Reader Question I read your articles regularly. I now have a question for you.
I have a 2001 Chevy 1500 extended cab with small v 8 4.6 I think with a automatic transmission it does fine until you get to 41 mph where it shifts to overdrive I guess. The RPM drop to 1100, when you speed up slowly to say 45, 46 mph it “bumps” real bad several times. I changed the fluid and filter 6 months ago at 50,000 but this has not helped.
I have taken it to a good trans shop 4 times and they swear nothing is wrong with the unit. It is aggravating to drive, if you kick it into passing gear it does fine. At lower speeds fine as long as you are not going 40 mph to 50 mph. I did take it out of town the other night and drove it hard; kicking it into passing gear and running it 90-95 mph many times and now it seems to be better. No check engine lights or warnings have come on, but it bothers me that it may act up again. I was just before trading it for a Dodge or Ford.
I bought this truck from my dad 2 years ago, who bought it new from the dealer and I know he has never abused the truck. I do not tow any thing and only have driven it 11000 miles in 2 years.
I usually drive my motorcycle, hope you have a solution, it is almost paid for, and I really like the truck and do not want a new one.
Hey there Greg,
I would HIGHLY suspect you have a bad spark plug wire that is breaking down. I would inspect and or replace the spark plugs, plug WIRES, distributor cap and ignition rotor. At 40mph in overdrive with 1100 RPM – that is like driving a 10-speed bike in 10th gear and only doing 5 mph….it take a lot of leg strength to gain momentum. Worn spark plug wires tend to break down when put through this kind of punishment. So, a full tune up is probably due, or at the very least a set of spark plug wires.
I would also recommend replacing the fuel filter if it has been more than 25K miles since the last one.