My mustang gt 96 ive changed cables,coils,plugs,mass flow sens,tps,iac,fuel pump,o2 sensors,fuel pressure reg,cleaned egr and throttle body and still having rough idles and back firing....


Asked by Mar 25, 2015 at 10:27 PM about the 1996 Ford Mustang GT Coupe

Question type: Maintenance & Repair

12 Answers


Is the check engine light on? Trouble codes? Backfiring out the tailpipe or the intake? -Jim


Yes check engine is on and its backfiring from tail pipe...

1 of 1 people found this helpful.

Trouble codes are po171 and po174 showing that its running lean.

1 of 1 people found this helpful.

Sounds like a vacuum leak. If you have an A.I.R. system (smog pump) check for a vacuum vacuum hose that's supposed to be hooked up to the diverter valve. If equipped this may cause the lean condition and the backfiring. Especially if it backfires when you take your foot off the accelerator pedal. HTH. -Jim


Ok thanks will check that out first thing in the morning..


Also consider a possible burnt exhaust valve


It seem that when i spray some throttle body cleaner it runs ok for a few hrs but then it starts again


But if thats the case on a burnt valve what should i do?


You need to do a compression test first, if it is a burnt valve the only fix is to remove the cylinder heads and have them done and replace the valve.


The diverter valve is part of the A.I.R. (Air Injection Reaction) system. When you decelerate the diverter valve dumps or "diverts" air from the system to the atmosphere. If you have a vacuum hose connected to the diverter valve as older systems did the strong vacuum from removing your foot from the accelerator signals the valve to dump. HTH. -Jim

Best Answer Mark helpful

Hey thanks for the advise jim i noticed that my car had cloged solenoid that comes from the fuel tank that connects directly to the throttle body what i did i just bypassed the solenoid and now runs like a champion ill replaced later anyways but thank alot for your time and advice!!!!

1 of 1 people found this helpful.

Good deal! Thanks for letting us know! Thank you for the best answer click as well. Glad to help. -Jim

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