dorkpunch Posted June 29, 2011 Report Share Posted June 29, 2011 Hi all. I have a '92 Olds Cutlass Supreme with the 3.1. About a month ago it started to "buck" while cruising down the free way. At first, it would only buck once and then it would fine for several days before doing it again. It started doing it more often, but still, just a buck once and then it would run smooth. The last week it has gotten much more severe- up to the point yesterday it bucked / chugged / sputtered the last 20 miles home- under load. Once you get it up to speed it smooths out and runs pretty good. Under acceleration or load, it bucks. It runs PERFECT for about the first 10 minutes until it warms up, then it starts the sputtering, and the longer it runs the worse it gets. Things I have already tried: Replaced fuel filter tested fuel pressure- ~38 psi unplugged MAP sensor unplugged TPS unplugged temp sensor found melted connector to o2 sensor, tested it changed spark plugs and wires tested coil pack secondaries- all measure at ~6.4k ohms sprayed around intake with ether for vacuum leaks removed EGR valve, didnt look plugged up but sprayed some Carb clean and blew it out anyways I'm at a loss. It will run fine until it warms up. It seems like even there that its taking less time for it start doing it now. I've been researching this on the interweb, and have found SEVERAL threads that describe almost identical problems, but not a single one has posted back with what they did to fix it!!! Please help! Quote Link to comment Share on other sites More sharing options...
jman093 Posted June 30, 2011 Report Share Posted June 30, 2011 Might be the ignition module. Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted June 30, 2011 Report Share Posted June 30, 2011 Is your catalytic converter clogged? Quote Link to comment Share on other sites More sharing options...
virtuetovice Posted June 30, 2011 Report Share Posted June 30, 2011 Try a "new" set of coils. New, as in a good set pulled from a 3x00 W-body in a junkyard. The coils on the 2.8/3.1 are mounted right under the front exhaust manifold so they get heat soaked. Quote Link to comment Share on other sites More sharing options...
regalman Posted June 30, 2011 Report Share Posted June 30, 2011 (edited) Its more than likely electrical problem cause it happens while warming up. Electrical component is changing values. Mine did similar problem and it was crank sensor.Run fine for 10 minutes and stall,wouldnt start again for 5 minutes, then same thing. same coil pack and ighition module was used for years in all those GM v 6s , my car was 88 buick and the pack in it was from a 93 chevy. Swap that sensor if you loose spark. Did you get new ignition module too or just the coil pack? Crank sensor is cheap, pain to change though. ITs theignition module or crank sensor im sure of it! Edited June 30, 2011 by regalman Quote Link to comment Share on other sites More sharing options...
dorkpunch Posted June 30, 2011 Author Report Share Posted June 30, 2011 (edited) Thanks all for the ideas... I wondered about the cat. It doesnt seem to be getting overly hot, and there is still plenty of flow out the tail pipe, according to my calibrated hand... I'm leaning to it being electrical... I've heard and read some more, and it sounds like the crank sensor could be a culprit, or the wires from the crank sensor up to the coil pack. Didnt replace any coils, just tested them while the motor was hot. I'll have some help tomorrow, so hopefully I can figure a way to check the spark while its doing its thing. Is there any way to test the crank sensor or the ignition module? I'd much rather know for a fact that a parts broken before I go spend money on parts. Edited June 30, 2011 by dorkpunch Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted June 30, 2011 Report Share Posted June 30, 2011 my first instinct is ICM. pull one from a yard and replace it. Coils would help too. Quote Link to comment Share on other sites More sharing options...
jman093 Posted June 30, 2011 Report Share Posted June 30, 2011 Is there any way to test the crank sensor or the ignition module? I'd much rather know for a fact that a parts broken before I go spend money on parts. Oreilly or autozone can hook it up to a tester and check the ignition module. I'd take it off after the car's been driven awhile and then run down there and when they test it make sure they run the test a few times to make sure the thing is hot. They often work fine until they get hot. Quote Link to comment Share on other sites More sharing options...
virtuetovice Posted June 30, 2011 Report Share Posted June 30, 2011 They often work fine until they get hot. That would be the main giveaway to me, and that is what makes testing complicated...the car has to be hot enough to replicate the problem AND you have to be able to access it. Quote Link to comment Share on other sites More sharing options...
