rb25det runs rich wont idle

[yanay]

I have gone through everything here trying to figure this out.
Car runs awesome after cold starts until it warms up (idles great etc)
When warmed up it shows multiple issues..
Doesnt want to idle.. ( i can sit in nuetral and rev it to 2000 rpm and when i let go it drops to 100-200 rpm and bounces up and down than blows a cloud of black smoke out after a couple seconds and idles regular again. it happens everytime i come to a stop at the lights when the car is warm wideband reads 9.8)
while driving i have a 13.6 -14.5 while cold but as soon as warm if im in 4th gear holding steady at 2000rpm or so it will sputter and jerk a bit as i watch the wideband slowly drop from 13.9 down to 10.1
I have pulled off the iacv and cleaned it with no change.
Tps is set at .45 when throttle closed and 4.1 when WOT.
Setup is a precision 5252e on a rb25det s2 with fmic screamer pipe external wastegate, exhaust, adjustable fpr Set to stock psi at idle, walbro 255lph, running 7psi new plugs gapped properly

[Skym]

My guess is o2 sensor was probably fouled due to engine running rich due to bigger lph fuelpump?

But if dropped fuelpressure, engine is probably running lean under boost. Also not hardwiring fuelpump adds to the lean problem.

[yanay]

i could not imagine the 02 sensor causing such a mess.. i am waiting on a new one.. other than that is there something else i could look into that may cause such a issue?

[Skym]

From what I understand, R33 TPS relies on idle voltage trigger (software) on ECU side (no idle contact inside TPS). If not set exactly on that voltage trigger, ECU probably won't kick rpm up.

But I think lack of fuel, knock could be the problem that ECU (knock), o2 sensor (engine going too lean, o2 sensor makes ECU hit run rich voltage trigger and engine runs rich) is reacting to. But o2 sensor could have fouled due to this.

[yanay]

So what should I replace?

[Skym]

Replace o2 sensor, hardwire fuelpump, adjust fuelpressure upwards (need more fuel rail pressure when engine is under boost to overcome boost pressure in intake manifold and not hardwiring fuelpump can be the cause of low fuel rail pressure or leaking fuel hose) and see if it disappears. If it doesn't check TPS and then check again. You should only take fuel out via ECU, not via fuelpressure regulator.

Then ECU probably needs a retune (cheapest way is to fit Nistune modified Z32 ECU Z32 MAF, Z32 MAF plug + retune) to solve running rich problem.

[yanay]

ok, i have never had low fuel pressure or leaning out under boost.. during boost it generally sits around 11.6 @ WOT

[Skym]

I would think it should be running into 10's at WOT to be safe at lower rpm with A/F ratio. It can lean out at lower rpm (when reaches peak boost) and have A/F ratio you have mentioned at WOT with stock ECU tune.

[yanay]

i have never seen the wideband get even close to leaning out while driving.. :S doesnt make sense

[yanay]

swapped out maf iavc and tps tonight with ones from a different motor and zero change i still can't get the tps to read properly at WOT

[Skym]

Would be hard to monitor it while driving. Need a dyno to run a A/F plot to see if it is running lean at lower rpm and see if ECU is dropping engine torque (ECU pulling ignition timing) due to detecting knock.

[yanay]

hmm i wish i lived somewhere remotely close to a dyno.. anything else i could check before towing it 650 kms

[markdett]

All the symptoms your describing sounds like an AFM issue.

I know you have swapped one out of a known good vehilce's, but have you checked the wiring?

Give the wiring to the AFM a wiggle and see if it replicates the symptom? Have had a few top mount turbo's melt the wiring around the strut tower, Give off much the same result (thats if you havent re-routed your wiring and are running top mount).

Usually a dead 02 sensor would give **** fuel consumption, wouldnt really cause problems to this extent.

[Skym]

Faulty o2 sensor (lazy) can make engine run rich, make rpm go up and down (usually at idle). MAF, MAF wiring could be the other, but assumed it was running ok. Also intake airleaks can cause idle to drop below idle rpm.

[yanay]

Issue still here. Tried 3 afms and a new o2. I notice when the motor is warming up I have good afr and a high idle ( rarely drops below 1100 rpm when cold) but as soon as its warm and I'm driving it creeps down from 14.5 to 10 and starts bogging until I rev it a bit it cleans up for a minute. Any ideas??