Coil Pack problem on 2001 LeSabre

[Gilgondorin]

Howdy all!

Sorry to make my first post a question here in this forum, but the fact is I'm desperate to fix our car, and there just aren't many reference sources for car fixes online for '01 LeSabres.

A little bit of background:

We're the exact opposite of rich, so running out and replacing parts by the carload until the problem fixes itself is unfortunately not going to work for us, as much as I'd like to.

Our number one coil pack (spark plugs 1,4) has burnt out for some reason. Packs two and three appear to be running fine. When the problem first started, we noticed the car seemed to be skipping and misfiring while driving, until the problem got so bad it threatened to (and at one point actually did) stall out in-transit. We took it to a mechanic that diagnosed the problem as needing to replace the crank and camshaft sensors, and we think he was wrong because we took it to another mechanic that is apparently familiar with Buick cars, and within 15 minutes had diagnosed the problem as being the faulty coil pack I mentioned earlier.

He replaced the pack for us with an OEM off another Buick, and everything seemed to work fine for about a week. Then we noticed the car started acting screwy again, and again, the performance rapidly degraded to the point that the new (used -- it was pulled off another car) burnt out. We figured maybe the pack he gave us was bad, so we went to an Autozone and bought their DuraLast model coil pack for our car. When we put it on, we the car seemed to idle in "park" fine, but would begin to misfire a lot when shifted to "drive". What confused us was that:

1.) Coil pack 1 from Autozone would work fine while idling in "park". Shifting to "drive", and especially while coming out of a stop/stop light would cause the car to seem like it was about to stall, and it vibrated pretty harshly.

We drove it for about 3-4 days, before we took it back to the auto-part store and asked for an exchanged coil pack, which we installed there in the parking lot.

2.) Coil pack 2 from Autozone worked like crap from the start. It will not run steady in park or in drive, and we've lost a large amount of power while coming out of stops, because you can depress the gas pedal to the floor sometimes and it will barely crawl up to 30 miles per hour, unless you release the gas and press it again to shift gears (it will vibrate again like crazy, but speed up a little faster).

I read somewhere on a Honda Civic forum that coil packs have to actually be tightened to a specific 13 ft. lbs. of torque to maintain proper resistance, or they'll readily burn out. Are we missing something here, like another electrical problem elsewhere in the engine... Or are we just not tightening them snugly enough? I'd really like to take it to a mechanic and have him fiddle with it, but like I said, due to our finances, that's completely out of the question. We're still holding out hope that maybe a new coil pack on the proper tightening setting will fix the problem; I'm not a real big car-guy, so I'm lost, and my dad's done as much as he could to help it along.

Any help would be GREATLY appreciated!!
Thanks in advance!
~G.

 

[1380Ken]

I would guess that you ICM may be bad

 

[redmondjp]

First, welcome!

Second, there is nothing unique about the 3800 engine in your 2001 LeSabre and there is a plethora of information available for the 3800 engine - the ignition system was essentially unchanged from the late 1980s up through the mid-2000s.

Do you know for sure that you have a bad coil? It can be easily checked with an ohmmeter (search this forum - it has been posted already).

To me, it sounds like you have a bad Ignition Control Module (or ICM) which is the thin module that all of the coils sit on top of and are plugged into. If you have a dead output for one of the three coils, you can replace all of the coils you want and it won't change anything (which to me is what sounds like is the case in this instance).

If you have any self-service junkyards near you, you should be able to obtain a used ICM for $10-20 (make sure that they mark the part so you can exchange it if you end up getting a bad one). I did this recently for a friend's car. Sometimes you even luck out and find a freshly-replaced ICM out in the boneyard too.

 

[Gilgondorin]

I was in such a rush earlier I forgot to mention that we tested our theory that it's the car burning out coil packs, by removing pack #3 (plugs 3,6) and putting it on slot #1 (plugs 1,4).

Once we put the confirmed working pack on the trouble slot and fired the car up, we observed it firing like it should. Just to be sure, we put the Duralast coil pack from Autozone in slot #3 (plugs 3,6) on to slot #3, which was where the confirmed working pack had been -- and we got nothing. Same thing with the coil pack that the mechanic sold us. No spark of any kind from either terminal, confirming our suspicions that the second new pack was either also D.O.A. (I doubt it's possible to get two in a row) or it got fried like bacon in a skillet.

Dad was hoping maybe the coil pack was just bad, but now we know for sure that for some reason, the car is running too hot electrically for that pack. I ask again if anyone is familiar with whether or not the tightness of the bolts affects the coil pack resistance; it sounds hard to believe for me because Honda's are not Buicks... But what the heck? $54 later, I'm willing to believe anything. 😛

 

[HotZ28]

I ask again if anyone is familiar with whether or not the tightness of the bolts affects the coil pack resistance; it sounds hard to believe for me because Honda's are not Buicks..

