Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Rough idle bad acceleration perfectly fine WOT

Recommended Posts

Hey guys, first post on here and I've got something that stumped me 100%. 

I have a 2005 silverado 1500 flex vin code Z. It Idles rough it has terrible acceleration, wide open throttle it takes off like nothing is wrong. It misses on 7 every time, misses on 2 every other time, every other cylinder misses here and there. No misses when in park and rpms are kept about 2500. CEL flashes most the time when accelerating (except WOT) otherwise the light is on solid. It has 220k on it and I have replaced alot of parts. 

New parts

All 4 02 sensors OEM

Plugs OEM

wires OEM 

Fuel pump OEM 

Throttle body cleaned

3 stage fuel system cleaner BG Brand

Air filter believe it or not OEM again

New transfer case (unrelated issue)


I have covers the base of the intake with brake cleaner multiple time, no signs of leaks. I've had the smoke machine hooked up 3 to 5 times and again no signs of leaks. At this point what is the best route to take? Remove intake manifold so it's easier to get to and replace the main grounds behind the heads and replace gasket at the same time? Replace the pcm? Replace throttle body maybe? Any other suggestions or recommendations would be greatly appreciated.  


Edited by KyleThe...Mechanic
Link to comment
Share on other sites

Really? I have looked at the data on my scanner, I have a snap on Apollo D8 and that did look normal. As far as I can tell anyways. I did attempt to do a crank relearn and it wouldn't recognize WOT, so basically it wouldn't allow the relearn procedure to be done. One thing I will admit I havent done I'd check the waveform on the cam and crank sensors. Maybe my fault was not thinking anything of the relearn procedure not being carried thru. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.