: 98 sts bogging and backfiring



nicbrown
08-03-07, 02:40 AM
I need a lot of help! I have a 98 sts that was stalling then the rpm gauge quit. I decided to look at the spark plugs and they were extremly dirty so I changed them now the car is backfiring and the rpm gauge did not come back when I cleared the codes. I am assuming I may have mismatched the wires. Any Ideas?

eldorado1
08-03-07, 09:55 AM
Check that the ignition coils are firmly bolted to the valve cover. Check all of the connectors (there are 2 on either side) are fully seated. Check that each spark plug wire is going to the correct cylinder.

Ranger
08-03-07, 11:10 AM
Yeah, I suspect you crossed a wire if you did not do them one at a time. Recheck the firing order.

nicbrown
08-03-07, 12:37 PM
Thank you for your advise. I checked the wires and they are correct. Prior to changing the spark plugs the car did not fire right away and it is still happening. It died on me once in the winter for about 2 hours until I played with the electrical wires on the distributor. Now it takes a few cranks but will start. I brought it to the dealer and they could not tell me what was wrong. They changed a gasket on something and charged me 300+ CAD. By the time i got the car home it was worse. It stalled every time I stopped the car. I don't trust the local dealers so I did not drive that vehicle for the rest of the winter. Took it out in the summer and since the rpm gauge stopped working it stopped stalling. I asked the dealer tech if the distributor had anything to do with the problems and he said no but I don't trust him. What do you think?

Ranger
08-03-07, 01:40 PM
If I remember correctly, the tach is driven off of the ICM, which the coils are mounted on. Someone will correct me if I am wrong. That would lead me to look at the 4 ICM connections and finally the ICM itself. A FSM would be indispensable in the diagnosis.

eldorado1
08-03-07, 05:43 PM
Did you check the connectors on the ignition module (the "distributor")? There are 2 on each side.

The tach is driven off the ICM. My guess is you have a loose or corroded connector. Check them all.

nicbrown
08-03-07, 10:09 PM
Thanks guys the connectors are seated fine but they are exposed and look dirty. Should I use contact cleaner on them and see what happens? When the car does not want ot start I adjust the connectors on the right (drivers) side and it starts. Do you think there is a broken wire, if so any recomendations? I appreciate all our help so far.

eldorado1
08-03-07, 11:11 PM
Check carefully for nicks and cuts in the wires. Contact cleaner would be a good start. Make sure it's completely dry before plugging it back in.

If that doesn't help, there are replacement connectors with pigtails available from AC Delco, however I believe they are fairly spendy. These connectors are used on many GM models from the 90's on, so going to a u-pull-it to clip one off would probably be a cheaper idea if the connector needs to be replaced.

Is it the connector with 3 terminals that you fiddle with to get it to start? That would be the power to the coils.

nicbrown
08-04-07, 12:44 AM
I like that, in Canada we call them "Pick A Parts" LOL. I fiddled with both so I am not sure. What would I have to do if it is the power wires and what do I need to do to get the tachometer working again?

eldorado1
08-04-07, 12:48 AM
I like that, in Canada we call them "Pick A Parts" LOL. I fiddled with both so I am not sure. What would I have to do if it is the power wires and what do I need to do to get the tachometer working again?

If the wires are damaged, you will need to remove the damaged portion and splice it back together. If the connectors are corroded, they will need to be replaced, which means cutting off the connector and splicing in a new one, making sure all of the wires are correct.

The tach I believe is the middle wire (white??) on that 3 pin connector. Try wiggling it around ,reseating it, spraying with contact cleaner... whatever to see if anything changes.

Ranger
08-04-07, 11:08 AM
Thanks guys the connectors are seated fine but they are exposed and look dirty. Should I use contact cleaner on them and see what happens? When the car does not want ot start I adjust the connectors on the right (drivers) side and it starts. Do you think there is a broken wire, if so any recomendations? I appreciate all our help so far.
I think you found your problem. Sounds like a dirty connector or bent pins.

nicbrown
08-04-07, 12:31 PM
the connection I fiddle with to get the car started is the one that is closest to the front of the car on the drivers side. It looks clean though.

nicbrown
08-05-07, 02:55 PM
I cleaned them again and there were no cracks or cuts. OBD2 says p1375 icm 24x reference voltage too high and p1350 ignition control system. What do they mean and what should i do?

danbuc
08-07-07, 02:24 PM
You might have a bad ICM.....just a thought. If you've checked the connectors, and have no pin damage, or breaks in the wires, then the problem might just be the source of the signal (ICM). They don't last forever, and can go bad. If you wanted to double check, you could try checking continuity in the wires from the problematic connector back to the PCM. If there are no breaks there, then I would guess ICM, since it's rather unlikely that the PCM is faulty. Anyway, good luck....hope you get it running.

nicbrown
05-14-08, 12:25 AM
Solution Found!!! After bringing the car into two different Cadillac dealers to no avail I finally requested they change both crankshaft sensors. The vehicle has since stopped stalling.