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High idle issue...

J

JoeOffRoad

NAXJA Forum User
Location
Vancouver, WA
I recently got my 89 4.0l renix XJ running again after it had be sitting for more then a year. You have to feather the throttle to get it started then hold it down about a 1/4 for a minute to get it to idle on its own. Then after it begins to warm up, NOT get hot the idle begins to crep up to about 1800 RPM! My first thought was vacume leak, but after a ton of searching I can find none..... What do you guys think?!? MAP sensor? TPS?
 
Make sure that your intake manifold bolts are tight , Clean your I.A.C. Make sure the vac line that goes to the M.A.P. is connected .
 
A vacuum leak will cause it to high idle at start, loose manifold usually seals better when warm so the idle would drop a little, and TPS or electrical usually high idles at startup.

I would clean and check all the connections, clean out the trottle body and idle motor, make sure the battery is fully charged and see why you have to give throttle when starting first. If the engine controller sees wierd TPS readings on startup it may cause the idle to vary.
 
JoeOffRoad said:
I recently got my 89 4.0l renix XJ running again after it had be sitting for more then a year. You have to feather the throttle to get it started then hold it down about a 1/4 for a minute to get it to idle on its own. Then after it begins to warm up, NOT get hot the idle begins to crep up to about 1800 RPM! My first thought was vacume leak, but after a ton of searching I can find none..... What do you guys think?!? MAP sensor? TPS?
Click to expand...

Disconnect and reconnect all the connectors on top of the intake several times to get the pins cleaned up.
 
alright, I tightened the intake mani... there was only one bolt that was actually loose... I cleaned all electrical connectors, and checked vacume lines... but still has the same issue....... Ideas??!?
 
When my TPS was bad I had high AND low idle at start. Sometimes, it would start, run for about 10 seconds and then die. Then when I started it back up...HIGH idle. Also, I had about 2 occassions in a 6 month period where I had to play with the gas pedal to make it start.
 
Okay, I replace the IAC (the old one was stuck) and fixed the cold start issue... BUT did not fix the high idle issue. I re-checked all intake mani bolts, vacume lines, AND cleaned and used dielectric (SP?) grease on all electrical connectors... Ideas?
 
biggest things that affect idle on the renix. vacuum leaks, IAC, tps settings, ground, bad MAP sensor, malfunctioning egr valve

have you tested or readjusted the tps settings? i see no mention of you doing this.

the renix ecu has a mind of its own when it comes to idle.

when i had a high idle issue and it went up past 1500rpm, it was due to the tps being out of spec.
 
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