Mechanics

HARD START WHEN WARM

1999 Jeep Cherokee

Engine Performance problem
1999 Jeep Cherokee 6 cyl All Wheel Drive Automatic 275000 miles

So my Jeep started having some issues, i'm wondeirng if they are all related. Symptoms are below:

- Hard start when WARM not cold, not hot. If I start the car in the morning, starts no problem. Start the car after having it off for 5 min, no problem. Start the car after 2 hours of sitting, hard start.

- Poor acceleration and rough idle.

- On two occasions the engine temp gauge showed high (over 220F) and the engine idled rough. I shut the engine off, restarted it after a few seconds and it registered fine.

- Normal operating temperature seems to be below 200F while cruising on the hwy with the AC on. Goes up to about 210 at at idle in traffic.

- Good fuel economy, not sure if this is a symptom, but the gas mileage meter in the evic says i'm doing 13.5L/100km which the truck has never done.

- No check engine or warning signals.

The only thing out of the above that really concerns me is the hard start. I'm worried that i'll drive somewhere and it will go from a hard start to a no start condition.
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MarkyZ
July 21, 2010.




Hi MarkyZ, Welcome to 2carpros and TY for the donation

Lets do this test the coolant temperature sensor its like a carbuerator choke that gives fuel during initial start ups. If okay check the static fuel pressure and residual fuel pressure with a fuel pressure tester this pressure should not drop to quick when you turn the engine off.

The fuel pressure should be 44.2-54.2 psi

Tiny
Rasmataz
Jul 21, 2010.
Thanks Rasmataz,

So for the million dollar question, how do I test the CTS? The CTS appears to be on top of the thermostat housing, do I have to remove it to test it? If it tests bad and I have to replace it, do I need to do something to the coolings system to make sure that there is no air in it? Thanks in advance.

Tiny
MarkyZ
Jul 23, 2010.
Take the reading before you start the vehicle and when the engine is fully warmed up.

Use a high impedance volt-ohmmeter. Resistance should be less than 1000 ohms with a WARM engine (examples = 212* would be about 185 ohms, 160* would be about 450 ohms, 100* (not warm enough) would be 1,600 ohms).


http://www.2carpros.com/forum/automotive_pictures/12900_cts_48.jpg

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Tiny
Rasmataz
Jul 23, 2010.
Alright so a friend tested it using your chart and the numbers are bit off, looks like it's not putting out enough resistance.

What is the procedure for replacing it? Do I just crank it out and replace it with another? Do I need to do something to make sure I don't get air in the system?

Tiny
MarkyZ
Jul 28, 2010.
Just remove it and make sure it doesn't leak

Tiny
Rasmataz
Jul 28, 2010.

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