Why does my car lose drive power when I am going 55 mph and let up on the gas? Then, when it hits 40 mph it starts up again. And this is random, not all the time. This morning I had no trouble at all, but sometimes I will have trouble the entire time I’m driving. Sometimes it tries to die on me at stoplights, and then it will spit and sputter and hardly move for up to a minute before it accelerates again. During this time, it is backfiring through the air filter, and not out of the exhaust. I took it to the shop and they couldn’t do anything because it ran fine while they were testing it, and the car can’t be tested any other way because it doesn’t have a computer system. Sometimes the car is alright to drive when it is messing up, and sometimes it is a huge hassle and dangerous.
Your car DOES have a computer system
Whoever’s telling you it doesn’t is either an incompetent buffoon . . . or they don’t have the right scanners and adapters to communicate with your pcm, but don’t want you to know they’re ill equipped to diagnose and repair your vehicle
Has anybody hooked up a fuel pressure gauge, checked out the ignition system, etc.?
The first thing I would do is take it to another reputable shop, one which is known for being thorough and having the patience to properly diagnose and repair vehicles. That would rule out the big name franchised shops.
The guy who does figure it out will probably end up being middle-aged . . . just a heads up. A young whipper snapper straight out of UTI probably won’t have the knowledge or patience to see this through
If it does NOT have a computer system, what type of carburetor has been installed to replace the fuel injection system? Who ripped out all the fuel injection and computer wiring? Please post back.
If the car hasn’t had a carburetor installed, then @db4690 is dead-on, find a better mechanic.