OK, I'm wondering : how stupid was I THIS time?.. Background: 1992 XJ40 Head gasket replacement 1500 miles ago. Have another open thread trying to find and fix a "miss, stalling,lurching", (or whatever name you want to call it) at steady throttle highway speeds . Car drives pretty good in town since repair. Have been slowly replacing, parts with mainly new parts (TPS, EGR solenoid used). CPS, OXY Sensor,EGR, wires, cap,rotors(times 2),coil,amplifier, thermostat,coolant sensor, and recently new injectors (and cleaned rust from fuel rail) have been replaced. Mileage and drive-ability have steadily improved to about 17-17.5 MPG in town driving. Talked to a local local Jag shop (non-dealer) about my frustration trying to find this last "bug". The owner was in the middle of a head replacement, was talking to his receptionist. She said "Are you sure your distributor is not loose?"
Went to check and no, wasn't loose, but I noticed that it was as far as it could get to one side of the "slot" on the mounting flange. I have a hazy memory of the late night install when putting it back together, and remember the alignment marks didn't match. I remember looking in the Haynes manual where it stated no timing corrections could be accomplished by moving the dist., but be sure not to rotate the engine with it removed or you would have to have a dealer/shop reinstall. Only place it would click into place was all the way to one side. Didn't worry about it because I assumed the ECM would self- correct.

In looking at the inside of the Dist cap, the "burn" or corrosion you see that normally is all across the contacts are only on the edge of the contacts, as if it it getting spark too early but close enough to still run. Is it possible that even though the ECM controls the spark advance, I may have the Dist. installed far enough off to be beyond the range of the ECM to correct to a more retarded position when not needing a full advance??? That could explain my problem, just too stupid to know if it is possible or not.

 

I have seen that problem on a Volvo at the shop I work at. Normally the distributor is fixed ie it has a block preventing it from being adjusted. The owner of the car had removed it and mover the distributor probably 30 degrees off its locked position. The computer corrected it enough that the the car idled fine but had some odd issue ( I don't recall what it was) but it can cause issues as the computer does rely on the base timing being correct so IMHO its def worth a look.

 

Shelby,

I can't help you, you have done more than I have to the components. What I can tell you is ...... lighten up on yourself!!!!

Your close....just chill, hate seeing someone being so hard on themselves. You'll figure it out... and be the "Master Brain Trust" go-to guy for the rest of us.

 

Shelby,

Just a question, you didn't mention if you replaced your fuel filter and/or pump?

I've noticed that my cat is 'bouncing' slightly (feels like a small miss) when driving with the cruise control engaged which I'm putting down to an old(er) fuel pump. I haven't got around to swapping out as yet so keen to hear what you come up with.

 

So you, or before you, did not do any of this.

I'm absolutely of no use to you with this problem, but in my experience (long time amateur) all components, gauges, and just about anything, are designed to either be placed or operated around a neutral central position.

Dizzy 'all the way to one side' strikes me as 'not normal'.

Maybe look into why?

 

Fuel filter was replaced. Fuel pump pressure was checked per Haynes and all values good, so fuel pump was not replaced. I did remove tank level gauge and eyeball tank, no visible rust or sediment.

 

Double checked the rotor position with #1 cylinder at TDC According to mark on front damper/pulley assy. and it is pointing right at #1 plug wire discharge point in cap.
Guess that should eliminate my question.