Rough idle/stalling

G

gbradleyb

New member
So I've been having this issue forever now (I think I posted about it awhile ago), and I think I pinpointed when it occurs.

I can hop in my cold car in the morning and fire it up and the rpms go up above 1000 and hold there for about 15 secs then drop to normal around 600....this seems to be how it should act.

I can also drive my car until it gets up to temp, shut it off, start it up and it will Rev to around 1000 then immediately drop to around 600 and idle...this also seems normal.

The problem occurs ONLY when I get the car up to temp, let it sit awhile but not long enough to cool down all the way, then fire it up. The car will Rev up to around 1000 then drop down to around 200, then up over 1000 again, then down to 2-300 again, and will eventually either even out around 600 after a minute or drop down and die.

It only does this when it gets up to temp then sits for maybe 15mins to an hour. Did it today about 15 mins after a 70 mile trip when I fired it back up to head home, again after being at YMCA for 45 mins, again after being at a buffet for probably 45 mins. After the buffet it kept dying on me when i tried to start it so i had to give it some gas to keep it running. I tried to get it to happen immediately after taking a trip by shutting car off, waiting a few minutes and firing it up, but it starts great then.

It used to only do this when I went to Walmart, but i now believe that is because it's the only place in town I go where it gets up to temp and I then let it sit long enough to cool but not get completely cold.

Any ideas on this??? I'm lost..I've got a video I'll try and post
 
G

gbradleyb

New member
Dou you have any idea why the IAC valve would only seem to act up in the described scenario. I would assume it would atleast sometimes act up on say a cold start
 
J

Jamesvinar

New member
My assumption would be different readings are needed for a cold and hot engine, might be throwing the wrong amount of air for a hot motor in there. I had a similar problem and this is what worked for me.
 
B

billcu

Head Moderator
I have a similar problem with my black Mark. It only happens like you say, after it is fully warmed up and I go to start it after a while of sitting.

I can keep it running if I throttle it, it seems like it's flooded, but then clears out as I rev it a bit.

I was thinking it might be an injector or 2 leaking after I shut it down, then when I go to start it, it's a little flooded. Possibly, if I don't start it for a longer while, like overnight, the extra fuel just evaporates and starts fine then.

I'm just guessing here, does this sound like your problem?

I was thinking a way to test it might be to check the fuel line schrader valve after it's been sitting to see if the pressure has leaked down.
 
B

billcu

Head Moderator
The IAC on the gen 1 is a pain to replace. I usually wait until I have to change the transmission for that one.:D

I'll check mine for pressure at the schrader valve first, that's much easier.:)
 
G

gbradleyb

New member
I don't have a fuel pressure tester so I'm gonna fire it up and only let it run for a minute or so then let it rest for a while and see if it does the same thing. If it was excess fuel leaking thru the injector I would expect it to happen regardless of engine temp
 
B

billcu

Head Moderator
What if it only leaks when it's hot?:D

I am just guessing here, I can't even check mine now, it's in storage. I was just going to use a rag and open the schrader valve to see if there was any pressure, under the same conditions as when it happens.
 
G

gbradleyb

New member
OK, I ran it for a couple mins, shut it off for half hour then started it. It started fine. But.....the engine did its cold start Rev so I don't know if that prevented it from sputtering....kind of a useless test I guess
 
You must log in or register to reply here.
Top