Questions and Answers
Chevy Blazer Has Surges
Q. We have a 1999 Chevy Blazer with the 4.3 liter Vortec V-6. When driving you feel a change in the power while under acceleration and also while cruising down the highway. It almost feels like a intermittent timing variation. While accelerating the power varies, it feels somewhat weak and then you will feel it pull stronger almost like the timing was retarded and then all of a sudden it advances on you.
On a hill accelerating, but not kicking it down a gear, if you watch the tachometer you can see a change in the RPM and yet the throttle position is constant. Say you are holding at 2,000 RPM's, it will drop to 1,900 and then kick back up to 2,100. If you "shower" down on it, the engine pulls strong and smooth. We have had this to four different shops and the say nothing is wrong.
No codes show up, but she still does not run correctly. The vehicle has 50,000 miles and other than this is like a new car. We love our Blazer, but driving it this way is very frustrating. Any help or suggestions would be greatly appreciated.
A. Kind of sounds like the EGR valve is opening too much. For me to help you I would need to drive it with a scanner hooked up. Also would have a fuel pressure gauge on it to make sure it's okay. Could be fuel problem, I doubt it's spark timing but you never know on these newer cars. Have you tried a Dealer? Could it be the A/C clutch kicking on and off?