whiteNrude01

iTrader: (8)

Hopefully someone can help because auto shop is clueless after 2days diagnosing. Car has headers, exhaust, lid, p&p tb and a dyno tune, 95k miles. I recently drove 800miles got too destination car started misfiring and stuttering around 4th and 5th gears, so I changed the air/fuel filter and cleaned the maf out. Didnt fix it, took it too a local shop, the said car was misfiring bad on cylinder 1, said injectors good, coils good, fuel pressure good. They replaced 1 sparkplug and said car was fine on scanner, get car back, it bucks and misfires and idles at like 300rpm, every gear is like that. Made them diagnos again, they cant find any problems, cept all my spark plugs are black even the new ones i put in. Computer says lean on both banks, but car is actualy dumping tons of fuel running super rich. They said it must be my custom tune and they cant figure it out. Im lost here.

New sparkplugs
New airfilter
New Fuelfilter
New O2 Sensors
Cleaned MAF
Reset PCM

DisasterFormula

iTrader: (1)

Are the O2 sensor connectors corroded at all? Also, the Engine Coolant Temperature can cause similar symptoms.

LS6427

iTrader: (2)

Maybe they have no idea how to read a scanner. 02 sensor(s) failing, but still working, might be the issue. Even if they are new, you might have a dud.

Make sure the spark plug wires or boots are touching NOTHING metal at all.

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whiteNrude01

iTrader: (8)

Yea i thought pepboys was a bad idea, i put brand new plugs and ive got basically new msd wires, the boots rest lightly on the headers.

LS6427

iTrader: (2)

You MUST get the boots COMPLETELY "OFF" the headers.

That is most likely the issue. Possibly not.......but in most cases that will cause misfiring and bad idles down low.

Cut that area of the boots away with a razor if you have to.......
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whiteNrude01

iTrader: (8)

Boots werent touching afterall, im not throwing any o2 codes those would be different then the po171/174? I just spent an hour sprayin carb cleaner cant find any change in idle from any lines.

mjs1012

iTrader: (36)

those are lean codes, look for a vacuum leak behind the MAF. i had the same issue and fixed it.

whiteNrude01

iTrader: (8)

around the bellow?

LS6427

iTrader: (2)

If you're rpm is dropping down to 300 rpm....not thinking its a vacuum leak. Vacuum leaks raise rpm's.

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whiteNrude01

iTrader: (8)

I drove thru 3 states if heavy rain, had lots of water on pcm, engine, headlights even shorted out, i winder if rain messed up the pcm, but pcms throw codes right? Do tunes ever get delted or messed up?

LS6427

iTrader: (2)

PCM's will NOT always throw a code or do anything when they are damaged. I had a PCM fry from the inside out over a years time. It never threw a code. First thing it did was disable my MAF and put me into a SD tune. I replaced it and everything was good again.

So yes.....the PCM could be damaged. Pop off the two tops and look for any burnt pins in the pin rows. Thats what I did and found a couple, thats how I knew it was my PCM causing my issues.

Also, make sure your grounds are tight. Back of the passengers side head. 2 or 3 bolts. Reach back there and check. I think, not sure though, that they are 15mm.

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