Mallone
Well-known member
- Joined
- 10 Feb 2017
- Messages
- 135
Slowly but surely working through the list of items on my new (to me) 996 and this one has me a little stumped so far. It's a 1999 C2, cable throttle.
Every time I start the car from cold I have an issue where it fires immediately up to 2000rpm for a half second and then stumbles straight back down to about 500rpm for a second or so before something (the ecu?) kicks in and it jumps back up to a rock solid idle at around 1100/1200rpm.
When it's warmed up it stays at around 6/700rpm with AC off, 900rpm or so with it on. Again, rock solid. Never had it stall, never had it run rough etc.
Fires up without this issue when warm. This little stumble only appears on cold starts, but it doesn't sound too happy about it and I'd like to try and fix it. It's not normal behaviour.
It's got a new air filter and I've cleaned out the ICV. It recently had a new water pump (and the bearing was really grumbling in that so wondered if that was 'dragging' the RPM's down until the ECU could compensate) but nothing has cured it.
I'd planned to do plugs and coil packs soon, as well as sort out a leaking spark plug tube, but not sure what else to try.
The only thing I had considered was that when I picked the car up it had a K&N kit on it that I removed and replaced with the OEM airbox. I reused the same MAF sensor (after a thorough cleaning with electrical contact cleaner) but didn't think the MAF was used in a cold start (might be wrong here..)
Any ideas?
PS. And because all threads are crap without pictures, here's one of the car after a cross country thrash as an intro to the forum
EDIT: Edited to include a bit more detail about the car for diagnosis.
Every time I start the car from cold I have an issue where it fires immediately up to 2000rpm for a half second and then stumbles straight back down to about 500rpm for a second or so before something (the ecu?) kicks in and it jumps back up to a rock solid idle at around 1100/1200rpm.
When it's warmed up it stays at around 6/700rpm with AC off, 900rpm or so with it on. Again, rock solid. Never had it stall, never had it run rough etc.
Fires up without this issue when warm. This little stumble only appears on cold starts, but it doesn't sound too happy about it and I'd like to try and fix it. It's not normal behaviour.
It's got a new air filter and I've cleaned out the ICV. It recently had a new water pump (and the bearing was really grumbling in that so wondered if that was 'dragging' the RPM's down until the ECU could compensate) but nothing has cured it.
I'd planned to do plugs and coil packs soon, as well as sort out a leaking spark plug tube, but not sure what else to try.
The only thing I had considered was that when I picked the car up it had a K&N kit on it that I removed and replaced with the OEM airbox. I reused the same MAF sensor (after a thorough cleaning with electrical contact cleaner) but didn't think the MAF was used in a cold start (might be wrong here..)
Any ideas?
PS. And because all threads are crap without pictures, here's one of the car after a cross country thrash as an intro to the forum
EDIT: Edited to include a bit more detail about the car for diagnosis.