# 1994 Altima engine stumbles when hot



## katehaun (Jul 31, 2007)

I have a 1994 Altima with 134,000 miles. After running for about 20 miles, or when the engine is hot, the engine begins to stumble. It will do this at idle or highway speeds. I have just replaced the distributor and ignition coil, and the #3 fuel injector. These components were replaced in the last week and the car has only gone 20 miles before the engine began stumbling (I replaced the distributor, ignition coil, and fuel injector because of the same problem; obviously it wasn't fixed with these new parts.) I have taken apart the new distributor and there was no oil on the camshaft position disk. 

The check engine light does not come on, but I do not know if there are any engine codes because the nearest auto parts store for the Altima is 35 miles away, and I can't get that far. When it stumbles at idle, there are times when it will come out of it if I manipulate the throttle cable. But the engine will still eventually die. 

The problem seems to be a heat related component because when the hood is open it seems to help the stumbling. But after awhile, even with the hood open, the engine will die. 

I have read that there could be problems with specific sensors (Temperature Sensor, Throttle Position Sensor, Mass Airflow Sensor, Knock Sensor) but am unsure if this is really the problem. I am unconvinced that my new distributor or the camshaft position sensor are at fault. 

I am a poor college student who would like to get back to college.... I can't sell the auto because of the problem... any thoughts???

Thanks!


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## rod_88 (Jan 13, 2007)

Im stumped. Maybe the timing belt, but you say its when the engine gets hot, um I guess try the timing belt, or just like you said the heat sensors=0!!!


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## smj999smj (Jan 1, 2006)

Altimas don't have timing belts...I would spray some carb cleaner around the intake manifold gasket when it's in "stumble" mode and see if the RPM's increase. If they do, there's a good chance your intake manifold gasket is the culprit; a fairly common problem and a bit of a pain in the butt on the U13U Altimas. That being said, this problem usually isn't an issue at highway speeds. Have you checked for oil in the spark plug wells or bad ignition wires? Look for white dots on the boots of the ignition wire as sometimes you can get a wire arcing to the cylinder head's spark plug tube. Other than these suggestions, it would be best to have the datastream observed using a compatable scan tool.


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## francisco006 (Dec 15, 2007)

have you fixed the problem yet? was it the knock sensor....mine does the same and im in the same boat but i do believe it is the knock sensor its a bitch to get at but im going to change it and see what happens


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## Altima SSS (Oct 10, 2007)

katehaun said:


> The check engine light does not come on, but I do not know if there are any engine codes because the nearest auto parts store for the Altima is 35 miles away, and I can't get that far.


You can read the trouble codes yourself ... it's pretty easy. Here's how.

http://www.autozone.com/az/cds/en_us/0900823d/80/1b/62/fc/0900823d801b62fc/repairInfoPages.htm

Also, look at the other links on the right side of that page for other trouble code info.


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## francisco006 (Dec 15, 2007)

OK so heres the deal, i self diagnosed the ECM and its flashes indicate that the knock sensor is bad as i predicted. Now, does anyone know any way to replace the knock sensor without removing the intake manifold? im really stuck.... i took out the axle so that i'd have more room but there is i believe its a coolant pipe connected to a hose, i was goin to remove the hose but the pipe will still be in the way and i guess having big arms doesnt really help much because theres barely any room to move around...
if anyone has any tricks or anything that would help that'll prevent me from removing the intake manifold...plz!!


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## mensagero4u (Dec 8, 2009)

*replacing knock sensor on 94 altima*

:idhitit:Yes it is there is an easy way, raise you car about 10 inches from the ground at the front to give you some space, make sure is safe to go under.
Remove you starter is only hold by two bolts and you can do it from the top, get a 12 inches range and replaced.
That’s how I did!


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## mensagero4u (Dec 8, 2009)

mensagero4u said:


> :idhitit:Yes it is there is an easy way, raise you car about 10 inches from the ground at the front to give you some space, make sure is safe to go under.
> Remove you starter is only hold by two bolts and you can do it from the top, get a 12 inches range and replaced.
> That’s how I did!



I also run into the same situation (heat related problems) and I just found something, one of my coolant or temperature sensors are bad and is the one at the top the red one with two pins.
That one is the one signal the ECU and at the same time turns on and off the radiator fan the other one is for the instrument panel.
My car was getting hot and the engine begins to stumble but the fans wasn't blowing.
I took the plug out and the fan start working.
ECU will give you code 31 but don't worry is just for the moment,erase code replace sensor and you are ready to go!

That sensor send information to the ECU and the ECU send more gas.
:givebeer:


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## Clubwise (Jan 3, 2010)

I don't know if this would help, but my dad (ASE cert. mechanic, blah blah blah) had an issue like this with his nissan hardbody truck, turned out he had a bad head gasket and when the truck got to operating temp, the thermostat would open and basically leak into the cylinder and make it sputter and eventually die.

Me personally, never heard of this, but I trust his words.


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## mensagero4u (Dec 8, 2009)

*drop resistor*

In my case it was the drop resistor next to the intake and the battery, you should check the selenoid ground cable after too. 
:givebeer:


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## Asleep (Jan 19, 2003)

you guys really are bumping this old thread for new questions?
really?


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