99 yukon slt - miss fire but not pulling codes.

[tulsa_bikertrash]

Hey all,
I have a 1999 Yukon SLT with 105,000 miles on it. The engine has a vibration at idle and sometimes misses and back fire during light acceleration but, it does not pull up any trouble codes with an OBD2 scanner.

I replaced the fuel pump, fuel filter, and cleaned the tank about 3 months ago.

Any ideas would be helpful.

[maxwedge]

Welcome to AF, if this in fact a misfire, a full scan will reveal a pending code or you can view misfire counts on a high line scanner.

[99_Yukon]

Had similar problem, and the problem ended up being a bad distributor cap. There was a hair line crack allowing spark to jump across.

[master1printer]

Had same problem on 98. Full scan revealed weak intermitent signal from crank position senser. I had already replaced cap button wires plugs at advice from shitty scan owner mechanic. Retired GM service tech. told me there was a lot of wiring problems and to check wires to sensor for being overly stretched at factory to save a penny. I ended up replacing crank sensor it and runs great.