# VR6T rich at idle, lean under boost. C2/42lb/8.5-1/t04e



## WheelHor (Apr 30, 2010)

*Edit: It was frayed MAF wiring, now it runs like a champ :beer: *


Backstory- picked up this car about a week ago, and have been trying to fix everything.

VR6 12v
C2 stage 2 programming
42lb green tops
8.5-1 je pistons
t04e
fmic
4" maf housing, MAF just replaced and working
tial 38mm
3bar fpr

Ordered and installed an AEM wideband, read approximately as this:

idle 10 a/f, could actually be lower, i think that's when the gauge starts...
3psi 11
5psi 12.8
6psi 13.4
7psi 14 
and i immediately stopped driving under boost.

Fuel is reading between 40-50psi, I was told by C2 that an inline pump wasn't needed until you go over 10psi. I am glad that I waited to start driving this car hard until I had the wideband in. 
Any ideas? Without building the car, it is tough trying to wade through the previous owners mistakes. Thanks everyone


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## dub_slug (May 12, 2008)

Your best bet with that car would be to get a new engine and bay wiring harness'. It's got to be electrical issues.


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## vergessen wir es (May 12, 2010)

Would be nice to know your fuel pressure over a range of boost.
Also double check you vac/boost ref signal to FPR.
No ref signal = more fuel at idle and less fuel under sboost.


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## WheelHor (Apr 30, 2010)

Ok sounds good. The hose used at the FPR (which is tapped for the boost gauge) is pretty thin and flimsy. I'm thinking of replacing it with some good quality silicon


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## d15nonvtec (Dec 19, 2006)

isnt C2's stage 2 for 36# injectors?


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## TBT-Syncro (Apr 28, 2001)

fuel pressure should be around 38psi at idle
43 psi at 0 vac
and 1psi higher than that for every pound of boost

have you tried re-aligning the throttle body?


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## dub_slug (May 12, 2008)

WheelHor said:


> Ok sounds good. The hose used at the FPR (which is tapped for the boost gauge) is pretty thin and flimsy. I'm thinking of replacing it with some good quality silicon


You should run a direct line from the intake manifold to the fpr. And if you follow the brake booster line back towards the firewall you'll find a nipple that probably isn't being used...just cut off the little green cap and your good to go for vac/boost gauge signal :thumbup: The one I use for the bov is located just behind the throttle body on the pass side, usually used for the evap. Doing it that way helps un-clutter things a bit :thumbup: does he still have the dual bov's on there?? :laugh: I thought that was the funniest sh!t ever the first time I saw it lol!!
That jetta's got a good heart, get the issues worked out and you'll have a decent vrt on your hands. Chris did the chains and **** too so your proly still good for another 75-100k miles  gotta love them vr6's!


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## BARELY LEGAL (Jul 2, 2009)

Adjust your fuel pressure up to 4 bar (about 55-60psi) off vacuum. VR6's need fuel pressure. I was running lean under boost before I did that and now I am good. I also have an inline walbro pump and am running 16psi now. Hope that helps.


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## V-dubbulyuh (Nov 13, 2005)

d15nonvtec said:


> isnt C2's stage 2 for 36# injectors?


He is running Green Tops, ie safe to assume he is OBD2 hence stg 2 OBD is 42lb (completely different from what C2 markets for the OBD1 platform). His software is correctly matched to his injector set.

BTW, stock fuel pressure (3 bar) is adequate in his car especially at the low boost numbers that he is running. This setup should not require any fuel "tweaking" as he is within the limitations of the software and hardware.


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## WheelHor (Apr 30, 2010)

V-dubbulyuh said:


> He is running Green Tops, ie safe to assume he is OBD2 hence stg 2 OBD is 42lb (completely different from what C2 markets for the OBD1 platform). His software is correctly matched to his injector set.
> 
> BTW, stock fuel pressure (3 bar) is adequate in his car especially at the low boost numbers that he is running. This setup should not require any fuel "tweaking" as he is within the limitations of the software and hardware.




Exactly. 

Thats why I'm wondering why it is going on...


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## TBT-Syncro (Apr 28, 2001)

BARELY LEGAL said:


> Adjust your fuel pressure up to 4 bar (about 55-60psi) off vacuum. VR6's need fuel pressure. I was running lean under boost before I did that and now I am good. I also have an inline walbro pump and am running 16psi now. Hope that helps.


wrong.

3 bar.


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## dub_slug (May 12, 2008)

Found these in my bucket, look familiar?


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## V-dubbulyuh (Nov 13, 2005)

WheelHor said:


> Exactly.
> 
> Thats why I'm wondering why it is going on...



You scan the car at all to see if there might be any codes?


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## WheelHor (Apr 30, 2010)

Changed out the vacuum line
now running one line (not spliced) from the intake manifold to the fpr

Did not change anything


Could the wideband be reading incorrectly?


