engine running horribly need help

[Deusxmachine]

when im running down the road my engine stumbles and misfires and sometimes feel like some cylinders are not even firing. The car starts up and idles fine and will rev up fine when you hit the gas while its sitting but as soon as i get on the road it starts acting up. I got a code 33 today and i replaced the map sensor, the code has not returned but the car is still stumbleing and missing like before. What else could be wrong?

 

[Larry's Yellow Rdstr]

Need more info as to what you have done to the car...new plugs...injectors..plug wires...vacuum leaks etc etc.

 

[vetteboy86]

I agree we need some more info. Does it act up when accelerating on the road, or when you are cruising at a steady speed? The reason I ask is because sometimes emissions controls can act up. I have also heard of some owners having problems with there catilytic convertors.

 

[MBDiagMan]

I would start by checking for any stored codes and checking fuel pressure. If the fuel filter has not been changed in awhile I would just go ahead and change it.

Good luck,

 

[Deusxmachine]

I have new plugs, plug wires, cap and rotor, and oxygen sensor. The egr valve is new. I have headers and the cats are gone. There is a small vacum leak at the front of the bottom rear runner on the pasenenger side witch im about to correct. The car used to have a far worse vac leak and never ran this bad. It runs the worse when just cruisng but the acceleration doesnt seem so great either exp after its warmed up. I used to get a code 32 so i changed the egr witch is when i created a vacum leak at both runners at the manifold. It was a rather large leak, i could hear it and the car would idle around 1500 rpm, and roll down the road at around 35 to 40 without giving it any gas. The egr light never came back on and i just recently found and almost corrected the vaccum leak(still leaks a little like i said before but not near as bad and only on one side now, car idles at 800 rpm) Last night i drove the car to town and it ran bad, spitting studdering and sounded horrible, it threw a code after about 5 miles i stopped at Autozone they scanned it and got a code 33 and a stored 32, i bought a new map sensor put it on in the parking lot and drove the car home. Ran just as bad on the way home as it did on the way to town, but the light never came back on. Im going to redo the runners agian and get them air tight today but i dont think the vac leak is the problem because it used to be a lot worse and the car ran pretty good except for the high idle.

 

[Deusxmachine]

I just finnished puting the intake back togther, all the vaccum leaks are fixed. I sprayed ether all over to make sure. The car idles perfectly now. I took it out on the road and it still stumbles and misfires while cruising and accelerating. Could a bad coil cause this or is it possible that the ecm is bad, i dont know what else to do. Thanks for any advice in advance.

 

[airman]

Check for water in your fuel tank the drain hose could be stopped up.I had simular problems on my other vet and it had water in the fuel tank.

 

[vetteboy86]

Does it seem like it is running rich? Does it backfire at all? You might want to check your spark plug wire routing. In some cases when you have two wires crossed the car will idle like it has a vacuum, kind of like a car that has a mild cam. Well when you drive it or accelerate it is where the problems really show up. More so on the road because the car is under a load. If it was backfiring this might further point me to this direction because the unburnt fuel would ignite because the spark plug would not fire at the right time.

 

[Deusxmachine]

It does backfire a little bit when i let off the gas. No real loud cracks just little muffled sounding pops.

 

[vetteboy86]

Well I know it is a PITA but pull some plugs and see how they are burning.

 

[MBDiagMan]

AGAIN. When was the last time you replaced the fuel filter?

Good luck with it,

 

[Deusxmachine]

AGAIN. When was the last time you replaced the fuel filter?

Good luck with it,

Less than 20K miles ago.

 

[speedmaster4]

new plug wires and it makes 'little popping sounds'--check plug wires for proper routing ( 18436572 )

next i'd verify distributor internals by substituting another whole distributor--much easier than trying to troubleshoot yours

 

[vetteboy86]

You really cannot trust the sounds he is describing though unless you hear them. That is what makes this somewhat difficult. When I have heard many cars rumble under deceleration, some have to do with back pressure, and exhaust. I think we are on the right track though.

 

[Deusxmachine]

I just fixed the problem, i changed the coil, cap and rotor witch was a hypertech unit i got from a cataloug. The thing had less than 10k miles on it. Im not sure witch component was at fault, I might experiment around on a sunny day, but right now im just happy to have a good running car. I want to thank everybody for thier advice and help. I think im going to have a celebration drink.

 

[vetteboy86]

Glad to help, and enjoy driving your car.