help with miss on 99 K2500 with 5.7L

**99blueburb** · 07-24-2007, 09:44 PM

Not sure if this can be here.

I have a 1999 OBS burb with 131K miles on it. I have a miss between 1500 - 2200 rpms. There is no code or SES light. I put it on a scanner and it does not show a miss. It is not in the trans, as I can get it to miss while in park and rev up to 2500.
I have replaced the following:
tune-up (plugs/wire/cap/rotor)
coil (2 different brands)
fuel filter
fuel pump
O2 sensor
TPS sensor
seafoam in gas tank to clean injectors
and swapped from the old poppet valve spider to the ungraded injector spider

Still can't find miss.
Any help?

Basically stock, has flowmaster cat-back, K&n filter, and a PCM4less computer. I have even put the stock computer back in. Same problem.
Motor still pulls strong to 5K rpm. If I am under light throttle and lite load, that is when the miss occurs. If I give it more gas, it goes away.

**GaryL** · 07-25-2007, 09:57 AM

You might try doing a compression test, you could have a cylinder that down a little bit. Also, are you hearing any valve train noise? Could be a bad lifter or cam going flat. Just some ideas.

**CaJuN625** · 08-02-2007, 04:32 PM

Sounds like a bad valve spring or seat, personally.

**Toymyster** · 09-03-2007, 01:46 AM

Also check your fuel pressure, your fuel pressure regulator might be out of range!!!

**Wayne S** · 09-25-2007, 12:09 AM

Check the gasket around the throttle body for leaks, might just need a $0.25 gasket. I had that problem on my previous Suburban (1989 with TBI 350), and it was doing the same high idle that you described. Worth a shot.