stretch86

I just got a 99 xj sport it has 218k miles but p/o said motor and tranny have 175k. it has a rough idle when its cold (keeps going up and down) ive done some research and took throttle body off today cleaned it and iac valve but it still does it if i hit gas rpms go up with no hesitation. Ounce its warmed up its fine idle is at second line on tach. As for the shifting ive adjusted the tv cable which helped a lil and the fluid was dark and stunk so i drained pan and added fresh fluid to it (gonna do this couple more times but drive it for lil bit then do it) which helped a lil as well. I noticed the ground strap from block to firewall is torn in half so gonna replace that tomorrow any ideas as to what those two "problems" are

cruiser54

You're on the right track.

Those 4.0s are due for plugs, wires, cap and rotor every 30,000 miles. I prefer NGK plugs.

stretch86

Im gonna give it a tune up eventualy and use the copper plugs as ive read thats what these notors like best. I got the jeep cause im in the proccess of rebuilding a 86 suburban. The rear ends junk so i cant drive it plus the jeep will be good in winter w the 4 wheel drive. I just gotta get jeep running better before i tackle the suburban. Im gonna do ground strap and get some contact cleaner to see if thise help. Also there was a engine code for some sort of solenoid/circuit on tranny but cant recall what it was.

cruiser54

See my Tip 10 for the trans issue.

stretch86

The code was either p0743 or p0753 i think i know it had to do with a solenoid/circuit and that was only code on cpu

cruiser54

I'm not familiar with codes, but it never hurts to check those connectors.....

stretch86

Ill wait for some others to chime in

Dumajones

Quote:

Originally Posted by stretch86

Ill wait for some others to chime in

P0743 JEEP - Torque Converter Clutch Solenoid Circuit

Possible causes
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
- Low transmission fluid level
- Dirty transmission fluid

Tech notes:
This is an electrical problem code. Could be a problem to the harness to the TCC solenoid, the TCC solenoid connector or the TCC solenoid it self.

When is the code detected?
By performing a voltage drop test, the ECM detects that the TCC solenoid circuit is open or shorted.

P0743 JEEP Description
The Torque Converter Clutch (TCC) solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.

Lock-up operation, however, is prohibited when A/T fluid temperature is too low.

When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

P0753 Jeep - 3-4 Shift Solenoid
- Low transmission fluid level
- Dirty transmission fluid
- Faulty shift solenoid valve
- Shift solenoid valve harness or connectors
- Shift solenoid valve circuit is open or shorted

Do like Cruiser suggested and do tip 10 in his tips..Cruiser’s Trans Plug Refreshing.

As for the idle thing, on my 2000 it was the IAC that was causing the funny warm ups. I put a Mopar OEM IAC in and all fixed.

stretch86

Mine only does it when first start it in mourning or when leave work

stretch86

I take back what i just said its now doing it warm any way of testing iac or tps gonna get new champion copper plugs tomorrow and take look at dizzy cap and rotor

cruiser54

Here's a chime for you. Ding-ding!! Tip 10!!!!!

CCKen

My tip: OP has a '99 XJ.

stretch86

I was talking about idle fluctuating not tranny

cruiser54

They don't have trans harness connectors in the passenger side of the engine bay at the rear of the engine??

stretch86

I plan on getting contact cleaner and spraying all of the plugs cause there filthy. I also took dizzy cap and rotor off and cleaned them up with sand paper (im tight on money) and it halped starting sooner but this idle thing is bugging me. As for the tranny if i give it small amount of gas it shifts fine but if i give it more it shifts later and a lil harder gonna drain pan again this weekend and refill