[Modified by ONLY 8V, 10:49 PM 4-18-2002]


[Modified by ONLY 8V, 10:50 PM 4-18-2002]


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (ONLY 8V)*

I agree, plugs are a "window" into the combustion chamber. Looking at them will tell you a lot.
Where can I get a high heat temp probe and gauge for cheap, Lab supply store? I never buy my parts from a "tunner", I am not wealthy.


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## gearhead455 (Oct 30, 2001)

*Re: Enrichment problems? CIS K-Jet guys: Try this mod! (gearhead455)*

Nevermind... I found a system that could be put together for under $100
http://www.aircraftspruce.com/catmain.php?dest=cathome.php


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