Misfire under load

[gpse_97]

Hello gang!

I notice when the TCC (Torque Convertor Clutch) locks up on my '92 STE at low RPM (1500-2600RPM) my car will misfire very bad rocking the car a bit.

I replaced so far:

-Fuel Filter

-Plugs (stock)

-wires (stock)

-intake gaskets

-PCV Valve

-had professional fuel injector cleaning also

-GM cleens

 

I still have the issue and none of the above has helped it still does it.

The car has 306,000km on the motor. the only "mods" are an Open cone and removed the Cat.

It also idles pretty rough, and at low RPM when crusing it does hesitate (1500-2600RPM)

however once I get above say 3000RPM it pulls nicely, even if the TCC is locked up and the RPM is high avove 3000RPM the car runs fine. So only at low RPMS do I get this misfire.

[DaveFromColorado]

any check engine light, or stored codes?

 

--Dave.

[slick]

ICM/ Coil packs maybe? Kinda wierd that it does it when the TCC is locked up, not all the time.

[99RegalGS]

ICM/ Coil packs maybe?

I agree. Taking off the ICM/Coils are a PITA but I'd start there.

[slick]

ICM/ Coil packs maybe?

I agree. Taking off the ICM/Coils are a PITA but I'd start there.

 

Relocate them while your at it.

[w-bodys_are_the_best]

Hi there, i would try the coil pack, on my 94 cutlass 3100, i had a very similar problem actually for about a year and a half and could never figure it out, mine would just miss and shake the car bad when locked up, and say climbing a hill right before it unlocked and kicked down, it would shake to beat hell, well i thought it was a tourque converter problem, but after i dropped my tranny and had another one put in it still did it, well last aug. on the way to ozzfest, i completely lost cylinder 3 on I-90, turned out to be the coil pack, and now it doesn't have the problem at all, so i would check that, if you think about it, the motor is under a very high load when in OD locked up trying starting to climb a hill so it makes sense.

[Regal_GS_1989]

It is the ICM/Coil pack. My 88 regal does that exact same thing whenever it is humid outdside. Sometimes it takes a while to clear up. I gotta change mine when i get the chance. Plus with my 88 being a winter beater, and me living in winterpeg, I gotta fix that before the snow comes.

[terryk2003]

i am having a similar problem on myt '97 cutlass 3100...when you take off easy its got like a miss (it doesnt show up as a miss with my scanner hooked up though)...but when @ WOT it pulls hard...sometimes when the cruise is set and it starts going up a slight incline it'll jump around a bit...it doesnt do it all the time though...its hit or miss...i've changed my fuel filter, plugs, wires also...and i can't seem to fix it...so, from what everyone else is saying...could be a coil pack!?... :?

[gpse_97]

How do I test to figure out which coil pack it is.

Thanks again everyone for the responses.

[slick]

How do I test to figure out which coil pack it is.

Thanks again everyone for the responses.

 

I'd just replace all the coil packs and the ICM while your at it. Look around on ebay, you'll be able to pick up a complete set, brand new, for a decent price. If you can, try to find a set off of a 3400. Suposidly, the 99+ 3400 ICM has a much better spark curve.

[gpse_97]

How do I test to figure out which coil pack it is.

Thanks again everyone for the responses.

 

I'd just replace all the coil packs and the ICM while your at it. Look around on ebay, you'll be able to pick up a complete set, brand new, for a decent price. If you can, try to find a set off of a 3400. Suposidly, the 99+ 3400 ICM has a much better spark curve.

 

sO i need to replace all 3 Coils and the ICM.

I should get one off a 99+ 3400?

What are the prices for these items at the dealership?

[93CutlassSupreme]

i'm surprised nobody's mentioned the Oxygen sensor.

 

 

my car shuddered under tq lockup under acceleration. new plugs, wires, and an 02 sensor fixed it.

 

put an Oxygen sensor. an ACDelco one won't run more than $50 at the dealer, a Bosch 02 sensor can be bought for $19.95. cheap and easy to change out

[Stealth]

get an excorsist 8)

[gpse_97]

i'm surprised nobody's mentioned the Oxygen sensor.

 

 

my car shuddered under tq lockup under acceleration. new plugs, wires, and an 02 sensor fixed it.

 

put an Oxygen sensor. an ACDelco one won't run more than $50 at the dealer, a Bosch 02 sensor can be bought for $19.95. cheap and easy to change out

 

Already replaced with an AC\Delco unit.

I really think its the coils, either that or my MAP sensor.

I also think I have a vaccum leak as my heater only blows through the Floor and Windshield and someone said that is because of a vaccum leak.

[sonyman87]

i think you have either borken plug wires OR improperly gaped plugs thats a common thing to happen withn you over gap plugs or they are fouled

[gpse_97]

i think you have either borken plug wires OR improperly gaped plugs thats a common thing to happen withn you over gap plugs or they are fouled

 

plugs and wires were changed a month ago. All 6 plugs looked a bit covered in oil... would that be the coils that are all bad or the ICM

[gpse_97]

are the coil packs the same between the 3.1 3.4 and 3.8?

as I am goin to the scrape yard in seach of a coil pack\ICM.

Also what years use the same coil packs?

My car is a '92 DOHC

[99RegalGS]

The coils are all the same. The ICM's are different from the 3800's to the 60*V6 engines.

[gpse_97]

The coils are all the same. The ICM's are different from the 3800's to the 60*V6 engines.

 

thanks, since all my plugs look fouled is it the ICM or the coils?

I don't want to waste money buyin both if I don't need to.

[sonyman87]

All 6 plugs looked a bit covered in oil...

do you have stock intake on? i would put a catch can on your vacume line to your intake. sounds like you are getting oil sucked in pretty bad. this could cause a miss fire if your plug tips are coverd in oil lol. at low rpms you will 0nly be getting minimal performance out of your oils maybe not enough to strick threw oil. try that issue first since it will be your cheepest route to start

[gpse_97]

All 6 plugs looked a bit covered in oil...

do you have stock intake on? i would put a catch can on your vacume line to your intake. sounds like you are getting oil sucked in pretty bad. this could cause a miss fire if your plug tips are coverd in oil lol. at low rpms you will 0nly be getting minimal performance out of your oils maybe not enough to strick threw oil. try that issue first since it will be your cheepest route to start

 

I have an open cone, Should I put a breather on that vaccum hose instead of runnin it through the intake?

[gpse_97]

Ok I got 3 new coils off a 99 GTP, how do I install them onto my 3.4

any walkthrough's???

 

thanks

[gpse_97]

I just got 3 coils and ICM from a '99 Pontiac Grand Am 3400

will it work on my '92 STE.

Thanks.

 

also how do I change them, what is the procedure.

[terryk2003]

well...i dunno what works with what...BUT...if the coils & ICM solve your problem please let me know...cause i've been chasing a similar problem ever since i bought my car... :?

[SloMo94]

I also have been experiencing this problem. I have new plugs, wires, coils, timing chain and serphintine (sp?) belt. I am now down to my fuel injectors.