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91 Bonneville Shaking
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Author:  extrabigjon [ Mon Apr 02, 2012 1:26 am ]
Post subject:  91 Bonneville Shaking
I have a 1991 LE. Drove the car about 7 miles down the highway then pulled over to check a rain gauge and left it running while in park. While I was out the car died. Got back in tried to start and it would just crank but not fire up. Towed it home and tried it later and it ran for about two seconds then died. The coeds I pulled were 27 - Gear Switch Diagnosis( Second Gear Switch ) and 44 - System Lean. While at home I could hear the fuel pump make noise and fuel comes out the pressure check valve on engine, don't have a gauge. Also checked the magnavox coil pack secondaries and all three said 0 ohms. I later checked them again and got 10.23 ohms on the one closest to the front of car and 0 ohms on the others, never checked the primaries.

Towed it to a mechanic. He test drove it for a while (a parts run or two, guy lives about 12 miles from town) said it always started but ran like crap. He determined it was some water in the gas. He put some HEET in the tank and recommended I do fuel treatments in the future every few tanks, I've never done any before. The tank was about 3/4 full with no prior problems. While he had it, he cleaned the throttle body said it had a lot of carbon on it. Mentioned my coil findings to him and he is aware of the problems with the older style. He said it had very good spark but I didn't ask where or how he checked it. Said he had it purring like a kitten and I went home a happy customer. I cleared the codes, he said he could not get power for his gauge to work.

A few days later after doing some errands in town, about 6 miles one way. I was almost home and the car started shaking very bad on the highway for about half a mile then quit. Almost like going on a washboard road. I was thinking it might be my coils and the car was running on only two cylinders. Didn't catch what any of the gauges were doing as I was preparing myself to put it in neutral and coast into the driveway. Checked codes and only had 27 - Gear Switch Diagnosis( Second Gear Switch ). Made another quick trip to town later that day and had no problems at all.

If you are still with me, first thank you and second what might you have for suggestions on what is wrong?
Author:  murderedout [ Mon Apr 02, 2012 2:03 am ]
Post subject:  Re: 91 Bonneville Shaking
gotta have something to do with the new icm and or coil. did you check all the spark plugs and wires? make sure they are all tight. does it do it while at idle?
Author:  extrabigjon [ Mon Apr 02, 2012 1:01 pm ]
Post subject:  Re: 91 Bonneville Shaking
The coils and icm were never changed. The plugs and wires were changed 3500 miles ago and seem to be tight. It only shook the one time on the highway going about 60 mph.
Author:  murderedout [ Wed Apr 04, 2012 1:11 pm ]
Post subject:  Re: 91 Bonneville Shaking
This may be weird but did you hit a bump before it started shaking? i ask this because maybe something got knocked loose and or is barely hanging onto (something). what i mean is say you just did your plug wires and you are driving around town and a plug wire comes loose, but is still firing spark to the plug. i still beleive its something to do with the spark, but what and where?

I experienced a sort of the same shake and misfiring feeling while driving and it was a loose and corroded negative battery cable. I cut off all the rubber and wire brushed it. runs fine. now i have my icm problem. CHECK BATTERY CONNECTIONS?!?!?
Author:  extrabigjon [ Wed Apr 04, 2012 1:26 pm ]
Post subject:  Re: 91 Bonneville Shaking
I reseated all the plug wires. I don't recall hitting any big bumps that would jiggle something loose. Battery connections are all nice and shiny. Since I had to reset the codes and wanted to clean the evap coil I just left it unhooked while I did the work. I do have a new bosch oxygen sensor to put in once I have time. No idea how old the one in there is. I am trying to locate parts to upgrade to the delco type II ignition. My local yards claim not to have anything that old though, and no longer let you pull the parts.
Author:  murderedout [ Wed Apr 04, 2012 5:20 pm ]
Post subject:  Re: 91 Bonneville Shaking
i think you shoulld stay away from bosch on the o2 sensor. i have heard bad things..just my opinion. i think our cars like oem ac delco stuff lol
Author:  extrabigjon [ Wed Apr 04, 2012 6:01 pm ]
Post subject:  Re: 91 Bonneville Shaking
Yeah I've been planning on returning it and getting an ac delco.
Author:  Jrs3800 [ Thu Apr 05, 2012 7:19 am ]
Post subject:  Re: 91 Bonneville Shaking
extrabigjon wrote:
I reseated all the plug wires. I don't recall hitting any big bumps that would jiggle something loose. Battery connections are all nice and shiny. Since I had to reset the codes and wanted to clean the evap coil I just left it unhooked while I did the work. I do have a new bosch oxygen sensor to put in once I have time. No idea how old the one in there is. I am trying to locate parts to upgrade to the delco type II ignition. My local yards claim not to have anything that old though, and no longer let you pull the parts.



