redmustang302

I have a 93 Gt with 120k miles. eq length headers, 3.55's, underdrives, cold air intake, k&n, and off road H to flowmasters. i just replaced plugs, wires, cap, rotor, coil, and fuel filter to try to solve this problem: when my engine has been running for a while, it starts to miss or "buck" durring any acceleration, or constant speed. it maily only happens above 1500 rpm's and does it even in neutral when reving. i don't know what to do and i can't drive the car without getting beat up by the jerking motion of it when this happens. it is not a constant thing, but rather seems sort of random. however, it does do it frequently, about 15 to 20 times a minute sometimes. i need help. could it be the stock MAF sensor going bad?

vfast

well tap the electronics with your finger while it's idling if idles changes like it's breaking up on quits it's bad...check your tps next...then an o2 senor...get it by autozone and they can pull the codes for free if there is any

redmustang302

nothing changes when it is tapped, and i have unplugged it while it was running and it still misses, also i have the smog pump removed and i have only had this car for 3 weeks and don't know much about the 5.0's yet
i had a 4.6 before it but never had this prob
i heard that the maf on the 5.0's goes bad normally and i don't know how to check the tps or the o2 sensors

LOVEMY88GT

Well i had the same kind of problem and to see if it changes anything unplugg your o2's from the pipes. There are two of them right on the H-pipe. You dont even need to un screw them you just need to unplugg the wires to them. If it runs better then i suggest getting a new set of o2's they will run you about 30 bucks. Also it could be a vaccum leak but then you would prob have idleing problems. But if you want to check for vacumm leaks then go to the drivers side of the car (in the engine bay) and spray some carb cleaner while the car is running on the black vaccumm hoses. I found that the major one that does alot is the black box that says ford and has a closter of vaccumms on it. So spray around there and under the intake manifold while the car is running with carb cleaner. If they car revs up or changes in its idel then you have a vaccumm leak in that area where you sprayed. Well try these things and i hope i could help.

PS: A little fuel injector cleaner would not be bad either just to make it run better.

Nick

redmustang302

unplugged O2 but it still acted the same, i also added injector cleaner a week ago, and it runs the same with the maf sensor unplugged also
i don't know what to do and i need to get it fixed soon whithout throwing a grande out the window for a mechanic to find the prob. any suggestions?

roundman

it could be you got some bad gas with lots of water in it. try adding one or two cans of gas line antifreeze to the gas tank and see if this helps any. this stuff has alcohol in it that chemically ties up the water and makes it easier to burn it off. you could also take a gas sample from the Schrader valve on the main fuel line and pour it into a clear glass container like a soda bottle and see if any water separates out at the bottom after letting it sit for an hour or so. if you see a second liquid at the bottom of the bottle, that more than likely is water and you got some bad gas somewhere.

redmustang302

i'll try that, but are these symptoms of a bad MAF sensor also?

redmustang302

anyone? i need to drive this car, it gets me to school everyday

88PatrolCar

When you are in nutral put your foot to the floor and take it all the way up to 4800rpm, if the rpm's go straight up with no hesitation then rule out the MAF, but if it hanges up then you might have a prob with the MAF. What you can do is take the MAF off and spray the windings down with carb cleaner to clean it, let it dry then put it back on then try again. If you clean it make sure that the can of cleaner says "No Residue" on it.

redmustang302

i cleaned the wires with Q-tios and alchohol but prob persists, haven't floored it like you are saying, ill try it, but could the internals of the maf still be bad?