engine pinging

Does the distributor have a vacuum diaphragm?

No it does not. It has the EEEC 4 distributor with the ignition module attached to the distributor. 1984 was the first year for this. I wish it had a vacuum diaphragm.

Somehow, the computer is supposed to advance the spark.

Then it is TFI and they can be a head ache. remove on side distributor to take to parts store have tested.

Does the module on the side of the distributor control the advance? Or is spark advance controlled by the ECM? Any other solutions to advancing the spark? Probably not linked to carburetor.

Again, Thanks for the reply.

TFI interfaces with ECM to advance and TFI modules are plagued with failures.

it should have a computer bypass that has to be removed in order to set timing. if this is in when timing the engine it wont be right.

It does have the bypass. It is a single black wire plug you disconnect next to the module. The process is to unplug, set it at 10dg advance, plug it back in and the engine idle speed increases. The timing is then about 13 df BTC. I hear that these run between 13 and 15 df BTC after set at 10 with cpu bypass wire off.

I am beginning to think it is not timing. Might be better to look at the EGR system. Possible carbon build-up in the head....

It runs very strong and accelerates well. Only at about 55 - 60 mph on a hill does the pinging occur.

Tires are 31x10x15 which are over-sized. Hard to believe that it is over "tired" so to speak.

All help is greatly appreciated.

Thing got centrifugal advance, down inside the distributor?

If a spring is broke, weights are thrown out 100% of the time.

Stays at max mechanical advance.

Upon checking the timing, it appears timing is too high.

You compensate by moving the distributor to make it right.

Now, all you have is Computer Advance (Vacuum advance, with my Older Jeeps)

Really, Now at idle, timing is right, as engine speed increases there is no "Mechanical Advance". The computer advance cannot make up for "lost" mechanical advance.

May not be the case with yours, but it happened with my Jeep, several times with the Prestolite distributors I once ran--I upgraded to newer Motorcraft used in 1979 on up, for this and other substandard attributes of the original distributor.



The Medic

There are no moving parts in the distributor other than the startor. No springs etc. All computer generated. I would change the distributor to a more conventional vacuum or mechanical advance, but I doubt that the computer would find it.

Ford wants the distributor at 10 dg btc with cpu bypass. That way, when plugged back in you get the 13 dg.

Wish it was all that easy and yes, I liked your story.

Plugged back in, watching the timing marks with a timing gun, does it climb on up as rpm's increases?

I do not know, are there specs as to what advance should be a certain rpm's?

Check really good for vacuum leaks, it would not hurt anyway, should do it periodically, just to stay on top of things!



GET REAL JEEP BE HAPPY!

Ex. of Reliability--CJ 5 made '55-'83, CJ 7 made '76-'86----see their forums, # of questions, vs: this new stuff!

Mr.Jeep is 35, Willy is 1965 Jeep, the name alone, speaks volumes!

I hope you get this figgered out, trade in valve might be higher!

Good Luck, I am still watching this, don't let me down!

The Medic

I have a CJ-5 with 304 V-8. Great vehicle. So is the 4.9 liter Ford 6. 1984 they went away from duraspark to TFI ignition, big mistake.

What happened?

DOC,

HE MUSTA COME TO HIS SENSES, AND FIRED HIS JEEP UP!

THE MEDIC