Turbo 3800 CRAZY rich at idle

[1fastkingcab]

Hello, I'm not sure if I have a mechanical issue like a vacuum leak or exhaust leak, if I have a problem in my tune or if my injectors are just plain flat to big. My problem is a VERY rich idle.

I got a mail order tune from a very popular vendor, I'm not sure which direction to go right now, the last thing I want to do is pay$400 to strap the car down on the dyno and have them say I have a mechanical issue and come back after I fix it. The car IS going to go on the dyno before I really drive it, I would just like to think I could get the car to idle before I waste any dyno time.

the car was prevously running just fine as a 3800 L67 supercharged Fiero, my problem has arisen since swapping the Eaton blower out for a turbo.

about the car:
1986 Pontiac Fiero
100% Stock 1998 L67 / 4t65e-HD trans (1998 Grand prix GTP)
Empty supercharger housing W/ ZZP block-off plate
80lb Seimens Deka IV injetcors
Holset HX-40 Turbo
EzPerformance Mini-AFC @ 82%
Frozen Boost water-to-air Intercooler
dual aeromotive 340LPH in tank pumps
Pump gas for now


I really just need to know if the tune is just crazy rich since it's a mail order base tune, or If I should be looking for a mechanical issue, 2 whole cans of carb cleaner hasn't exposed a vacuum leak, My STFT's and LTFT's are about 16~20% to the positive, I have tried running only in Open loop and I have tried using a stock Regal GS .hpt file from the repository with only the "Injector vs kpa" table adjusted for the 80lb injectors and no Mini-AFC.

I did not post a log file because I'm not quite sure what to log. I've googgled a bunch but It seems like a lot of recommendations are based on LS1's and aren't available to log on the 3800

Thanks,
Tom D

[Kyne]

I haven't looked at the tune yet, but your fuel trims are +16-20? What happened in open loop and how do you know it's rich? +16-20 fuel trims means the O2 is telling the car it's lean and to add fuel.

[1fastkingcab]

I have a Inovate LC-1 and gauge. I thought that a + fuel trim was adding to the desired AFR which would be taking fuel away. either way when I start the car my WBo2 says 7.4 (the lowest it will display) and as the car runs the STFT & LTFT start going up and the WBo2 will settel at 8.2 the narrow band o2 is also in the 40-60mv range.

in open loop the WBo2 just sits on 7.4

[Kyne]

Your narrowband and wideband voltages are saying the complete opposite. Your narrow band mV being 40-60 means it's lean which is why you have +20% fuel trims which is trying to richen up the mixture.

[1fastkingcab]

Sounds like a vacuum leak, but I have 19in of vacuum and i unloaded an entire can of carb cleaner all over the intake manifold and vacuum hoses with no result. and when I disable closed loop it's the same rich idle.

Why would my Narrow O2 say im lean and my LC-1 say I'm rich and the sensors are 5" apart on the same pipe?

I have attached my .HPT file in which I believe i have disabled closed loop ( PE Throttle /Pedal hot =0% TPS & Closed loop enable ECT = 283deg)

[Kyne]

I have no idea unless your O2 is bad or not hooked up right. When you are in open loop does it have fuel trims? I use the scanner controls to turn close loop off when tuning.

[1fastkingcab]

that's the thing in open loop the trims are sitting on Zero and the car is running like a lawn mower with the choke on. the plugs are black and nearly fouled. I replaced the O2 sensor & MAP sensor before I posted here. and I just unloaded another can on carb cleaner on the intake alone.

I am about to just pull the intake off, and put new gaskets on everything i know says it's unaccounted air getting in after the MAF. But if that was the case running it closed loop would make it lean if un-metered air was getting in, but it doesn't it's still rich even if my WBo2 was broken I can still smell it and it's running like it has a choke on.

I pulled the car in the shop while supercharged running fine, I had to pull the blower off to pull the rotors out for the turbo swap, I don't know what else to do other than just pull it apart and replace the gaskets and hope carb cleaner just wasn't getting to the leak I clearly have? Maybe PCV valve I just don't know.

[1fastkingcab]

Also, while It's possibly the worst tuning practice EVER I got pissed and just mashed the gas at 30MPH the car droped to 1st gear shot up to 20PSI and the AFR when straight to 11.8 on the gauge then proceed to burn the drag radials through the 1-2 shift and chirp 3rd gear. I let off and the car went pig rich as soon an I was off the gas.

[Kyne]

If your o2 is saying lean when you are pig rich and if isn't misfiring I would check your o2 wiring. Misfiring and exhaust leaks would make it read that way but since you haven't mentioned any misfiring and your wideband is reading rich I would assume the o2 is reading lean for some reason and diagnose that first. I'm grabbing my computer now to check out your tune.

[1fastkingcab]

I was just grabbing at straws before I tore it all back apart, I'm sure I have a vacuum leak somewhere the carb cleaner can't get. It does have a "miss" at idle and while trying to "power though it" but once takes off (a few seconds of more than 11% TPS) it's as smooth a butter, I was just hoping something stuck out like a sore thumb. I just swapped out all My autolite 104's for a new set of 103's gapped @ 0.34" the old plugs where all equally black and wet with fuel from all 6 cylinders, I swapped out the plug wires, coils and ICM with others I had laying around the shop just to see if anything changed with no luck.

[Kyne]

Check your o2 wiring.

[1fastkingcab]

Will do, thanks for your time

[G_P_K]

i would also start with the O2 wiring. however, with two big fuel pumps i would also suggest putting a gage on the fuel rail to see what you have at idle. if it is the O2 i would expect it to straighten itself out when you force it to open loop mode.

did you put a big cam in it that would make the MAF considerably wrong at idle?

[1fastkingcab]

Nope stock cam,

[1fastkingcab]

For what it was worth, the issue was a stuck PCV valve.