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Random Misfire, All Cylinders

I have an 2004 Acura TL, 97,000 miles, with a check engine light that keeps coming on. I get seven codes, a random misfire for each of the six cylinders, and a random misfire multiple cylinders. There is no pattern of the engine being hot, cold, fuel tank being full or not, weather, what ever. It is truly random. And it is running rough when the light comes on.



The Acura took the car in for several weeks, finally ended up replacing the short block, on their dime, because compression was a little low on three cylinders. I problem reduced in frequency, down to once a month instead of every day. Now, the problem is increasing in frequency, and is up to once every couple of days.



So, the problem is not likely a vacuum leak, because each cylinder has it’s own injector, it is not likely the spark ignition, because each cylinder has it’s own coil. I replaced the EGR valve, no luck. Since the problem reduced in frequency for a time after the short block was replaced, it was probably something they took off and put back on, or disturbed in some way, like a wiring harness, hose, or some other part.



So, before my warranty is up, in about 3,000 miles, I need to find and fix this problem, or get rid of the car. Any ideas what the problem might be?



Thanks,

Mark

Presumably the fuel system, including the pump and its connection has been checked thoroughly?

I would have the compression checked - again. As far as I’m concerned its the first thing to do with random issues of this kind. What exactly about the motor was replaced? Are you saying you got a whole different engine? Used? Rebuilt? Or just a rebuild of yours? If they rebuilt yours did they mess only with the block or did they also worry about the head? Your comment about the replacing the block was just vague - but I’d run the compression again either way.

The Acura Dealer said they put a “short block” in it. I was raised to take that as block, crank, piston, rings, and such. I have no idea if it was “re-manufactured” or brand new. I doubt that the dealer would put in a used block.

They did check the the heads, valve timing, and such. They did do a bleed down test after re-assembling the engine (so they said). At this time, the dealer does not want to deal with the problem. Clears the codes, and says, “bad fuel”, “temp code”, or their excuse of the week.

What part of the fuel system would give intermittent problems? Not the filter. Pump? Pressure regulator? Some other part I’m not familiar with on these new fangled cars?

You’re right about the short block part - its just that once you start asking you find that the general idea can go with a lot of actual practices.

As for other stuff like the fuel pump…it is all guesswork - but a damaged/frayed pump connection could do this sort of thing.

I’d say the other things to look at for poor/weak/damaged connections would be the crank and cam position sensors.

Either of those would knock out all cylinders - though intermittently if you just had a bad or damaged wire/harness.

Your dash lights aren’t involved when it misfires are they?

Have there been any other codes in addition to the misfire codes?

You say they clear the codes and say their excuse of the week. Are you saying the check engine light is still on? If it is, go get it read at an auto parts store or something. Post the codes here and someone might be able to help you out a little better.

The light stays off for a few days to a few weeks, random. I took it in a few times to the dealer, they just clear the codes, light goes out, they make up an excuse. So I just clear them myself, waiting for the problem to get so bad the light stays on, and they have to fix it, if it is before my warranty expires.

The codes are P0300, P0301, P0302, P0303, P0304, P0305 and P0306 if I remember right. I’ll double check in a day or two when it happens again. :slight_smile: