Camshaft timing and ping

[likestogofast]

Cranking compression is 130-140 cold.

Checking timing advance is still in the works, had to order an advance adjustable light since the local parts stores don't seem to loan the adjustable type any more.

Another question came to mind - is there a difference electronically between the different type distributors? I think I have the newer style that came on the later XJ OBD1's. I noticed in some of the pictures that my distributor is different than the original OBD1 YJ one, yet it still has the same plug. The number on it is 56027028. See attached for the clocking. I don't recall changing the distributor when I did the cam, but it has been a while and I just can't remember with all the stuff I work on. Could this be part of the problem? The PCM in the jeep is out of a 93 XJ auto.

I'm going to pull injectors and inspect this week also. Since pressure is good, if there is a fuel problem it has to be there.

[likestogofast]

Timing is 38 deg at 2500 rpm.

I pulled the fuel rail and tested all the injector plugs and injectors. Everything fired, but the injectors had a fair amount of varnish on them. So I pulled them and took them to be cleaned and flow tested. Should have them back by the end of the week.

[akadeutsch]

I don't understand how a clogged injector could cause a ping? What is your altitude?

[wjtom]

Doesnt you distributor have ears that only allow you to turn it a little bit?If so you need to open up the slot so you get more rotation.Injector timing will definitely cause ping.

[akadeutsch]

Injector timing will definitely cause ping.

I guess I could get behind that. ie. a clug could cause an injector to fire late could cause a ping?

[likestogofast]

It was running lean, that's why it was pinging. Injectors were flowing as little as 60% of rated flow. After the injectors were cleaned and tested, they flowed 314 cc/min or about 25 lb/hr. A couple of laps around the block resulted in much better performance, and no ping at all initially when cold. After warming up to operating temp it still has minor ping at mid throttle while pulling up hill. Now it's time to figure that out. I already cut the ears off to index the distributor. Might try tweaking it a little more now that it's drivable.

[rammit11]

I have a similar situation with the ping when pulling a hill. I am in the process of building a map sensor adjuster to see if that helps. Once I get it installed I will post back on the outcome.