# Newly built MKIV VRT running lean + backfiring



## Tom FTW (Feb 22, 2010)

Hey guys,
My first thread under this name but I've been on the tex for a while now.
So I recently got my VRT "running", though I'm not driving it very often because my AEM wideband is telling me it's running lean (so lean that it shows dashes) and yet backfires. My setup:
-MKIV 12v vr6 (60k on engine)
-BKR7E's stock gap (.025)
-36lb fuel injectors
-36lb fueling software by c2
-kinetic turbo manifold
-kinetic 2 1/2in downpipe
-t3/t4 turbo
-forge 007 DV
-kinetics FMIC
-kinetics TIP with 4" MAF housing
-38mm tial wastegate with what I believe to be a 5lb spring (open dump)
-deleted cat in place of homemade 2 1/2in straight pipe (where wideband bung is welded)
-obx 2in catback secured to 2 1/2in straight pipe with adapters (making a whole 2 1/2in soon)
-fully deleted SAI with all connections removed and IMT tuning valve secured straight to check valve. Took out SAI relay next to waterfall

So the engine starts up fine with the Wideband reading in the general vicinity of 14.5 at idle for about 30 seconds and then starts idling lower after about 30 seconds (much like when SAI was installed), though the WB readings shoot up to 17 or even dashes (passed 20).
I give it some gas to get going, and it will hover around 17 AFR at about 2k RPM (about 16 vacuum or so), and sound almost like a diesel (but not run rough).
Once I get going about 3k RPMs to shift (usually around 5 vacuum), I put the clutch in to shift and I get very loud backfires under load. At this point my AFRs are at about 12. If I shift quick enough I can avoid the backfires.

What could this be? My areas of concern:
- Spark plug gap
- Injectors
- fuel rail
- fuel line
- fuel pump
- software
- bad wideband
- bad vac connection to FPR
- something to do with SAI removal
- cam timing issues (don't see how, but I guess I can't rule anything out)

I was planning on gapping my plugs to .023 as that seems to be common around here. Does anyone have any ideas or insight for me?
Thank you very much








p4c

Also, could get video in cabin of wideband while driving if it helps



_Modified by Tom FTW at 11:13 PM 2-25-2010_


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## GinsterMan98 (May 19, 2008)

*Re: Newly built MKIV VRT running lean + backfiring (Tom FTW)*

I don't think you can remove the SAI without loosing O2 control on MK4's. Scan it with vagcom and see if you have codes related to O2 control.


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Thanks for the quick reply Ginster. Yeah I read about that as well, but usually removing of the SAI sends the ECU into base mode doesn't it? Much like unplugging the MAF or o2 sensor? Base mode is usually very rich for an N/A car, would it really make me run that lean with FI?
Also, I forgot to mention, the AFRs as stated above are with the MAF unplugged. With the MAF plugged in, it doesn't seem to give me the 14.5 AFR for the 30 second startup period.
I've been waiting on a friend for a vagcom scan, I was just curious if these were obvious signs of something.


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

My suggestion would be plug all your sensors back in and vag it to look at o2 adaptation at idle and long term adaptation. I just did a quick search and I am pretty sure you need your SAI. Their is no telling how the car will run without an o2 telling the ecu to take or add fuel. 
Don't drive it until you get it too idle correctly and definitely stay out of boost.


_Modified by GinsterMan98 at 2:32 AM 2-26-2010_


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Thanks. I really appreciate the suggestion.
I'll give that a try. I guess the thing that really baffles me is the fact that I'm backfiring while running lean. How would something like this happen?


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## Tom FTW (Feb 22, 2010)

*FV-QR*

My bad. I hadn't read too much into backfiring, which was stupid of me. I had thought that backfiring only happened when running rich.

_Quote, originally posted by *Wikipedia* »_
* Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires
* Improper wiring in the ignition can also lead to timing issues and backfires
* Low fuel pressure, clogged fuel filters, and weak fuel pumps could cause a severe lean air-to-fuel ratio during fuel injection
* Missing or damaged catalytic converter can result in backfires out the tailpipe


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

Lean = hot exhaust gasses. Any unburnt fuel will ingnite from the heat. Mine does it sometimes when I shift while on it hard.


