Intermittent misfire help

[brainpan]

Been chasing misfires for a few weeks now, it first started in cylinder 1. I swapped cylinder 1 and cylinder 2 coils and the misfire traveled to cylinder 2, perfect bad coil.

Thought after that I had it all figured out. Replaced the bad coil in cylinder 2 (originally from cylinder 1) with a new one straight from the dealer.

Later that night, I get a code again, cylinder 1 misfire... so after reading a few threads I change the 2 remaining coils on cylinders 1 and 3 problem gone...

Fast forward 8 days to today, cylinder 1 misfire again...

So my question is, what are the odds of getting a new coil that is faulty? I'm sure its possible, but unlikely. The parts guy did say they have a 1 year warranty on ignition coils...

Tomrw at work I will swap 1 and 2 again and see what happens. But I was wondering if there's anyone out there that's been through this before ?

Running giac stage 2 pump, still pulling hard when it's not misfiring. Misfires only happen on WOT pulls usually after a shift.





Side note: after clearing the codes the car wouldn't turn over, was almost like the ignition cycle was cutting itself short... tried 3 times and nothing, would get like half a crank and just quit. I checked voltages on battery getting 12.2 so tried to turn over again and it started.. wtf.





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[s4matty]

Try putting it in N instead of park after you clear the codes..My car does the same thing after I scan it

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[Loe]

How do the plugs look?

[jran76]

Have you checked the plugs? What year is your car, how many miles, and have/when were the plugs last replaced?

I saw quite a few misfires when logging (never threw a code), but just proactively replaced all the plugs and coil packs to be safe. At the end of the day, it's a couple hundred bucks, and at least in my case, the car ran much better after doing so.

Outside of plugs and coilpacks, the most likely culprit is a leaky intercooler, so if the problem persists, I'd consider pulling the S/C to check for leaks.

[brainpan]

Try putting it in N instead of park after you clear the codes..My car does the same thing after I scan it

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Awesome thanks, kindda shit myself a bit, things haven't been going my way lately lol..

How do the plugs look?

I never check it, they have about 20k km on them, assumed they were ok.. guess that's something to check for tomrw..thanks!. what should I be looking for on the plug?

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[jran76]

I never check it, they have about 20k km on them, assumed they were ok.. guess that's something to check for tomrw..thanks!. what should I be looking for on the plug?

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I'd check the gap first, and just make sure they don't look too fouled up. Something in the 0.028 range is a good gap. You could even go a little lower (or a stage colder) on a stage 2 tune.

[Loe]

Outside of plugs and coilpacks, the most likely culprit is a leaky intercooler, so if the problem persists, I'd consider pulling the S/C to check for leaks.

yes, this is something that can happen as well. Check the plugs to see if there is a white mold-like substance on the tips of the plug. Check your coolant levels as well. If all is clear, swap the plugs on cyl 1 and 2 to see if it moves.

If it's a coolant leak on the intercooler, I would advise to revert everything back to stock and take it to the dealer ASAP (or ind. shop if out of warranty) as the coolant may lead to a hydrolocked engine (worse case scenario) or contaminating your cat.

[brainpan]

I'd check the gap first, and just make sure they don't look too fouled up. Something in the 0.028 range is a good gap. You could even go a little lower (or a stage colder) on a stage 2 tune.

OK I'll definitely look into this tomrw, i don't own a spark gap tool so maybe something for the shop to look at for me.

yes, this is something that can happen as well. Check the plugs to see if there is a white mold-like substance on the tips of the plug. Check your coolant levels as well. If all is clear, swap the plugs on cyl 1 and 2 to see if it moves.

If it's a coolant leak on the intercooler, I would advise to revert everything back to stock and take it to the dealer ASAP (or ind. shop if out of warranty) as the coolant may lead to a hydrolocked engine (worse case scenario) or contaminating your cat.

You had an intercooler leak right? Looks like I'm gonna be going to the shop this week and get him to check it out. Don't wanna mess around with something like that. My coolant is slightly below min when cold...

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[brainpan]

Pulled cylinder 1 plug, seems ok to me? Any thoughts, seems pretty worn for just 20k km ?



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[brainpan]

Just to add, measured .32 with feeler gauge

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[jran76]

The pic of the spark plug is a little hard to see as far as how much white build up is there. It looks ok from what I can see there though. A small amount of buildup is normal.... I would personally gap the plugs to .028 or so, and then try swapping them around like Loe mentioned.

[brainpan]

The pic of the spark plug is a little hard to see as far as how much white build up is there. It looks ok from what I can see there though. A small amount of buildup is normal.... I would personally gap the plugs to .028 or so, and then try swapping them around like Loe mentioned.

Thanks for the reply jran, I'll try swapping 1 and 2 tonight, as for the gap I don't have the tool to close it up. Is it that much of a hassle to change the gap? I've never done it before but doesn't seem like it's that hard to do

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[jran76]

Thanks for the reply jran, I'll try swapping 1 and 2 tonight, as for the gap I don't have the tool to close it up. Is it that much of a hassle to change the gap? I've never done it before but doesn't seem like it's that hard to do

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It's easy. Depending on the plug, some are hard to move though. I don't use special tool in most cases. Just press it down on something, and use the feeler gauge to check. I prefer the feeler gauge over a spark plug gap tool.

[brainpan]

It's easy. Depending on the plug, some are hard to move though. I don't use special tool in most cases. Just press it down on something, and use the feeler gauge to check. I prefer the feeler gauge over a spark plug gap tool.

Awesome thanks!

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[Loe]

The plug looks 100% healthy. However, it doesn't hurt to swap. It doesn't appear to have a white moldy-looking substance I was referring to (think cauliflower head, only not as massive), your white substance is 100% normal looking.

[brainpan]

The plug looks 100% healthy. However, it doesn't hurt to swap. It doesn't appear to have a white moldy-looking substance I was referring to (think cauliflower head, only not as massive), your white substance is 100% normal looking.

Great thanks Loe! Hopefully tonight I can get around to swapping plugs. I did a few hard pulls this morning and couldn't get a code.

Seems like when the ambient temp is around 20 degrees I get the misfire. This morning was around 12 degrees.

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[schirm]

When I chased a misfire on the same cylinder it ended up being a bad CAT

[brainpan]

When I chased a misfire on the same cylinder it ended up being a bad CAT

That was my first worry, the exhaust note changed and later misfire. Turned there was a weld issue on my center res on my borla exhaust, which they warrantied.

Just un update, re gagged cylinder 1 to 28 thou and cylinder 2 was already at 29. Swapped em and so far so good. What was also strange is cylinder 1 plug was Bosh and 2 was NGK.

A plug is a plug but.. the dealer did the maintenance under audi care and replaced both front wheel bearings too, only to have fail 10 months later and deny any wrong doing because I'm lowered...




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[Italiano]

having a similar issue, just ordered an new set of factory plugs to see if it resolved the issue. My dealer of course blames it on the aftermarket NGK plugs i have, they would not replace them so i have to do it.

[A4MZ]

I had a random misfire that couldn't be diagnosed which ended up being a dropped valve. Complete engine rehaul. Was GIAC stage 2 as well.