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Check Engine Light and Higher RPMs.

98XJLongBuild

98XJLongBuild

NAXJA Forum User
Location
San Jose, CA.
So heres the story. The other day went to leave my house and got the rig warmed up to operating temperture and then it started to make a clunking noise. Drove it to work and home that day. Got up this morning ang retightened the four flex plate bolts again. That seemed to stop the noise.

Know the issue is half way to work my Check Engine Light came on for the first time. Also to go 55mph. the motor runs at 2100 RPMs. Before this happened it would run 2000RPMs at 55mph.

Why would there be a difference in RPMs and a CEL?:repair: I did not change anything at all.

Oil pressure reads around 25 psi. Also going to my friend who just so happen to work at a dealer who has access to a code reader for free.


1998 XJ Sport, 32" tires, 6.5" lift, I6 4.0, 4.10 gearing, D30 & D35.


.
 
Guessing is futile. Strategy for a check engine light is always the same. Use the technology provided to you by your Jeep.

Pull the codes and post the exact code(s) here for comment.
 
98XJLongBuild said:
So heres the story. The other day went to leave my house and got the rig warmed up to operating temperture and then it started to make a clunking noise. Drove it to work and home that day. Got up this morning ang retightened the four flex plate bolts again. That seemed to stop the noise.

Know the issue is half way to work my Check Engine Light came on for the first time. Also to go 55mph. the motor runs at 2100 RPMs. Before this happened it would run 2000RPMs at 55mph.

Why would there be a difference in RPMs and a CEL?:repair: I did not change anything at all.

Oil pressure reads around 25 psi. Also going to my friend who just so happen to work at a dealer who has access to a code reader for free.


1998 XJ Sport, 32" tires, 6.5" lift, I6 4.0, 4.10 gearing, D30 & D35.


.
Click to expand...


Correction - At 55 mph. the RPMs are at 2200 instead of 2100 as posted above.

Also engine has 154346 miles on it. Just some more info.

.
 
Alright just got back from using my friends code reader and this is what it came up with.

-P0700 Transmission Control System
-P0740 Torque Converter Clutch Soleniod Circuit

Are these easy enought to change without taking the trany out and to do it myself?
Or, is it easier to take it to a transmission shop and have them do it? If I go this route about how much would it cost.

My friend had the same one go out on his and he said to put a magnet to the trany pan and allow it to collect metal out of the fluid. Then change the fluid and filter after about 30 miles. I'm trying this one right now and hope that will help clear out those sensors.

.
 
Not hard to change, drop the pan and there they are. You can do the filter and fluid change at the same time.

But check the little things like fluid level, wiring connections, and pressure cable adjustment first of course. No point changing parts if it's just a fluid level or wiring issue.
 
Can you actually feel that overdrive is "locking up" properly?

What is the history of "routine transmission maintenance?". Meaning, how fresh is the fluid?

The fluid should be at the proper level on the dipstick, should be red in color, and should not smell burnt. If yours have any of the above characteristics, CHANGE IT. Should use Dex/Merc III compatible fluid, available most anywhere.

If fluid checks out and is fresh, I would drop the pan and test the solenoids as the next step. Can do that with a meter and a manual with the test specs.
 
Issue all fixed. Seems that sometimes the older people maybe right. I put 2 magnets to the pan and drove around a while and all these issues seem to have just gone away. So I will be changing out the fluid and filter tomorrow. Thanks for all your help.
 
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