'93 Regal 3800 chucks idler pully at low engine speed.

['93RegalGS3800]

I recently did a tuneup on my car to get it running better and the exact opposite thing happened. I've now have a miss and the engine chucks the idler pulley at low engine speed. I'm pretty sure it's because I installed the spark plugs as a dumb shade tree mechanic and got some dirt on them or cracked one installing them or something. It didn't do this before I pulled the plugs. It's gonna make me insane if this keeps up.

 

 

[Padgett]

May just be one bad new plug. Had one in a Jag that would not fire under 3000 rpm. Sounded neat. For a 3800 with Delco ignition I use either AC Iridiums or RapidFires (#14) gapped .060

['93RegalGS3800]

May just be one bad new plug. Had one in a Jag that would not fire under 3000 rpm. Sounded neat. For a 3800 with Delco ignition I use either AC Iridiums or RapidFires (#14) gapped .060

 

Is there any physical way I can find the bad plug?

[Imp558]

Study them, what kind of plugs did you install? They should be iridium.

[Padgett]

I use an IR temp gun and look for the cool pipe.

['93RegalGS3800]

Study them, what kind of plugs did you install? They should be iridium.

 

I installed standard Delco copper plugs. That was what was in the car before. Ran well with the old set.

 

I use an IR temp gun and look for the cool pipe.

 

IR temp gun? I don't think I have one of those. I'd wind up pulling each one looking for the bad one.

 

-----------------

 

I'm about tempted to blast off the old plugs and reinstall them if I can't get this figured out.

[Psych0matt]

It throws the idler pulley? Like across the room? I've never heard that term before, and I'm not sure what it means to "chuck" something in such a way

[Padgett]

Can see the idle pulley bouncing on the spring if the engine is misfiring badly.

 

No Harbor Freight nearby ?

[Psych0matt]

Ok, that's what I assumed

[rich_e777]

Sometimes the wires dont like to clamp down all the way, check all your connections. Might also be a coil going out, IIRC you can check them with a multimeter. 

['93RegalGS3800]

It throws the idler pulley? Like across the room? I've never heard that term before, and I'm not sure what it means to "chuck" something in such a way

 

Yes...the engine chucked the idler pulley across my work area and in reaction I threw all my tools across the yard.

 

I love how there is always somebody on here to make me laugh at these situations. This forum is the best.

 

Can see the idle pulley bouncing on the spring if the engine is misfiring badly.

 

No Harbor Freight nearby ?

 

This is exactly what it is doing. I must have missed something when I installed the plugs if it's that bad. I'm just not looking forward to having to pull them again.

Harbor freight is nearby. I'll have to look into what IR guns they have.

 

Sometimes the wires dont like to clamp down all the way, check all your connections. Might also be a coil going out, IIRC you can check them with a multimeter. 

 

I thought they were all firm. I'll be able to confirm that when I go through the plugs.

I don't think a coil is going out as it did this after I changed the spark plugs. Would not hurt to check them though.

[Psych0matt]

Yeah, I'd start by checking all the plugs and connections, and I'd also double check their all plugged back in the right order too, it's an easy thing to miss

['93RegalGS3800]

Found out that it runs better on 4 cylinders than it does 6. Cylinders #2 & 6 are acting up at the coil pack. I'll check those plugs to make sure they are ok but it looks like I might ether be out for a set of coils or a new PCM if it goes that far. Funny how it ran fine with the old plugs though...I really wonder if my car has a mind of it's own sometimes.

[Nas Escobar]

Try the ICM before blaming the ECU

[Imp558]

firing order?

['93RegalGS3800]

Try the ICM before blaming the ECU

 

If I don't need to replace the ECU then it won't. I just need to diagnose what is all before it untill I rule it bad.

firing order?

 

It's correct. it's just that the #2 does not give enough spark and the #6 is totally dead. The rest are fine.

[Padgett]

Does not compute, 2 and 6 are not on the same coil, should have 4 misfiring cyl.

[Imp558]

Look more closely at firing order. Something is not right there

[Padgett]

Here is a 3800 Delco coilpack connector is on right. Both plugs fire together  (First saw this on a 64 Honda). Since each coil pair is just opposite sides of the same coil it is hard to fail just one (can happen if plug wire breaks or plug fouls but coil failure will usually take both out.).

 

Odd numbers are front bank, even are rear.

 

ps at idle you would be amazed how much the computer can compensate.

 

Edited July 25, 2016 by Padgett

[Psych0matt]

Something is definitely plugged in wrong

[Imp558]

There's a fantastic write-up in the faqs section on distributorless ignition systems. Not to mention the several hundred posts that have to exist here.

I can remember clearly going over firing order at least twice in the last 6 months in different threads.

[Galaxie500XL]

I like the firing order of the 60 degree V6...1-2-3-4-5-6 is hard to mess up. 

['93RegalGS3800]

Here is a 3800 Delco coilpack connector is on right. Both plugs fire together  (First saw this on a 64 Honda). Since each coil pair is just opposite sides of the same coil it is hard to fail just one (can happen if plug wire breaks or plug fouls but coil failure will usually take both out.).

 

Odd numbers are front bank, even are rear.

 

ps at idle you would be amazed how much the computer can compensate.

 

plugwireorder.jpg

 

I knew most of this, but the engine idled well on 4 cylinders rather than all 6. It actually smoothed out and stopped throwing the idler around.

 

Does the computer compensate for the other side of the coil or some crap? I'm no good with car computers. I'd rather just carb swap and call it a day.

 

Something is definitely plugged in wrong

 

What though? I can swear it's wired correctly. It's the coil not firing at the #2 and #6 cylinder correctly. One has little fire and the other has none at all.

[Psych0matt]

Where are you testing for spark, at the coil pack or at the plug? Maybe bad wire(s)?

[Padgett]

I always keep spare ICMs and coil sets around, on a 3800 it is a five minute swap.