Neener

So I decided to let my 97 Upcountry with 194K miles stretch his legs a bit...I left onto a county highway and let him go. Right around 4500 RPM I heard a muffled pop and the car instantly died.
I can crank it and he turns but it doesn't "feel" like I'm getting compression at all. I know it's nearly impossible to have a chain snap but it certainly seems like this is the case. I'll do a compression check today and let you all know.

If it is a timing chain issue...is there a write-up for replacement? Do I have to drop the oil pan?

CCKen

Pull the distributor cap off and have someone crank the engine while you see if the rotor turns.

BillyBoy

Wear safety glasses.

cruiser54

And latex gloves with a condom.

Jeep Driver

Read his sig line.

cruiser54

LOL.

Neener

So I checked the rotor and THANK YOU CF that I did! The pop I heard was the rotor self destructing as my distributor shaft bearing was sooo bad that the rotor was flailing around under the cap. The rotor must have smacked the side of the contact point when I was at 4500rpm and bam...Jeep instantly died.
So a new distributor went in and she fired up

So no the timing chain didn't break...
Question though...why did Jeep make it so that the distributor can be installed in one of four positions? Seems like a key slot would rid of any mis-installments?

Neener

I had to do the ECM flash though cause the under load response was atrocious after the new distributor. Must have been adding a bit of advance with that rotor being all sorts of whacked out before.

Jeep Driver

Is your distributor missing any chucks?

CCKen

Only two positions. One correct and the other - wrong.




Oh, and, you're welcome.

cruiser54

Woodchucks?

Neener

I could have sworn I can rotate the distributor 90 degrees and have it slip into position...maybe not. Anyhow, how long after I reset the ECM should everything normal back out? I drove it last night and it drove fine after being a bit bogged and gear hunting for about 4 min. This morning it started but was at a super low idle. The temp is pretty cold this morning in CO. Does the factory ECM settings have an operating range I should be adhering to until the 50 cycles?

CCKen

Generally after resetting the PCM the only thing that takes time for it to relearn is the idle setting (IAC) but that really doesn't take long.


With issues like bogging you may have the distributor out of time.


You can check this by setting the crankshaft damper timing slot at the zero (O) mark on the timing chain cover timing marks. Then remove the distributor cap and see where the rotor is pointing. It should be pointing just past the #1 spark plug wire terminal on the cap. If is pointing 180 * out that's #6 terminal. If so, you'll have to rotate the damper 360* and realign the timing marks again.


If the rotor is pointing just past #1, Remove the rotor and cam sensor, reinstall the rotor, then insert a 3/16" pin punch, or drill bit, down through the alignment hole in the plastic plate in the distributor down through the hole in the base of the distributor. If it won't go through, the distributor is out of time. See pics.


Timing marks:





Alignment hole:





Pin punch shown installed when rotor is just past #1 and timing marks are aligned at zero. Modified cap shown.

Jeep Driver

Yeah........Thumbs.........

Chunks........or bits?

BlueRidgeMark

I've had to replace two of them, one on each of my Jeeps. The last time it wiped out my cam sensor.