Hey all I have a 91 s15 Jimmy w/ 4.3 & TBI. On the interstate at 80mph in low grade hills the mph drops off of 80. Tranny unlocks and raises rpm's. Is it too old being made when the speed limit was 55. Gave it tune up with no help. Thinking about a hypertech chip or K&N filter to try to help it get down the road. Any suggestions would be helpful. Thank
91 GMC low power at highway speeds
Jan 30, 2004
6 Replies
No, it's a problem with your lock up. The 4.3 is a balzy little prick, baby 6cyl version of the 350. Gary knows what ails your tranny.
~TLGM
If it's unlocking it's not the AT. I'd change the fuel filter, run some Chevron Techron thru the tank, and run a compression test.
Doc
Is this a recent problem or something that is getting worse? A restriction in the exhaust could be at fault, as well as timing that's off.
CJ
Your very right, I should have sat back and taken that 45min to remember. But chips and filters aren't going to help this problem. To the OP: K&N stands for Krap & No-good. Your engine has balls, if you fix whets wrong you should be happy.
~KJ~
Yeah the 4.3 is a ballsy little sucker ain't it? I love taking my wife's truck out for a romp (98' Sonoma SLS, 4.3L CPI, 3.42's) minus her in the passenger seat so I can abuse it every now and then. Gotta burn the carbon off the plugs right? He he he he he.
Doc
I like my mother's 99 Malibu. Handles pretty well and has some real guts....
~KJ~
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