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (GinsterMan98)*

Awesome. Thanks a lot.
Ill try plugging things in and see how it plays with a vagcom and post my results.


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

I would really not recommend driving it with AFR's that lean. You stand to loose a lot if you pop your motor.


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## Tom FTW (Feb 22, 2010)

*FV-QR*

i'm not going to. I'll plug the sai back in (at least the electrical portion) and get it scanned.


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

word.


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## littlenr (Jan 23, 2002)

*FV-QR*

C2 software can write out the sai! Give them a call and see if your version has that or not. MY car backfires more when its lean than rich. While its rich it crackles. When it goes lean it pops. 
Check for exhaust leaks as well. They will contribute to "backfires" as well.


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (littlenr)*

Yeah I read about that. The PEM software right? I think BFI sells it. 
I didn't know the second o2 had an effect on how the motor ran, I thought it was strictly to tell whether the cat was working or not. Or does the SAI unplugged affect the *first* o2 sensor?
I'm wondering if I can get away with plugging the SAI solenoid back in, but not the pump itself.
From all accounts I've read, removing the SAI makes the car run really rich, not lean. I need a vagcom bad


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

Like I said, you loose primary O2 control with a deleted SAI on a MK4. MK3's you can delete both the rear o2 and the SAI without any issues. Unless they have changed it?


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (GinsterMan98)*

That makes sense. Runs on base maps until the primary com starts reading, then starts running poorly
I plugged the solenoid back in, though it wasn't attached to any hoses. Didn't make any difference. Next ill plug in the power to the pump and see how that feels.


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (Tom FTW)*

Just idling by the way. Not putting any throttle until I get scanned


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## TBT-Syncro (Apr 28, 2001)

*Re: FV-QR (Tom FTW)*

maf sensor
tps sensor
02 sensor
you need to verify that all of those are working properly
first question. after you did all of the work, and before you started the car, did you do a throttle body alignment?


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (TBT-Syncro)*

Hey TBT. I'll take a look at all of those.
I was told that when the battery reconnected, the ignition could be put into the "on" position for 30 seconds and the TB would realign itself automatically. Is this a MKIV myth?
Thanks a lot!


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## TBT-Syncro (Apr 28, 2001)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Hey TBT. I'll take a look at all of those.
I was told that when the battery reconnected, the ignition could be put into the "on" position for 30 seconds and the TB would realign itself automatically. Is this a MKIV myth?
Thanks a lot!

nope. that is correct.


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Damn. I was almost hoping that to be the problem. It'd have been an easy fix. I could see how that would cause a lean condition with the ECU thinking the TB was shut, yet more forced air was still being introduced. That would greatly affect my vacuum though wouldn't it?
Tomorrow I'm hoping for a scan. Hopefully that will tell me what's up. I've been plugging and unplugging different combinations of MAF, SAI relay, and SAI solenoid to no avail. The only thing that seems to make the car run slightly better is unplugging the MAF. With the MAF unplugged, the primary o2 is completely forgotten correct? 
I recently got a used MAF off of here after mine crapped out on me. So since neither of you seem to think spark or fueling is a problem, my new list of could-be problems is:
- SAI
- TPS
- MAF
- O2
or any combination of them. I'm going to double check tomorrow to make sure the freeze plug I stuck in the block where the combi valve was is still secure.
I might invest in that SAI delete chip because my short runner came in the mail yesterday (thank you Paul) and the SAI will not fit with the SRI.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*

Dude, i am having very bad problems with my mk4 jetta vr6t.
i have Unitronic 440cc software and im getting constant EPC light, and lean backfiring type stuff.
i have my SAI deleted,.
ive been told you can resistor off this stuff, but now some of this is starting to make me regret ripping the SAI out, but my SRI required it.....







