engine running funny

[SXYXC]

OK i will start off by saying this is a really hard thing for me to try to explain to ppl its one of those problems you have to see to know, or thats what i'm getting because most ppl have no idea about what i'm talking about.

OK so this has happened a little before but only lasted for a few hours. but it has been like 3 or 4 days and it keeps getting worste and don't want to hurt my engine.

Symptoms. When i get on the gas, now almost anything past half throtle my car will run good then randomly my exhaust will start to pop really bad, i will look at my tach and i see the RPMs jumping up and down, about 100-200 rpm and my car will just kinda sit there for a second, not speeding up or slowing down. It normaly happens around 2500 when WOT then again around 3500-4000, or jusut regular cruising when my car wraps up around 3000 RPMs. it really sucks because my car runs fine then BAM it hits slows my car down, then it goes on like nothing happend. I really can't hear if there is a knock or something in me engine, but i do notice the exhaust popping really bad, and thats when i started to watch my tach more often to see what happened. I have tried to discribe the symptoms to Protech performance in town (all mustang shop) and he has no idea what it could be and wants me to call and set up an appointment for next week so they can hook there computer up and see the volts and a/f ratio and fuel pressure and stuff. but i really don't want to have to pay to get it checked out if i can fix it myself.. any advice

Thanks

 

[WANNA_BE_GT]

Start by pulling plugs. What mods do you have?

 

[the98stang]

plugs/wires...possibly o2 sensor

 

[BobHyatt]

Another issue. I've seen this on multiple 5.0's, but it applies equally to any motor. Ford decided to make pulling the engine easier by installing some wiring disconnects so that you don't have to undo the fuel injectors, the various sensor wires, and so forth.

Whenever you have a connector, you have the potential for hidden corrosion. Two weeks ago a local kid had taken his old '90 5.0 fox to several shops with random cases of the motor dying, and also the MIL light coming on. He replaced the EGR sensor / control 3 times because each time the code said something was wrong with the EGR.

He brought it over to the house and we tried the "wiggle test" (if you don't know what that is, don't sweat it) with no results. But then as we sat there with the motor idling, I was following the main wiring from the motor to the firewall, convinced there must be some contact somewhere that had worn thru the insulation. As I moved a wire, the motor died. We repeated this a few times and discovered that I could "tap" one of the two wiring disconnects and the motor would die. I opened them up and they had the usual green oxidation inside. A thorough cleaning later, we reconnected everything, and the motor ran fine. No MIL to date either. Simple fix. Three different shops had looked at it and could not find what was wrong, since it was intermittent.

He did remember later that the problem started after he pressure-washed (!) his motor. Not the brightest thing to do of course...

 

[SXYXC]

ok update, i don't know if this makes it any harder to know whats going on. but this morning, when it was like low 80's outside me car ran awsome, even barly getting on it, it was smoother. then i romped on it just to see and nothing. later today when it got into the 90's it started to run ruffer, and the popping came back.

But i will check the plugs tomorrow, (which will really make me mad if they are bad, i replaced them when i got the car about 4 months ago, and i changed them with OEM plugs) the wires how can i check them, or do i just have to replace them and see if it helps??

as for mods, all i have are O/R x into flowmasters and a K&N air filter.. I know that 1 of me O2 sensors is bad, but i put it at the back of the pipe, and odly i havn't had an code since i went o/r which has been around 600 ish miles.