Misfire on 1997 Firebird 3.8 V6- Help!

[Mio]

Hello,
On my Firebird a have a misfire problem ! the code given is P0300 Engine misfire detected i have changed Plugs and Wires and the Problem is still there. When I try and hold the RPM at 4000 the engine keeps taking reving up and down by itsself can anybody help ?

Mio

[ChevMCarlo84]

i have the same problem with my Trans Am... I can;t figure the fucker out

[XMan9]

do you have a brain? it is called the "rev limiter". it keeps bone heads like you from blowing up the motor... :silly2:

[ChevMCarlo84]

no dick eater... mine does it all the time... at ANY RPM... at idle it revs from 700 to 1800 rpms and keeps doing it until I hit the gas...

[audiotech]

have your crankshaft checked . I had the same problem you are describing on a 94 V6 Camaro . The crankshaft controls the timing on these cars, and when that goes ouot of whack , it sends the wrong signals to the computer , which makes it misfire or rev up .
I had to replace the crankshaft ($ 700.00) problem fixed .

[Blackbird01]

It may not be the crankshaft. It could be a few bad things.
Bad O2 Sensors, bad MAF, bad crank sensor.
I believe it could be emissions related.

[ChevMCarlo84]

I bought an extended warrenty with the car and is all that kind of stuff covered????

[86TA]

as far as the warranty ?... it should be covered... and to everyone else out there i have a question... is it serging when you are in park and sitting still... or is it while your going down the road... if it is both, then it could be you TPS...if it is just going down the raod, check your transmission... as far as the miss - is it a constant miss, or speratic?? let us know how it turns out...

[custom mccannix]

you need to be more specfic than a PO300 that is just a category and not a code. it will be something more like a PO306,PO304,PO303. the last number standing for the affected cylinder(s). This is standard for all OBD II. and if it is at idle it could be a number of things such as your IACV, TPS, MAFS, or ECM. you also have to remember that the computers don't understand what roots type problems are so it can say one thing and be totally out of left field. FOr instance I just got a Saab in at work and it would not run or turn over. The computer said it was the starter soleniod but i knew better because i have seen it before. I check the rear light bulbs and sure enough the left brake light was blown. This system networks with the ECM and it shut the whole system down. Now that wasn't actually the problem something made the bulb blow so i checked the Body control modual that controls the rear lights and it was bad. problem solved. as you can see these things are not related and the computer had no idea of what was going on. Plus if you are going to Autozone or something to get you codes read, you are getting nothing. We refer to these scanners as "code catchers" because that is all they do and no more. they do not have the capability of reading specific codes such as which cylinder is misfiring on a misfire code. the dealerships and government are making these systems more and more complicated and less owner friendly (as far as working on them). this is how it is going to be and we can't do anything about. OBD III is on its way and nothing will be aftermarket compatible and stay street legal so get ready for it.

[99onI95]

Well please tell me mine is a P0303

I know that cylinder 3 is misfiring by the 303
I've replaced plugs, plugwires, cat, fuel pump, camshaft sensor, coil.

I'm only getting 200 miles to a tank of gas

[custom mccannix]

have you done a compression test on that cylinder? Did you check the D.I.S. modual that the coils atatch to?