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stalling issue

1

1990heepxj

NAXJA Forum User
Location
Apple Valley, Ca
ok specs 1990 aw4 np242 6 cyl blah blah...

anyway i just picked this thing up this past sunday and allready put all my suspension axles all that on it from my other xj and the other is now stock. i went for a test drive with the new one and now find it tries to hesitate almost stall or it will just stall. now it only seems to do it when i slowly press the gas pedal it. it sometimes almost hesitates a little when i hit the gas quickly but it doesnt try to stall. i replaced the fuel filter cuz lack of fuel was first thing that came to mind. it definately has pressure it blasted fuel when i went to put the new filter in. and i do hear the pump prime when its supposed to.

ok so does anyone have any suggestions?............ paging joepeters!
 
Clean the throttle body, pay particular attention to the IAC port. Make sure the throttle plate stop screw hasn't been monkeyed with--3/32 allen, back it out until it no longer acts upon the throttle plate, then screw it back in until you catch the first perceptible movement of the throttle plate--done, leave it alone after that.

Clean the IAC, be careful of the pintle it can break. Never energize the IAC when it isn't mounted, there is no built in stop and it can break.

Ok, with the throttle body/plate cleaned, the throttle plate stop set, and the IAC mounted, test/adjust the TPS.

You should end up with 700~750 rpm idle. Test it after the engine and transmission are fully warmed up, after about 20 minutes of operation. Use a separate tach, don't rely on the dash unit. Autos are checked in DRIVE, so have a friend apply the service brakes while you are doing it.

Post up your results.

Good luck.
 
1. Clean throttle body and IAC as Joe mentions.
2. TEST your fuel pressure with a gauge. For your vintage, you should have 31 psi, and when you disconnect the fuel pressure regulator line, it should jump to approx. 39 psi.
3. Test AND adjust your throttle position sensor. Best way to do this is with an analog meter and a manual showing the procedure. Your vintage tps IS adjustable.
 
Ok, be looking for your follow up post.

Good luck.
 
ok swapped in a nice clean iac i grabbed at pnp a while back cleaned up the inside of the throttle body, it wasnt too dirty but its good now. reset the set screw for the throbble stop. and reset the tps so it sits at dead on 750 in drive and no more stalling. good to go thanks much guys!
 
Glad you got done!

Now go wheeling this weekend!
 
i want to, gotta test out my new beasty! still gotta swap my open system radiator over, swap my bumpers and trim my fenders. ill get to all my fluid changes next week, get her in tip top shape, shes only got 183k and i want her to have a long life.
 
ok so i thought it was fixed buuuuuut nope. just to make sure i swapped the iac from my other renix and it didnt help i also swapped the fuel pressure regulator and still nothing. i know i set the tps right ive now double cheked it a few times and cleaned out the TB. i dont know what to do, need more suggestions
 
I don't see any mention of actually "testing" your fuel pressure. Really should be done early in the troubleshooting process. Swapping out the regulator doesn't mean that you have pressure in the proper range.

Must be done with a GAUGE. You should have approx. 31 psi at idle. With the line from the fuel pressure regulator disconnected, the pressure should jump to approx. 39 psi.

How are you setting the TPS? Using a meter? IF the meter tests out smoothly with an analog meter and it is properly adjusted via meter, you could eliminate that from the equation. But only when those two things are done.
 
birchlakeXJ said:
I don't see any mention of actually "testing" your fuel pressure. Really should be done early in the troubleshooting process. Swapping out the regulator doesn't mean that you have pressure in the proper range.

Must be done with a GAUGE. You should have approx. 31 psi at idle. With the line from the fuel pressure regulator disconnected, the pressure should jump to approx. 39 psi.

How are you setting the TPS? Using a meter? IF the meter tests out smoothly with an analog meter and it is properly adjusted via meter, you could eliminate that from the equation. But only when those two things are done.
Click to expand...


Excellent advice.
 
ill find a fuel pressure guage and check that but yes im gettin a smooth set on numbers out of the tps gettin a ratio of .83 for that so i know thats fine. ill see what the pressure says but i gotta find somewhere with a guage. to describe my issue better it drops rpm's, tries to stall, does stall or sputters a bit ONLY befor 1000 rpm EVERY time and ONLY as i take off. other then at take off its totally fine. it starts right back up no problem but some of the time it starts racing to sit at 2k rpm at idle out of gear and about 1250 in drive.
 
Last edited:
Try spraying some contact cleaner in the connector from the TPS to engine harness. Although the TPS may read okay at it's connector, there could be some resistance in the connector causing the ECU to get an inaccurate signal. BTW, have you ever done a good ground refreshing on this vehicle?
 
i only bought this thing last sunday. buuuuut i think i may have found the problem. some knuckle head put 4 diff looking injectors in it, god knows what they came from so ima swap my 5.0 injectors in and see what happens. but also i was getting a good reading from both sides of the connector, the vehicle side and the sensor side so no problem there. i have 3 orange top silver body, one black top black body its actually about an 1/8th inch longer then the rest, a black top silver body, and a white top silver body all of which are single pintle. im hoping my nice 5.0 4 pintle mustang injectors will fix my problem
 
i will since i now have good injectors, new fuel filter, new air filter, proper set tps 4.7 input 3.9 out put a perfect .83 ratio, a working/clean iac, a good fuel pressure regulator, clean throttle body all vacuum lines hooked up properly, and yet im STILL having problems. ill make new grounds tomorrow and see if it helps. it keeps wanting to rev to like 2500 rpm when i start it up after driving it around. it ran perfect the 96 mile trip from burbank to my house. i put the lift on and the first test drive it started the stalling thing. i do have a 1" t-case drop could that have pulled on a wire or messed with the function of the trans in a negative way? i know i didnt bump anything when doing the lift to cause it to do this. the only time i was under the hood foor the lift was to swap shocks.
 
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haha ive been reading that the last 20 mins. it appears im getting close to the same issues ecomike was. what a pisser i cant believe it ran perfect all the way home then took a dump after i put my stuff in it. i WILL fix this damn thing!!!!!!!!!!!!
 
1990heepxj said:
haha ive been reading that the last 20 mins. it appears im getting close to the same issues ecomike was. what a pisser i cant believe it ran perfect all the way home then took a dump after i put my stuff in it. i WILL fix this damn thing!!!!!!!!!!!!
Click to expand...

Ok, LOL! I guess great minds think alike. A little bit of a high idle on start with the Renix is normal--no memory in the ECU, I think it likes to rev up a bit to see what's up.
 
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