No, tightness has no effect on resistance! The coils bolts should only be snugged up. If you tried to tighten to 13-ft lbs, they would break. Last year I installed three new (china built) coils for a customer with a PA. Two failed in the first week. We changed the complete set over to ACDelco, and no more problems.

 

[jerreich]

I had 1-4 go bad, replaced the ignition control module with one from Rockauto.com, no more problem. Rock auto will send one at a more reasonable cost than anyone. If you drove the car much with the 2 cyls missing, you will have damaged your cat con. The service engine light will come on, mine does, and I only drove about 6 miles with it missing. I have a scanner, I just erase the code, and it will go a few weeks, then light comes on again. I am getting 30+ MPG on the freeway, so I guess there is no serious problem. The ICM is easy to change, it is the flat plate the coils sit on. Do not tighten the coil hold down bolts too tight. Make sure all mounting surfaces are clean, and put dielectric grease on the plate under the coils, and around the plug in the front of the ICM.

 

[HotZ28]

[ame="http://www.youtube.com/watch?v=2woQT1eOy8U"]Click Here[/ame] This is not vehicle specific, but is DIS specific. Like mentioned earlier, you may have a problem with the ICM, but the fact that you moved a known working coil to the place of a dead coil and the replacement coil sparked as normal, seems to discount that theory, unless the ICM problem is intermittent and causes coil failure after a period of time. (like one week of driving) Sound familiar? Big part stores offer ICM testing, however the results are not always 100% accurate. Have the ICM tested and if it fails, Click Here and get the ICM & coils for $25.00! BTW, how are you testing for spark, with a spark tester, or using an old plug?

 

[SAYBER]

I had 1-4 go bad, replaced the ignition control module with one from Rockauto.com, no more problem. Rock auto will send one at a more reasonable cost than anyone. If you drove the car much with the 2 cyls missing, you will have damaged your cat con. The service engine light will come on, mine does, and I only drove about 6 miles with it missing. I have a scanner, I just erase the code, and it will go a few weeks, then light comes on again. I am getting 30+ MPG on the freeway, so I guess there is no serious problem. The ICM is easy to change, it is the flat plate the coils sit on. Do not tighten the coil hold down bolts too tight. Make sure all mounting surfaces are clean, and put dielectric grease on the plate under the coils, and around the plug in the front of the ICM.

I know this is an old thread but use thermal paste instead of the dielectric grease. A WAY better conductor! Lasts way longer to, doesn't dry up and crystallize. And ALWAYS ALWAYS buy delco parts for the replacement of electrical and sensors. Trust me.

 

[HotZ28]

Seven year old thread here! LET ME MAKE THIS PERFECTLY CLEAR, the ICM mount has nothing to do with the ICM ground after 1993. GM finally realized they needed to install a dedicated ground to the ICM that is grounded to the engine/chassis/PCM. All after 1994 had that dedicated ground. Look at terminal L/M on the schematic below, that is the ground!

 

[SAYBER]

Seven year old thread here! LET ME MAKE THIS PERFECTLY CLEAR, the ICM mount has nothing to do with the ICM ground after 1993. GM finally realized they needed to install a dedicated ground to the ICM that is grounded to the engine/chassis/PCM. All after 1994 had that dedicated ground. Look at terminal L/M on the schematic below, that is the ground!

View attachment 21257

It's basically a heat sink/bracket, so the thermal paste is a better choice at dissipating the heat from engine. Thefts wheat I was meaning. But great info beavis! 😆Thanks.

 

[HotZ28]

It's basically a heat sink/bracket, so the thermal paste is a better choice at dissipating the heat from engine. Thefts wheat I was meaning. But great info beavis! 😆Thanks.

Thank you once again Butt-head! I should add, the mounting bracket is not a heat sink!

 

[SAYBER]

Thank you once again Butt-head! I should add, the mounting bracket is not a heat sink!

Your right.

 

[Jstewart78]

Seven year old thread here! LET ME MAKE THIS PERFECTLY CLEAR, the ICM mount has nothing to do with the ICM ground after 1993. GM finally realized they needed to install a dedicated ground to the ICM that is grounded to the engine/chassis/PCM. All after 1994 had that dedicated ground. Look at terminal L/M on the schematic below, that is the ground!

View attachment 21257

What shows/means is the ground location is beneath the ICM mounting plate I have 1999 buick park avenue ultra and that is where it is physically grounded from the ICM harness. It’s not grounded through the PCM like some sensors.

 

[HotZ28]

What shows/means is the ground location is beneath the ICM mounting plate I have 1999 buick park avenue ultra and that is where it is physically grounded from the ICM harness. It’s not grounded through the PCM like some sensors.

Do you have a ground problem to the ICM, or are you just trying to elaborate on the locations of the ground connections? 😕