please help! major misfire when car reaches operating temp, no cel
1998 altima 160k miles
I have tried many things to fix this problem, probed tps, ohmed injectors, swapped distributor, swapped maf, swapped crank shaft sensor,ohmed temp sensor. Car runs perfect when its cold but give it about 1 minute and it starts to runs really bad, barely any power, I did a headgasket test with the fluid in the glass and it didnt show any combustion issues, cylinder with lowest compression was 165. Its gotta be electrical. Fuel pressure was within specs even when engine warmed up and fluctuated when i pulled regulator line. This is driving me nuts! . I sprayed brake cleaner (yea i know i should use starting fluid but i dont have any) all around the intake and didnt seems to effect engine. well after writint all this im really thinking possibly ecm. All advice is greatly appreciated
Last edited by dirtrider5001; 01-31-2012 at 01:55 AM.
I know its a long shot, and you didnt mention this above, but did you pull the plugs and see what they look like? Mechanical damage to a plug's electro tip could cause this. Also, if you replaced the plugs, were they replaced with the correct ones....meaning correct heat range? How about the spark plug wires? Have you checked them for cracks or other damage that would allow them to ground out causing this type of issue?
the wires and plugs are pretty dang new, previous owner replaced them in trying to fix this issue, the plugs actually look really white on the tips, i know lean, they are black elseware but the distrubutor was arcing out when i bought it from the spring not being put in the right place. the car wouldnt run for more than 3 seconds when i bought it till i moved the spring, so i suppose that could have fouled out one of his new plugs??? still though when i pull each plug when the motor is running they all drop in power equal to the other.
today i swapped out all the injectors with some other ones and no difference, my problem absolutly positively has got to be the ecm, last time i had an ecm go bad (chevy) the tps wire from ecm was reading way off, on the nissan my readings going to sensors from ecm read correctly. Ill tell you this though that lumina ran exactly like this thing runs and it ended up being a bad computer. Still though i am seriously stumped. Tomorrow i will grab an ecm from the junkyard and pray it is my issue. I will let you know how it works out, if anyone thinks of anything else let me know ill be checking the forums
no reference voltage to crankshaft sensor (with key on). So now what? haha, o boy this ones a doozi. im gonna look at this wiring diagram and try and figure it out. maybe bad pcm?
I did come across another puzzling discovery. Both of the wires that are going to the crankshaft pos sensor are grounded! I just bought an automotive multimeter to help me do some more test. This just gets better and better!
I did come across another puzzling discovery. Both of the wires that are going to the crankshaft pos sensor are grounded! I just bought an automotive multimeter to help me do some more test. This just gets better and better!
Have you checked your valve clearances? Sounds like they could be incorrectly set. Need to also look at the emissions control devices. They can cause this exact issue. Ever shut off on you?
a believe it or not i ran a compression check right away and i forgot to hold open the throttle, so i i had pretty good compression readings on 2 cylinders and crappy readings on the others, so i dug into the motor and ended up putting the timing off like a tooth, only to have to go back and set it up correctly lol. NOw u can see how much of a pain in the arse this all has been! Like i said when its cold it revs up so frekin quick its not even funny, just like a nissan should. But probably half a minute all goes to hell. It stays running though! It wont shut off! But has absolutly NO power, I would not try and drive it like this! Back to the timing thing im getting 180lbs on 3 cylinders and like 165 on one. I was worried about that one cylinder for a little bit but i really dont think its an issue anymore as i did a leak down test on each cylinder and they all have the exact same leakdown. It has been a while since i had a car take me this long to fix. I buy and sell cars and i fix them all on my own, ive torn into many engines. Well tonight i just bought an automotive multimeter from harber freight to help me with continuity test. My garage is kinda a mess, my room is a mess, (u get the picture this issue is making me life a mess!!! lol) so im just takin some deep breaths, cleaning house, and then going back into it with patience. Oh yea i have to add that when i disconnect the tps the car has power, (when i drive it with the tps unplugged it feels like it has its normal power!!, i think i stated this before) and i think i also stated that i replaced the tps and even tested the old ones resistance and it was not even bad, Thanks so much for the support i need it in this time of crises haha, im not giving up dont worry about that
Last edited by dirtrider5001; 02-01-2012 at 11:43 PM.
could the intake gasket going bad cause such a loss of power?? or in other words on this particular engine have you even seen an intake gasket issue cause such drastic loss of power? i sprayed around the intake at 3 and 4 cylinder. BUt i was spraying from the top and im wondering if maybe i just missed the leak.. i know the intakes are an issue on these but....
a believe it or not i ran a compression check right away and i forgot to hold open the throttle, so i i had pretty good compression readings on 2 cylinders and crappy readings on the others, so i dug into the motor and ended up putting the timing off like a tooth, only to have to go back and set it up correctly lol. NOw u can see how much of a pain in the arse this all has been! Like i said when its cold it revs up so frekin quick its not even funny, just like a nissan should. But probably half a minute all goes to hell. It stays running though! It wont shut off! But has absolutly NO power, I would not try and drive it like this! Back to the timing thing im getting 180lbs on 3 cylinders and like 165 on one. I was worried about that one cylinder for a little bit but i really dont think its an issue anymore as i did a leak down test on each cylinder and they all have the exact same leakdown. It has been a while since i had a car take me this long to fix. I buy and sell cars and i fix them all on my own, ive torn into many engines. Well tonight i just bought an automotive multimeter from harber freight to help me with continuity test. My garage is kinda a mess, my room is a mess, (u get the picture this issue is making me life a mess!!! lol) so im just takin some deep breaths, cleaning house, and then going back into it with patience. Oh yea i have to add that when i disconnect the tps the car has power, (when i drive it with the tps unplugged it feels like it has its normal power!!, i think i stated this before) and i think i also stated that i replaced the tps and even tested the old ones resistance and it was not even bad, Thanks so much for the support i need it in this time of crises haha, im not giving up dont worry about that
Which TPS harness did you disconnect? If the car is A/T there's two harnesses there. Even though you replaced the TPS I'd say start by tracing those wires and test the new TPS unit to make sure it is adjusted properly and it's putting out the right signal with the key set to the on position and the engine off.
well i just sprayed all around the intake again and i find no difference in how it runs when i spray. I am now taking a serious look at the iacv. That has got to be the most pain in the ass of an iac ever made! coolant! back of the motor!! im hoping its not gonna be too much of a bear. I unplugged it with the motor running and it did start to run worse like it eventually starts to run if i let it run longer. Im gonna look in the book and see if theres any vacuum test or anything to test it but i dout it.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
