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post #1 of (permalink) Old 09-05-2002, 07:44 PM
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2.5L Runs rough when cold

My 2.5L Tbi runs very roughly when cold. I am thinking coolant temp sensor but I can't find anything about it connecting to the fuel injection system according to my Haynes manual. Before I go and buy a new sensor can someone tell me if the CTS even sends info to the computer for fuel mixture? If the sensor only sends a signal for the temperature indicator, the indicator seems to work fine so I maybe should look elsewhere.

Thanks again to the best source of info for SWB Jeeps anywhere.
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post #2 of (permalink) Old 09-07-2002, 09:27 AM
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Re: 2.5L Runs rough when cold

to the top, someone must have some input?!
post #3 of (permalink) Old 09-07-2002, 11:11 AM
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Re: 2.5L Runs rough when cold

Won't this work for you? <a target="_blank" href=http://www.jeepresourceuk.co.uk/main26.html>http://www.jeepresourceuk.co.uk/main26.html</a>

I don't know if they use a separate sender/sensor for the computer and the dash ..on my TJ everything on the dash comes from the PCM.

Since you didn't mention what else you've done to it ...have you eliminated more simplistic causes? Bad wires can arc when the engine is cold and work just fine when the engine is warm (found this out at the car wash - I owned so many $hit boxes that I assumed rough running when cold was normal).

Good luck!
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post #4 of (permalink) Old 09-07-2002, 04:42 PM
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Re: 2.5L Runs rough when cold

I wish that would work, but I don't have a check engine light, I think maybe they started using those later on.
post #5 of (permalink) Old 09-07-2002, 07:05 PM
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Re: 2.5L Runs rough when cold

Ok, I'm not only depending on this board, I am asking around also, good thing it seems. Anyway someone mentioned the idle sensor. I am not seeing that one but I have not gotten or come up with any other ideas, any comment on that idea?
post #6 of (permalink) Old 09-07-2002, 07:19 PM
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Re: 2.5L Runs rough when cold

Man ..you're getting no where here [img]images/icons/frown.gif[/img] The sad thing is that I believe that your 4 banger shares the same fuel/electronic system as the 4.0. For some reason this place is just piss poor for 4 bangers.

(shhhhh) try this ..shhhh ... repost it saying "4.0 runs rough when cold" ...and see how many respond ...remember ..shhhh [img]images/icons/laugh.gif[/img][img]images/icons/wink.gif[/img]

You need "dorfs" ..he knows all about this stuff. If you're fortunate ..he may pick up the post. The guy is a rightous world class service tech and goes beyond the knowledge of mere mortal mechanics. If you put his name in the topic "dorfs HELP!!" he may notice it.
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post #7 of (permalink) Old 09-07-2002, 11:44 PM
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Re: 2.5L Runs rough when cold

Cantdrive55,

Have you cleaned your throttle body? This is for the 88YJ right? The idle stepper motor is a good place to check. The TPS and IAS are usually the two main reasons for problems. I don't know if the YJs had it, but there's the good old three turns of the key trick to check engine codes. My guess is a cleaning might do some good. How do the spark plugs look?
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post #8 of (permalink) Old 09-08-2002, 07:27 AM
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Re: 2.5L Runs rough when cold

ok, getting input now, thankyou.

Yes this is for the 88 YJ. It is TBI, not MPI like the 4.0's. There is no check engine soon light so the self check idea won't work here.
The problem has been weird, used to be when I got down to a 1/4 tank or less it ran terrible, almost like I was running out of gas. I would fill it up and it would still run bad for about the next entire tank. I replaced the fuel filter, external and in the tank. I replaced the fuel pump, put it all together and now this runs rough when cold deal. Runs quite like it did before at the 1/4 tank thing, only now it's when it's cold. Cold engine keep in mind, not necessarily cold weather.

Other things I have done, new wires, rotor, cap. Ran some (silver bottle, good stuff) STP, fuel injector cleaner through it.

I will check the plugs.
I will look at cleaning the tbi today.
I will also look to see if it has EGR, I haven't noticed.
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