Running Rich as Hell Under Full Boost HELP!!

[BrianV8]

Hey guys, so need help figuring out this running rich problem i'm having.

Car is running a little rough on idle and full boost its gone from running its usual 11.5:1 to pinning my wideband at 10:1

I thought it was a boost leak, found no leaks up to 24 psi.
I then determined a MAF, so i replaced it with a new rebuilt one got 10.2 to display on the wideband.

I honestly don't know where to go from here. Fuel pressure is 38psi, never changed. I"m completely stumped?

Any ideas?

Thanks Brian

[collector240sx]

Hum,

Which wideband do you have ?

How is the boost controlled ?

What ECU do you have ( If stock do you have a piggyback system, if aftermarket which one) ?

What your ratio at idle, partial throttle ?

What kind of injectors are you running ?

Any chance you might have a sticking injector ?

[BrianV8]

Hum,

Which wideband do you have ?

How is the boost controlled ?

What ECU do you have ( If stock do you have a piggyback system, if aftermarket which one) ?

What your ratio at idle, partial throttle ?

What kind of injectors are you running ?

Any chance you might have a sticking injector ?

AEM wideband, o2 sensor died on me read rich before it died completely new sensor reading exactly the same all around. It was compared to a innovative wideband both were exactly the same.

Boost controlled via HKS EVC-S

RB20 chipped ecu.

AFR neutral and driving oscillating around the 14.7 area due to O2 sensor

RC racing 550cc, never had a problem.

I would imagine an injector problem would effect things all over the rpm range not just under boost??

[Skym]

If stock ECU, could be knocks maps. Faulty coilpacks, anything knocking against engine or makes excessive noise near knock sensors, engine knocking.

[nelsonmxmarc]

hmm.. what have you been doing lately, Brian? Track events or have you been driving the car the same over the span of the season?

I'm going to say TPS. What's your idle RPM? Sometimes the TPS loosens off or the tb plate sticks so check both voltage and the tb to make sure they're still in top shape.

I know the IACV is useless after warmup - but does the AACV solenoid have an influence on idle? Could be dirty..


*Not knock maps - knock maps are <11 across the board for 'real' values. So under power you'd be pushing <11 theoretically. When my car ran on knock maps its saw a pretty consistent 10 flat on the wideband no matter what RPM.

[nelsonmxmarc]

O2 is a good place to check if its still in operation. Normally chips/nistune tuners will cut the o2 out and use the raw data values from the AFR tables they tune, meaning they do this with a wideband on a dyno, and the values written on the tables will always be the values drawn from on the ECU, and not from the O2.

If you're running an O2, there are two loops - Open and closed. Under idle and lower RPM, the O2 is running on Closed loop circuit, meaning it relays info to the ECU and works to mate a target AFR. When the O2 is in Open loop, it runs off the tables on the ECU and lies dormant.

Could be that your O2 is fudged..

[BrianV8]

ya its not hitting a knock map, way i have my knock map tuned the car would go stupid rich and fall flat on its face from 20 degrees less timing

[Black BNR32]

o2 can't be fudged...its running good afrs in closed loop.

have you cleaned the mafs? check their wiring too.

[BrianV8]

its a top end problem for sure, over 10psi she starts getting really rich really fast. So i that rules out the o2

I figured maf right off the bat once boost leak tested good. Bought a rebuilt one and it read exactly the same as mine so thats ruled out also

[BrianV8]

like with absolutely everything testing good i'm wondering if i should risk it and try pulling the fuel back via tuning?

[Skym]

I see.

Ok. If not knock maps, then it could be the way injectors are setup or fuel map.

From my experience with faulty 02 sensor it throws flames from exhaust (popping sound from exhaust on decel at mid to low revs).

[BrianV8]

injectors are setup just like a gtr. Resistor pack whole 9 yards. No more popping or anything out the exhaust than normal. Besides running rich under boost it runs perfectly normal

[Skym]

I see.

Ok. I remember someone mentioning (might have misread it) on Nistune forum that playing with injector settings on ECU can shift the richness to topend or bottomend. When you mentioned rich at topend, fuel map or those settings came to mind.

[BrianV8]

hmm no don't think thats the problem, tune has always worked fine, i've gone through and checked resistances etc on all my sensors, don't know why it changed, nothing seems to be wrong, wondering if i should go and see if i can work it out with the tune. Really don't want to knowing it ran perfect before but i don't see any options.

[BrianV8]

well still have not solved this problem, the major over fueling seems to be over 3500rpm. Getting really frustrating, i even swapped my ecu coolant sensor today with no luck. Hate to give up and try tuning it out. Something must have happened if it ran perfectly before.

Any suggestions would be great

Thanks Brain