If you can find a 93-95 Vin L 3800 you can just undo the 3 bolts at the bottom of the ICM plate and take the whole thing... This will be all you need... 100% plug and play..
Author:  extrabigjon [ Thu Apr 05, 2012 11:21 pm ]
Post subject:  Re: 91 Bonneville Shaking
Well it died again this afternoon. I was going down the highway and the car started shaking. Almost like from a sub putting out really low notes. I might of heard it backfire a time or two while it did this. The rpms didn't seem to jump around though. It seemed to only shake while applying the throttle and not when you let off. Coasted off the road and parked. Tried to start it back up and it just cranks and won't fire. I did check the fuel check valve with my key and there was fuel there. Didn't have time or tools to do anything else. Went to tow it home about 5 hours later. Tried starting it before hooking it up and she fired up on the first try then drove home. Turned it off and on a few times and no problems.

I did make a trip to town in the morning to do some errands and never had any problems. Could it be a heat related problem. The only code I had was 27 - Gear Switch Diagnosis( Second Gear Switch )
Author:  MattStrike [ Fri Apr 06, 2012 10:12 am ]
Post subject:  Re: 91 Bonneville Shaking
This is starting to sound like ICM heat soak or crank sensor or cam sensor.
Author:  extrabigjon [ Fri Apr 06, 2012 11:39 am ]
Post subject:  Re: 91 Bonneville Shaking
Any suggestions on where to get the icm tested at? All we have is a NAPA store and a Auto Value store. Is it worth buying used coils and an icm or is new the only way to go? I'll need to do some searching on how to check the crank sensor and cam sensor though.
Author:  MattStrike [ Sat Apr 07, 2012 1:07 am ]
Post subject:  Re: 91 Bonneville Shaking
A type 2 (delco w/3 coils) should be good used, individual coils may need replacement. see jrs3800's post

It's worth a shot to remove your icm, clean up the mounting surfaces (sandpaper or wire wheel), and grease up the mounting surfaces and see if it helps.
Author:  murderedout [ Sun Apr 08, 2012 10:00 pm ]
Post subject:  Re: 91 Bonneville Shaking
autozone tested mine. I WATCHED CLOSLY as they attatched the correct wires making sure it was connected right. you just need the metal part without the coil packs on it for them to test it. they got new ones with lifetime warranty for 99.99 but i went with wells from rock auto with built in heat sinks. The wells unit feels like a brick and more sturdier than the autozone one. mine was 117 with rock auto discount code. But it may not be your icm. make sure they test it more than twice
Author:  extrabigjon [ Thu Apr 26, 2012 3:53 pm ]
Post subject:  Re: 91 Bonneville Shaking
Finally had time to pull the ICM and coils off to get it tested. Didn't expect the front driver bolt on the mounting plate to be such a pain. Anyways I noticed some blue green goo on one corner of the ICM.
Image
Then I noticed the wire connecter on the ICM looked like it got hot on the two center pins and melted a little. The wire harness on the car looked good.
Image
And finally I took out the coil bolts. The front driver bolt had goo on the threads. One bolt twisted off. Then I attempted to separate the ICM from the coils and this is what happened.
Image
I do not think it is supposed to come apart like that. I'm hoping doing the delco type II swap will now fix my problems. Any comments appreciated and enjoy the pics.
Author:  MattStrike [ Thu Apr 26, 2012 7:05 pm ]
Post subject:  Re: 91 Bonneville Shaking
The green goo looks normal, but it shouldn't be leaking out the connector side. It's a thermal paste IIRC.
Author:  SSEBonne4evr [ Fri Apr 27, 2012 11:52 am ]
Post subject:  Re: 91 Bonneville Shaking
That coil pack doesn't look good at all.
Author:  extrabigjon [ Fri Apr 27, 2012 3:20 pm ]
Post subject:  Re: 91 Bonneville Shaking
Well on the bright side I'm getting very good gas mileage these past three weeks.
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