Dumb comment here, but, you seem to indicate you always use Chevron gasoline with Techron.
As much as we all praise Chevron on this site, have you tried 87 octane from other retailers? It may not matter if all gasoline in your area is single sourced.
I know my Cavalier and 97 F150 pinged like mad when I ran 87 octane Amoco gasoline. 89 Octane Amoco was OK. ANY other brand of 87 Octane also worked.
Thus, my solution was ntot buying Amoco gasoline for those cars in this market...
Might be a cheaper fix than looking into anything else...
Oh - and the 4.0 does have an EGR for some model years (87-90 or 91). Later ones did away with it as posted.
As much as we all praise Chevron on this site, have you tried 87 octane from other retailers? It may not matter if all gasoline in your area is single sourced.
I know my Cavalier and 97 F150 pinged like mad when I ran 87 octane Amoco gasoline. 89 Octane Amoco was OK. ANY other brand of 87 Octane also worked.
Thus, my solution was ntot buying Amoco gasoline for those cars in this market...
Might be a cheaper fix than looking into anything else...
Oh - and the 4.0 does have an EGR for some model years (87-90 or 91). Later ones did away with it as posted.