98 stalls when hot but restarts and will idle but misses

[JTProuhet]

I just picked up this 98 classic 4.0 auto on the cheap. Needed brakes front to back.and put plugs and wires on it, but didn't do cap and rotor. Drove it for about 2 weeks, no problems.

Passenger side door speaker wasn't working so I went to put a new speaker in it. But it wasn't the speaker, the wire goinh from the connector in the kick board to the speaker was bad. Well I didn't have the supplies to fix it right away and I needed to go to work so I just unhooked the connector to keep anything from shorting out. Went to work (30 miles) and it missed twice. Fixed the speaker, replaced driver door speaker and put a different head unit in it.

Yesterday I went to my grandmas for thanksgiving, it started to miss on the way there but never stalled. But threw check engine light. Left my gmas to head to work was a little hard to start at first. Made it about 5 miles started missing really bad and finally just cut out and left me on the side of the road. it would restart but it would sit and idle and miss really bad and if you tried hitting the gas pedal it would stall out. my sister came and picked me up and took me to work and my dad went and picked it up, started right up and pulled on to the trailer and unloaded it no problem. I did a lot of reading while I was at work and determine that it was the CPS especially after reading that was a faulty CPS will work once cooled down.

I went to the dealership this morning and picked up a new OEM CPS. and when I went to pull the Jeep into the shed it wouldn't even idle without missing so I thought for sure it was the CPS. I finally got the new one in and it started up and ran just fine with no problems I let it sit in idle for probably 15-20 minutes it got up to running temperature. so I thought it was fixed. but I was wrong as soon as I pulled out of the driveway it made it about a quarter mile it started missing and finally stalled out within a matter of seconds. and now I'm back at square one and not sure where to turn. any help would be greatly appreciated.

also I do not have an obd2 code reader nor will it run long enough to make it to the auto parts store.

 

[JTProuhet]

I also forgot to add the po had electrical problems with it but it turned out to be the ecu and says he never had any problems after that.

 

[Tim_MN]

If the Check Engine Light light is on, the Jeep is trying to tell you what is wrong. Download the CEL trouble codes.

 

[JTProuhet]

I tried doing the holding the trip button and cycling the key three times and five times, cycling the key three times and 5 times and it won't show the codes. The odometer display counts up,all the gauges test and then it shows my odometer.

 

[birchlakeXJ]

I tried doing the holding the trip button and cycling the key three times and five times, cycling the key three times and 5 times and it won't show the codes. The odometer display counts up,all the gauges test and then it shows my odometer.

That won't work on a 98. The luxury of doing that went away mid-1997. All it will give you is a dash self-test.

Yup, you need the codes. They are invaluable in determining root cause.

You'll need either a code reader or a scan tool. Beg, borrow or rent one. Call around to parts stores; many will rent you this tool very inexpensively.

Post the EXACT codes here (not a description) for advice on how to attack it.

 

[JTProuhet]

Ok thank you. I'll post results tomorrow morning when I get off work.

 

[JTProuhet]

Ok just pulled the codes. I've got a

P0505 IAC

&

P1698... but I had the motor running when i pulled the codes

 

[Sidewinder CC]

Have you ever inspected/cleaned the electrical system ground points in your engine bay?

P1698 is a CCD Bus communication problem, between the TCM and the PCM, or just the TCM.

Ground point G101 (see pic) is the main ground for both the TCM and the PCM. Corrosion between the wiring ring terminals and the coil mount studs has caused PCM/TCM problems in the past.

G100 is a bad guy and is often overlooked. This is the main ground between the battery and the chassis. See pic.

If you haven't cleaned these grounds, do so.

Disconnect battery negative cable from the battery.

Detach the ring terminals and use ScotchBrite pads to polish the ring teminals and the furface that they face, then reassemble. Check engine function.

 

[JTProuhet]

I just got done redoing all of the battery and ground cables using 2ga wire.. and took that w hole bracket off in that first pic and got good bare metal on everything. I cleared the codes and let it sit and idle and with in 5 mins P1698 comes right back. The only ground I haven't changed is the ground from the intake manifold to the firewall.. the previous owner said he just replaced the computer next to the air box. I don't know the correct terminology for it.

 

[JTProuhet]

And now after redoing all the grounds, when I give it any gas and hold it, say 2k rpms, the dome like slightly flickers but as soon as it goes back to idle it stays steady

 

[JTProuhet]

Alright so I think I figured it out. Knock on wood at least..

Since it threw the p0505 code for the iac I decided to pull the throttle body cause it was dirty with carbon build up, and I took it over to O'Reilly's cause I ne eded the torx bit to get the valve out. And the old valve was gunked up really bad and the shaft was loose so I forked over the $65 bux. And I cleaned the shit out of that throttle body.

Got it all put back together, CEL light is gone p1698 no longer exists and it is idling way smoother, even tho it didn't idle rough to begin with. I bet it sat and ran for a good hour. Drove it across the street to get gas. And drove it around the subdivision next to me several times, everything is peachy. Cleaned all my stuff up picked tools up locked the shed and as soon as I pull into the road.. check gauge light comes on.. volt meter is on 9..

Weird because I had just got done testing the volts and continuity after doing the wire upgrades. Was pushing 14.1-14.3v idle or revved up. Sure as shit as I stop, now it's only reading 12.3v at the battery. Shut it off, started it back up, volt gauge is sitting about 11v.. Drive it back to the shop, check again and same thing. Multimeter is showing 12v at the battery running. I'm gonna check all my grounds and wires to make sure they are all tight, but I think the alternator shot crap on me.. but still no codes and knock on wood, not missing anymore!