chris88z24

Never had this happen before. When accelerating and under boost, the car misfires and the exhaust sounds like a machine gun. The CEL flashes when this happens.

Other times it's fine and you can wind it out to 7k at 15 psi without an issue.

I'll randomly get a "check gas cap" message on the DIC sometimes. Otherwise it seems to run fine.

Also when I let off the gas, the car vibrates like crazy. If I press the clutch in it still does it. Could a bad motor mount cause a misfire? One of my snow tires lost a weight but I feel like it would vibrate all the time and not just on decel if it was that bad.

145k, stage 2 but stock otherwise.

Did I just get some bad gas?

jdbaugh1

iTrader: (1)

I'd suggest to check your spark plugs first but, I'd think, vibrating like crazy on decel would not be spark plug related. Bad gas shouldn't affect that either. Which tire did your weight fall off of, front or rear? Does it vibrate while you are just cruising at a constant speed?

armcclure

iTrader: (2)

chris88z24

I'll check the plugs. I have BKR7E's (copper) with about 50,000 miles on them.

Decel vibration went away - I guess I might have had some snow caught in the wheels.

Thanks guys.

armcclure

iTrader: (2)

When diagnosing plug gap, you can save a ton of time but just setting them stupid tight (like 0.015") to see if the issue goes away. The machine gun sound usually is a bad ignition coil, but those are rarely intermittent.

Sharkey

iTrader: (1)

you got 50k miles on a set of bkr7e plugs? thats amazing lol. i gotta change mine every 20k km at most.

chris88z24

I honestly didn't think they were that old until I checked my service records. lol. I'm mainly highway and don't really romp on the car at all anymore so maybe that's why.

63 Nova SS

iTrader: (3)

Could also be your injector seals are toast. I'm with sharkey, I change my plugs no more than 15,000 miles.

Sharkey

iTrader: (1)

your thinking of an LNF car. port injected cars with bad injector seals just have a vacuum leak.

63 Nova SS

iTrader: (3)

My bad, forgot it wasn't di.

Sport Red LNF

50K on copper plugs? They typically only last around 30K in naturally aspirated engines; I've never seen an FI application last even that long. My bet is on plugs; make sure to measure the gap when you pull them out! I'm guessing it will be close to 0.080".

chris88z24

Maybe I'll make a video

chris88z24

Changing the plugs fixed it. Gap looked HUGE on the old ones. I saved them to measure when I get a chance.

63 Nova SS

iTrader: (3)

Good to hear it's fixed