garry

when i started my jeep the engine turns over okay but doesn't idle when cold/hot. i have to depress the gas pedal until the engine warms up, when the engine heats up the RPM needle would drop below 1000 rpm then goes up to about 5000 rpms or more and will do that for the whole day. It even experience missing throughout driving which often times sound like a backfire.

i really need to have this problem sorted out

rich

If you can get it to run for yourself try spraying starting fluid around intake manifold right around the gasket,see if it really revs up.

garry

i am getting it to run over 10 miles plus however it's just that problem, i'm thinking that it might be the knock sensor. however i'll try the starter fluid arround the intake to see if it revs up.

garry

if it revs up what do i do next?

rich

that would show your intake gasket is leaking,your sucking in too much air.See if your intake bolts are loose first if not and your sure the spray only went there meaning like no hoses onhooked or anything like that,your gonna need a new gasket if your bolts are tight no vacuam leaks throttle body is tight just make sure cause thats a pain to change.I would also check all my sensors on throttlebody too first.

rich

check your egr too ,and your plugs wires cap rotor, do you know if your injectors are dirty, also look around your head for any leaks at gasket. Just trying to make sure you check everything before you pull anything apart. Also try to wait and see if someone comes up with something i missed or i dont know.

4jeepers

Check the IAC and TPS on the throttle body they both can wreck havoc on your idle when they are bad or not adjusted correctly!

garry

i checked the EGR valve with the engine running, i depressed it all the way inward and the engine stalled out; and returned to normal idle speed after i released it.

i also changed spark plugs as well, my distributor wires and cap + rotor have been changed recently. i have even changed fuel pump as well

rich

what is your fuel pressure should be idle 31 wot 39 I think anyone verify this,how is your fuel regulater.

garry

i did a check on my fuel pressure it is fine

garry

yesterday i tested my TPS with a digital multimeter using instructions that i got; it turned out that the tps was faulty so i had it replaced with a new one

my jeep is not cutting of anymore and is idling much better; however there is still a bit of intermitent idle and i still get a flat spot during acceleration.

I have noticed that the engine revs up to 10,000 rpms; and breaks down to about one stroke before the zero marking on the RPM gauge before revving back up to just about 10,000 rpms

anyone got any ideas as to what could be causing the interment idle & and flat spot

superj

did you check that other sensor that was suggested? the idle air control sensor? its the one on the left side of throttle body, when you stand on the right side of the engine bay and look in over the intake filter box. if its dirty then you will have idle issues also. pull it and clean it really well and it should be ok. that is a common 4.0 issue for all the engines

garry

i remember cleaning it in the past when the problem started but it didn't stop the problem

however with the engine running i removed the electrical connector from it and it didn't cause any change to the engine idle speed

garry

should there be a change in idle speed if i remove the electrical
connector from the IAC when the engine is running?

garry

i did as you said and a checked the TPS; it turned out that the TPS was faullty so i had it replaced with a new one

the jeep is idling really better or at least it isn't cutting off anymore; but there still is slight intermitent idle.

and the engine revs up to just around 10,000 rpms and breaks back down to one stroke before the 0 mark on the RPM gauge