icebox2000 Posted May 6, 2015 Share Posted May 6, 2015 Good morning all. I'm at my wits end and need your guidance. I have a 1998 Nissan Pathfinder LE 4x4 AT and am having noticeable misfiring between 0 - 3000 RPMs along with little power; but exactly at 3000 RPMs, the engine comes to life and has alot of power and no misfires. I was having this back in January and then while on a trip, my radiator plastic top split right open. I had it towed to the closest Nissan dealership to have it repaired. After putting in a new radiator, changing out the engine from a 140K to an 80K due to a blown head gasket and possible cylinder damage, and new plugs/wires/distributer w/ cap&rotor, I still am getting the random misfire. I do not have any vacuum leaks, the fuel pressure is good, and I am not getting any other error codes. The dealership had it for three months and could not figure it out. I am thinking about changing out the ECM under the dash, or maybe having the exhaust looked at... Am I on the right track? Charles Link to comment Share on other sites More sharing options...
Precise1 Posted May 6, 2015 Share Posted May 6, 2015 Welcome to NPORA Charles. First, go to the Garage section and into the pinned FSM thread to download your free copy of the manual. Ok, so this happened before the motor replacement, so we can safely assume this is electrical/sensor, not motor mechanical and probably not fuel either. Go to page 255 of the manual and follow the trouble shooting instructions that pertain, that is what I would do. Obviously keep us informed of progress and ask any questions you might have. I'm wondering if it might not be the ECU itself, since it changes running parameters at 3000 rpm, which is were limp mode would kick in with certain faults. Anyway, no real way to be sure without you or someone trustworthy/competent checking off most of that list; I'm opposed to throwing parts at a problem... As for the dealership, I have no idea what they did or didn't check/replace, and at this point it would be best to verify previous findings anyway. B 1 Link to comment Share on other sites More sharing options...
jyeager Posted May 6, 2015 Share Posted May 6, 2015 Icebox, after the engine swap was there any time during which the misfire was gone? Or has it continued as always right from then? Second question: is it dependent on engine LOAD? for instance, does it happen in first gear? second gear? third gear? Or only overdrive? When it's happening, if you lift off the throttle about 50% does it diminish? Link to comment Share on other sites More sharing options...
icebox2000 Posted May 6, 2015 Author Share Posted May 6, 2015 Jyeager, The misfire has continued on even after the swap without mercy. It does happen in all gears, at all speeds, but only when the engine is below 3K rpms. I usually only feel it when I'm stopped at a light, when I'm accelerating, or when I'm maintaining speed. It gets real jerky when I set cruise control too. Link to comment Share on other sites More sharing options...
jyeager Posted May 7, 2015 Share Posted May 7, 2015 You mentioned new plugs, wires, cap and rotor. But not the ignition coil. So that's still a possibility.... Does it do it when you first start the vehicle cold, during the first minute of operation? (Open Loop) Actually, find and disconnect the coolant temp sensor and test drive it. Link to comment Share on other sites More sharing options...
Rebelord Posted May 7, 2015 Share Posted May 7, 2015 The ignition coil is built into a 3.3 distributer Sent from fat fingers on S6 Link to comment Share on other sites More sharing options...
jyeager Posted May 7, 2015 Share Posted May 7, 2015 The ignition coil is built into a 3.3 distributer Sent from fat fingers on S6 Right, but that's not a part that was changed. Link to comment Share on other sites More sharing options...
Rebelord Posted May 8, 2015 Share Posted May 8, 2015 He said in 1st post he did. At least what I see reading it on mobile. Sent from fat fingers on S6 Link to comment Share on other sites More sharing options...
icebox2000 Posted May 8, 2015 Author Share Posted May 8, 2015 JYeager, I had also thought it was the coil, but I did validate that the new distributor did come with a new coil. It does have misfires even when first started. I will try the coolant temp sensor disconnect tonight. Thanks. Link to comment Share on other sites More sharing options...
Rebelord Posted May 8, 2015 Share Posted May 8, 2015 I would double check all wires. Make sure all go to correct plug and seated. Even double check your distributor is set right. Real easy when dropping it to have it go a tooth off. Which can cause mayhem. Heck with that much miss fire I'd pull all plugs too. Sent from fat fingers on S6 Link to comment Share on other sites More sharing options...
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