More boost=lower air fuel ratios???

[dubgunit]

I just got back from street tuning my car and l was trying to get my a/f ratios perfect. l have a 50 trim kit on STOCK fuel system and everytime l turned the boost up, the a/f ratio would go down lower and lower.

Here's a breakdown of my boost against the a/f ratios. All the pulls were in 3rd gear.

13psi-11.9(lowest),12.01(highest)
14psi-11.6(l),11.9(h)
15psi-11.3(l),11.6(h)
16psi-10.9(l),11.3(h)

Also, when l hit full boost, it holds and then starts falling down like the stock turbo. I thought big turbos didn't drop like that. Could it be a boostleak?

Mods

50 trim .63 AR
TurboXS MBC
Safc II w/ tach adapter
NGK Wideband

[Gmanigio]

no....... I hope you didnt mess up your car already. 16psi on stock fuel is crazy, thats pushing the limits of st2 injectors, imagine stock

[dubgunit]

That's the crazy thing about it, l'm on stock 05 injectors. I talked to fullybuiltchris and he was stumped by this too. I'm sure there's a reasonable explaination for it.

[apoczen211]

Do it right and get the bigger injectors all the supporting mods. Do you have a internal or external wga? externals dont spike from what ive learned from a friend that had a dsm. and internals do.

[dubgunit]

Quote: Originally Posted by apoczen211

Do it right and get the bigger injectors all the supporting mods. Do you have a internal or external wga? externals dont spike from what ive learned from a friend that had a dsm. and internals do.

I know what l need to do it right, but l just don't have the funds right now to get the bigger injectors, so l'm tuning what l have. I have an external wastegate like all other 50 trims for our cars do and l thought they didn't spike either.

[ryman546]

if his ratio is getting lower then why would he need bigger injectors....was the wideband or whatever u happened to use working properly.

[dubgunit]

The a/f ratios are not suppose to be going down, they should be going up. 13-14 psi should be maxing out my stock fuel system. I tested the wideband and it's working properly, l'm pretty stump on this problem.

[fixit]

first guess, pulling timing? pinging?
second guess, map clamp - try .1v lower (something like 4.1v)

[dubgunit]

Quote: Originally Posted by fixit

first guess, pulling timing? pinging?
second guess, map clamp - try .1v lower (something like 4.1v)

Timing! That's what l was thinking. The car must be pulling timing and adding more fuel to compensate for the higher boost, that's why it keeps getting richer as the boost rises. Why does the boost drop after l hit full boost?

[fixit]

next i would check the plugs, gap .035, and verifying not pulling timing (odb2)
if everything is okay then the safc needs to be tuned...

with your setup i would have guessed 20lbs+, with afr approaching 12 (maybe high 11's)

btw.. even if you have a boost leak, it doesn't matter since you supplying enough air 16+lbs

[moltenice]

I was just out testing my S2 WGA and I had similiar results....

When I would get on it in DAB 2-3 i would spike 17PSi with a AFR of about 10.0
In DAB 0-1 I would get on it and it would spike at like 12psi and run like crap throwing a AFR of 12.1

Shit is pissing me off... seems totally back asswards

[fixit]

crap gas?

[dubgunit]

Quote: Originally Posted by fixit

crap gas?

You know what, l did put 91 oct in and l almost always use 93. I got some new plugs that l haven't put in yet also.

[moltenice]

for me it's same ol 91

[projectNEON]

With a big turbo kit and using the LM-1 tuning in 3rd gear I can boost 18 psi safely around 11:7 AFR. I now Have my cooling mist single stage running now too. But figured I will wait to up the boost too much still until I get the rest of my fuel set up in. I also have an 05. BTW you have a boost leak. While doing my w/i install found a 1" cut in my lower hump coupler. Now that was fixed I can hold 18-19 psi all day and still in safe AFR with just MOPAR stage 2 injectors. Hope that helps