# Cold stumbling



## KDragon (Oct 9, 2006)

Ok so with it getting colder (about 45-50F) when I start my car its a little slower to start by like 1 second and if i rev the motor at all it stumbles and will not rev higher. It also blows blueish and black smoke. but after about 20-30 with light reving it smooths out and runs fine.

I was almost thinking a cloged cat but it runs fine the rest of the time so maybe egr?


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## KDragon (Oct 9, 2006)

Well i checked the EGR system and it seems to be working so I'm replacing the fuel filter in the AM and see if that helps.

In addition to said problems there is an extremely bad idle.


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## Altima SSS (Oct 10, 2007)

My 94 stumbles some when cold, but 5 min of warm-up and it runs smoother and the stumble goes away.

I'm suspecting maybe the coolant sensor for the ECU input. There are 2 separate coolant sensors ... one for the ECU input, and one for the gauge on the dash. I haven’t checked mine yet, but plan to.

If you have a manual it will tell you how to test it at room temp and at operating temp ... it's a resistance check.

It could be possible that it's way off on the cold side and causing the engine to run way too rich or lean, which would definitely make it stumble and idle rough when cold as the ECU would be off on it's control due to a faulty coolant temp input.


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## KDragon (Oct 9, 2006)

well i replaced the sensor about 2 month ago so that should be fine but ill test it any way.

The rough idle is all the time but is worst after a long hwy drive i.e. going to milwaukee from fond du lac :lame: but i think that it might be my intake gasget


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## KUMADE8 (Nov 9, 2007)

What kind of car do u have. If u have a air flow meter (hot wire style) check your air flow meter for debree on wire. U will have to pull it off. This is very common, us electrical cleaner and a q tip and clean wire. Be careful touch lightly.


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## KDragon (Oct 9, 2006)

I have the OBD2 95 Altima. Yes it has a hot wire maf. ill look into that too.

Thanks.


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