.
and at this point,i was hoping that Unitronic could delete the SAi but they cannot...
so it might not even e-test with out it...
and i have no clue what to do, i can drive the car cause it runs to lean.
but maybe he's right about it ignoring primary 02 readings cause of this.
if so, thats a huge deal for us with these mk4 vr's


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*


_Quote, originally posted by *GinsterMan98* »_Like I said, you loose primary O2 control with a deleted SAI on a MK4. MK3's you can delete both the rear o2 and the SAI without any issues. Unless they have changed it?

i hope this isnt true...
cause i tossed my SAI and the car runs like ****, with a CEL and an EPC just cause of the SAI AND i cant pass e-test.
it runs lean cause of the ignored primary o2...









now ive got to figure out how to get the SAI pump to fit in there with the SRI...

any ideas?


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## TBT-Syncro (Apr 28, 2001)

*Re: FV-QR (CorvetteKillerVr6)*

just plug a sai selonoid in to the harness and see what happens.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (TBT-Syncro)*

ive also been folwing this post, scroll down till u see the part about adaptive fueling not workign cause the SAI in a mk4 was deleted....

http://forums.vwvortex.com/zerothread?id=4770851


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (TBT-Syncro)*


_Quote, originally posted by *TBT-Syncro* »_just plug a sai selonoid in to the harness and see what happens.

tried it, with out the right resistor, it still throws a code.
and i dont have the SAI pump, so i get the flow code, which could also be cause primary o2 problems??


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Hey guys,
I actually JUST got inside from sticking a string of resistors (equaling 300ohm) on my SAI pump. It started running very promising and I was uber excited. After about 1 minute of 14-15AFR readings, the dial flew to the lean side and my car started sputtering. This was with SAI pump resistor-ed and the solenoid plugged in but not hooked to any hoses.
I think tomorrow I'm going to try to stick resistors on the plug for the solenoid as well. I'm also going to finally get a vag scan for the first time since my car has had the turbo.
I feel pretty confident that the problem lies within the SAI, however, it always seems to be within 30secs-1minute that the system starts running lean. That's about the time the SAI should be turning OFF correct?


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*

ill keep u posted on my progress with this resistor trickery tomorrow afternoon http://****************.com/smile/emthup.gif


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (CorvetteKillerVr6)*

I would put it back in and hook up all the lines. Make sure you put a check valve in the feed line too the sai vacuum thingy, you know what I mean







Clear the codes and see if it works. If you get an incorrect flow code you make have criss crossed the vacuum lines. As far as I know right know you can't delete the SAI from the code on MK4's. Also, as far as I know right know if you remove it you will loose primary O2 control. You will get a bank 1 multicaptive fuel trim too lean code among others.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*

man that sucks.
seems to be i need to somehow rig up the SAI system but re-locate it to fit elsewhere??
cause im getting major EPC light stuff related to MAF and really lean fuel trims, but in the end i thinks its all cause of the SAI.
think id be able to make something to route the hose to the combivalve /blockoff plate area in order to relocate the SAI pump??


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## Tom FTW (Feb 22, 2010)

*FV-QR*

My vag scan. So recent that I haven't even looked up any codes. Without digging, it looks like the used MAF I bought was garbage. Along with that, I need to check connections/replace my primary o2. 
I'll do a search on what the "power supply terminal 30" and "load calculation cross check" means.
-----------------------------------
6 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 35-10 - - - Intermittent
16497 - Intake Air Temp. Sensor (G42): Signal too High
P0113 - 35-10 - - - Intermittent
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-10 - - - Intermittent
17524 - Oxygen (Lambda) Sensor Heating; B1 S1: Open Circuit
P1116 - 35-00 - -
17550 - Load Calculation Cross Check: Lower Limit Exceeded
P1142 - 35-00 - -
Readiness: 0000 0000
-----------------------------------


