help! running problems

[frosho]

I have a 1994 SHO MTX. Within the last three months or so, the car began to run rich randomly. Sometimes it does this as soon as I start the car, and sometimes it happens while I'm driving, but it corrects itself eventually. I've tried to diagnose the problem myself, but I can't figure out what it is because I've never heard of these symptoms before. The tachometer shows that the engine is running much slower than it really is. Instead of showing 800 rpm at idle, it falls as low as 400-500. If I rev it until the limiter kicks in, it only shows about 5500, but I can hear that it is spinning at 7300 where it should be. Also, there is a dramatic reduction in the engine's power and the exhaust note drops to big-displacement muscle car levels instead of the normal high-revving Japanese tone. Since the engine is getting too much fuel, the car's gas mileage has also dropped quite a bit. I can't afford to keep driving it like this. What's going on?

 

[frosho]

i did the koeo, koer, and sefi tests... heres what i got:
koeo: 136, 536, 521
koer: 176, 211, 212, 215, 542
sefi: 5
i looked on shotimes.com so see what they meant but it didnt help me very much. perhaps some of you who have dealt with the codes before can help me out??? it would be much appreciated!

 

[frosho]

ok i think i found the culprit. my dad suggested i try using his timing light to check the plug wires so i did and sure enough cylinder 5 was misfiring when the car seemed to run ok, and then it would stop completely when it ran like crap. i switched wires 5 and 6 to see if it was just the wire, but 5 was working fine on cylinder 6 so it wasnt that. and im almost positive it's not the plug because it does seem to work ok. i plan on replacing the ignition module because it seems like it's just not getting power to the plug. any suggestions before i spend $120 on a new module??? if you can think of something else that could cause this please let me know!!!

 

[Rockledge]

If it were mine, I'd pull the plug on #5 and see what it looks like.

The fact that you are getting PIP, SPOUT and Coil codes at the same time also makes me think that it's possibly a bad DIS module. But $120 is a lot of skins. Look around for a used one. Maybe a junkyard has one for you. They are on eBay all the time, or you can post an ad in the "Wanted to Buy" section here.

FWIW, the 3.0/3.2L SHO shares the same DIS module with the supercharged 3.8L (T-Bird, Cougar).

 

[frosho]

thanks for the input. i tried testing wire 5 with a different plug that i had laying around and it didn't work, but i did the same thing to 6 and it sparked so im almost positive its not the plug. also last night and today it was firing pretty well for the most part. anyway i was planning on calling the junk yards tomorrow to get a cheaper ignition so ill do that and post whatever happens.

 

[frosho]

ok i pulled an ignition module from a 95 mtx at the junkyard today, put it in, and found that that wasn't the problem. i think i'll replace the DIS next and see if that will help me.

 

[projectSHO89]

ok i pulled an ignition module from a 95 mtx at the junkyard today, put it in, and found that that wasn't the problem. i think i'll replace the DIS next and see if that will help me.

"ignition module"??

The DIS IS your ignition module.

No telling what you actually did replace.

FWIW, these symptoms are almost always a faulty DIS module.

Steve

 

[frosho]

sorry, i didn't know what the part was called but it's whatever the spark plug wires connect into. coils perhaps?

 

[Rockledge]

sorry, i didn't know what the part was called but it's whatever the spark plug wires connect into. coils perhaps?

That's the coilpack.

The DIS module is mounted on the upper intake crossover tube, passenger's side of engine, gray in color. It has the two wire harnesses clipped to it on each end. In this picture of yamahaSHO's '95, you are looking right at it (hope you don't mind Jason ):

If you can grab one from the junkyard from the same '95 MTX, that ought to be your next step.

.

 

[frosho]

thanks i knew what the DIS was but i thought it might have been the coils causing the problem so i tried that first. that 95 i was looking at has had the hood taken from it, so everything is now exposed to the elements. plus the plastic isn't in great shape, it's dirty and cracked so i didn't wanna buy it and end up 2 crappy ones on my hands. there weren't any other SHOs at this particular yard though. did they use the same DIS on any other models?

 

[Rockledge]

Maybe a junkyard has one for you. They are on eBay all the time, or you can post an ad in the "Wanted to Buy" section here.

FWIW, the 3.0/3.2L SHO shares the same DIS module with the supercharged 3.8L (T-Bird, Cougar).

(Hey, is there an echo in here? )