Bad idle / stalling when hot
06-30-06, 04:07 PM
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Bad idle / stalling when hot
I bought my 93 Touring about 3 months ago and I noticed this problem about a week after I bought it. While it varies a bit, when this problem actually crops up it takes about 20 minutes of driving around to happen. The coolant temps are in normal range and after driving for a while it starts to stumble when idling. The vacuum is about 11-13" Hg but I couldn't imagine a rotary pulling too much vacuum at 300-500RPM when this is happening.
The frustrating thing about this problem is that it only happens every once in a while and it doesn't really matter if I take it on a high speed run (90+) or if I'm just putting around the neighborhood.
I've changed the spark plugs, radiator, positive battery terminal and installed a PowerFC since all of this. The radiator was replaced due to a coolant leak and it took a couple weeks for this bad idle problem to happen after I installed that. The PowerFC was purchased because it seemed to fix the problem for a month or so (I borrowed a friend's for a while). This stalling issue has occurred with both the stock ECU and the PowerFC so I'm sure that can rule out the fact that I still have all the emissions garbage still connected (yes I cut the pins from the PowerFC as instructed).
I honestly thought I was on to something with the positive battery terminal though. The old one had a hairline fracture in it and wasn't making solid contact and I thought it somehow would affect the alternator when the car really warmed up. According to the PowerFC, my battery voltage is around 11.8-11.6 before starting up and 13.2-13.8 when driving around. According to the workshop manual I should be seeing 14.1-14.8, correct?
Is it possible the alternator is failing when underhood (not coolant) temperatures start to climb? I took it to O'Reily's to have the electrical system checked and the highly skilled cashier's equipment said the alternator was fine but the car did not have nearly enough time to have this problem crop up in the 10 minute drive there. It's worth mentioning when I was replacing the radiator I took the battery in to get it checked up (and charged, it had died) and it was peachy keen. The battery itself is a few months over 2 years old.
While somewhat frustrating, I suppose I should count my blessings because when the car is allowed to cool down (3-4 hours) it starts right back up, no problems. I see 19" Hg from the boost gauge with a solid 720RPM idle, no smoke from the exhaust and a perfect 10-8-10 boost pattern. The TPS voltages are in spec and the only thing I can tell (from the pfc commander) that's off is the voltage while running. Is the low voltage while running something to worry about?
Mods are very minimal. Just some basic reliability mods (Al AST, downpipe, cat-back), polished UIM, PowerFC, and a larger, all-aluminum radiator. Thanks in advance for the help.
The frustrating thing about this problem is that it only happens every once in a while and it doesn't really matter if I take it on a high speed run (90+) or if I'm just putting around the neighborhood.
I've changed the spark plugs, radiator, positive battery terminal and installed a PowerFC since all of this. The radiator was replaced due to a coolant leak and it took a couple weeks for this bad idle problem to happen after I installed that. The PowerFC was purchased because it seemed to fix the problem for a month or so (I borrowed a friend's for a while). This stalling issue has occurred with both the stock ECU and the PowerFC so I'm sure that can rule out the fact that I still have all the emissions garbage still connected (yes I cut the pins from the PowerFC as instructed).
I honestly thought I was on to something with the positive battery terminal though. The old one had a hairline fracture in it and wasn't making solid contact and I thought it somehow would affect the alternator when the car really warmed up. According to the PowerFC, my battery voltage is around 11.8-11.6 before starting up and 13.2-13.8 when driving around. According to the workshop manual I should be seeing 14.1-14.8, correct?
Is it possible the alternator is failing when underhood (not coolant) temperatures start to climb? I took it to O'Reily's to have the electrical system checked and the highly skilled cashier's equipment said the alternator was fine but the car did not have nearly enough time to have this problem crop up in the 10 minute drive there. It's worth mentioning when I was replacing the radiator I took the battery in to get it checked up (and charged, it had died) and it was peachy keen. The battery itself is a few months over 2 years old.
While somewhat frustrating, I suppose I should count my blessings because when the car is allowed to cool down (3-4 hours) it starts right back up, no problems. I see 19" Hg from the boost gauge with a solid 720RPM idle, no smoke from the exhaust and a perfect 10-8-10 boost pattern. The TPS voltages are in spec and the only thing I can tell (from the pfc commander) that's off is the voltage while running. Is the low voltage while running something to worry about?
Mods are very minimal. Just some basic reliability mods (Al AST, downpipe, cat-back), polished UIM, PowerFC, and a larger, all-aluminum radiator. Thanks in advance for the help.
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