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Full rich A/F while under boost. Help!!

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quiksilver20004

quiksilver20004

10+ Year Contributor
115
1
Apr 6, 2009
Cincinnati, Ohio
Ok i have a 95 Talon TSI AWD that i 6Bolt swapped. Car runs great with no issues other than the fact that when i hit full boost (15psi) my A/F reads completely rich.
Yes I know you are going to say that it is a boost leak but i assure you that it is not. I work for Infiniti so i hooked a pressurized smoke machine up to my turbo and checked all my connections. It came back with two small leaks which i fixed. Even after fixing these it is still hitting full rich under boost. Yes i have my BOV recirculated and no it is not leaking.

I am running stock 450 injectors and a SAFC tuner which is tuned just a little lean.

I need some ideas other than an ECU tune due to the fact that i dont have hardly any money at the moment. Anything you can think of i will look into
 
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This test was at more than 5 psi but i will do a more thorough leak down lest on it tomorrow if i can find the right tools in the shop to do so. It is hard to diagnose stuff like this when the shop is not equipped to work on turboed cars
 
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quiksilver20004 said:
This test was at more than 5 psi but i will do a more thorough leak down lest on it tomorrow if i can find the right tools in the shop to do so. It is hard to diagnose stuff like this when the shop is not equipped to work on turboed cars
Click to expand...


If you are running 15 psi, you need to test it at 20 psi. That additional 5 psi provides a bit of safety margin. :)

All you need is a boost leak tester made from $5-$10 worth of Home Depot parts, and an air compressor with a halfway decent pressure gauge.

Just for clarity... it's a boost leak test (BLT)... not a leak-down test. They are totally separate animals.
 
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most smoke testers are regulated to .5 psi, so thats not gonna help you very much at all. it would be good to know the a/f numbers that youre seeing. on my stock turbo and fuel map, my aem wideband wouldnt even read because it was so rich. the stock map runs very very fat, so if you dont find any boost leak problems, i would just write it off to being stock and tune it a little leaner.
 
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No a wide band is my next purchase. Its just odd though cause i had this motor in a 91 with eprom ecu 550 injectors 225 pump big 16g 20lbs and a SAFC and when i hit full boost it would read right in stoich. Yeah optimal A/F mix is 14:1 Im just gonna cal it a wash untill i get my wideband my 550's and pump back in and a chip for my ECU. I think it may also be running very rich due to the fact that a 7bolt has higher compression and higher fuel pressure than a 6bolt so the ecu is adding the fuel that it would for the stock motor
 
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quiksilver20004 said:
No a wide band is my next purchase. Its just odd though cause i had this motor in a 91 with eprom ecu 550 injectors 225 pump big 16g 20lbs and a SAFC and when i hit full boost it would read right in stoich. Yeah optimal A/F mix is 14:1 Im just gonna cal it a wash untill i get my wideband my 550's and pump back in and a chip for my ECU. I think it may also be running very rich due to the fact that a 7bolt has higher compression and higher fuel pressure than a 6bolt so the ecu is adding the fuel that it would for the stock motor
Click to expand...

It should not have been at stoich especially on that much boost. A pretty decent tune on that same setup, would show around 11.0:1 under WOT.
 
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quiksilver20004 said:
550 injectors 225 pump big 16g 20lbs and a SAFC and when i hit full boost it would read right in stoich. Yeah optimal A/F mix is 14:1
Click to expand...

It probably was at stoich, which is roughly 14.7:1, not 14.1:1. The problem is, that is only optimal during closed loop. At WOT, you should be much richer than that...normally around 10.5:1 or 11:1 on a good tune. With that setup ^^^ you mentioned, you were probably way leaner than that which = not good.

You need to do a real boost test, and find a way to log actual AFR's or airflow and injector duty cycles. Toss the blinky narrowband light show and get a wideband. ;)
 
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Holy shit! Quick, tune it so it's stoich WOT, make sure to detonate the #### out of it and burn your pistons up.

BlackMount said:
Forced induction engines run on the rich side by nature.
Click to expand...

Fixed


It's great you're an infinity mechanic, apparently you're clueless when it comes to tuning and performance though. 10-11.5:1 A/F is about safe for any forced induction engine running a fair amount of boost. Any leaner and you risk detonation.

EVEN if it were a N/A motor you'd still want to see A/Fs in the high 12s to mid 13s for optimal combustion.
Welcome to internal combustion engines :|
 
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Plenty of N\A motors run rich by nature. mainly imports.


My N\T DSM always ran on the rich side. and so has all the other imports i've owned
 
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