MY 85, idle surge and stalling when hot
08-30-2020, 12:36 PM
#1
Rennlist Member
Thread Starter
MY 85, idle surge and stalling when hot
I've been experiencing this lately. When the engine is hot (not overheated), slowing to a stop and taking it out of gear. The idle surges ,drops real low and then stalls.I may even hear a low backfire when I get out of gear. It will sometimes start right up and idle. Or if it keeps stalling, I'll have to have the clutch pressed in, start it, put it in gear and go. This does not happen in normal driving times. Even when the engine is up to temp. It seems it takes a lot of driving for it to happen.
Example yesterday. Did some very spirited driving for the first 60 miles. No problems when coming to a stop, parking etc. It sat parked for about 45 mins. On the way home we did some more high speed driving for another 60 miles. But coming into town and having red lights and stops, the stalling and rough idle problems started. I really had to baby it the last 10 miles of starts and stops, until I could drift it into my driveway.
Before yesterday, I removed and tested the ISV that I replaced in 2014. About 12k miles on it. It tested (I think) fine with a 9v battery. Clicking open and close quickly. Sprayed it with a little WD40, even though I'm not sure that trick works on a 85 MY ISV before I put it back in.
What else can I check before driving to Frenzy at the end of Sept?
Example yesterday. Did some very spirited driving for the first 60 miles. No problems when coming to a stop, parking etc. It sat parked for about 45 mins. On the way home we did some more high speed driving for another 60 miles. But coming into town and having red lights and stops, the stalling and rough idle problems started. I really had to baby it the last 10 miles of starts and stops, until I could drift it into my driveway.
Before yesterday, I removed and tested the ISV that I replaced in 2014. About 12k miles on it. It tested (I think) fine with a 9v battery. Clicking open and close quickly. Sprayed it with a little WD40, even though I'm not sure that trick works on a 85 MY ISV before I put it back in.
What else can I check before driving to Frenzy at the end of Sept?
08-31-2020, 07:29 AM
#2
Rennlist Member
Thread Starter
No ideas or other things to check from the wisdom here?
08-31-2020, 08:04 AM
#3
Team Owner
I would look for a false air leak could come from the vacuum valve on the right fender or the brake booster for the booster remove the check valve from the booster and plug it you won’t have power assist brakes so be careful when driving
for the valve unplug it and plug the return line to the intake road test
Note do this when the engine is hot
When was the MAF replaced? How about the TPS short harness? Did you replace the shaft bearings with new double sides O rings bearings
Who makes the ISV you installed ?
Bosch or Lowe?
for the valve unplug it and plug the return line to the intake road test
Note do this when the engine is hot
When was the MAF replaced? How about the TPS short harness? Did you replace the shaft bearings with new double sides O rings bearings
Who makes the ISV you installed ?
Bosch or Lowe?
08-31-2020, 12:12 PM
#4
Rennlist Member
Thread Starter
I would look for a false air leak could come from the vacuum valve on the right fender or the brake booster for the booster remove the check valve from the booster and plug it you won’t have power assist brakes so be careful when driving
for the valve unplug it and plug the return line to the intake road test
Note do this when the engine is hot
When was the MAF replaced? How about the TPS short harness? Did you replace the shaft bearings with new double sides O rings bearings
Who makes the ISV you installed ?
Bosch or Lowe?
for the valve unplug it and plug the return line to the intake road test
Note do this when the engine is hot
When was the MAF replaced? How about the TPS short harness? Did you replace the shaft bearings with new double sides O rings bearings
Who makes the ISV you installed ?
Bosch or Lowe?
MAF was replaced in 2014.
TPS short harness also in 2014
No replacement of the shaft bearings
The ISV is a Bosch.
I'll check for vacuum leaks as described and get back.
Last edited by WyattsRide; 08-31-2020 at 12:22 PM.
09-01-2020, 10:50 AM
#5
Rennlist Member
Bump and following. What other things could be causing this besides MAF. Also, why would a vac leak wait until the car was hot? Wouldn't it manifest itself from the get go?
09-02-2020, 07:40 AM
#7
Rennlist Member
Thread Starter
