JStrib

iTrader: (6)

I searched and found Fendamonkey's thread about it, but my situation may or may not be different. I'm just wanting to get a more solid opinion on it.

Here's the basic rundown on my car.

Engine
-Aggressive street port and 3mm apex seals
-Ported upper intake manifold
-GReddy elbow, SMIC, and intakes
-'99 Y-Pipe and Crossover
-Non-sequential stock turbos with a ported wastegate set at 15psi
-3in exhaust from the DP back, with an oldschool GReddy cat back.
-HKS TwinFire ignition with trail plugs all around
-3bar GM MAP sensor

Fuel
-Walbro 255 pump with constant 12v wiring
-850/1680 injectors
-Aeromotive FPR

Electronics
-APexi PFC
-Innovative LC-1 wideband

Okay. The build was finished this past December and had an issue with the factory wiring harness. Changed that out, re tuned the car, and the shop claims it ran great. I believe them. I get my car back and have ignition breakup at high rpms, but this was before the twin power. Installed a twin power and it was a little better, but quickly went back downhill. My AFRs in boost were anywhere from 9.6-10.0. Garbage. So I took it back for a retune. We street tuned it and it ran great that day! Solid 15psi running up to 8500rpm. 11.5 AFRs. It felt really solid. I make the drive home (2 and a half hours) and bam. I've got breakup again THAT NIGHT! Car won't rev to 8000 with a load, and even breaks up during part throttle. It's really aggravating. Now my car is back to running 9.8-10.3AFRs and I'm worried about getting a dyno tune. i don't want to pay 600 for a tune that's going to "forget" on the way home.

Any ideas and/or advice?

Also, I don't know if this has anything to do with it, but my odometer has been going in and out intermittently since I picked the car up with the new wiring harness in late January...

PS. It's so rich that it only went 110 in the quarter on this set up. My buddy's car went 117 on a Pettit unlimited...

arghx

iTrader: (3)

there's something else going on here. Maybe these guys don't know how to tune the air temp fuel correction map. Maybe your air temperature sensor is messed up. You can tell if the PFC is holding the tune or not by comparing the map loaded into it now and the one the shop has saved on its computer. You need a Datalogit to do that. It's highly likely that either a mechanical problem has developed or the air temp has changed and the tune can't account for it.

For example, I have built a custom IAT correction curve for my car. I use the Triumph open element "dudemaan" sensor, located in the TB elbow near the manifold. Here is a comparison:



my AFR fluctuates about .2:1 through the seasons, so at high boost it'll be anywhere from 10.9:1 to 11.1:1

JStrib

iTrader: (6)

What mechanical problem development would you expect to be suspect?

Thanks,
Jim

arghx

iTrader: (3)

boost leak. i'd get the fighter's garage tester

fabiano

don`t map around problems ;-)
boost leak? fault map sensor?