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Another high idle thread.. renix

Gunter said:
LOL i misunderstood. i have it now.
my voltage on the flat plug is 4.96V and .381
so 4.96 divided by .381 is 13.01
still no regular idle.
at this point i think one of three avenues. IAC or cpu/transmission module, or still chasing ground wires.
and my voltage goes up when it is running by .17 roughly. is it normal for the voltage to slightly increase once it starts?
and i was so far unable to get to the ground on the back of the head with the tools i have at home. so i have a new ground i made from 6 ga and soldered on ends. from front valve cover bolt to one of the welded in factory nuts for the upper rad support . i sanded all paint and dirt off to have clean connection.
Click to expand...

AHHHHHHH!

4.96 input voltage at "A" times .17 equals .84 output voltage at "C".

Do not disconnect the plugs!!!! Backprobe them.
 
"so i have a new ground i made from 6 ga and soldered on ends. from front valve cover bolt to one of the welded in factory nuts for the upper rad support . i sanded all paint and dirt off to have clean connection. "

Very poor locations to use. Get away from the radiator!!! Go directly to the battery if possible. Also need the other contact on the block of head directly. Valve cover has a gasket and those VC bolts get loose too easy...oil on the threads is and insulator

Gunter said:
LOL i misunderstood. i have it now.
my voltage on the flat plug is 4.96V and .381
so 4.96 divided by .381 is 13.01
still no regular idle.
at this point i think one of three avenues. IAC or cpu/transmission module, or still chasing ground wires.
and my voltage goes up when it is running by .17 roughly. is it normal for the voltage to slightly increase once it starts?
and i was so far unable to get to the ground on the back of the head with the tools i have at home. so i have a new ground i made from 6 ga and soldered on ends. from front valve cover bolt to one of the welded in factory nuts for the upper rad support . i sanded all paint and dirt off to have clean connection.
Click to expand...
 
Gunter said:
idle still high. anything to reset?
Click to expand...

With the engine running and the TPS connected,

you want ".84 output voltage at "C"." when you back probe enough to get a sold contact and reading.

With the engine off, what is the ohms resistance from the ground on the flat plug to the negative battery post?

With the engine running, and the TPS connected, what is voltage from the ground on the flat plug to the negative battery post?

Engine running, disconnect the TPS. Does the engine idle return to normal?

If not, I suspect a vacuum leak or or stuck IAC valve, or a problem with the CTS or IAT temp sensors.
 
With the engine running and the TPS connected,

you want ".84 output voltage at "C"." when you back probe enough to get a sold contact and reading..847 not running and 880 running

With the engine off, what is the ohms resistance from the ground on the flat plug to the negative battery post? 7.2 ohms

With the engine running, and the TPS connected, what is voltage from the ground on the flat plug to the negative battery post?.084

Engine running, disconnect the TPS. Does the engine idle return to normal? no change still have high idle
 
you want ".84 output voltage at "C"." when you back probe enough to get a sold contact and reading..847 not running and 880 running

With the engine off, what is the ohms resistance from the ground on the flat plug to the negative battery post? 7.2 ohms

With the engine running, and the TPS connected, what is voltage from the ground on the flat plug to the negative battery post?.084

Engine running, disconnect the TPS. Does the engine idle return to normal? no change still have high idle
Click to expand...

1) Get the 7.2 ohms down to 1.0 or less by running a ground from the flat connector wire harness side, to the battery negative post.

Then if the idle voltage is not .84, adjust the TPS to read .84
I have not looked up the .84 value, did it come from Cruiser? IF so, use it. I don't recall the spec.

.084 on the ground wire to battery negative post, engine running is nearly .10 Volts on the TPS at idle. It should be way lower. It is consistent with the other 2 high readings you gave me here.

.01 to .02 volts change on the TPS idle voltage is nearly 100 rpm increase as I recall from tests years ago.

The last issue is the no change in the idle with the TPS disconnected. 99.9% of the time, in my experience that is vacuum leak. Other times it might be a stuck IAC, but most of the time the IAC and throttle body have been worked on cleaned already!!!

Vacuum leaks can be a pain to find. Also they can be at the oring seal to the fuel injectors in the intake manifold, or bolts at the intake-exhaust manifold clamps. There is a tone of vacuum hose all over the place you might have damaged or overlooked. You said some of the harness was burned, what about the vac hoses?

With the TPS disconnected, turn the engine off and restart it. Does the normal idle return?
 
i agree with your post, and from the last 2 days my own experience backs up what you said. my wires were just heat damaged. there was no fir but they were laying on the exhaust manifold at the front of the engine. the loom had long since fell away. i ll get after the head ground monday and the battery to ground wire you suggested. i ll check back when i get home -- and thanks to you and Cruiser for the help!
 
vac hoses are all crap. i have them plugged and will address them after i get an idle i like. yes on the cruiser /.084 question. no normal idle under any circumstance my injectors all have new o rings from last summer. My MJ had loose manifold nuts too, i ll double check them too.
 
One idle issue I had was never solved until I installed a 100% new vacuum harness front to rear. I have even seen a leaking/poor sealing/ valve cover gasket screw with the idle some. I finally installed the newer silicone VC gaskets, got sick and tired of cork leaks. Take my word for it, there is nothing like a complete new vac harness to make these jeeps purr. The smallest vac leaks play havoc with the idle and missing plugged vac lines are no help. IIRC Rock Auto (and Napa) had the complete hose sets pretty cheap 2-3 years ago, rockauto was a great buy and have had few idle problems since then, but I had done all the other stuff already.
 
Ecomike said:
One idle issue I had was never solved until I installed a 100% new vacuum harness front to rear. I have even seen a leaking/poor sealing/ valve cover gasket screw with the idle some. I finally installed the newer silicone VC gaskets, got sick and tired of cork leaks. Take my word for it, there is nothing like a complete new vac harness to make these jeeps purr. The smallest vac leaks play havoc with the idle and missing plugged vac lines are no help. IIRC Rock Auto (and Napa) had the complete hose sets pretty cheap 2-3 years ago, rockauto was a great buy and have had few idle problems since then, but I had done all the other stuff already.
Click to expand...

Thanks Mike, for driving a very important point home.
 
i agree about teh vac leaks. this Jeep is my DD and only vehicle, so i cant address the leaks yet. so for teh moment i am capping the parts i cant fix. i have XX amount of money for teh repairs. i discovered my ground cable has a huge hole in the insulation so there is another part to replace. i do believe i am fighting a wiring/ground problem.
my idle was fine with occasional low idle and the odd time the engine died. then one day i lose 1 and 2nd gear and my throttle was really messed up.now all i have is high idle and i drive like that to and from work. gotta get this fixed.
 
" i discovered my ground cable has a huge hole in the insulation so there is another part to replace"

waste of money, the entire ground wire could be bare, in fact the OEM one was stainless steel and braided, bare wire.

Is the current TPS the one you bent? And probably damaged in the process? It might explain why you can not adjust the idle voltage on the TPS!
 
Have you read the RenX file thread yet?
 
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