Now it won't start!

jeep
cherokee

#1

Sunday my 93 jeep grand cherokee started and ran fine. (or as good as expected at 211,000 miles anyway)



Monday morning it would not start. After working my way around the ignition system for the last couple of evenings I discover that it will in fact start, if you hit the key and add mash the accelerater. If I use the accellerater I can keep it running and after a minute or so it will begin to idle on it’s own. If I let off the gas before then it will die.



I read online that the IAC valve could be the culprit so I pulled the throttle body and clened the IAC valve. It was very dirty with a lot of build up. I cleaned the outer surfaces of the IAC but could not see any way to easily disassemble it so there was not much I could do to clean any internal components.



Because it was so dirty I assumed that I had found the problem but no go! After reinstalling everything the result was… no better, no worse.



What now?


#2

Have you considered replacing the IAC with a new one? Cleaning a part does not guarantee fixing a part. They cost about $35 in my local area. Since your vehicle is 18 years old and has 211K on the clock…I think you need a new one.


#3

Have you considered putting a meter on the wiring for the IAC to find out if it even gets the right supply of power?

It is also likely that a bad IAC would result in something more like a start briefly then stall condition rather than a simple no start. Do you truly have to “mash” the accelerator - or maybe just give it a little bit of throttle. This is called “giving it gas” but with fuel injection it is really “giving it air.” A tiny bit of throttle (air) should make up for a dead IAC. If you need a lot of throttle (air) then I’d be looking for a flooding condition - e.g. a bad fuel pressure regulator or leaky injectors.


#4

If the idle air control valve is so dirty, what about the rest of the intake intact, throttle body bore, and throttle plate? Clean with Throttle Body Cleaner.
How did the iacv get so dirty? Dirty air filter? Then, the MAP (or, MAF) sensor would be dirty, also.


#5

Thanks for the advice folks… I will check into these other areas as well.

I am a radio control wehicle nut and I have been on the phone witha fellow nut who I chat with a online and lucky for me turned out to be a mechanic (shop foreman 23 years… SCORE!

So due to some other symptoms that I described to him he was leaning toward a bad TPS. So anyhoo the point is thanks to all of you I now have direction that I would not have had otherwise. Thanks everybody!

BTW… cigroller, heres an interesting bit of information! My friend said that what I am doing when I “mash” the accelerater is called “clear flooding” and that when you floor it, it actually causes some sensor overides which allow for start up. Anyway that was the basics (I think, lol) of what he told me about why it will start when I floor it.