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starting, idle, and acceleration problems!!!!

S

slowjeep

NAXJA Forum User
Location
imperial valley
I have been reading a few threads on tps, nss, fuel filters and pumps, ecu's, and would appreciate some help from all you experienced guys.

First off its a 1990 xj 4.0 automatic 4x4. I've only had it for one month and am loving it since it is my daily driver(to and from work), work truck(mobile wash on weekends), and toy(dunes and trails:tears:haven't yet tried). The only thing I've replaced is the fuel filter and added 2" coil spacers.

My issues are these: when starting I have to hold on the ignition for a long time for the car to start. Once running the idle is at about 200 or less then it only goes up to about 250-300 in park or gear. If I give it a good slam on the gas it seems as if it is going to stall, more when in gear.

What should I try or check before spending on new parts that won't be needed?!?!?!?!?!?!?!?!
thanks for any help!!!!
 
Give it a good tune up.

Anytime you get a new older vehicle change everything you can out so you are starting from scratch on maintenance record.

Coil, Plugs, Wires, tranny fluid and filter, t-case fluid, air filter, radiator flush, and Diffs.


First and foremost do a tuneup and see what that does for your low idle it could be so many thing lets get rid of sparks since it prolly needs is anyway.
 
I've got a 90 XJ 4x4 too, had it for going on 3 years now, considering its the only vehicle ive got it sees alot of use ( I deliver pizzas in it six days a week so daily it sees 150-300 miles just from work) and does what sounds like the same thing, after cleanin up the tps back when i got it the idle dropped from 1500 to about 500 in park and gear but recently it started idling around 200 or so and stalls out when i let off the gas in gear, tried some sea foam hoping it was just bad gas and though its helped a bit it hasnt fixed the problem. if i find anything that makes it better ill let yah know
 
Search and read about ground wire issues, TPS and IAC. All three contribute to idle probelsms. The IAC gets dirty and sticks in the throttle body, it controls idle speed by controlling the idle air feed rate and the computer controls IAC. Computer uses ground reference and TPS readings to control and set the IAC.

Search for my old thread, lots of good how to and why discussion in it on these guys, search advanced search for "Renx Files" and Ecomike as author in the OEM forum, then runs some tests with a meter on the TPS and grounds.
 
PLEASE HELP!!!!!!
sprayed some degreaser on grounds next to dipstick and firewall to block, used it 20min. later no problem. 50 min after spraying I had no start. I was only able to check spark from the coil. Suggestions?????????????
 
slowjeep said:
PLEASE HELP!!!!!!
sprayed some degreaser on grounds next to dipstick and firewall to block, used it 20min. later no problem. 50 min after spraying I had no start. I was only able to check spark from the coil. Suggestions?????????????
Click to expand...

Did you have spark?

You need to remove the grounds, sand ALL the connecting flat surfaces all down to bare metal than reasemble. Some coat the parts with De-Oxit (IIRC) before reasembly, but I have yet to try it.
 
Got it to start. Took the negative off the battery and put it back about 2 mins later and started up the same way it was. So I am back to figuring out why it bogs when I give it a sudden gas...........will keep updated
 
now removing the battery is no good, I have to start the car with the TPS off and reconnect it once running....signs of bad TPS? or should I wait before replacing?
 
Since you have spark it is either a fuel or air problem. Too much fuel can be overcome by flooring the gas peddle while cranking. At WOT the ECU shuts off the fuel injectors.
 
slowjeep said:
now removing the battery is no good, I have to start the car with the TPS off and reconnect it once running....signs of bad TPS? or should I wait before replacing?
Click to expand...
Sounds like a possible bad ground, or bad TPS or both. Also could be the battery and or alternator.

Get a volt-ohm multi meter and start testing those voltages, and grounds!!!!! Or get a bigger bank account and start lots of expensive parts to throw at it!:D

IIRC Renix won't start with a slow cranking weak battery.
 
Ecomike said:
Since you have spark it is either a fuel or air problem. Too much fuel can be overcome by flooring the gas peddle while cranking. At WOT the ECU shuts off the fuel injectors.
Click to expand...
90 Renix is fuel injection hittin the gas pedal just operates the throttle body plate doesnt it, cant flood a FI
 
Alucard226 said:
90 Renix is fuel injection hittin the gas pedal just operates the throttle body plate doesnt it, cant flood a FI
Click to expand...

Fuel injector(s) that leak or are stuck open can flood the engine. If the computer gets bad sensor data it can feed too much fuel by holding injectors open too long, The throttle also operates the TPS sensor which tells the computer aproximately how much fuel to add. If the IAC is stuck closed it starves the engine for air at idle or during start up, which can flood the engine. Some fuel plus no air = flooded engine. At WOT the TPS tells the computer it is at WOT, and the computer turns off the fuel injectors, thus allowing the engine to quickly dry out during cranking to start operation.
 
I've been following some suggestions. Cleaned the throttle body, and replaced the IAC, also checked some grounds. My new problem is that when I go into gear it either stalls right away or within a minute.......now what??
 
slowjeep said:
lunch.......disconnected the tps and idle was better. Not quite good yet but better........signs of bad tps??????
Click to expand...

Have you tried running volt-ohm meter tests on the grounds and sensors like the TPS? See the thread called "RenX files" if you need details.
 
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