Could this be my PCM?
Could this be my PCM? So I keep having this issue. It's not every time I start the car, more like every 10th or 15th time I start it and happens when the car is hot or cold. My car is a 2002 z28 with just under 70k miles on it and it's pretty much stock.
The issue is that I get into the car and start it and it starts then the idle drops down super low (like between 250-500 rpm) and jumps up and down like the engine is trying hard to keep itself alive. After a little while it'll get back to idling at it's normal speed, but once I put the clutch in it'll drop back down to like 500 rpm. If I wait for the car to get a little warmer then turn it off and back on the problem goes away.
Last night it happened the worst so far. I get in the car and turn the key and everything dies. I thought I'd blown a fuse or something so I clicked my remote and everything worked fine except the clock had reset so I put the keys back in and tried to start it again. When I did the engine bogged and died real quick. I tried again and gave it some gas and it got going, but real rough for a few minutes.
Any ideas what this could be? I think this has to be a pcm or battery issue.
The issue is that I get into the car and start it and it starts then the idle drops down super low (like between 250-500 rpm) and jumps up and down like the engine is trying hard to keep itself alive. After a little while it'll get back to idling at it's normal speed, but once I put the clutch in it'll drop back down to like 500 rpm. If I wait for the car to get a little warmer then turn it off and back on the problem goes away.
Last night it happened the worst so far. I get in the car and turn the key and everything dies. I thought I'd blown a fuse or something so I clicked my remote and everything worked fine except the clock had reset so I put the keys back in and tried to start it again. When I did the engine bogged and died real quick. I tried again and gave it some gas and it got going, but real rough for a few minutes.
Any ideas what this could be? I think this has to be a pcm or battery issue.
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
Make sure the battery terminals are clean and tight - check voltage key off and when running. Almost sounds like it's losing voltage and the PCM has to relearn the idle. Might not be it, but something easy to check.
Just cleaned the MAF about a month and a half ago when I put the my lid on (And yes I used the correct cleaner). So I guess I'm a little bit of a n00b on the IAC though. Where is it and what's the best way to clean it?
This is my guess. Check the battery connections at the starter, engine ground, and fuse block.
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The idle air control valve is on the TB. If nobody else does I'll post a pic tomorrow pm. Search it and I am sure you'll find something as it is a pretty common issue. I cleaned mine with carb cleaner but your MAF cleaner will work just as well.
Search it and there is prolly plenty of reading as it is a pretty common issue.
Search it and there is prolly plenty of reading as it is a pretty common issue.
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Checked the battery and the negative terminal was a little loose. This would explain why the problem was becoming more frequent as the connection was probably getting looser. Tightened it up and the car seems to be doing fine. I'll see if this fixed it for good in a few days I guess.
Checked the battery and the negative terminal was a little loose. This would explain why the problem was becoming more frequent as the connection was probably getting looser. Tightened it up and the car seems to be doing fine. I'll see if this fixed it for good in a few days I guess.
