I have a 1993 Jeep Wrangler fuel injected 4 cyl 5 speed .
Recently the idle has gone down to 500rpm when it usually runs at 1000 , it starts to shake and sometimes stalls at the light .
This doesnt happen all the time but usually on hot days , no problems with indicators , been tuned up 2 months ago , fluid levels , oil and water temp OK .

Jeff4570@aol.com

Checked the dist cap & wires? How bout the fuel pump or filter? Checked for vacuum leaks at the intake manifold? How bout the PCV Valve?

Had the idle problem a couple of years ago. Replaced the throttle switch on the throttle body (toward the firewall held on by two screws and a plug connector)Took care of the idle problem. About $30.00

Take this with a huge grain of salt as I'm stepping way outside my comfort zone... but if idle is crappy when hot, only, to me that suggests the idle mixture isn't quite right. If I'm not mistaken, idle mix on EFI systems is typically controlled by an Idle Air Control valve/system which is basically a solenoid operating a valve to let less or more air into the mix (thinking of what I know of the GM EFI systems and based on crap idle problems with my 03 WRX) -- as well as by the O2 sensor, and either a MAF or MAP sensor. If it uses a MAP sensor like GM, then vac leaks would wreak havoc (probably more noticible at idle). As the other person stated, the throttle position sensor (TPS) lets the computer know to go into idle mode (again generalizing from what little I know of GM TBI) so if that is horked, you may not even be in idle mode.

I don't know much about the Chrysler inline 6 EFI systems... but with the GM there are a list of diagnostics you can perform to find problems with each of the sensors that the computer doesn't -- or can't -- detect. The GM system is pretty sophisticated in its error detection and reporting, but again, no clue about the Jeep stuff. What I am talking about is taking a Multimeter and measuring resistances or voltages on sensors.

Don't know if any of this helps but I guess the bottom line is, I'd be leery of trial and error troubleshooting as it can get expensive. The more you can methodically measure and test with anything electronic, the quicker and cheaper you can find and fix the problem.

Michael

Check for codes. I sold both my Wrangler's in 2005 but I think you turn the ignition switch on and off three times then turn the switch on again. A light on the dash will flash three times, then flash a sequence of times for the code, then flash three times again to signal the end. Post the number of flashs, someone can look up the code and tell you what problem you have. I no longer have my books or I would look up codes for you.

The problem went away , put in fuel injector cleaner and 'Dry-Gas' , filled up a couple of times at a differant gas station and in 2 weeks the problem cleared up . <img src="/forums/images/graemlins/cheers.gif" alt="" />