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

After reading a little the p1602 maybe from a low battery (less than 11.5V). If it sat for awhile and you tried to start it could cause this. 
The other codes maybe from you unplugging the maf with the car on or driving with it disco'ed. The p0113,p0102 would be from that. The p1142 may also be from the maf or the O2. Did you run the car with the O2 disco'ed, that would account for the p1116 code. The p1136 could be from the maf or unplugging the o2. I would delete the codes and then let the car sit with the ing on for one minute. Than start the car and let it idle for 20 min or until the afrs stabilize around 14.7. Do not touch the throttle for that period, its very important. This lets the o2 regulation at idle trim itself correctly. Then drive the car normally for about two to three days and then rescan for codes. Also, check in OBD2 tab and select read data. Their will be several options to choice to read. Select idle adaptation and long term fuel trim. Both should be around + or - 3 from 0, but no more than + or - 10 from 0. I hope this helps you.
I don't see any SAI codes though


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (GinsterMan98)*

Hey ginster. Wow thank you for the analysis!
Yeah I ran the car for a little while with the MAF disconnected, though never the o2. Ill check down there to make sure everything is looking OK. Now would the o2 be throwing a different code if it was malfunctioning and not just unplugged?
The car ran slightly better with an unplugged MAF.
Its strange there weren't any sai codes thrown. I ran with the whole system removed until the other day when I threw a resister on the pump plug and the solenoid plugged.
After scanning, I had my friend readapt my TB as well.
So basically I should reset all codes, check that the O2 is in correctly and drive it to see if it adapts?
I'm hoping the o2 is disconned because after 30 secs, it literally bogs down


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

If you never disco'ed the O2 than its bad. The heater circuit is what keeps the O2 from getting carbon fouled. I would replace the O2 and go from there. Clear codes, let idle for 20 min with no throttle input and drive like grandma at varying speeds for a few days then recheck for codes. At that time I would also check that the fuel trims are acceptable. It usually takes a few days of driving for the car to realize a problem with the SAI, would explain that if you never really drove it for long since it was removed.


_Modified by GinsterMan98 at 3:25 AM 3-1-2010_


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*

so in the end... are we 100% sure the SAI delete screws around with primary o2 readings, and possibly MAF calculations aswell?
im getting an EPC MAf related code


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## hpfreak (Jun 21, 2005)

*Re: FV-QR (CorvetteKillerVr6)*

From my experience the SAI has to be plugged in. Having said that you only have to have the electrical connections. You don't need the physical pump or associated hardware (pump, vacume lines, tubing). I believe there are two connectors 1 for the solenoid and one for the pump. What I did was take the pump apart so I was left with just a cap with the connector, plugged it in and secured to the motor. I think there are only 2 connectors but it has been 5 years so I am not sure. Just make sure that all of the connectors associated with the SAI are connected. My car was running pig rich and I was not able to boost and had an EPC light with it disconnected. As for the o2, removing the second o2 (behind cat) has no effect other than showing up as a code when vagcom'd.


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (hpfreak)*

I really hope both you guys get your cars squared away. Just follow my directions and make sure you plug all your stuff back in and you should be good.


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (GinsterMan98)*

Thanks a lot. All of you. 
All my connections are pseudo connected (ill get pics of my resister setup for you Corvette), so I think ill order a new o2 and see how that plays


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Thanks a lot. All of you. 
All my connections are pseudo connected (ill get pics of my resister setup for you Corvette), so I think ill order a new o2 and see how that plays

no worries man, keep us posted and ill keep intouch with my situation.!
and i would LOVE to see pics of how u set up your resistors to get them to clear the codes properly http://****************.com/smile/emthup.gif








thanks bro


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*


_Quote, originally posted by *GinsterMan98* »_I really hope both you guys get your cars squared away. Just follow my directions and make sure you plug all your stuff back in and you should be good.

awesome, thanks so much. http://****************.com/smile/emthup.gif 
so you really think the SAI needs to go back in the eh?
i will need to source someones old SAI system then








i tossed mine when i took it out!


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (CorvetteKillerVr6)*

ive been checking my ground and i think i might be on to something.
possibly my fuel pump relay aswell??


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (CorvetteKillerVr6)*

Nah we don't need to put the SAI back in, just need to trick the system into thinking the SAI is there.
What makes you think the fuel pump relay is bad?


