cavaks89gt

ok so i am new to the 5.0 i got an 89 mustang gt i traded my 4wheeler for. ok so it had a cel only under acceleration as soon as you let off the gas it would shut off. so i tried to get the cel to flash the codes i jumped the sti to the negative battery terminal and no cel flash. the cel wont flash anything so i thought i hooked it up wrong and jumped another solo wire with black wires going to the plug to the connector it made a spark so i disconnected it. i got the car to run the egr self test where it ran the engine to 2grand for a little bit and then back down to idle still no cel flash. shut it off then the next time i started it a few minutes later the engine runs like when u start it cold like a higher idle rpm now the car does this every time i start it even when warm it runs at about 1200 for a minute then down to 900. also there is no more cel during acceleration and i have terrible spark pinging and the timing is set a 1o degrees advance at base timing the little gray thing uninstalled. ok so also the car will randomly die and wont start for like half hour 45 minutes. could the ecu be bad? any help would be awesome i really am stumped with this. thank you

enix187

First off, welcome to the forums, secondly SLOW DOWN I couldn't help but read that whole post extremely fast. From what I gathered, you probably need a tune up something terrible, the hanging idle at start may be weird but my car does it too,

as per the dieing and not cranking right back up it sounds like the TFI has gone bad, its a little electron piece on the side of the distributor that is a pain to remove without a little tool thats about five dollars at the parts store, you can google or search TFI Module and find out all you need to know, you can take it off and to the parts store (orielly's) and they can check it.

dreamer1uk

+1 on the above poster

I think its estimated that 99% of ECU returns that are thought to be faulty are usually not the case and are incorrectly diagnosed by the person working on the car. Thats an interesting fact i learned a few weeks ago from a Volks. Tech

cavaks89gt

thanks for the input guys another reason i thought ecm is because it doesnt flash ecl at all now. not under accleration or anything and it didnt have spark ping and ran fine besides the light flashing until i jumped the terminals to try and get the codes. also it didnt even flash the first few flashes that it does at first. unless its some kind of coincidence the the tfi went at the same time i did this and whatever problem the car had under acceleration magically fixed itself. just doesnt make sense to me. i read on another post possible cooked a couple of the pins on the ecm?

enix187

TFI's have the ability to just break, there's a rule of thumb, if your fuel pumps come on your ecu is good, not always the truth but most of the time it holds true.

cavaks89gt

ok so im kinda leaning towards the tps being bad but then again this car has been going haywire since i tried dumping the codes. the tps reading was out of control wouldnt stay at any specific voltage i know its supposed to read like .98 or something like that i have it written down and ive adjusted it before. car is doing this now 1/4 throtte is fine as soon as i give it more gas tons of pinging and tons of power loss let off and its fine is it possible tps is sending wrong signal and its not creating the right mixture and leaning out?

TrimDrip

It would help if you could find a way to run tests. but yes, detonation can be caused by a tps.

also, the only test I have ran on my car are the KOEO, KOER, wiggle and injector balance test. I have never heard of an egr self test for these cars.

cavaks89gt

ok guys i know you are all probably going to be against this but the tps isnt getting voltage from the car all of these things the spark ping, the cel all of a sudden being fixed, no voltage at tps, the dying and not starting back up, the car had none of these problems until i obviously did something wrong trying to dump the codes, im no master ASE or anything but there is no way all these systems all F*** up at the same time i did that. i must be the 1% that the ecu actually goes bad. i also read in a thread about dumping the codes that if you jump the wrong one you can damage the ecu. i got the $94 for the ecy and my gutt says it would be that. ill let you guys know how it goes. thanks for all the input.

dreamer1uk

Well you could find the ECU pin-out and start checking for voltages with a DVOM and so forth.

Let us know how it goes though

TrimDrip

If you put the black wire from the voltmeter on the black tps wire and the red wire from the voltmeter on the green wire from the tps and turned the ignition key to the run position and got nothing, there is something wrong with either the wiring or the computer. I would pull the kick panel and test the ground to make sure it is getting at least -.05 volts. If it is, I would look at another computer.

Here is a tutorial for pulling codes.
http://www.youtube.com/watch?v=ivxDYSmGjHc