dorkpunch Posted June 30, 2011 Author Report Share Posted June 30, 2011 Well, we're going from bad to worse... Now it does it even when its cold. Little more description of how its acting now- It will start just fine. It is having very intermittent problems idling now though- every now and then it will miss or sputter while idling. In park or neutral, it will still rev fine- no issues. Sometimes, if I rev it up and let off the gas, it will die, but starts right back up. If driving- from a stop, if you stomp on it hard it will accelerate fine up to about 20 mph and then it starts doing its thing- sputter sputter cough chug. There *were* some codes when I checked this morning- 15, 22, and 42- low temp reading, tps sensor low reading, electronic spark time EST circuit grounded. I THINK I caused those codes by unplugging things, but I'm not sure. The one that doesnt make sense is the Code 42 EST thing... any ideas there? I cleared the codes and cleaned the battery terminals while I was at it, still does the same thing, and no codes have come back yet. I should ALSO mention that yes, its an older car, but it has VERY low miles. We bought it with 76k on the clock. It currently has 89k, most of that was put on it in the last 6 months. My wife drives it to school and averages around 4-500 miles per week. Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted June 30, 2011 Report Share Posted June 30, 2011 If It's getting worse, I still vote ICM. Pull it and swap. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted June 30, 2011 Report Share Posted June 30, 2011 I agree with everyone so far that has said ICM (ignition module) failing when warm is a classic symptom. I'd take it off after the car's been driven awhile and then run down there.... I wouldn't exactly recommend that considering the proximity of the exhaust manifold to the ICM... it'll be pretty toasty down there! Quote Link to comment Share on other sites More sharing options...
dorkpunch Posted July 1, 2011 Author Report Share Posted July 1, 2011 Sheesh. Problem solved? I had decided to pull the ICM and take it in to test it. Laid down, looked at it, decided I didnt feel like pulling it off right then, but I poked around and found the wires to the crank sensor. Pulled the wire about an inch more forward in the process of wiggling it to see where it went around and underneath the engine. Came back in, read a bit more, learned about and did the vacuum gauge thing, and it suddenly seemed to run fine. Just got back from driving it- 32 miles and not a hiccup. ??? Near as I can figure, the wires to the crank sensor ARE melted back there somewhere (I've read this can be a common problem), and when I pulled the wires up the melted part is no longer contacting ground. Dumb luck? Guess we'll know if my wife calls me from 50 miles away on her way to school saying the car died. Quote Link to comment Share on other sites More sharing options...
regalman Posted July 1, 2011 Report Share Posted July 1, 2011 Take a good look at that module, they crack eventually and the electrical runs open wider when warm causing loss of spark. Like said yesterday its the ICM,same module and coil pack on lots of gM vehicles. J/Y can reference it for u and you can get one off a later model vehicle. Cost me 50 bucks for module with coils, the newer ones were not mounted in that bad spot were oil leaks on them and exhaust cooks them. Quote Link to comment Share on other sites More sharing options...
dorkpunch Posted July 2, 2011 Author Report Share Posted July 2, 2011 Wife drove it to school and back (100+ miles) and it didnt miss a beat. It HAS to be in the crank sensor wires.... Guess I need to dig in there and find the bad spot. Quote Link to comment Share on other sites More sharing options...
dorkpunch Posted October 2, 2011 Author Report Share Posted October 2, 2011 Just for the record.... 6,000 miles later it started doing it again. Finally got around to pulling the wires from the coil pack to the sensor off, and sure enough, they were melted. I just cut the connectors off and made a new wire with the old connectors, plugged it back in, and the problem seems to be solved. I let you know for sure when the wife gets back from testing it... Quote Link to comment Share on other sites More sharing options...
urbex Posted October 2, 2011 Report Share Posted October 2, 2011 I'm glad you gave a follow-up! A lot of people may never return to say what the culprit was when they figure it out. I'll have to go check those wires on mine, since that's one thing I haven't done... Quote Link to comment Share on other sites More sharing options...
GP1138 Posted October 2, 2011 Report Share Posted October 2, 2011 Just for the record.... 6,000 miles later it started doing it again. Finally got around to pulling the wires from the coil pack to the sensor off, and sure enough, they were melted. I just cut the connectors off and made a new wire with the old connectors, plugged it back in, and the problem seems to be solved. I let you know for sure when the wife gets back from testing it... I had this happen to me a while ago, and it was FRUSTRATING as hell. Glad you got it fixed! Quote Link to comment Share on other sites More sharing options...
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