Thanks to everyone that replied to my post. I finally got the problem fixed. It turns out that it was a bad coil pack that was causing the engine to miss under a load. I also went ahead and changed the plugs and plug wires. The car drives great now. Thanks again.

did some deliveries tonight. it's still doing it.

i think i'm just going to ignore it. :grin:

ok. it appears i might have solved the problem.

labour: 30 seconds @ $0.00 = $0
parts: $0.00

1) take off intake manifold plastic cover that says '3800 tuned port injection'.

2) if the wires leading to cylinders 2, 4 and 6 have direct contact (i.e. are pulled flat against) with the intake manifold, reposition them so that they lay in the little hook in the PCV valve cover. you may have better luck with wiring looms. if the wires are already there....well then.... your (and probably my) problem lies elsewhere, probably.

my guess is that the heat from the intake manifold is creating too much resistance in the wires. i can almost verify this, because it doesn't matter how hot the transmission gets, it's how hot and worked up the engine is. for example if i sat in front of the engine and pressed on the throttle cable from idle to WOT over and over again until the temperature got well above 90*C (the first big notch on the gage, where it usually sticks around) and took it for a drive, the chugging problem would be terrible.

i'll drove about 200 km today, very intensely, and there wasn't a single hitch, however i will keep driving and keep everybody posted.

replaced, twice. vacuum lines leading to canister and modulator were rusty so i replaced them, still no luck.

i think this one is a candidate for the 'common problems' portion of the site. although o2 sensor and coil packs and wires and plugs replacement didn't fix mine.

ug, problem came back. replaced fuel filter which apparently was clogged to hell and didn't affect it. i asked them about a vacuum leak since i could hear a whistling when hot but they said it would affect it all the time not just when it's hot. maybe it's too much exhaust pressure. who the hell knows, it's time to stop sinking money into this car.

ok, i replaced all my coil packs today. idle smoothed out a bit after i drove it around, no repeated bucking in lockup yet...

i'm doing some deliveries tonight and that's usually when it acts up the most since things tend to heat up a lot, i'll keep you posted.

any updates Kressdog? is the problem still fixed? how did you find out which coil pack was weak?

mine does it too. can anyone else verify the coil pack solution? i was thinking more along the lines of a bad TCC solenoid, plus adding a transmission cooler helped a little bit...

_________________
1992 Bonneville SE
~245,000 km

<font size=-1>[ This Message was edited by: Greg on 2002-04-29 06:32 ]</font>

I'VE SEEN THIS ALSO HAPPEN WITH A WEEK COIL PACK OR BAD WIRES! JUST A THOUGHT!!!

Kressdog: no.. not that i remember.. on the 95ssei, the SES light came on when it started jolting/missing up hills in OD.. the O2 sensor replacement fixed that.. and your problem seems consistant with the 88 sse I had.. letting up and depressing the gas the 2nd time would allow it to unlock the TC.. but.. it still would jolt now and then, even in town.. i think the supercharged models have a different Xmission.. good luck..

<font size=-1>[ This Message was edited by: craigpr on 2002-03-15 12:49 ]</font>

i had the similar problem with an 88 SSE.. had to depress the gas twice to unlock the converter.. that was strange.. if it is jolting going up hills.. you may need to change out your O2 Sensor, and.. check your ignition coils.. i had to do that with both of my Bonnevilles.. i currently have a 95-ssei, with enough new parts on it to call it a new car.. including a new transmission after 88k miles.. when it jolted up hill, the O2 sensor was the problem.. my new Xmission works perfectly, no problems what so ever.. you may have a transmission flaw, but, if you haven't checked the sensor and coil, i would do that... Good Luck..!!

<font size=-1>[ This Message was edited by: craigpr on 2002-03-14 14:37 ]</font>

Greg

The car is still running great. As to how to tell which pack may be weak I had my brother who is a mechanic fix the car and i'm not sure how he knew which one to replace. I'm sure that there is a test that someone knows about. The next time I see my brother I'll ask him how he did it and report back.

When you think it should be shifting out of overdrive, have you tried manually forcing it out of overdrive?

-Jeff

craigpr,

Did you have a error code that told you that the o2 sensor was bad or what pointed you in that direction.

Teuobk, no I haven't tried to shift into drive when it does but i will try that to try to narrow it down some more. The way I get it to downshift is push the accelerator to the floor where it downshifts properly and does not jerk. It seams to do it when I am going up a hill on the highway and first the torque converter should unlock and your rpm's go up then if that is not enough the car should downshift to the next lower gear to maintain your current speed. That is the way it used to operate. However when driving in town at the 30-40 mph speeds the car does this just fine. It only does it on the highway when the car is in overdrive. Csprague has your car done this for a long time. This just started happening and 87,000 miles for me. Just wondering and thanks for the replies.

I have a 95 SE with series II engine but not sure what model of tranny. Anyway, recently the transmission seams like it will not down shift out of overdrive when you press on the accelerator. The car starts jerking repetedly like its trying to downshift but it never completely shifts. The car drives fine around town around 30-40mph but cannot use cruise control on a hilly highway. Any insight as to what may be the problem would be greatly appreciated.

*cough* rebuilt *cough*

Strange that this should happen to me at the sam etime of this post...
coming home from school today i was going about 100 (km, not MILES...:grin:) and let off....going up a hill because it was 50 on the other side. anyway when the car hit 90, it gave 2 little jerks...you probably wouldn't even notice them unless you drove the car every day like me. I tried it again, and it did it again. It almost feels like a back fire, but of course it's so where near severe, and it dosn't seem bad enough to be a tranny slip...plus no light comes on. ??

I love cheap fixes.

Modulator?

Any major electrical "issues" can cause this...Coil pack battery ground. When you are having problems it is always safer to get a mechanic you trust to go over it so you have a second opinion to your own or other people who may have given you advise. If you cant spend the money for a diagnostic, then do one yourself. I mean go over the car checking every part that may be causing the problem. It is truly the only way to go. After checking every part and you are still not sure where the problem is weigh the cost of replacing parts until you fix the problem against a good diagnostic. Mine was the negative battery terminal on my "new" battery. This also caused a drain on my alternator and killed a few of them. Actually I could get a nice lumpy cam sound out of the car when the juice was low. lol No performance though. Best of luck. Remember to check all the inexpensive areas first.

Another thing, I have the torque converter lock up in both OD and D, and both exhibit the same symptoms of not wanting to unlock.

My car has 140k on it, and I talked to my dad (he had the car before I did), he said it's been doing it for at least since 60k miles or so.

My '92 SE does that as well. The 4T60E (found in both our cars) likes to lock up the torque converter and not release it under light load. I'm told it's a design flaw with the transmission.