Sorry for the multiple posts everyone, had a bad subject title on the last one and can't find a way to edit.

If you haven't read my first post I've replaced everything on this 1991 D21 4x4 in respect to fuel pumps, lines, filters, sensors, vacuum lines, coil, spark plugs, wires etc...all replaced and now I've got backfire at high rpms when I decelerate or shift down to engine brake.

Now when I first got this old heap, I was tinkering around with everything trying to learn it and one thing I did that I think I messed up with F'ing with the screw adjustment on the throttle body. I have no idea what that original setting was and no idea how to get it back to where it should be.

Does anyone think that could be the issue with the backfiring? (running a little too rich?) Does anyone know the procedure to resetting that screw to where it should be? Or does anyone think it's something else? Keep in mind there's nothing left to replace except maybe the timing chain and the oil rings on the pistons.

Welp when i went thru this recently, i found that i incorrectly put the dist rotor on incorrectly. jmo

Check the ERR valve...May be stuck or no vacuum.

velkin wrote: ↑

Sun Aug 28, 2022 8:01 pm

Welp when i went thru this recently, i found that i incorrectly put the dist rotor on incorrectly. jmo

Not me! You've just made me realize I forgot a part! I haven't changed out the distributor! ... although I don't think that's my issue but thanks for the reminder!

whomadewho wrote: ↑

Mon Aug 29, 2022 7:12 am

Check the ERR valve...May be stuck or no vacuum.

EGR? Thanks for the heads up will check it!

ooops! Also when i was backfiring my spark plug wires were incorrectly pluged into the wrong plugs