3.1 mpfi flutters

[efmathis]

Hi, my brother and I have 1994 chevy cavalier Z24s w/ 3.1 mpfi. My brother's engine flutters through the rpm ranges of 3900 to 4600. Its hard to run 75 mph. It seems like it is getting too much fuel. He recently had replaced the o2 sensorwhich turned the check engine light off , spark plugs, wires, and we swaped the coil packs and ignition control modual, and it still does it. Confusing! If I have to get diagnostics done to it I will, just wanted to see if any of y'all could help first.

If you have had this happen to you, or you think you know what it is please let me know!

Thanks for your input!

[Baldeagle242]

Sounds like it may be starving for fuel not getting to much. Check/change your fuel filter and check your fuel presure. Could be a weak fuel pump. Also make sure your return fuel line is not damaged or pinched off somewhere. I would also check your air filter. If your air filter is dirty it could cause loss of power at those RPM's but I dought it would miss/flutter.

Good luck
Steve

[efmathis]

HEy thanks! Ill get right to it!

[efmathis]

UPDATE

Well we changed the fuel filter, checked the fuel lines up to the engine, and tested the IAC, TPS, air temp sensor, and took out the air filter. I dont have a fuel pressure checker, but I know some one who does but they are out of state right now. But this didnt help it any. What do you think this could be? ANYONE?
ONE THING fishy: When we relieved the fuel pressure (on the fuel rail) only a little came out. Not much pressure. When you check the fuel pressure, is there a certain procedure to go about it?

[IsaacHayes]

You use a pressure gauge while the pump is on :P

The FPR isn't flooding out is it? Take the vacuum line off and see if it has gas in it.