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Running rough on startup

pablo_max3045

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
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Rubi D

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
I have noticed it once or twice. Only for a few seconds, so figured it was just the ECU adjusting for the cold engine.
 

JLJessieJeep

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
Both my 2.8lt JK and 2.2lt Jl run a bit rough first thing in the morning, usually when below 5 degrees.
I just put it down to a cold engine and cold fuel making it work hard for ignition.
I also have a 2lt Amarok that does it as well.
 

TangoRomeo7688

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Check fuel injector correction. You will notice a big difference between one or more and the rest.

Replace and config bad injectors. Also check compression of each cylinder, if one or more has a difference to the others, engine has to be replaced.

That's what I have to go with my 2.2, was told so by an FCA technical employee.

Think about changing my 2door 2.2 for a 4door 2.0
 

rickinAZ

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Don't all engines run rough for a few seconds after a start up in cold weather? We even notice it here in AZ.
 

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TangoRomeo7688

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No, my engine ran smooth in first winter after cold starting it. This year it runs very rough for the first 10-15 seconds. We now found two bad injectors ( cylinder 2+4). New ones will be putted in next wednesday.will see if things get Vetter :)
 

TangoRomeo7688

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Well., we now replaced:

- 2 fuel injectors cylinder 2+3
- rail pressure sensor
- pcm

Nothing changed.. I now wait what Jeep tells us to replace next.....
 

calemasters

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
You did not state which engine. The coldest temps I have seen with my JLUR diesel has been 3 degrees F. It started easily (glow plugs cause about a 1 second cranking delay at 3 degrees) and goes to a very smooth fast idle (~900 rpm). After about 5 minutes of driving, the idle returns to ~600 rpm.
 
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pablo_max3045

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You did not state which engine. The coldest temps I have seen with my JLUR diesel has been 3 degrees F. It started easily (glow plugs cause about a 1 second cranking delay at 3 degrees) and goes to a very smooth fast idle (~900 rpm). After about 5 minutes of driving, the idle returns to ~600 rpm.
True.. but this is the 2.2 D sub forum.. so...

Normally, modern diesel engines run "normal" at startup unless the temp is quite low. At least the last several I have owned.
I still have 2 more years on the warranty though. So I guess I will not stress too much for now.
 

mnicho29

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Just a theory. It may just be some of the electric pumps starting in sequence or something. I know the feeling you’re referring to, and I get it too but if I listen to the actual idle carefully, engine is running smooth. But it feels like some pumps are staring up. Dunno just a theory.
 

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mnicho29

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
I think it’s because many of the pumps like AC and power steering are electric pumps a progressively start up. If you listen carefully, the actual engine runs smooth. Or it should
 
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pablo_max3045

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I think it’s because many of the pumps like AC and power steering are electric pumps a progressively start up. If you listen carefully, the actual engine runs smooth. Or it should
No. It is clearly the engine.
 

The1970 jules

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Has anyone else noticed that the engine is a bit rough upon starting when it's cold outside?
Seems to last only 5-10 seconds and then it's smooth again.
Wonder if it is just mine and something is wrong or normal behavior.
Yep, happens to mine randomly in hot or cold weather. Always clears after a few seconds.
 

Riotfunk

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Direct injection without port injection runs rougher on cold startups. Most newer turbo vehicles that are DI only all do this.

DI sprays a ton of fuel during starts because is at way higher pressure than port. So until it warms up enough to burn that off it’s louder. In a nutshell.

Is also why you see fuel dilution of the oil in these motors since they don’t burn off all that excess fuel until they warm up. Stop and go driving with short trips is the worst for this. But is how most of us drive.

It’s not a huge dilution, but still. I saw 2% dilution at 8k on my bronco turbo motor.

I’m only talking about the 2.0 since I believe the 3.6 is still port injected
 
 



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