Dreaded Random Misfire at high speed or under load- next steps?

[Tbruz]

I have a new AcDelco distributor (94672691)complete with new cap and CPS on order as well as an AcDelco crank sensor (213-4761). Waiting on both to arrive and in hand before I move ahead, Understood I'll need to do ckp/cps relearn after each replacement effort. In the meantime I'm keeping it under 70 MPH and enjoying a smooth ride with no SES light or codes shown. Will report back with results.
Thanks for everyone's input, its truly appreciated.
Tbruz

 

[Tbruz]

Secondary question: is the relearn procedure required after the CAMshaft sensor( dizzy replacement ) or only after the CRANK shaft sensor replacement? Replacement distributor is in hand now and the crankshaft sensor doesn't arrive until Friday. Getting anxious to resolve this
Thanks
Tbruz

 

[exp500]

If Dist was removed/moved, then must do the Scanner. Above 1000 rpm. Should scan after any repair really. If you have the P1345 code (I think it is) then you are out of range on dist adjustment. What scanner are you using?

 

[exp500]

Missed the still waiting part, a decent cheap scanner is BAFX obd2 . Doesn't do much but will read cam angle sensor/ dist position. (about$30.00) There is a thread on that if your readings are out of range. Won't do ABS or air bag or body codes. About $300 for a clone laptop based or handheld Tech 2 which is highly recommended.

 

[Tbruz]

Using a Bosch 1350 scanner, which wasn't cheap; it will read ignition advance which isn't the same thing.

I've learned that after a distributor replacement/move, you may or may not get a Cam retard error; depends how close to perfect you get it installed. Since I'm chasing this misfire issue, I need to be spot on.
You do need to dial in the cam retard to 0 degrees.

After a crank sensor replacements you need to do a crank sensor relearn.

I'm starting to recall why I HATE new cars where you cant do anything at all without a scanner.

Thanks
tbruz

 

[exp500]

Yeah- my friend and I are in agreement- nothing newer than 1980!. Good luck on this fix, keep us posted.

 

[Tbruz]

Got the crankshaft sensor today and unlike the picture, NO SHIMS came with it, does anyone have a couple of shims left over that they didn't use?

Much appreciated.
Regards
Tbruz

 

[exp500]

Make one- anything with a hole in it- piece of milk jug....
Are you sure you need one? Measure old and new CPS.

 

[Squirrelsmith]

I have had the same issue for 3 years and recently is turned into back firing, lean codes, missfires, loss of power. Piece of junk barely runs. I said screw it im ls swapping the *****, these engines suck anyway

 

[Tonyrodz]

I have had the same issue for 3 years and recently is turned into back firing, lean codes, missfires, loss of power. Piece of junk barely runs. I said screw it im ls swapping the *****, these engines suck anyway

I had an 01 Express van with basically this same motor--after I sorted out everything, it ran beautifully. I prefer it to my 05 4.8 LS! POS, nothing but problems since I bought it. Even has the 4l80 trans.