heep92

Hi all i am new to the forums and to the jeep world entirely i picked up my 92 XJ from a friend of my moms for $700 bucks...

Anyways the bad news is when i go to start it i have to be giving it gas while starting it in order for it to turn over, and once it does it idles really low almost to where it cuts out then without even touching it will randomly rev up to about 3k rpms then just repeat this cycle. A friend of mine suggested cleaning the IAC which i haven't yet gotten a chance to do but i was wondering if anyone on here has had the same problem or has any thoughts of what it could be?

jd4x426

clean the iac its a pretty common problem on the older rigs that were neglected

XJ Stryker

Well a common no start is the CPS crank shaft position sensor it has been covered numerous times. Run a lil search and you will find it.

fantic238

Check the idle stepper motor near the tps and fuel pressure and flow in case u find out it runs lean, check also the vacuum supply to the map sensor.

heep92

thanks everyone im gonna go give it another try now and i had searched its just i couldn't quite find anything quite like my problem but thanks again

BuckB91XJ

All good advice but, it sounds to me like you are going to find a very cruddy IAC step motor when you remove it from it's bore in throttle body. Give it and it's bore a really thorough scrub with a toothbrush and carb. cleaner.

heep92

me and my friend have done the following to the 92 XJ and it still will not even idle:
new plugs
new plug wires
new fuel filter
new air filter
new batter
cleaned the IAC
and are in the process of purging and replacing the gas in it because it had sat for awhile without running before i purchased it
does anyone have any suggestions as to why it still won't run?
im getting desperate here...

BuckB91XJ

Starting to sound like a bad CPS, now. (CPS) Crank Position Sensor. Controls spark timing and Fuel Injector firepulse timning. When this little jewel goes bad you lose spark and fuel.

BuckB91XJ

Getting rid of that skunky gas might just do the trick, though.

BuckB91XJ

Can ou see any vacuum lines that might have rotted or cracked while it's been sitting for so long?

heep92

my friend and i are sitting right by it right now and are gonna go check all the things you listed so i will get back to you once we check it all thanks for all the advice and help tho my friend has a v8 zj so hes not used to the 4.0 lol

heep92

so we checked everything out had another buddy come by and look at it
found a dry-rotted vaccum line which we taped as a temp to see if itll run it will be replaced soon
and once all the old fuel was out we replaced it and it idled pretty normal...somethings still wrong tho...
my other buddy thinks on top of it being gunked up that its starving for fuel...does this sound like it might be my main problem?
thanks for all the help you guys have been a big help as you can tell i know almost nothing haha

earthtojohn

Hey heep, I just went though a similar problem with my 89 xj. The people on this site were crazy helpful. I would add that replacing the coil and the CPS will go a long way towards addressing your issue. Replacing the CPS was one of the trickiest things I've ever done on a car. If you are ready to try it there is an old post on this site with good photos that will save a lot of knuckle skin. You could always just say a little prayer that the great and powerful Bluexj chimes in to help you. Good luck

heep92

yeah thanks john i have deffinately noticed and its been such a huge help the people on here id be lost without um

but to update she still won't idle so idk im gonna keep searchin the forums and trying different things and just keep hoping its something small somewhere that im missing

o and i found out my leafs are pretty much arching the wrong way so im debating going and getting set from the jy in better shape as a temporary fix till i can lift it

heep92

if anyone has any ideas im still open to help lol
some things have changed tho i attempted to seafoam the engine from a friends advice...and it turns out it will actually idle with the seafoam...just smokes a lot haha
everyone i talk to seems to think its an air fuel mixture problem
and i apologize to everyone if my post is annoying this XJ is only my second vehicle and first 4x4 so im pretty anxious to get it running so if anyone has any ideas they would be greatly appreciated
thanks