Hunting idle, Resolves with restart?
Hunting idle, Resolves with restart? Ok all, I picked up a 98 Firebird tonight, dead stock other than cat-back, and it seems that on an initial start it sometimes will not immediately find an idle and will hunt up and down consistently. If I shut it off and restart it immediately, it’s smooth as silk.
Does that give anybody any idea what I should be looking for?
Appreciate it!
Does that give anybody any idea what I should be looking for?
Appreciate it!
Joined: Nov 2001
Posts: 34,564
Likes: 2,472
From: Schiller Park, IL Member: #317
Lots of potential causes and hard to say with such limited data.
- Could be an IAC motor that's failing.
- Could be a weak battery condition that's causing the need for a partial idle relearn after being discharged by an engine start (this is a rare one, but it has happened to mine - and would clear up with a key cycle just like yours).
- Could be an intermittent vacuum leak that is cleared by a restart (such as the EVAP purge solenoid).
- Could be an issue with the EGR valve (this was actually a recall on the '98s).
Have you looked at fuel trims (scanner), fuel pressure (gauge hooked up to the rail), IAC counts (scanner), and/or performed any other diagnostics yet? Any codes pending, stored, or active?
- Could be an IAC motor that's failing.
- Could be a weak battery condition that's causing the need for a partial idle relearn after being discharged by an engine start (this is a rare one, but it has happened to mine - and would clear up with a key cycle just like yours).
- Could be an intermittent vacuum leak that is cleared by a restart (such as the EVAP purge solenoid).
- Could be an issue with the EGR valve (this was actually a recall on the '98s).
Have you looked at fuel trims (scanner), fuel pressure (gauge hooked up to the rail), IAC counts (scanner), and/or performed any other diagnostics yet? Any codes pending, stored, or active?
I haven’t made it so far to scan or anything. There’s no dash lights but unsure on stored codes
My immediate thought was the IAC but wasn’t sure it made sense it would clear up on an immediate restart if the hard part itself was bad.
I’ll keep digging.
My immediate thought was the IAC but wasn’t sure it made sense it would clear up on an immediate restart if the hard part itself was bad.
I’ll keep digging.
Joined: Nov 2001
Posts: 34,564
Likes: 2,472
From: Schiller Park, IL Member: #317
In the engine bay, on the driver's side of the engine, just behind the throttle body and next to/on top of the intake. Small black piece that connects to the intake via a hard gray plastic line (be careful with this line, they break easy and I think they are discontinued). It's a quick-disconnect style.