nasty_ss

recently my car has been running hit or miss. i fire it up and straight fuel from the exhaust and idles real low. once that sorts out then after about 30-40 minutes of driving it starts hesitating under light throttle. then if i put it in neutral and let it coast while it's having fits it'll idle super low and almost die. i noticed the other day my front pass o2 came unplugged and didn't even throw a code. so i plugged it back in thinking this would solve the problem. it didn't. bad o2? runs the same unplugged as when plugged in. still doesn't explain why it wouldn't just run like **** all the time.

wssix99

iTrader: (5)

You should check for codes first. If your O2 was unplugged, I'll bet there are a bunch stored in the system.

LS6427

iTrader: (2)

These PCM's will try to adjust things for a little while, then it will switch to SD tune. When both of my 02's were bad from the car sitting for 4 months....I would start it up, it would run like HELL for about 3-5 minutes...then smooth right out. Then occasionally after it was up to operating temp it might try again for a few seconds, then go back to running perfectly fine.
I've been in and out of town the past few weeks and haven;'t been able to deal with my issue......buit I think I bought a bad "new" sensor and when I start my engine now it runs perfect in closed loop, then when it tries to switch to open loop while its warming up it breaks up so bad it will not accelerate and feels like the engine is falling apart...then about 20 seconds later the PCM clears things up and it runs 100% perfect all day...till I shut it down again.

These things are wacky man........these PCM's are still not totally figured out, not even by the most experienced tuners and computer geeks.

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FiredUpZ28

Gotta post codes man. Cant do anything else until then. How does an 02 "become" unplugged? It has a lock on the connector. All four do (should).

HAZ-Matt

iTrader: (8)

A better question is how it doesn't set a code when unplugged. What are your mods? Has anyone ever reprogrammed it to open loop and or removed the O2 codes? Does your SES bulb work?

LS6427

iTrader: (2)

Remember I posted about wierd **** my PCM would and wouldn't do, that most other PCM's do......

I'm tellin ya....PCM's are all not created equal. I unplugged my MAF a couple weeks ago and went for a drive, never threw a MAF code......

Strange joo-joo............

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FiredUpZ28

Its not that PCMs are different but EACH dtc has its own very specific criteria that needs to be met to set. Then it has its own amount of times it needs to set to light the MIL. I had a Suburban yesterday. MIL on, throwing 2 MAF codes and 1 MAP code. Pulled it in, scanned it, read some freeze frame data, when I started it back up the MIL was off.

VandykeT/A

If I unplug my MAF my car won't back out of the driveway. Never unplugged an 02 sensor but when they were bad it never acted any different. Also on my trans am a friend of mine cut a wire going into the computer that kills the check engine light bulb. No light but it still stores them in the computer, for the longest time I had a code for a ground and I could not figure out what it was but it turned out to be the wire he cut itself.

FiredUpZ28

..... Ok so you need your car scanned for codes. Gotta tell you, sounds like your car is action packed with issues, especially if your letting buddies just cut wires as "needed".