Car is in not running right, need help!

[99GT-owner]

Ok, so something is wrong with my car. It happens both when I have a tune installed or just as stock, but for some reason the car runs a little better with tune? The car misses under load, has a rough idle, and exhaust smells awful. While driving it feels like my clutch is gone (only way I know how to explain it), but its not because it does the same thing at idle. The rough idle is different than an idle surge or dying out. It just seems like it is not getting air or fuel one. Any ideas guys?


I cleaned the MAF, didn't work. So then I replaced it with a working one, nothing still. Plugs are brand new, just replaced the alternator. I checked TPS voltage, its good. Fuel filter is new, air filter is k&n and was just cleaned. I have done everything I could to try and find out what is wrong and no luck. No C.E.L. or any kind of codes. Car just runs like crap. I am just tired of loosing sleep trying to find out wtf is going on...

Thanks in advance to all!

Andrew

[99GT-owner]

Oh yeah, Car is a '99 Mustang GT 4.6L SOHC.

DiabloSport tuner U7146 (currently not installed)
H-pipe (Off road... no cat)
Flowmaster 40's
K&N filter
Short Throw
3.73 rear

Just in case ya needed to know...

[Phil]

It sounds like a fuel or electrical problem. Since you say the spark plugs are new. Pull them all to see it one might not be firing. It will look clean compared to the others if it is not working. At that point it could be a coil or plug wire. You can also pull one fuel injector connector off at a time. If the running of the engine changes you know that the injector is working. If you disconnect one and there is no change you know that one is not working. Give these a try.

[99GT-owner]

Thanks Phil, I will give it some shots. I am leaning more towards fuel myself, maybe injectors? Is there anything that I can do with the Predator that would show me anything? I have tried to run a log but I don't know what numbers I am looking for...

[sohfast94]

Because of the way the circuitry works with the injectors there aren't many test besides the one Phil described... Just have car idling and pull one plug off at a time until you find the one that makes no change when you pull it off then you know which is bad....

The plugs when all pulled you'll notice one looks completely new if it's not firing...

[99GT-owner]

I will try all of that. It wont harm the engine unplugging stuff like that? How tough of a job is it to pull out the injectors? I have never done that on a my car...

[06MonteSS]

you're not pulling out the injector itself, just unplugging the connection to it...

[99GT-owner]

Yeah, I know. But what if one is bad. How tough of a job is it?

[06MonteSS]

aaaaah, gotcha...

http://autorepair.about.com/od/fixityou ... instal.htm

[99GT-owner]

Thanks for the site. I am hoping that they do not need to be replaced... Could a dirty one or just plain bad gas be the problem? If so, what is the best recommended way to clean your injectors?

Thanks a lot guys...

[99GT-owner]

Unplugged one injector at a time, Engine responded to each. They work. Listened to them with a screwdriver like a stethoscope and they all "ticked" ticked like they were supposed to. Took off EGR, cleaned and tested it. It works. Car still has problem!

Any other ideas guys?

[99GT-owner]

Ok, I think I have the problem narrowed down to coil packs. Anyone got suggestions on how to troubleshoot them? Which are the best?

[mikel]

Try moving them around to see if the problem moves with them.
Dont want to replace coils if you dont need them.

Also, have seen issues with most of the aftermarket stuff, so my suggestion would be to stick with the stock coils.

[99GT-owner]

Ok, Thanks! I will give it a try...