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*

but even when the ECU thinks its there, you will still get an improper flow code cause the o2 sees the airs not there.
Unitronic and C2 have yet to write out the SAI on mk4 VR6, in my case.
i guess it might not apply to 1.8T...









im in Ontario,Canada. and E-testing requires all emissions systems to pass readiness.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (CorvetteKillerVr6)*

the resistors make the ECU think 1)the pump, 2)the SAI solenoid, and 3)the Intake changeover solenoid. is all there.
the o2 will then see that there is less air in the mix and throw a code for Improper flow from the SAI.









thus not passing emissions.
that improper flow code is the only code leftover on what seems to be most of the 1.8t's and vr6 mk4's with it removed


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (CorvetteKillerVr6)*

Oh you're worried about emissions. I'm not sure if there is a way around that. I just want to get the car running.
Only thing I could suggest is space out the second o2 sensor, thus giving a lower carbon amount than the first o2, tricking the ecu into thinking the cat is working


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Oh you're worried about emissions. I'm not sure if there is a way around that. I just want to get the car running.
Only thing I could suggest is space out the second o2 sensor, thus giving a lower carbon amount than the first o2, tricking the ecu into thinking the cat is working

yeah and i heard the spacers do sometimes work in that case.
i just got back from installing and trying more resistors.
i finally got the SAI Relay code to go away, cause i now found out the proper way to install the resistor after removing the relay under the hood.so the 330ohm worked for that one, but i cannot get the SAI Solenoid code to go away no matter what, either with the Solenoid plugged in OR with it unplugged and the resistor installed by itself.( or am i suppost to use the Resistor and the solenoid????)
the only odd part now is, even with the EVAP purge valve AND the EVAP leak detection pump all still plugged in. im getting EVAP short to ground, for both the purge valve and the leak detection pump.
and all night, i just checked every ground in the whole car, every fuse and relay under the dash, all the fuses in the box under the hood.
everything seems clean and good.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*


_Quote, originally posted by *GinsterMan98* »_Like I said, you loose primary O2 control with a deleted SAI on a MK4. MK3's you can delete both the rear o2 and the SAI without any issues. Unless they have changed it?


you might be right,
ive got everything fooled, except for the SAI solenoid valve, that code wont go away for that one no matter what, the pump relay and the others are gone(intake change over valve,pump relay,PCV)
but with that one SAI code, and the EPC light on for MAF signal too low, the car doesnt seem to be adapting AT ALL. 
VAG-COM mesuring block 032 it reads 0% in both colums....









and i really dont understand why that last Solenoid code wont go away, im going to try a different spare resistor, maybe i got one bad one.
And ive definatly got the two different Solenoids(Intake change over, and SAI) both differentiated. as well as the wiring colors all figured out with a bentley.
so im positive everything is plugged in right.



_Modified by CorvetteKillerVr6 at 1:28 AM 3-2-2010_


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (CorvetteKillerVr6)*

Sai isn't really that bad, It comes on at idle anyway. Just put it back on, what have you got too loose. http://****************.com/smile/emthup.gif The fact that both read 0 tells me you have no )2 control at this point = bad. You should defiantly see the idle adapt bouncing around 0 to 3 or so.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*


_Quote, originally posted by *GinsterMan98* »_Sai isn't really that bad, It comes on at idle anyway. Just put it back on, what have you got too loose. http://****************.com/smile/emthup.gif The fact that both read 0 tells me you have no )2 control at this point = bad. You should defiantly see the idle adapt bouncing around 0 to 3 or so.


but ive got the car thinking everything is there so far, the intake changeover valve code clear up with tyhe resistor as did the SAI Motor relay code with a resistor aswell..
just the SAI solenoid one wont go away.

and the 2 EVAP ones i really dont understand.....


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (CorvetteKillerVr6)*

anyone know why it would give me evap codes if the whole evap system is installed and intact?


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (CorvetteKillerVr6)*

Bad gas cap maybe?


