ooops forgot to say in my previous post that I had the distributor bearing seize up,I think this caused my already sloppy timing chain to jump. Anyhow, just went out and reindexed the distributor.. and bingo! Runs and drives great now. Wags,thanks for posting the issue and finding the answer.

 

I already reset the ECU before I figured out this problem.

The thing you have to understand about an ECU is that it is only capable of following commands. When the engine is new, & everything is tight, the ECU is programmed to respond according to the input it recieves from the engine at the time. Since the ECU cannot reason, it cannot adjust for changes in the engine as it wears, therefore it always reverts back to its "programmed" settings. It will try to adjust the timing & fuel according to those settings, & if it cannot obtain a proper Fuel/air ratio with those settings, it will shut the engine down as a means of self-preservation, as was my case.

By advancing the distributor 1 tooth, the computer was able to adjust the timing & fuel to be within those parameters, so now it runs. I have driven it about 100 miles since I made those adjustments, & it runs great.

Even putting a new timing chain in may not cure the problem, as in fishfast's case, because the new chain may not set the timing in the exact same position as the old chain did when it was new.

If I were able to adjust the timing manually, then I would have resolved this issue long ago, but since I cannot, then I have to postion the distributor in such a way so the ECU can adjust the timing within specs from where the distributor is installed at, whether than be in the correct position, or 1 tooth off.

Its either gonna work or its not, & it costs nothing but time, so why not try it. It would not surprise me if someone, sometime has to advance it 1 tooth to make it work. Just be sure to check the timing with a timing light to be sure it is within specs to avoid detination.

 

Did you index it forward 1 tooth or back 1 tooth?

 

Here are the pix I took. as you can plainly see, it is indexed way forward of the #1 tower on the distributor cap. The last pix are of the jeep. Not bad for $300!

 

Wags, I indexed it forward 1 tooth, so that the rotor electrode's trailing tip was just past the mark I made on the distributor directly under the no. 1 tower on the cap. It looks like mine is pointing the same amount past the no. 1 tower as yours. I'm pretty sure that this is the proper index from the factory. If you Google "jeep distributor indexing" you'll find lots of hits on doing this that say to set it just past no.1 tower. This makes sense if the ECU does ALL the timing adjustments. The chain was replaced 'cuz it jumped when the dist. bearing seized. I did the chain first, then went to replace the distributor. I set it to point at no.1 tower at TDC on no. 1 compression stroke. It ran like that, but like crap, undriveable. That's when I started looking online for answers.

 

i know this is kind of an old one, but thanks wags that really helped my problem. who ever had this jeep before me had taken the distributor and milled off one of the ears on it, so all i had to do was loosen it up and twist it. thanks for the idea!

 

Thanks Wags for posting this. I am going to run outside now and reindex mine and see what I get. I am having issues similar to yours so this might help get it running again.

Jeff

 

I tried it where yours is in relationship to mine wags and no dice for me. I need to see if my fuel pressure is within specs, and probably add some gas and see if I'm not getting good fuel to the injectors. I've had it running, but your way makes sense as the #1 fires prior to the 0 marks. I still need to do more testing, I'm just kinda running short on time to get this thing running.

 

I know this is an older thread, but I thought I'd put in a third report. This is exactly what I needed to do to mine. Thanks a lot.

 

Im glad to see that this thread is still helping people LOL!

By the way I did a little more work to that Jeep & sold it for $3200 plus another Jeep which in turn did a little work on & sold for $1200! I was glad I bought it!

 

Just wanna say thanks for this write up wags. Just reinstalled motor and trans in a newly purchased Xj that has had a rough life. Pulled the distributor when doing the timing chain and apparently didn't have it indexed properly. First attempt to start I was 180 off, then pulled the distributor again and managed to get it indexed center of my mark. It would start after 3 attempts and idle good but high. The engine was also running high temps. Came across this thread tonight and 20 minutes later it's running like a champ.

 

I have been reading your thread about your Jeep timing issue I'm having a similar problem I have put number one cylinder on top dead center bought a new distributor stabbed it the Jeep runs but at idle is rough idle and I can just tell it is not running correctly I'm not that good of a mechanic just starting to learn but I know quite a bit is there any advice you could give me to help me

 

Proper indexing is not directly at no 1.....

http://www.angelfire.com/my/fan/dist_index.html

 

just my 2 cents to this thread, as I've had similar problems getting timing on my jeep right after installing a new distributor. In my case indexing the new distributor one tooth ahead did'nt resolve my problems. Turned out my new distributor had the drive gear installed turned 180 degrees. (as there are 13 teeth in total this does make a difference). Pulled the pin out, turned 180 and put it back together and installed in my Jeep. Worked like a charm. Hope this might help someone out there, took me a while to get this one figured out..

 

Thanks for posting this I am having the same problem here.I am going to try this today