plugs/wires affecting idle?

[BrendonSAIT]

Hey everyone, i've got a 1992 lumina euro, and my mom has a 1993 lumina sedan, both with 3.1s.... i just read a post that might apply to me, but i wanted to check.

 

 

Both 3.1s run somewhat (mine much worse) rough, and harsh on idle. Lately, at a stop light, mine will jump around between 250rpm and 1000 rmp.... sometimes stalling. my mom's stalls once in awhile too. (scared the hell outta me one day when it happened)..

 

they're both automatic transmission, so i'm not just a dumbass with a clutch.

 

the last post i read was about spark plugs and what i read follows:

 

 

"when you change the plugs, change the wires too... if you move the carbon core wires around, they'll break down on ya and it'll miss erratically at low throttle positions just cruising and run just fine at full throttle. Get AC Delco plug wires... lifetime warranty... get a free set any time you change your plugs..."

 

 

 

if i change out the plugs and wires in my 3.1, will my problem stop? if so, how difficult is it, REALLY, to change those rear plugs, i've heard some real horror stories.

 

 

Thanks

 

Brendon

[bartonmd]

Brendon,

 

It's not really all that hard... although any time I've had the idling you describe happen, it's been on an HEI module (2.8 mpfi ciera I had) or a ICM on a 3.1L. I say that, but hesitate to tell you to spend the money on one... If you can thieve the one from the car that's running better and put it onto the one that isn't, and the running traits switch, you might have your source...

 

Plug wires failed is specifically at speed, loading the engine at low rpm (up a hill, top gear, in lockup; or just going 65-75 on highway), but it cleans up at higher rpm (the higher the cylinder pressure, the stronger the spark gets, and therefore it jumps the minute gaps in the broken up carbon core of a plug wire). The missing will be eradic, not a constant like 2 cylinders missing.

 

Changing plug wires on a 3.1 in a W body (early 90's) isn't bad.. you just have to rock the engine forward and put the bolts in the small holes on the outside of the motor mounts to get access to the rear.

 

Mike

[Guest TurboSedan]

how difficult is it, REALLY, to change those rear plugs, i've heard some real horror stories.

 

 

Thanks

 

Brendon

 

it's really not bad at all. all you have to do is remove the long bolts from the engine side of each dogbone motor mount. then grab the alternator and pull the motor forward enough so that the slave hole in the driver's side dogbone motor mount is aligned with the hole that the long bolt previously went thru. have a friend slide the long bolt in thru that hole and it will keep the engine in the forward posistion. this will give you enough room to access the rear plugs. you will only need a 3/8" drive ratchet, a 3" extension, and a 5/8" spark plug socket to finish the job (and a spark plug gapper of course).

 

alternatively you could pull the alternator out along with its bracket. the bracket is bolted to the engine with 3 bolts and then you have to unplug the alternator and remove the power wire (10mm nut). remove the negative terminal from the battery before you disconnect any wires from the atlernator(!) you won't have to rock the engine forward but the downside is that you'll have to do the idle relearn procedure afterwards since the battery has been disconnected.

 

i used to just remove the alternator, but i think rocking the engine forward is easier.

 

good luck.

[GP1138]

how difficult is it, REALLY, to change those rear plugs, i've heard some real horror stories.

 

 

Thanks

 

Brendon

 

 

i used to just remove the alternator, but i think rocking the engine forward is easier.

 

good luck.

 

I do both, it makes it 10x more easy. And I have slender arms and hands.