My 96 1/2 ton is still missing intermintantly. When this happens the SES lite flashes and then comes on. The miss will dissappear and the SES lite will go out after a few mins. I assume it's the same missfire I had previously but I can't get it scanned with the lite out. My question is: Will the ECM store codes or is it clearing itself when the lite goes out. Can scan still determine what is wrong?

Charlie

 

Have it checked for codes it should store them. Provide some more info on your truck like engine, transmission etc.

I wouldn't drive too much with a flashing Check engine light.

 

Yup same as before...scanner sez "missfire #7". With good compression on all 8 cyls and no constant miss I'm gonna bit the bullet and order the updated spyder as I believe the poppett valve to be sticking and it's only gonna get worse. I've tried fuel sys. cleaners and MMO seemed to help for awhile but now it's back again.Thanks for the input.

Charlie

 

let us know how it goes

 

Does your engine have a knock sensor?

It will give the same misfire codes if loose or out of position. Seems there might have been a tech bulletin for the knock sensors in some models.

Maybe the tech bulletin experts can find something.

 

I don't think it's the knock sensor because it always drops the same cyl. momentarly #7. A faulty knock sensor thst is loose or out of position will show a random code and not pick on the same cyl. ...So I've been told by a GM tech.

Charlie