Ok so I have a 89 Cherokee 4.0 auto with under 100 thou miles and I have a problem where my car will appear to be idling at 300-400 rpm then at some times be up at 1500 rpm in park or neutral at atleast a 1000-1100 rpm in drive.


I have replaced every sensor changed a vaccum harness checked grounds new fancy copper plugs I had a stalling and idle problem before.

For those that have followed a few old posts I figured out the egr valve was junk so I disconnected the vaccum from it and I have been driving it for months plenty of power no stalling or anything throttle seems right on.

recently I went out in the am and tried to start it on a fairly cold morning and you would crank it would seem to fire then cut out nothing . I tried to crank it over several times and nothing it would seem to fire then die instantly.

I pressed the gas a couple times then tried to fire it 2 more times and it finally went engine was barely running like a very low idle like 300rpm then after a min rose to like 500 which seemed like just enough to keep it running don't know if pressing the gas helped anything but figured id try it.

The other thing I have been noticing is that some times when it first fires up the rpm races way up then after a few seconds drops back down around 500 and you will see the rpm bouncing alil up then down to like 400 then back up to like 5 or 6 till it like warms up from driving around then usually it idles around 900-1000 in drive.


Now I don't know if the bad egr valve would cause all of this the only other thing I do is run a system 2 subs and door speakers I had the alternator replaced 2 years ago from stock to a 100amp one don't know if it might be already crapping out I also have a big marine style deep cycle battery.

I tested the battery after I charged it a few months ago it seemed decent.

Any ideas anything worth trying

 

Of my Tips 1,3,4, and 5, how many have you completed?

 

which post are you referring to . I know you have given many tips in the past but its been years .

 

The tips link is in my signature, but here's the link.

https://www.cherokeeforum.com/f51/cr...x-tips-153657/

 

Ok so this problem is of recent all of those tips have already been covered some posts back ground has been covered.

I changed my fuel filter 4 years ago I don't know if maybe that has become clogged already.

This problem when you try to crank the car over it fires then dies.

Sometimes when you try and start it it will run but sound rough idle will be real low like 300 rpm. if you wait a min the rpm will go up to like 5-700 rpm just enough to keep it running.

Now when you go to take off a couple mins later you put it in drive and the idle will just drop real low motor will sound rough thing barely running you will drive it up to a stop light and the idle will seem low around 500 rpm you put it in neutral and the idles up to about 1000.

I went to work one day and after the thing wouldent start so a guy I worked wit told me to press the gas alil bit then hit it so I did and it started I let off the pedal and the tac dropped right down then bounced up to around 500 and I was able to leave.

When I drive around for say 20 mins the idle appears normal however everytime I start the car after going into a store or something the idle is right back down to 300 and the thing is barely running sometimes it will go up after running a min to a normal rpm other times you will have to wait till you drive it around for 10 mins.


The only thing I have done since a few years ago was unhook the vaccum from the egr because the spring was junk in it I drove it I ran into some license issues lost it dident drive it for a year and a half but I started it up and put gas in it every so often.

I put it back on the road in September drove it it ran fine and then sometime around novemeber noticed this problem all of the sudden

 

Maybe the unplugged eGR isn't seating fully closed?

 

Yah what that guy said, and definitely something having to do with the choke not opening and closing possibly pop a different throttle body on it or take it off and check to see all the springs working properly.

 

Check the ECM. Mine did that when it was going bad. Then it died all together while I was driving 30mph on a straightaway on Tarmac. Brought it to a diagnostics center and they said the ecm was half fried for some reason. Bring it to a diagnosis center and have them test the cps and ecm.

 

There is no choke..................Geez.

 

LOL. Make cleaning the choke tip #29 and use that as an intelligence test question

Have great New Year Cruiser!

 

Thanks Greg. some peoples" kids these days.

 

yes that's what I'm thinking cruiser we have though that so I will prob have my dad find a way to keep it closed I could just buy a brand new one but we don't have a good garage and its hard to get at and rusty old if I cant get it straightend out ill just get a new one and have a garage put it in sucks because the egr valve is almost 100$.

Most oldschool race car guys will tell you that they just remove the egr all together and install a plate.

 

Pull it off and see if it leaks.