which switch/sensor is bad?

[393foureyedfox]

My 95 SHO auto has been parked since May and I want to get it fixed now that I have some time from school. Early this year, I'd be driving down the road and it would feel like the engine shut off, or went down to just a few cylinders running, and the CEL would come on. If I flicked the ignition switch off and back on really quickly, everything would reset and it would be fine for a while. It started doing this inscreasingly more often, until it did it so much that the ignition switch flip wouldnt reset whatever it was, and I parked it until I had time to mess with it again.

At that point, I could go out and start it and almost every time, it would run SO poorly it had almost no power, felt like it was missing badly, the CEL would come on, and by the smell of the exhaust, it was running richly or some cylinders were just plain not firing at all. and heres the weird thing....about half of those times it did this, the transmission would barely pull itself. Other times the transmission pulls great.

All this crap is a symptom of an electrical sensor or switch somewhere, but I am not sure which one. Last december I did a FULL 60k service (belt, gaskets, crank sensor, cam sensor, throttle position sensor, plugs and wires, etc), so I doubt it is any of that stuff. My next bet is either the ignition module on the passenger intake, or the EEC itself.

What else could control both the motor and the transmission? it is an automatic car, 120,000 mi.

Any ideas?


Thanks!




Doug

 

[jimtash]

Get the codes.

 

[rubydist]

yup, pull the codes. we can speculate all day, but if you tell us the codes, then we can help you.

 

[393foureyedfox]

forgive my ignorance, I am mostly a mopar guy.....on dodge's, you flick the switch on and off three times, and the CEL flashes a code on the dash for you. How do you get codes on a 95 SHO?

also, the intake air bypass valve is new (ford), and the tps is new (aftermarket replacement).

i just started it up and it's not doing any of those issues now, but I know it will again anyway.

what sensor/relay/switch is likely to cause a rough running engine AND throw the automatic all out of what at the SAME time? I'm thinking EEC most likely, but I have never had an EEC go bad on anything before, so I'm unsure on that. I'm about to head to the junkyard and grab the DIS off a junked SHO and try that since theyre $6 there.

any ideas? code retrieval?


thanks!

 

[Sarge1400]

Look here >>>http://www.shophoenixproject.com/eec/eec.htm for info on retrieving codes.

Do you know if the car is chipped? If you're not sure, swing the glove box down and look on the firewall.

 

[393foureyedfox]

no chip. the original owner I bought it from last year gave me a chip that he used to run in it, but I never put it back in. The car is all stock except I did the 96 brake upgrade last year when I rebuilt the whole suspension after buying it. Trans has never been rebuilt, but he religiously had the fluid changes done at the dealer, and he had all service records on it since new. It was due for its 2nd 60K when I bought it, so I did all that myself. He had just had the Ford dealer do the wires, plugs, bypass valve, and valve cover gaskets weeks before I bought it, then I did the rest when I got it home. It ran great for 6-8 months then started doing all this. I'm in nursing school and didnt have time for it so I let it sit until now, when I have a month off.

As a side note, once it is running, you can unplug the cam sensor and the MAF and it still runs fine. Is that normal?

I suspect the EEC just because when it acts up, both the motor and trans are off, and when it runs okay, both are great.

 

[luigisho]

If you unplug the MAF it runs in a default mode. Unplugging it will trigger that code in the computer so that will be in there along with the rest. Sounds like a sensor.. just need the codes to help narrow it down.

 

[393foureyedfox]

as suspected....

511 (O) No power to PCM pin 1 or bad PCM (processor)




but also....

158 (O,R,M) MAF sensor is/was high or short to power - MAF





what do you guys think? Is having unplugged the MAF while running solely responsible for the 158 code, and I should just suspect the EEC itself to be bad? If the computer is coding a PIN 1 power fault, I assume it could just as easily be that the wire to/from PIN 1 is damaged somewhere along its length, such as an intermittent short or ground?


if the computer is bad in itself, would it be able to report that it was bad, even when it is currently running perfectly?


thanks guys!

 

[393foureyedfox]

just for ***** and giggles, i pulled the glovebox door and sure as ****, there WAS a superchips card in it! I dont know what that other one was he gave me with the car.....anyway, I pulled it out and restarted the car and it seems fine (but then again, its a hit and miss problem).


I'm gonna clear the codes and try again.

 

[393foureyedfox]

after removing the chip that "wasnt in there" and clearing the codes, I got an all good 111 code.

I'll roadtest it over the next few days and see what happens.

Thanks, guys







does the Superchips chip have any control over the automatic transmission?

 

[rubydist]

depends on what kind of program was in it.

often what happens is that the chip is not seated properly or comes partly off and that causes all manner of issues.

glad you got it running right again so quickly.

 

[Sarge1400]

often what happens is that the chip is not seated properly or comes partly off and that causes all manner of issues.

Truer words were never spoken! http://www.shoforum.com/showthread.php?t=124190&page=2

 

[393foureyedfox]

i just pulled the chip out and left it out. Its a Superchips brand, I dont know if it was a universal tune chip or a programmed one to this car. The original owner was a 50-something guy who bought it new, I doubt it was a custom tune. Whoever put it in wrote the date (11-99) on it, his last name, and the factory computer calibration code (d401 or something) on it. It was in tightly, and was secured with a strip of duct tape....it wasnt loose.

maybe that fixed it, maybe not. sometimes it would go a week without doing its issues, sometimes just a block or two. It shows no codes now though....

thanks guys, I never wouldve thought to check for a chip in it.

 

[SHOMON]

That will deff fix it.