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## Love2Spool (Sep 10, 2010)

could be the wideband reading incorrectly but not likely. if you want to rule that out plug in one of those autozone scantools and check the fuel trims at idle. if its sitting at anywhere above -5% to -9% then you know its running rich


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## slcturbo (Apr 19, 2010)

That rich at idle? Does it smell rich? 

How old is that O2 and coolant temp sensor?

As for under boost I have to say my 42# tune does run leaner than I would expect at lower boost. It'll go 13's all day especially at torque peak ~4k rpm. 20psi at the track and it stays 12's.

Not worrying about it. The car isn't blowing up at 10psi in the 13's or even 14's.


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## BARELY LEGAL (Jul 2, 2009)

V-dubbulyuh said:


> He is running Green Tops, ie safe to assume he is OBD2 hence stg 2 OBD is 42lb (completely different from what C2 markets for the OBD1 platform). His software is correctly matched to his injector set.
> 
> BTW, stock fuel pressure (3 bar) is adequate in his car especially at the low boost numbers that he is running. This setup should not require any fuel "tweaking" as he is within the limitations of the software and hardware.





TBT-Syncro said:


> wrong.
> 
> 3 bar.


Check your Bentley, it's 4 bar. No wait I'll check it for you...


That looks like 4bar to me. 

Let's check another shall we...
http://en.wikipedia.org/wiki/VR6_engine


No you guys can keep running 3 bar, I'll run the STOCK fuel pressure and I bet mine runs better. 
:banghead:


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## TBT-Syncro (Apr 28, 2001)

BARELY LEGAL said:


> Check your Bentley, it's 4 bar. No wait I'll check it for you...
> 
> 
> That looks like 4bar to me.
> ...


as been stated already, he is obd2

obd1 was 4 bar, obd2 is 3 bar 

your car is also obd1.


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## slcturbo (Apr 19, 2010)

Not the cocky/confident scan the manual - remove foot from mouth move

I hate when that happens:facepalm:


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## .LSinLV. (Nov 13, 2009)

TBT-Syncro said:


> as been stated already, he is obd2
> 
> obd1 was 4 bar, obd2 is 3 bar
> 
> your car is also obd1.


correct , stock:

AAA is 4 bar
AFP is 3 bar


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## WheelHor (Apr 30, 2010)

My Fuel pressure gauge is reading between 40-45, so that seems about right.

I'm going to take it out today and see what the numbers get to over 7psi... I'll be back, hopefully the motor will still be going too


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## BARELY LEGAL (Jul 2, 2009)

I forget how goofy you OBD2 guys cars are sometimes, my bad. 

Wouldn't a 4bar FPR be an upgrade for an OBD2 MK3 or MK4 VR6? Just a thought, since there isn't mechanically too much different with the engines.


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## .LSinLV. (Nov 13, 2009)

BARELY LEGAL said:


> I forget how goofy you OBD2 guys cars are sometimes, my bad.
> 
> Wouldn't a 4bar FPR be an upgrade for an OBD2 MK3 or MK4 VR6? Just a thought, since there isn't mechanically too much different with the engines.


all other things being equal; an injector will flow MORE fuel at a higher pressure for a given cycle.

I'm not sure what you mean about "upgrade".


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## BLSport (Dec 24, 2005)

.LSinLV. said:


> correct , stock:
> 
> AAA is 4 bar
> AFP is 3 bar


Correction; AAA fuel pressure changed along with change from OBDI to OBDII:
AAA 92-95 is 4 bar
AAA 96-99 is 3 bar


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## vwturbofox (Jul 31, 2010)

if you dont think the wideband is reading correctly pull a sparkplug out and check it idle at 10 the sparkplugs will be super black/smell like gas bad easy check.


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## slcturbo (Apr 19, 2010)

vwturbofox said:


> if you dont think the wideband is reading correctly pull a sparkplug out and check it idle at 10 the sparkplugs will be super black/smell like gas bad easy check.


Exactly, if the car is really idling at 10:1 you should be able to see and/or smell it.


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## WheelHor (Apr 30, 2010)

Yup it is quite rich indeed


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## slcturbo (Apr 19, 2010)

If your car is idling at 10:1 and it didn't before you have a bad O2 signal (sensor/wiring) or a bad MAF. That's if fuel pressure is good. 

Unless you have a stuck open/faulty injector.

Is the car heating up properly?


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## .LSinLV. (Nov 13, 2009)

BLSport said:


> Correction; AAA fuel pressure changed along with change from OBDI to OBDII:
> AAA 92-95 is 4 bar
> AAA 96-99 is 3 bar


good info, thanks. :thumbup:


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## WheelHor (Apr 30, 2010)

Took it for a drive today... 

At idle, it fluctuated between super lean and super rich. 10-1 then to 17-1 and back and forth 

Driving, went to 16 and 17-1 AFR under some boost, tried it once and then went home not getting under boost. 


hummmmm


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## SpOoOling1.8T (Dec 12, 2004)

what about your fuel pump? going out slowely or maybe u gotta clean the sock on the fuel pump


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