P0125 code, hard starting, and high idle speed. - GM Forum - Buick, Cadillac, Olds, GMC & Pontiac chat

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P0125 code, hard starting, and high idle speed.

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Old 10-23-2006, 12:21 AM
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Default P0125 code, hard starting, and high idle speed.

The car has been idling fast for the last few days, often in the 1500-1600rpm range. Starts have become hard, requiring a few seconds of cranking and partial throttle to get the engine to fire. When the engine catches it often stumbles a bit, then revs to 3000rpm on its own until settling down to ~1500rpm after several seconds. Additionally, the car set a P0125 code after accelerating onto the freeway earlier tonight.

I sprayed all the obvious vacuum connections with carb cleaner while the engine was running, but there was no stumbling. The car needs new vac lines whether it solves the problem or not, as many of the rubber boots are cracked. Not sure where to go with this one. EchoSSEi is already enlisted for a Tuesday work night.

Also (and probably unrelated), while driving along, the air conditioner blows alternating cold and hot. This occurs while cruising at normal throttle at ~40mph. I can also feel heat blowing lightly on the floor when I have the climate control turned off. As I said, probably unrelated to the DTC and engine issue.
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Old 10-23-2006, 02:24 AM
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What temperatures are you running? Is it cool enough to where the code could be accurate? Fuel pressure good? Have you done the TB, MAF,IAC cleaning lately?
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Old 10-23-2006, 04:26 AM
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Haven't checked fuel pressure, as I don't have a tester. Could these symptoms be due to a faulty FPR? I'm down in Phoenix (temperature at the time was in the 80s), so there'* no reason why the coolant shouldn't be heating. My temperature gauge has shown normal operation in the 180-190 degree range every day.

TB, MAF, and IAC cleaning are next on the list. I suppose this could all be due to a sticky IAC, but with the symptoms I figured a vacuum leak sounded likely. Can someone remind me of the standard test to check for a faulty FPR?
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Old 10-23-2006, 08:13 AM
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Hold the presses gents.

P0125 According to the list of trouble codes is Insufficient Operating Temperature. Won't allow closed loop operation.

This can cause all kinds of crazy behavior. Especially since operating temperature is about the normal outdoor temp there.

Check your temp sensor on the front of the engine under the thermostat housing. Look for loose or broken wiring.
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Old 10-23-2006, 01:56 PM
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I'll do some checking, Bill. That still doesn't explain the hard starting, though. I'm still thinking there'* some kind of fueling or vacuum issue.
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Old 10-23-2006, 03:49 PM
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Ben.. you are in the dry rubber captial of the country.

One of your vac lines may be hiding on you and blow to pieces.
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Old 10-23-2006, 09:39 PM
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Boosty....

Sorry for my last post. I realized you were right about the temperature sensor. Many months ago MLBB and I accidentally broke part of the sensor housing, then super-glued it back into place. I totally forgot about it until now

I think it might explain some of the problems as well. Fast idle could be because the car keeps staying in open loop. Hot air blowing through the vents might be due to the CC thinking the coolant temperature is much colder than it is. I'm not sure if this explains why starts have been hard, but I think it'* worth it to change out the sensor.
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Old 10-23-2006, 09:54 PM
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MLBB = Secret code name for Doug?

Interesting..Bob and I discussed it a little. My comment.. "you know Ben and Doug were all over that engine bay, somehow the trans wiring got mushed, worth a look"

Sounds like it might be an easy fix. At least we hope that'* all it is.. gotta get it done before the sun comes out and fries you desert folks..
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Old 10-23-2006, 11:44 PM
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Originally Posted by BillBoost37
MLBB = Secret code name for Doug?
Yeah... MLBB = MyLittleBlackBird.


I guess I could have just said "Doug".
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Old 10-24-2006, 03:32 AM
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High rev and having to hit the pedal to start, TPS sensor??
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