My 91 firebird 350 has less power than my 1988 Iroc 305. How could this be and any suggestions???


Asked by Apr 14, 2013 at 10:55 PM about the 1991 Pontiac Firebird Formula

Question type: Maintenance & Repair

When I press on the gas of my iroc
it's very solid and you can feel the
power. With my firebird the pedal
feels hollow and is slow getting up to
speed help!!!

5 Answers

the timing is too far retarded for maximum power. The air filter is choked. The PCV valve doesn't rattle anymore, fuel mix is too rich, spark plugs are gapped too small (should be .040) or if platinum are crudded up. The catalytic converter is carboned up on account of the rich condiiton. the EGR valve is stuck so it is breathing it's own exhaust instead of fresh air/fuel mix. fuel filter ain't flowin' fast enough~I'll think of more but thoughts grow increasingly evil....the vacuum advance on the distributor is missing and suckin' air (buy silicone vacuum hoses from summit) and/or the centrifugal advance inside the distrubutor has missing/broken springs----

1 people found this helpful.

If it's really pukey, you could have jumped a timing belt tooth~

1 people found this helpful.

The distributor would have to been removed or loosened for the timing to change, PCV valve won't cause the engine to lack power. Fuel mixture is electronically controlled. The catalytic converter would prevent the engine from achieving higher rpms not cause issues across the rpm band. Egr causes idle issues and the numbers in power loss would only be seen on a dyno. The distributor is electronical not vacuum or centrifugal and its a timing chain not belt and if that has jumped he wouldn't be complaining about slight power loss it would be major power loss. To start with I would put most of my money on the fact that your iroc has something along the lines of a 4.00+ rear end if not a 4.0 then a very high 3.-- where your 91 has more of a highway rear end (low 3s) so it doesn't have a quick take off but gets great highway mileage. Look in your glove box to see if the factory equipment sticker is in there on both if its not then jack it up, pull the drive shaft, and spin one wheel counting the turns on the yoke to the tires one turn. Divide that number by two and that's the gear ratio. You might be able to call a GM dealer and give them your VIN and they can pull the build sheet for your car but that's iffy with its age.

Best Answer Mark helpful

Try checking /replacing wires, distributor cap, and rotor, pvc valve, vacuum hoses, air filter, also try cleaning out your trottle body with carburator/fuel injector cleaner while car is running use the entire can, that will clean out the entire intake and exhaust system, including cat and muffler. try that my friend and you will definetly see some driveability improvement. Also check trottle linkage at the gas pedal where they connect for any play,you can improve response on the trottle by shimming with 2-3 wire ties.

1 people found this helpful.

Find out what day the two cars were made. Monday cars were generally slow and Wednesday cars were better. Some came out of the Factory fast and others not so much even if they have the same engines and all.

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