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Old 07-27-2020, 08:31 AM   #5
30 Closed Cab PU
Senior Member
Join Date: Aug 2018
Location: Wisconsin
Posts: 2,290
Default Re: Backfire in overrun mode (load change)

Originally Posted by DRG-ler View Post
Valve guides, ... I don't want to think that far.
However, the problem should be identified by means of a compression test / pressure loss test.

I tried to open GAV further. Even with a full turn, there was no change. So I don't think he's running too lean. But there the spark plug picture should provide information.
Alternatively, I made a lambda sensor adapter that can be installed between the manifold and the rear silencer. It is possible that you will also gain new knowledge in this way.

The thing with the leaky manifold gaskets I find absurd, because I also made sure that the installation was reasonable. Nevertheless, I will check it all again. I will use brake cleaner for this.

Greetings Andy

I was just trying to throw some easy things at you, hoping that it would get the discussion started. Personally even if testing does not make sense, I like to try it anyway, then I can know/prove it wasn't the issue and can check it off the list of possibilities. I do not like to assume anything when troubleshooting. Seems you are most likely a better mechanic than me and have already performed some additional troubleshooting to narrow the issue down.
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