So I’ve had an intermittent misfire for awhile. P300/301/306. In the beginning it wasn’t all three, but recently it has been and clearing codes didn’t last more than a minute.
Replaced spark plugs, spark plug wires, cap and rotor oh… let’s say 10,000 miles ago. It didn’t fix it.
Replaced cracked exhaust manifold about 5,000 miles ago. Runs better, but didn’t solve the problem. Found that in addition to the cracks… one of the bolts at the back was stripped out. Used a helicoil to fix that. Likely had a bit of a leak at the #6 cylinder exhaust and possibly intake.
Last week I replaced the injector connectors. There was some damaged insulation that I had “fixed” when I replaced the exhaust manifold, figured it was time to just replace the connectors entirely. Still no change.
My remanned 4 hole injectors from K Suspension arrived the other day, so I decided that was the next step, decided to replace the spark plugs while I was at it just for S&G.
To my surprise, the injectors I pulled were 4 hole. A couple had different color O rings, so they might have been replaced at a different time. Then I ohm tested them, all between 12.6 and 13 ohms. Visually they looked “ok”, though a couple had slightly chewed up pintle caps. Might have been damaged during removal, can’t say for sure.
Pulled the IAC valve to clean it and it looked really clean already. So…. Starting to scratch my head.
Pulled the spark plugs and while there is no damage, they are all much darker than the previous plugs I removed 10,000 miles ago. Considerably darker. What’s interesting is that the #6 plug from the older plugs is the only slightly darker plug, consistent with a single misfire.
So new injectors and spark plugs… knock on wood, I drove a few miles, both low speed city, then giving it the Italian tune-up on the freeway. About 10-15 minutes and no CEL.
So I guess my question, based on the color of the spark plugs, are we thinking too cold of plugs causing it to misfire? Hoping this mess is behind me, but I’d like to understand the cause.
Plugs on top are the older plugs. I have no idea how many miles on them (previous owner). Plugs on bottom are around 10,000 miles.
Replaced spark plugs, spark plug wires, cap and rotor oh… let’s say 10,000 miles ago. It didn’t fix it.
Replaced cracked exhaust manifold about 5,000 miles ago. Runs better, but didn’t solve the problem. Found that in addition to the cracks… one of the bolts at the back was stripped out. Used a helicoil to fix that. Likely had a bit of a leak at the #6 cylinder exhaust and possibly intake.
Last week I replaced the injector connectors. There was some damaged insulation that I had “fixed” when I replaced the exhaust manifold, figured it was time to just replace the connectors entirely. Still no change.
My remanned 4 hole injectors from K Suspension arrived the other day, so I decided that was the next step, decided to replace the spark plugs while I was at it just for S&G.
To my surprise, the injectors I pulled were 4 hole. A couple had different color O rings, so they might have been replaced at a different time. Then I ohm tested them, all between 12.6 and 13 ohms. Visually they looked “ok”, though a couple had slightly chewed up pintle caps. Might have been damaged during removal, can’t say for sure.
Pulled the IAC valve to clean it and it looked really clean already. So…. Starting to scratch my head.
Pulled the spark plugs and while there is no damage, they are all much darker than the previous plugs I removed 10,000 miles ago. Considerably darker. What’s interesting is that the #6 plug from the older plugs is the only slightly darker plug, consistent with a single misfire.
So new injectors and spark plugs… knock on wood, I drove a few miles, both low speed city, then giving it the Italian tune-up on the freeway. About 10-15 minutes and no CEL.
So I guess my question, based on the color of the spark plugs, are we thinking too cold of plugs causing it to misfire? Hoping this mess is behind me, but I’d like to understand the cause.
Plugs on top are the older plugs. I have no idea how many miles on them (previous owner). Plugs on bottom are around 10,000 miles.
