Misfire along with stalling

[roadbratt]

Hiya,
The past week we've had some problems with the motor misfiring. We changed the oxygen sensors along with the ignition coil, because the codes said something about oxygen sensors and the ignition coil.

After replacement, the car ran ok for about a day, with me driving it to and from school, maybe about 5 miles total. The next day, as soon as I turn it on, it begins to misfire. I was pretty ****** off. I havent ran the codes since the second time it started misfiring, but when it does, it runs very rough, and idles just above 500rpm. Earlier today, my father and I took a look at one of the spark plugs because we thought it might be one of them that arent firing. It turned out to be pretty worn. So tonight, right after we bought some bosch platinum plugs, on the way home, the car would stall when you put the clutch in or let it get low. It just wouldnt idle on it's own! My father who was driving was able to keep the rpms up, even when stopped at a light. Could the car not idling right be part of the misfire problem? A while ago, we added some fuel injector cleaner to see if that helped, nothing noticable happened. If anybody has a tip or a question, just ask or even better, email me.

My car is a 1992 MTX with about 145k miles on it. No mods except for a catback system(that we know of) and a spoiler which wasnt original. It has a new ignition coil along with new spark plugs(not in yet). Also, if anybody knows a good mechaniac or who knows something about the SHO motor in northern VA, let me know. thanks

-andrew

<small>[ March 13, 2003, 08:11 PM: Message edited by: roadbratt ]</small>

 

[BlackOnBlackATX]

you should check some of the other plug wells for oil, it could be your problem, but your symptoms sound a little more severe.

i think you will find that you will be warned against using bosch platinums in the SHO, alot of people here have recounted horror stories when using anything other than the stock plugs. not everybody, but *alot* of poeple. have you checked your wires? you may need new ones if they were never replaced. run your codes and see if it has anything in the memory. let us know how it turns out.
Bob

 

[sdpatt]

The Bosch plugs are not better for the SHO than the Motorcraft AGSP32PP double platinums. If you use the Bosch plugs, you will soon have to replace them again since the electrodes have eroded away.

If you run the codes, post the numbers and not just what part was identified. There is more to diagnosing error codes than just swapping the part that was not within its normal operating range. In your case, a problem with the DIS such as a loose connection or ground could cause the ignition coil fault which in turn could cause the O2 sensor to read rich. It's not just throwing money at the car, it's figuring out what is wrong and then fixing the problem, not the symptoms.

 

[roadbratt]

thanks for the info. i'll go swap the bosch plugs for the motorcraft ones with the double head. the stalling doesnt really matter much, it's just that I want to get the misfire problem solved before I sell my car. i've also heard that it could be the crankshaft sensor but i know the labor would be very long to replace it. could that be a part of the misfire? also i heard about the camshaft sensor and the DIS(dont know what it is) that could be the problem. any tips?

I'll pull the codes tonight and i'll let you know what they say. thanks for the info so far.

-Andrew

 

[BlackOnBlackATX]

a bad crank sensor will cause stalling but not misfiring as far as i know.

the DIS is on your intake, (as youre staring at the engine from the front of the car) left hand side on the crossover tube, rectangular plastic box on the side of the tube with two wiring harnesses on it. make sure all 4 screws are holding it in, and that there are 2 bolts holding the big crossover tube in place.

i guess its possible your cam sensor could be the problem, but it will probably come up in the codes if it is.

 

[roadbratt]

hiya,
I just finished replacing the plugs, and they seem to run fine, so that isnt my big concern as of now. the thing that makes me furious is the fact that it still misfires even after the plugs and ignition coil. i tested the plug wires and they are fine, so it cannot be the plugs nor anything between there and the coil.

the funny thing is that two cylinders must be misfiring do to the fact that you have about the same power as a geo metro, and once in a while you'll idle about 950rpm but the engine light will NOT be on, but you can still feel a misfire. the tach also kinda jumps around a bit, nothing big, but you can notice it. so I do believe it is misfiring on at least two cylinders. any info I can help will i will be glad to provide. please, i really need this to be fixed or i will be forced to sell the car.

-Andrew

 

[luigisho]

ummmm...got codes? Plug wires on right? The Chiltons has the wrong diagram.

 

[roadbratt]

i'll get back to you with the codes. and why do you say that the chilton's book has the plug wires on backwards? i know if you look at the coil from top right and go down, it's 1 2 3 then left bottom going up, 4 6 5. the car ran pretty bad for about 20 min of driving around, then it fixed itself and ran fine from there. kinda odd.

 

[projectSHO89]

Run the cylinder balance test portion of the Quick test. See what it shows as to whether there is a weak cylliner (or more).


Steve

 

[BeatDaSHO]

i'm thinking faulty plug wires for the misfiring issue.

Greg

 

[roadbratt]

We tested the plug wires using an ohms meter. they were all the same(i forgot the value) and they looked pretty new.

 

[roadbratt]

Hiya,
I ran the codes the other day, here are my results:
When I did the key on engine off test, it said system passed and then an error code having to do with my clutch wire(something like that). that was the only error that came out on that test. Now when I did the key on engine on test, I got the clutch code along with "not able to control the rpm". i cannot remember if there was more, but the car was misfiring during the test, that might be why I got the rpm error. After I goosed the throttle after I was done testing, it went back to normal. I'm thinking maybe it wasnt getting enough fuel? maybe a bad fuel injector? I dont know how that could be the problem, unless they're bad, I even put in fuel injector cleaner about two weeks ago. when i'm home i'll post the codes on what I got out of the car. In the meantime, any ideas?