Large Fluctuations in Idle

Joined
Nov 24, 2004
Messages
13
Yesterday I got home from work and my wife relayed a problem she had with her 92 LandCruiser (180K miles).

Upon starting the warm engine, the idle began rapidly fluctuating between approximately 1000 and 3000 rpm. It was enough to scare her into turning the car off. She started the rig again and the problem repeated itself. She put it in drive and the problem stopped. I'm not sure if the AC was on: it may have been.

I started the truck when I got home and it was fine: some normal cycling with the AC, but nothing strange.

Now my wife thinks the cruiser is "dying" and this is giving her fuel to pursue the purchase of a Tahoe or a Suburban: WE MUST STOP THIS by fixing the fluctating idle problem.

I'm a decent mechanic and with a steer in the right direction I can tackle just about anything.

What should I do?

Another thing: I read about started contacts a lot in this forum. Should I just replace them now?

Thanks for your help,

Bill Black,
 
Joined
Apr 21, 2004
Messages
263
Location
Bainbridge Island
 
 
Any coolant leaks?

Check to see if the coolant level is low in the radiator. Sometimes if the CTS cooalnt temp sensor, has a air bubble, it will cause the idle to fluctuate. The solution for the leak is to find it and fix it. Make very sure that the cooling system is purged / burped.
 
Joined
Dec 13, 2002
Messages
6,159
Location
buggerville nj
 
 
 
Don't know about with the 3fe in the 92, but my 97 with the 1FZ-FE did this and it ended up being the IAC (idle air control) and the wires leading into it. Possibly it could also be the TPS (throttle position sensor) but I'd look at the IAC first.
 

beachcruiser

SILVER Star
Joined
Nov 25, 2004
Messages
151
Location
Austin TX area
 
 
I have the exact same problem, and have yet to be able to isolate it... I have had some suggestions (check air intake tube for leaks, check/ clean fuel pump relay contacts, check throttle cable to make sure it is moving freely, etc.) If I come up with anything, I will keep you posted...
 

turbocruiser

SILVER Star
Joined
Dec 24, 2003
Messages
3,562
 
Junk already gave the most likely answer but look at IAC and TPS, my money is on the TPS but my experience is that when the TPS goes bad putting it in gear wont help much, so that sorta points to IAC but anyways assuming no major vacuum leaks etc, I think yer gonna find the problem there. There are very specific ways to isolate and test those two components, refer to FSM. HTH :cheers:
 
Joined
Nov 24, 2004
Messages
13
Thank you all

Thanks for you time and effort. You all have steered me in the right direction.

I ordered a shop manual for the truck (Ebay, $50!). I'll dig into the truck in a week or so. I'll focus on the IAC and go from there.

There's no substitute for experience and I appreciate your advice.

If I get a definitive solution, I'll post it.

Kind Regards,

Bill Black
 

beachcruiser

SILVER Star
Joined
Nov 25, 2004
Messages
151
Location
Austin TX area
 
 
Any luck?

Just wanted to check in to see if you had any luck with the fix for the idle... I have been having the same problems and absolutley no luck in isolating the problem...
 
Top Bottom