V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

High idle, then bogs down and dies

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Old 11-06-2013, 10:30 AM
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Matt's 95 Stang
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Default High idle, then bogs down and dies

So my '95 is having some issues. I let my father in-law drive it as I have my '11 for DD duty so this is all second hand info.

Car info - '95, 5 speed, new engine (10k on it), 165k miles on body, trans.

Car was driving fine, then coming off the freeway, out of gear the RPMs shoot up about 3k, then they come down to about 300-400RPMs, and the car dies. So he drove it home and parked it. I come over and look at the car, clean the MAF, and TB thinking maybe those are dirty causing the idle issues, also pull the battery to reset everything. Put it all back together, start the car and it fires up fine, runs fine, no CEL, 30 seconds after starting the engine bogs down and dies. No CEL, but I could smell the car was running very, very rich. Restart the car, runs 30 seconds then bogs down and dies again. I had to go to work so I didnt get to play with it any more but my first ideas were:
Bad spark plug/wire/coil
Bad gas
Stuck open injector

Other ideas?

Thanks,
Matthew
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Old 11-07-2013, 10:51 AM
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03shadow
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IAC? Also, check the connection of the 02 sensors. I had a problem with my car running goofy at random times, and it turned out that one of the 02 sensors had partially unplugged itself from the 02 sensor extension
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Old 11-08-2013, 10:53 AM
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Thanks. Not the O2s, checked the connections. Any other options out there.

Thanks again,
Matthew
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Old 11-08-2013, 08:00 PM
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Daehawk
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From reading around online some others think its a vac leak or perhaps a exhaust leak near an O2 sensor.

Someone also said it may be worse with the AC on. Might be dumping fuel into a CAT.

As said the idle control valve is a likely culprit.
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Old 11-09-2013, 05:41 AM
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petrock
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It sounds like it is dying when the computer goes into closed loop mode. If I’m right that means a sensor is bad somewhere. The O2’s may be shorted or some other kind of electrical/sensor issue.

Your probably not getting a CEL because the car hasn’t been running long enough for the computer to tell. It is still in ‘learning’ mode since you disconnected the battery.

I would hook up a scanner that can read live data (available at most auto parts stores) and check out the various data points and see what looks out of place (if anything) when it dies. Good luck…


btw, I thought you sold your ’95? Its not in your sig anymore...
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Old 11-15-2013, 01:32 PM
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Originally Posted by Daehawk
From reading around online some others think its a vac leak or perhaps a exhaust leak near an O2 sensor.

Someone also said it may be worse with the AC on. Might be dumping fuel into a CAT.

As said the idle control valve is a likely culprit.
Originally Posted by petrock
It sounds like it is dying when the computer goes into closed loop mode. If I’m right that means a sensor is bad somewhere. The O2’s may be shorted or some other kind of electrical/sensor issue.

Your probably not getting a CEL because the car hasn’t been running long enough for the computer to tell. It is still in ‘learning’ mode since you disconnected the battery.

I would hook up a scanner that can read live data (available at most auto parts stores) and check out the various data points and see what looks out of place (if anything) when it dies. Good luck…


btw, I thought you sold your ’95? Its not in your sig anymore...
Sorry forgot about this thread.
Thanks guys for the suggestions, I didnt sell the car my father in law drives it as I dont really have space at my little place for it. He is going to take it to a mech as I dont have time to go out and look at it again so I will update when I get more info.

Matthew
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