Gojira94

iTrader: (4)

I agree; anything that can be fouled by lots of excess fuel (plugs, O2s). Sounds like you've encountered a self-propogating rich condition.

Yes, the O2s can be electrically fine, but if they're gummed over with fuel residues from low temp/ incomplete fuel burn they won't sense properly. Then the PCM responds by dumping even more fuel.

Pull a few plugs and see how they look. If you've lost the puck on a few the gap will be too wide and will explain a lot. If changing those doesn't help. look at the O2s.

JoeliusZ28

iTrader: (2)

kinda what i am thinking too.

Gojira94

iTrader: (4)

He tried that with the same result, unfortunately:

"Checked:
tried swapping PCM for another, no change..."

YodiBrodi

bad pcm's aren't very common and typically end up with a component that simply doesn't work or phantom fault codes. do you have an after market throttle body? could explain the ses light on at wot only. or tps failing either way it'd be the same fault, but shouldn't flicker, it should stay on then turn off. with your entire instrument panel behaving like this, ground is the only answer, there are many to check. as far as the bad running, i was down at 8-10 mpg before a simple spark plug change and 2 seafoam treatments regained 7 mpg's, it'd only been 2 years since the last treatment (but a bunch of racing too). no need to go fancy iridiums, if the gap isn't the 0.055" required the car will NOT run properly. i also wouldn't really suspect the injectors unless you're in the habit of running cheap gas, letting it sit for months before driving, and simply not driving it like an f-body. simple check to see if each individual injector is firing, hold a small screwdriver close, the magnetic field should draw the tool in. this will tell you if the solenoid is firing, pull them out and check the nozzles for carbon build-up and clean accordingly. you may have to re o-ring them before reinstalling them , however, and put a little petroleum jelly on each o-ring and clean the injector bore before reinstalling. fuel regulator is a simple check, check vacuum as well, cheap gauges work well. erratic signal says you have a leak, steady signal says you don't, should be 18-22". also, get some aeresol maf cleaner, clean the sensor but don't touch it.

Gojira94

iTrader: (4)

Have you had a chance to pull a couple plugs yet? Can you get under it to unbolt the cats and see if they're clogged or smell like unburnt gas?

xDaytona955

iTrader: (1)

I pulled the hose off the FPR while the car was running, no leaks so I guess its good. I could hear the RPMS go up when I unplugged it which is expected from what I have read.

Stock TB, and i did take it out and clean it real good, I also cleaned the MAF with the proper electrical cleaner.

No cats, so their not clogged

The smell is foul, maybe like rotton eggs like one poster said. hard to describe, doesn't smell like unburnt gas

the gap on the iridiums was set right, I remember I had to get a wirestyle gap tool so i wouldn't break the iridum tips

I got some standard NGKs and I will try to swap them in over the weekend.

As far as the ECU, when I did the swap, I kept my LT4 knock module. I wonder if that is bad, I'll try putting my LT1 KM back in to see if it makes a difference. I originally suspected the ECU because the live data log output would pause every time the engine stumbled...

Thanks to all that have posted suggestions! I promise I will post my final fix when I find it

taner

iTrader: (6)

change the fuel pump! my brothers car did the same thing you are mentioning. unless you can tape a maek shift gauge to your wiper arm and watch in under load, i am not sure you will be able to tell if pressure is dropping off.

my brother had a near new opti, and it **** the bed shortly after 6 months of driving.

it is unfortunate there can be a number of things to look for. lots of good ideas thrown around here though.

g'luck with it!

xDaytona955

iTrader: (1)

Update:

Took a plug out from each bank, looked perfect. No fouling or carbon on the insulator or conductor. The rim had a little carbon on it but I would expect that from a car running rich.

I noticed a 1/2" tear in the intake elbow, so some unmetered air was getting in. As a temp measure I glued the hole shut, no change.

I disconnected the MAF and the car is running great! As I understand it, this makes the car run off the MAP sensor as a backup. The car would occasionally stall while waiting for a light because the idle was rough. But never during takeoff like it was. 90% improvement. So I guess the issue may be a bad MAF or the MAF plug on the engine harness.

Any thoughts? If unplugging MAF mostly fixes the problem can that indicate any other issues other than the MAF itself?

Brian

96ssindeed

mine was doing some of the same stuff when i first got it, running rich. had to change the o2s and got it tuned. afterwards it started acting up again and the maf had to be changed.

AChotrod

iTrader: (17)

I was just going to post Id bet its 100% the MAF went bad and to unplug it. I have had it happen to 3 cars and everytime it was the MAF. Glad you found it!!

t/afrom504

man im having the same problems, i tried unplugging the MAF but it runs even shittier, so i know thats not the problem. But im glad you found your issue. But probably your MAF is dead or maybe the plug to it.

xDaytona955

iTrader: (1)

Does anyone know if the MAF is the same for LS1 and LT1 cars? I would like to try the MAF out of my LS1 car to see if it solves the issue..

stburgpete

Hears something else you can try my car was doing some of the things your was and I was told to check for vacum leak check for vacum leaks I did over and over. Check the EGR valve. you would be surprised what it will do to the idle when it sticks open and closed. most people dont realize that the EGR is vacum to.

Gojira94

iTrader: (4)

Someone we trust here has answered this exact question recently on another forum:

http://www.camaroz28.com/forums/show....php?p=6282086

(yes )

xDaytona955

iTrader: (1)

Ok, its been a couple days with the MAF swapped from my LS1.

Oddly, both cars are running great?! If the MAF was bad, I would think that the LS1 car would now be running shitty..

Maybe its the MAF connector, or the IAT since I had to unplug it and replug it when I swapped the MAF..

David94TA

Check your ICM wiring harness. It seems that I remember reading about someone have a mysterious problem like yours and that was the answer.

xDaytona955

iTrader: (1)

Update:

running like crap again. I picked up a fuel pressure gauge and taped it to the windshield.

Key on, engine off: 38psi
Key on, engine on, FPR vacuum unplugged: 43.5psi
Idling: 31psi
WOT:40psi, but then starts falling as the rpms climb, as engine starts popping near redline the needle is twitching +-3psi

This sounds like a bad pump? Would a bad FPR do this? I pulled the vacuum line and there is no leaking gas