Tps?

4.0L 87 Renix. Lately when i start the jeep in the morning i get a really high idle usually between 2500-3000 RPMs and normally it drops down to around 500-1000 after around 30 sec to a minute. Well today it didnt drop down and stayed around 3000 RPMs my whole drive to school(which is only about 2 miles) but it is extremely annoying. After school i started it up and it idled pretty high around 2500 and then finally dropped down to normal but every time i pushed the clutch in it stalled, which i was used to since it has been doing that a while. I was thinking TPS....any ideas on this? there are two electrical connections on the throttle body(thats where the TPS is right?) and im not sure which one it is. I think one is a four prong flat one and the other is a four prong square.

So do these symptoms sound like TPS? or should i check something else? Also if it is the TPS can i get one at a place like kragen or napa? and how much do they usally cost? Thanks Guys!


Brett

It might be a TPS but could be a number of things... like your Idle Air Control Valve... it is to the left of your TB when facing the grill. Could be a vac. leak in one of your vac lines. It kinda sounds like the IAC though... if it has never been changed it is responsible for adjusting your idle. I would start by adjusting the TPS if you do a search you can find the process, you will need a volt meter unless you have access to a snap on scanner tool with the Jeep one cable. If that does not do it then check for vac leaks in the vac lines and at the base of the TB... just spray starter fluid along the lines and at the base of the TB if the truck stumbles then you found the leak, replace the line or tighten down your TB, may need a new gasket. If this fails then have you gotten the engine bay wet recently? The TPS on the Renix hates water and will fail if doused, if so you may have to replace around $70 plus at a NAPA or Advance, some swear by OEM but be prepared to pay. The IAC is a strong suspect though and if so it is about the same price as the TPS, do a search and you can find a neat trick to find out if its bad... can't remember it off the top of my head. Welcome to the Renix gremlin and good luck... I've chased this demon before. 87 Comanche 4.O MT gotta love her

Oh forgot to tell ya that the TPS is the connection on right front of the TB as you are facing your engine the IAC is on the left. Also the TPS adjustment differs for automatics and manuals, mainly in the voltage you are looking for both are discussed adnauseum on this sight, just do a search and you will find out all the in's and out's. Also there is a screw on the linkage at the back of the TB that you can try to adjust if nothing else works. Once again good luck, finding the exact cause can be a real pain in the @$$.

Thanks for the info that helps a bunch. I disconnected the TPS and started it up and it ran fine. about 10 minutes later i went back and started it again and it started up fine and idle was around 700. so does this mean anything? i dont have a voltmeter to check it so thats out for now. but its fine without the TPS connected.

Another thing i noticed was a little stumble when im idleing and i step on the gas. it stumbles a little bit sounds like it might die and then revs fine....these issues connected?

I've never ran mine without the TPS connected, I would think that would affect the driveability, my guess that the stumbling when you step on it is because the TPS is not connected and the ECU is getting no data from the TPS messing with it's brain a little so to speak. You can get a cheap voltmeter for around $10, get one and adjust your TPS, or maybe you can get lucky and get a loan of a snap on MT2500 scan tool that makes it a snap to adjust. Sounds like now it is most likely your TPS, they do go bad quite a bit... it could still be the IAC though.

gapirate72 said:

I've never ran mine without the TPS connected, I would think that would affect the driveability, my guess that the stumbling when you step on it is because the TPS is not connected and the ECU is getting no data from the TPS messing with it's brain a little so to speak. You can get a cheap voltmeter for around $10, get one and adjust your TPS, or maybe you can get lucky and get a loan of a snap on MT2500 scan tool that makes it a snap to adjust. Sounds like now it is most likely your TPS, they do go bad quite a bit... it could still be the IAC though.

Click to expand...

The stumbling happens when the TPS IS connected...? A good friend of mine's dad has a shop i bet he has a nice voltmeter to check it. I might have to go there and get it checked out.

Sounds like the TPS then, see if you can adjust it to spec and see if that takes care of it. If not it could be time for a new TPS shop around sometimes you can find some a little cheaper.

could this also be causing bad gas mileage?