1986 back firing

[Rick Hendel]

I have a 1986 350 tpi that is back firing only then cold. The I scaned it and it said to look at the EGR valve. Does this sound like a EGR valve could be the problem. How difficult is it to take off the plenium and the tuned port to get at the EGR valve. Thanks

[Jim T.]

Re: 1986 back firing

Are you getting a check engine light when it backfires when cold? Codes as you probably know will stay in the computer for a measured time for scanning. Removal of the plenum is not to difficult if you have the necessary tools. The runners don't have to be removed, but do have to be loosened from the intake to remove the plenum. My experience is on EGR valve removal on my 85. Torx sockets will be required and the passenger side front two runner torx head bolts are accessed from the drivers side going under the plenum with a extension. Don't know if your 86 EGR is the same as my 85, anyway there is bolt that secures the EGR valve to the intake that does not have real easy access. Did the removal about 10 years ago, don't remember exactly what I encountered with this bolt.

[Andrew Strauss]

Re: 1986 back firing

I had an 87 doing the same thing that turned out to be the airmass sensor.Be careful gm wants big$ for one,local auto parts want much less for a reman,depends on your prefernce.