Thread: Installed PLOG, now studders under boost. Please help!

my car runs lean on decel. unless your tune is way off your car should run lean too.

Sounds to me like your plugs need to be changed. My car was doing the same thing you are describing.

Its a misfire, check your plugs/wires like they said... If it only happens under boost, stick with the stock heat range and gap them all at .040 If it still does it and its not the wires, start closing the gap on all of them until the studder goes away.

.040 is a pretty small gap.

If you have a bad short to ground from a sparkplug wire, is it possible its pulling spark from the other cylinder on the coil?

Dunno how the coils are wired but my theory is if it grounds out bad enough it desaturates the coil reducing spark on the cylinder w/ good plug / wires.

Had a spark plug wire short out on my olds on a road trip and it felt like it dropped more than 1 cylinder....pretty much basing this entire theory on that encounter.

How long will our coils last shorted to ground anyway? Cause it cant be healthy....

Originally Posted by Bio248

my exhaust backfires all the time. that doesnt matter.

so does mine. wouldnt worry about it

Seafoam job caused the car to want to stall like crazy for the first little while, and then seemed fine, but didn't produce any noticeable smoke. Of course it was dark, but I didn't see anything when driving. I took the car for a nice 20 minute drive with ranges from 30 MPH to 70 MPH, easy acceleration runs and WOT acceleration runs.

Here is the other odd thing. I didn't notice any studdering. Not at low boost, not at medium boost, or full boost. When I was disconnecting the vacuum line on top of the S/C to put the Seafoam in, I noticed that the line was a hair loose. Still looked to be all on, but still not as securely in place as it was after I reconnected it.

I still need to put the plugs in anyway, but hopefully my problem will be solved. I'll report back tomorrow.

Got the plugs replaced, and wow, the old ones were really bad. Interestingly though they were NGK Laser Series Platinum Plug # PTR4B-15. Looks like those were $10 plugs. I replaced them with Autolite 606's for $1.79 each. We'll see what happens, but I would think that getting rid of a cracked plug, plus just getting new ones in there that aren't so worn will be an improvement. The NGK's electrodes came to a nice, worn point. Yuck!

I am off to get a haircut (just realized that my driver's license expires in 2 day, so I need to get my mug-shot taken tomorrow when I renew) and I'll throw some highway/city driving in there to see what happens.

Here's hoping for the best!

All seems to be working well again. Not sure if it was the cracked plug or the slightly loose vacuum line (not even sure if it was leaking), but either way, the car needed new plugs.

Although, now with everything running fine, and my new TDC FWI, I aggressively pulled up to a stop light (to turn left) and a guy pulled up to my passenger window and was laughing. He was driving a Toyota pickup. I tried to roll down my window to let him know that he clearly does not know squat about vehicles and that the sound was called a supercharger, but the light turned green, and off he went...

you do know platinum plugs are a no no for our supercharged motors, right? Glad all is running well for you at least for now......

Yeah, I heard that it is best to just go with copper, which is what I did. What is the issue with the platinum plugs?

they just dont work as well. copper plugs need to be replaced more often, but they are more effective for our application.

not sure if this is true, but I was told by someone on here that the platinumb burn hotter than the copper equivelant..........not sure how this is true if getting the same heat range plug........

I found some info about plugs yesterday and it was showing that the copper fire more efficiently and spark better, but the others last longer. I don't remember where I saw it, but there was a nice table giving numbers on the differences and the copper ones were considerably better than the others for spark.

You just want to stay away from Iridium plugs...they are a no-no in a Boosted GM V6 application IMO.

there are some who were running the iridium plugs on our cars........I guess everyone has their own opinion about plugs........I wish we could see some exact numbers for our cars........I would be willing to sacrifice 5HP so that I wouldnt have to change my plugs every 6-10K.......so in your opinion what is worse iridium or platinum?

changing your plugs every other oil change adds...what, a half hour to the process?