AKA_04

I have a multi cylinder misfire that's driving me crazy. Cylinders 1 & 3 are not firing below ~3000 RPM's. At idle the check engine light is on, between idle and 3k the check engine light flashes, and above 3k the check engine light stops flashing, turns off, and the misfire goes away.

I've done all the standard things: listened for air intake leaks, swapped coil packs and swapped fuel injectors, connected the cylinder 1 & 3 coil pack plugs to a new coil pack and new spark plug outside the engine to visually check that the spark and fires. Checked the fuel injector with stethoscope (just cylinder 1, couldn't reach cylinder 3) and had heard a solid tick, plus I smell gas in the exhaust. Bottom line: There's spark and there's gas. Why is this going away in the high RPM range??? And if it's a camshaft/crankshaft position sensor why would cylinder 5 fire? I'm new to Maxima's but rapidly building experience, I've combed the forums and haven't found a misfire that disappears and reappears due to RPM's.

This all started after replacing the left cylinder head (cylinders 2/4/6) because of a VAIS bolt failure. I did not remove the right head (1/3/5) when replacing the left head. My engine was running very well before hand, perfect maintenance record and I even know both of the original owners. After I put the engine back together the misfire on the right bank started. I ruined my rings and had to replace those thanks to the precats. I hollowed out the precats to prevent this from happening again and then I did the spark plug/O2 sensor anti-fouler trick.

Remember, this was happening before and after to the anti-fouler install and my exhaust smelt like gas in both situations. Could this just be a sensor?

AKA_04

Bumpdate: Compression test is GOOD... I was really beginning to worry that I had bent my valves on accident. Compression test was conducted on a cold (60 degree) engine under dry (no oil added) conditions. Results: Cylinder 1: 147, 2: 148, 3:155, 4: 153, 5: 158, 6: 155.

TunerMaxima3000

iTrader: (4)

There are a ton of things this could be given the repairs just performed and the apparent damage that happened. The first question though is how do you know its cylinders 1 & 3?

AKA_04

To answer your question, I was able to disconnect the cylinder 1 and 3 coil packs and the engine idle wouldn't change.

As for the solution: I'm an idiot. I switched the cylinder 1 & 3 coil connections. It was very difficult to figure out since the misfire would disappear. Also, I took the engine apart back in September. I was taking 21 hours this last semester and didn't finish putting the car back together until the beginning of January. Still doesn't excuse my error, I even labeled the connectors before disassembling the engine.

On the plus side, the info is out there. I hope this helps someone in the future. I drove my car and all is well so far; there's a few issues to iron out but it looks promising.

TunerMaxima3000

iTrader: (4)

Nice work figuring it out, and doing this all yourself, kudos, sir!

Happy you got it fixed. FYI, Nissan always lables #3 cylinder on their harnesses, both coils and injectors

AKA_04

Thank you. It's been a long project, I'm really liking the extra power (at least it feels that way, no dyno ) from hollowed out precats and new rings.

I had no idea that Nissan labeled the #3 cylinder, I'll look for it today when I fix a leaking valve cover. Aaaaand I have a write-up to do this weekend... Cheers!

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Low RPM misfire multicylinder multi cylinder goes away when revved