This is driving me Crazy!

87 Renix Cherokee. This idle is driving me up the wall. My problem is high idle on startup. When I start it, it revs to about 2500 rpm and after about 10-15 seconds it drops down to normal.

What have I done. I tried 2-3 diffrent TPS settings with an additional ground. The TPS is new. The ICS is new. The CPS has about 10-15k on it. MAP is new. I redid the front breather of the valve cover. It still runs to airbox I just had to modify it. I cleaned out the TB yesterday. I didnt clean the ICS part yesterday, but I did when I put in the new one.

Pretty much the only thing that I didn't replace is the FPR and the fuel pump.
One note I want to make. When I put the CPS in I couldnt get both bolts in. I have been driving it for the last few years with one bolt.


This problem is really driving me crazy. Is my slow/bad starter causing this? Where should I look now?


Thanks

BuGG

i had the same prob. for years and it was the TPS, that would drive me crazy going thru what u have done.

Yeah but its new. Is the smooth sweep the only way to test a TPS?


BuGG

My suggestion would be to clean the bulkhead connector above the brake booster at the firewall...

Dirt accumulates on the inside of the dust cover (where the wires come into the connector) and allows conductivity between the tps 5v and signal wires.

Remove the dust cover and flush it out with brake cleaner and apply liberal coat of silicone dieelectric grease.

I ended up taking it to the dealer to set correctly after replacing the TPS myself. They found that the idle speed screw on the side(?) of the throttle body,which you are never supposed to mess with, had been messed with. Worth a look.

The renix ones have a different set up procedure than the HOs. The smooth sweep test is for the HOs, IIRC. The renix have a high range/ low range kind of thing to set. I fiddled with mine quite a bit and never got it right. The dealer mechanic (Eddie the Grand) could have done it in his sleep Of course, I have a great dealer, most are not so lucky!!

My '88 is original to me and the TPS has never been touched. I periodically experience the high idle on start-up. When it happens, I run one or two cans of fuel system cleaner through the tank and the problem goes away for another 6 months to a year.

Try cleaning the throttle body.

Cleaned the TB, was in the original post. I'll throw some cleaner in the fuel to see what that does.


BuGG

Make sure all intake/exhaust bolts are tight.

i had the same problem on the jeep i just sold but it did that when i bought it so i thought it was normal

My idle was all over the place for a short period. Cleaning the battery terminals (?) cured it.
Good Wheelin'
Cherokid