jerardisflossin

So this weekend while on a wheeling trip, I had some instances where the idle would jump to 1200-1500 rpm and then another instance where the idle went to 2000. Everytime if I shut it down the idle would settle down. Now a guy on the trail said the renix is a vacuum leak nightmare and it could cause this issue. Thoughts? Do they make a full vacuum line replacement kit I can buy? I have searched and found the diagram attached, would this work on my 90?

Also, when doing my front bumper I noticed I didn't have a vacuum canister like I see on other Renix motors, would this be causing this or is it even on my year in the first place? It runs fine otherwise.

cruiser54

Renix is not a vacuum leak nightmare. What you're describing is typical TPS failure.

That said, I would click on the Pink Link in my signature below and perform Tips 1,3,4, and 5 before proceeding down any other rabbit trails.

Also, make sure your intake manifold bolts aren't loose.

jerardisflossin

Thank you sir! Do uou think I should replace the vacuum lines anyway as a precaution? Would a map sensor going bad cause this too?

cruiser54

Not MAP. Intermittent high idle is generally caused by bad TPS or poor ground circuit in the sensor ground circuit.

Replace the vacuum lines and grommets as needed.

See Tip 22.

DFlintstone

It's always smart to listen to Cruiser. There is a large vacuum line off your intake , rear of the TB that goes back, across, then all the way forward to the Vac ball. If that's not hooked up right , or at least capped at the manifold you will have issues.

You could clean your IAC connector (well), while you are there!

jerardisflossin

Ok, I am attempting to follow Cruisers Renix tips and I have a few questions.

How exactly do you probe the A,B or C terminals with them connected? The connector is water proof and sealed so I do not know how you guys say to do that when I cant get my probe to a wire or terminal.

Also, I disconnected the flat connector of the TPS and ran from terminal B to the negative post on the battery and got what I think to be 4.5 ohms. My lowest setting on my meter was "200" and the reading came out to "4.5". This is in fact 4.5 ohms, correct? I am a complete noob when it comes to electrical issues. Im purely a gear head haha.

The vehicle in question is a 1990 so is this maybe a grounding issue?

cruiser54

Do Tip % next.

Here's how to backprobe.

jerardisflossin

Im not sure what you mean by tip %?

Also, the issue is now happening nearly whenever I just touch the throttle after idle. If I turn it off, the idle will be back at 700 or so, touch it and it will either take a couple seconds to settle back or stay at 1500.

cruiser54

5. I hit the shift button. LOL.

jerardisflossin

Haha ok!

I did want to try to knock out number one on your list but the only thing on the dipstick ground is the battery? Where is the fcu and other engine components ground? Your pic looks the same as mine except there is only a line going to the battery.

cruiser54

Should be 3 or 4 eyelets with black wires on the engine dipstick stud.

jerardisflossin

Update: Went to clean the connections to the at the block and decided one more time to test the resistance from B to the battery but this time using a better meter and I got 0.5 ohms. Im guessing the el-cheapo one I was using the first time (from radioshack) was giving a bad reading?

At any rate, I put replaced a few vac lines and un-kinked one. After this I couldn't get the high idle to come back and it seemed to run smoother.

I have a TPS on order so hopefully that will help when I swap it out.

93_xjcherokee

I threw a bunch of parts at my 92 including cleaning the throttle body very well. I had the same idle issue. Finally replaced the tps and it went away

cruiser54

Where are your ground wires then?

jerardisflossin

They are in that location, you were right as in there are like 4 connectors on that bolt.

I just decided to skip it because I was getting good ground connections according to the meter. I still am going to add a wire from the fuel rail or the intake manifold to the firewall for some additional assurance.