1995 SE cold start OK, misses and will not start when warm.
Posted: Tue Sep 22, 2015 4:36 pm
Hi guys
I need some help fixing my old Pathfinder (SE-V6), which has 210,000 miles on the clock and ran very reliably until a couple weeks ago. The problem is it starts OK cold, but develops a progressively worsening misfire which begins at around 2400 rpm once the engine is warmed up and/or the vehicle is driven a few miles. Then she stalls and won't start again until the engine is cold. Now and again it will start (barely) when still warm, and then the misfiring is instant and very severe.
The fuel pump runs at turn-on and primes the system as it should. I've checked the fuel pressure at the rail, and it's normal.
I've changed the ignition coil, plugs, plug wires, the dist. cap and rotor, the O2 sensor, the fuel filter, air filter, oil, and oil filter.
I've cleaned and checked the output of the MAF sensor, also the throttle rotation sensor, checked and charged the battery and cleaned all the electrical connections and vacuum hoses I could see.
I also checked the coolant temp. sensor against a new one and it seems to be fine. The engine has never overheated or burned oil.
Other things: There is a rattle in the vicinity of the AC compressor; the exhaust system around the cats looks very rusty, and the exhaust note sounds a bit too 'open' as if a cat might have broken up (this noise despite a new muffler just a few weeks ago.)
(Could all this be caused by a bad cat?)
The ECU fault code mode III sometimes reads 34 = 'detonation sensor', but that seems to have stopped. Recently it's also shown 21 (no signal to ignition primary circuit), and 12 (MAF--but this was just after I'd been checking it). I have noticed that the engine check light only comes intermittently, and only when when you try to rev the engine while it's missing. (Strangely, the last two ECU mode III checks showed 55 (normal!)
ECU mode I shows green/red both lit, mode II is green only. This indicates the fuel mixture is OK (I think). It definitely seems like an ignition timing problem to me, but damned if I can find the source of it.
Any help would be much appreciated--thanks!
Shaggy
I need some help fixing my old Pathfinder (SE-V6), which has 210,000 miles on the clock and ran very reliably until a couple weeks ago. The problem is it starts OK cold, but develops a progressively worsening misfire which begins at around 2400 rpm once the engine is warmed up and/or the vehicle is driven a few miles. Then she stalls and won't start again until the engine is cold. Now and again it will start (barely) when still warm, and then the misfiring is instant and very severe.
The fuel pump runs at turn-on and primes the system as it should. I've checked the fuel pressure at the rail, and it's normal.
I've changed the ignition coil, plugs, plug wires, the dist. cap and rotor, the O2 sensor, the fuel filter, air filter, oil, and oil filter.
I've cleaned and checked the output of the MAF sensor, also the throttle rotation sensor, checked and charged the battery and cleaned all the electrical connections and vacuum hoses I could see.
I also checked the coolant temp. sensor against a new one and it seems to be fine. The engine has never overheated or burned oil.
Other things: There is a rattle in the vicinity of the AC compressor; the exhaust system around the cats looks very rusty, and the exhaust note sounds a bit too 'open' as if a cat might have broken up (this noise despite a new muffler just a few weeks ago.)
(Could all this be caused by a bad cat?)
The ECU fault code mode III sometimes reads 34 = 'detonation sensor', but that seems to have stopped. Recently it's also shown 21 (no signal to ignition primary circuit), and 12 (MAF--but this was just after I'd been checking it). I have noticed that the engine check light only comes intermittently, and only when when you try to rev the engine while it's missing. (Strangely, the last two ECU mode III checks showed 55 (normal!)
ECU mode I shows green/red both lit, mode II is green only. This indicates the fuel mixture is OK (I think). It definitely seems like an ignition timing problem to me, but damned if I can find the source of it.
Any help would be much appreciated--thanks!
Shaggy