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (GinsterMan98)*


_Quote, originally posted by *GinsterMan98* »_Bad gas cap maybe?

someone else mentioned that, and i tried to tighten it, to no result.
still have both evap codes....
other than that, i AM actualy making progress.
got rid of the SAI relay code and Intake changeover valve code so far..
still working on the MAF related code, and the SAI solenoid...
for some reason the resistor OR the solenoid being plugged in isnt working on the SAI solenoid..


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (CorvetteKillerVr6)*

Very nice. So I have a question for you Corvette, where did you get the post-intercooler piping for the SRI?
Just plug your solenoid in, seemed to work for me. Let's hope when my o2 gets in that'll fix everything


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Very nice. So I have a question for you Corvette, where did you get the post-intercooler piping for the SRI?
Just plug your solenoid in, seemed to work for me. Let's hope when my o2 gets in that'll fix everything 

my I/C plumbing is 2.5" on the hot side( turbo to i/c inlet) and 3"coldside(i/c outlet to throttle body).


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (CorvetteKillerVr6)*

i think its actualy a generic Ebay type 3" intake pipe kit i bought,


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## Tom FTW (Feb 22, 2010)

*FV-QR*

And it matched up to the SRI that well? With no modification? Very cool. I'm running kinetic IC and piping and I'm trying to figure out a way to modify the post-IC piping to make it to the SRI


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*

yeah it worked out really well.
ill get some pics of the post i/c setup with the bumper off for u


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Awesome dude thanks. I just got a Schimmel short runner (i know.. no runner compensation), and I am hesitant about putting it on because I'll have to fab I/C piping.


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## GinsterMan98 (May 19, 2008)

*Re: FV-QR (Tom FTW)*

If you have a MK4 the runner compensation is in the cams, not the manifold. Mk3's have the runner compensation manifold. http://****************.com/smile/emthup.gif If you switch cams from stock then you may loose the compensation, but you would have to ask the cam manufacturer to be sure. I know that DSR FI cams do not have runner compensation. http://****************.com/smile/emthup.gif


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Interesting.. I thought it was the other way around. Just looking at a stock MKIV intake mani looks like it has runner compensation. I've seen a pic of a busted open one and it has extra plastic on the inside of every other runner.
So I tried to start up the car today to take a quick video of the wideband and audio of the engine to show exactly how intense the difference is after 30sec-1min and I realized my battery was dead.








Looks like I'm just going to wait until the o2 sensor gets here and I'll jump it. If the problem persists, I'll take the video and get it up here.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Interesting.. I thought it was the other way around. Just looking at a stock MKIV intake mani looks like it has runner compensation. I've seen a pic of a busted open one and it has extra plastic on the inside of every other runner.
So I tried to start up the car today to take a quick video of the wideband and audio of the engine to show exactly how intense the difference is after 30sec-1min and I realized my battery was dead.








Looks like I'm just going to wait until the o2 sensor gets here and I'll jump it. If the problem persists, I'll take the video and get it up here.

yeah mk4 compensation is in the cams.
ive seen a ton of guys go with stock type mk4 cams (autotech 262's is what i run in my mk4 )in a mk3 vr6 running SRI.
seems to work out
keep us posted about your o2 http://****************.com/smile/emthup.gif 
and sorry, im still working on those I/c pics...


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## vw_owner (Dec 19, 2008)

*Re: FV-QR (CorvetteKillerVr6)*

this all seems very interesting. tricking the SAI connector with the proper OHM resistor would typically do the trick, which leads me to believe that something else is going on. its an obvious air flow problem, but what? people can say TPS, MAF, and what have you, but everything needs to be checked before diagnosis. a friend of mine was running a MK4 1.8T with 30R and was running like crap, so we gave it a scan, cleared everything, then it ran like a champ, thats just typical VW ECU's for ya. i have scanned, diagnosed, and fixed who knows how many VW's and they always lead to something pretty stupid. another 1.8T running some big a$$ turbo was going into limp mode just after first getting into boost, so we scanned it, found a throttle problem, put in a new TB, and she ran like a champ. cleared the codes and we were off. from the sounds of this, it is going to be something small and simple, but that little thing can ruin everything in the end, so take your time, check everything, and when your done checking, check again


