maniac_3_2000

Originally I had an issue were at random, when I pull to a stop like at a light, the engine would go rough, under 500 rpm, until it stalled itself out. Also most of the time it would run up and down the rpm scale while at idle, from 800 rpm to 1300 rpm over and over and over again, kinda annoying but wouldn't affect anything. Then the other day on the way home from work it started to misfire and have extreme hesitation to the point were I almost didn't make it home just cause I couldn't make it up hills. I should mention the week before last I checked my spark plugs just to see how they were doing, and they were okay looking. After I checked them after this incident they were covered in black carbon and looked burnt. So I changed them out, along with new wires, and now at cold start engine it miss fires alot and stalls out after about 1 minute of being on. After the engine is hot, it stops doing this, and the idle was super smooth with almost no movement in the rpm scale, it stayed steady at 780.

After it was hot I was testing it further by using my snap on counselor 2, where I tested each waveform for each cylinder for primary and secondary ignition, and then I tested all 4 fuel injectors, and all have a great waveform. I plan to go back and run a quick test of both those systems while the engine is cold, as fast as I can before it misfires to see if I see anything, but I wanted to know if anyone has had experience with this and could recommend what it might be.

Further test data: I did a compression check on all cylinders, and they all came up as 195 (engine has been rebuilt with bored over pistons 9000 miles ago). I can't seem to find any vacuum leaks either.

Parts recently replaced: All motorcraft: Speed sensor, air temp sensor, O2 sensor, throttle position sensor (done 3 weeks ago)
parts recently replaced: napa brand: ignition pick up, cap and button, knock sensor, egr valve position sensor, map sensor, Idle air control valve (all done at the engine rebuild)

If you have questions please ask, as this problem has plagued me for awhile now, and after rebuilding the engine for a turbo and not even able to consider putting the turbo set up in yet because I can't even get the idle to run right. ( and no i haven't converted the fuel injectors, computer, or added the vam sensor, its basicaly all 87 stock, except the engine was rebuilt with all forged parts.)

mg man 75

I assume no codes when codes are pulled. Have you set the tps voltage? .90 to 1.0 vdc. The idle control valve on these cause problems. Maybe take apart and clean. [Don't use brake cleaner will destroy it, carb cleaner only.] Maurice
How to tps and check rest of engine electronic and parts.
http://www.rothfam.com/svo/reference/sensors.pdf

maniac_3_2000

I have no codes. Although I had one question about my computer functions, I own two scan tools, a generic and the ford ngs, and both I can't get sensor data from my 87 mustang but I can retrieve it from other cars i'v run across like my friends 86 ford LTD with a 5.0. On my car it just wont pull it up. Is that normal for our cars, or might my computer actually be bad?

To your other questions, my tps is at .95 volts. My idle air valve is new, but i checked it just in case, and it was good. I also spent some time today checking for vacuum leaks, I was able to pump pressured air into the system and found 2 leaks, one going to the transmission and one going to the the egr valve solenoid. Now of course this is assuming I dont have a leak on the intake side, as I pulled the hose that goes from the intake to the tree and used that point to tests pressure holding of the vacuum system. Still had no change in the issue of misfires at cold start up. I then went ahead and changed the ignition control moduel, and still had no change. Next weekend i am going to change out my ignition pickup, and if no change i'll plan to go through every sensor and check for resistance problems going to the computer, and double check that the sensors themselves are functioning properly from that website you gave me. But just in case I still can't find anything wrong do you have any other suggestions?

maniac_3_2000

Okay, so today I decided to pull the computer out just to inspect it visually. I noticed on the bottom sticker that covers the upgrade port it said 3.0 Taurus / sable only. Looked up the part number to verify. The ford part number is the almost the same, but the last 3 digits, plus the big 3 digits say FC1, which isn't for the 2.3 4 cylinder. This car has been in my family for years, my brother had it, then my sister, while they were in college, and then it was given to me. Before I got a hold of it all my dad ever did was take it to a repair shop for them, and then I went to a tech school and got my automotive technology degree, and I do all the work on it, but never looked at the computer. I do know the car was flooded in 1997 by my sister, and they probably had to change the computer out, probably at a shady shop or something, with someone who doesn't know they have that match the 3 digit code.