[meko49301]

it is a 96 mustang, when started it runs fine. if you let it idle for about 10 minutes, it will drive fine. BUT, if you start it and let it run for only a minute or two it will not run proper. it acts as if it is misfiring but no CEL comes on. you can hear it backfire into the intake i believe. but, if you put your foot all the way to floor and give it 100% you can hear it not firing or it is just attempting to. and at that point, you can feel it catch itself and the rpm's will jump up maybe another 100. it does not matter where the rpm's are, or what gear. then all is well until you let off the gas for lights or stop signs. then it will do it all over again. on the highway, it will act up constantly, and will take a downshift just to hold 70 (speed limit here in michigan). then you get back up to 70-75 and let off to do 70, and youll go through it as long as you drive.

my thought is, between partially clogged cats and the MAF sensor. but, was wondering if anyone has experienced this.

other issues that just to be aware of in the thought, is the rear end is pretty much toast (hums like a SOB and slams into drive or reverse but not while shifting), alignment is not too great, exhaust rattles, and little things along those lines.

repairs done in the past year: coil pack, wires, plugs, rebuilt transmission, rebuilt basically front suspension completely, 3 calipers, all rotors and pads, master cylinder, rear shocks, alternator, battery, and the list goes on. i have alot into it already, but with this happening its almost undrivable.

with that being said, any ideas? thats as much information as i can remember.

 

[JonR2006]

Even though the CEL is not illuminated, I would run codes anyway and see if the computer is throwing any...let us know what codes.

Simple things to start: fuel filter, clean the MAF sensor with MAF sensor specific cleaner, pull a few plugs and look them (how do they look?).

Have you verified there are no vacuum leaks (sspray carb cleaner around all vacuum hoses and intake gaskets...if idle surges then there is a vac leak).

Are your battery and alternator working properly?

Report back and let us know...

 

[meko49301]

fuel filter is also new. maybe...late summer.plugs looked fine a few weeks ago when i looked at them last. I will take my scanner out again on it, I havent checked lately. but I will re check. i have not cleaned the MAF sensor since...maybe a year or so ago.

 

[Ryan S]

Get your fuel pressure checked. If it doesn't hold about 39-40 psi at idle/ regular driving, you've found your problem. The fuel pressure check is cheap to do (you can buy a fuel pressure tester) or get your local shop to do it.

You probably don't have an SCT tuner, but if you do, you can check it in your datalog with Livelink....that's what I usually do, to see if various systems in my car are doing what they're supposed to.

 

[meko49301]

have not yet tested fuel pressure. had all codes read, and popped up an egr code with it possibly being stuck open. could this cause the sluggish-ness and backfire into the intake im hearing?