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

mustang newb...rough idle

Old 06-14-2017, 08:02 AM
95GT Poni
Join Date: Jun 2017
Location: Wisconsin
Posts: 1

Originally Posted by warthogdriver View Post
95 3.8l man.......sorry lots of info here.

i have replaced the plugs, plug wires, fuel filter, oil change, pcv valve, and all vac lines that i could find. my usual welcome to the family treatment for used car buy.

i also just replaced cam pos sensor...only thing that came up on the c.e.l scan

i have two issues, first rough idle engine will shake and stall when coming to a stop, at higher rpms and normal driving all is great.

i dont know if it is related but i am noticing a gas smell at passenger fender. i took a look behind it when changing vac lines and noticed some sort of black box..guessing part of fuel of the lines running from that box that goes towards front of car and winds down by radiator is the source of gas smell.

big question (mustang gentle) is that an issue related to my idle problem? is something in fuel system plugged up causing a vapor lock?

coil pack maybe...that is the other thing i have come up with after some searching.

oh and no check engine light.
Had similar problem with 95 V8 Mustang. From running rough with check to not even able to start to running perfect. Ended up being MAF sensor. Found easy way to check for bad sensor on YouTube which appeared to diagnose problem correctly. This YouTube video was the one and only place I found this solution so I want to pass it on. Simply, with car running, disconnect the MAF sensor. If car continues running the sensor is bad. I disconnected the IAC sensor and the car immediately stopped running. So following the same thought process, it is good and didn't replace. Maybe this is BS but it worked diagnosing the bad MAF which has my son's mustang back running perfectly.
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Old 06-25-2017, 08:34 AM
Paul Blakey
Join Date: May 2017
Location: ok
Posts: 20

Originally Posted by warthogdriver View Post
ok, well i can report back now a happy camper.

the culprit was the maf, bought some maf cleaner
(thought it was funny can said..4-10 hp improvement..really?)
put it all back together and presto, a run up and down the road and all is good.
well almost, i still have to clean/replace iac...the idle is smooth but now is going up and down ever so slightly. man double whamee.

is maf routine maintenance on these cars? i have a 99 blazer ( i know long way from mustang) and have never cleaned the maf...let alone look at it.

still happy though, thanks for all the help
It's not a bad idea to routinely clean the sensor off, when you have your air filter changed. That would be a good rule to follow. Also cleaning the IAC around the same time would insure it stays clean preventing future idle problems.
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Old 08-06-2017, 12:34 PM
Join Date: Aug 2017
Location: Alabama
Posts: 6

My 96 sounds like had same kind of problem. I changed eeg erg a couple of sensors. The last one that I changed that seem to fix it was a mass air sensor. On my particular it had to be a oem a aftermarket would not work the guy who works on my car tried it and still had miss after getting into higher speeds it was not as bad but he put a oem on it cleared it right up..
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