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (vw_owner)*


_Quote, originally posted by *vw_owner* »_this all seems very interesting. tricking the SAI connector with the proper OHM resistor would typically do the trick, which leads me to believe that something else is going on. its an obvious air flow problem, but what? people can say TPS, MAF, and what have you, but everything needs to be checked before diagnosis. a friend of mine was running a MK4 1.8T with 30R and was running like crap, so we gave it a scan, cleared everything, then it ran like a champ, thats just typical VW ECU's for ya. i have scanned, diagnosed, and fixed who knows how many VW's and they always lead to something pretty stupid. another 1.8T running some big a$$ turbo was going into limp mode just after first getting into boost, so we scanned it, found a throttle problem, put in a new TB, and she ran like a champ. cleared the codes and we were off. from the sounds of this, it is going to be something small and simple, but that little thing can ruin everything in the end, so take your time, check everything, and when your done checking, check again


checked, and checked, and checked.
im well beyond just "checking" the setup over at this point.
i have a year into building this entire thing, and i know exactly whats where.
I am 100% sure its a bad MAF sensor or tune related.
i will know today when i get the maf.
http://****************.com/smile/emthup.gif


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (CorvetteKillerVr6)*

Funny thing is, with the EPC light on for the "MAF signal too low" code, and these two evap codes.
i am seeing no adaptation in Block 032 at all.
annnddd my MAF g/s, is constantly reading 0...................








i just noticed this the most recent time i plugged in vagcom to log it at idle.
before it was always reading like 5- 9 g/s....
and gave me the maf too low code,and now it wont read anything at all...
and the wiring is all perfect and resistance free..


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Very strange... Did you get your new MAF in?
"before" being how long ago? Has it ever adapted with the Unitronic software? If it's not reading anything at all and not even throwing a code, then I don't know. Is Unitronic a standalone or a flash? Sorry dunno much about them.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Very strange... Did you get your new MAF in?
"before" being how long ago? Has it ever adapted with the Unitronic software? If it's not reading anything at all and not even throwing a code, then I don't know. Is Unitronic a standalone or a flash? Sorry dunno much about them.

there a 440cc flash tune, and no i havent tried it yet, i receive it today hopefully.
ill post later today with an anwser. http://****************.com/smile/emthup.gif 
wish me luck


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## Tom FTW (Feb 22, 2010)

*FV-QR*

Good luck bud http://****************.com/smile/emthup.gif
You deserve it.
Make sure it's not in backwards. I know it sounds stupid but it's a pretty easy mistake to make if you've cut the harness to make it longer for the SRI.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*

thanks man, ive had enough of Unitronic.
and here's the result of tonights work,a brand new maf Sensor not curing my EPC light MAF related code.

http://forums.vwvortex.com/zerothread?id=4790533


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## Tom FTW (Feb 22, 2010)

*Re: FV-QR (CorvetteKillerVr6)*

Amazing news!
Got the new o2 in and it seems to be running fine. At idle its from about 14-15 afr and I've been babying it, so no WOT yet.
When I first started it up, I heard some tick (possibly timing chain), but after the car warmed up it went away.
I'm going to drive it for a couple days and then get it scanned again.
Fingers crossed that it keeps working.


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## CorvetteKillerVr6 (May 9, 2007)

*Re: FV-QR (Tom FTW)*


_Quote, originally posted by *Tom FTW* »_Amazing news!
Got the new o2 in and it seems to be running fine. At idle its from about 14-15 afr and I've been babying it, so no WOT yet.
When I first started it up, I heard some tick (possibly timing chain), but after the car warmed up it went away.
I'm going to drive it for a couple days and then get it scanned again.
Fingers crossed that it keeps working.

awesome dude!!
i seem to have found my wiring problem too!
but i still have the MAF sginal too low code :-(


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