Hey guys, My exhaust was rotten all the way from the manifolds to the tail pipes when I bought it so I had it replaced at friends muffler shop, he told me he would make it better than it was new, it has bigger pipes all the way and he took off the converter, he also put a almost new Spintech muffler on it that someone took off there car and sold it to him cheap, the problem is the car runs fine when it's cold and in cool weather, but when it warms up it has a uneven jerky acceleration to it. The car has a new tune up with all new spark plug wires, cap and new coil. As far as I know the car is stock except the previous owner put a different air cleaner on it, it's the open type where you can see the filter. Oh and the car has a 5.0 engine and a manual transmission. Any suggestions!!!!

 

Kick your friends *** for f'ing up your car.

 

well you say its only when it warms up is that just the out side temp or is it the car its self.... if its the car when it warms up it will probably be a problem in closed loop and so i would say check the o2 sensor because he did exhaust work and the o2 is very close to were he was working if he replaced the y pipe... other than that it would be good just to check your car for codes by the paper clip method to see if any codes are stored in there or even if u have a friend with a scanner to hook it up.

 

i would make sure your friend put the o2 back in ,and it might have broken on removal too

 

Ok, I went a talked to my friend who did the exhaust, he said he put in a new O2 sensor after he did all the welding, so that's not it. And he checked for codes and it didn't have any.

 

Mine ran rough after I put in my hooker cat-back system for some reason. It ran better after unplugging the battery cable for about 10 minutes and plugging it back in. Maybe the computer just needed to be reset? I am not sure. But it ran better. Just something to try.

 

It sounds like it could be going lean. Try to turn the fuel pressure up a little.

 

I would 2nd that about the lean condition, my car had the same problem after I put my new exhaust on, I had to bump up the fuel pressure by making the regulator adjustable, that solved the problem, if you don't want to mess with that you might try putting a new cat back on it, that might get it to run like it did by causing a little more backpressure.

 

i would question the 02 sensor, since it is brand new, maybe it is defective :shrugs:

also does this only do it at WOT, or does it do it at part throttle whenever the car warms up?

 

it sounds like it is running lean to me too. If your exhaust need that much work chances are so does the rest of the car. I would check the fuel pressure to see if the pump is going bad. Also you might try cleaning out your intake manifold. My GFs camaro was having a similar problem and we ended up replacing the fuel pump, o2 sensor, and ran some cleaner stuff from schucks through the intake manifold before the car was entirely fixed. Can you give us more information about the symptoms and what is on the car? this would help determine the problem.

 

Did you remove the CATs if so your O2 sensor may cooling off sending cpu in to forced open loop. get a 3 wire o3 and use it

 

Sounds like O2, however......

Putting an exhaust system like that on the 305 is basically killing all the back pressure out of the exhaust. This could also cause the car to run lean, which it sounds like it's doing.

When the car is "Cold" the computer tells the engine to give the car more fuel, then when the temperature reaches a certain point, the 02 sensor takes over and adjusts the fuel rate according to how much fuel is unburned in the exhaust.

This makes me think your problem is that your car is leaning out(which means it isn't getting enough fuel) when the car is warm. I think you might need to BOTH
1. Have that new 02 sensor checked out
2. Get an adjustible fuel pressure regulator and let someone change the fuel pressure of your Throttle Body to a larger rate. I recommend about 22lbs on a basically stock 305 as opposed to the factory setting of 15lbs(I think).

When you open up your exhaust the car will pull more air/fuel into the cylanders, so if your puttin the same amount of fuel into it, then its getting more air and robbing itself of HP and gas mileage.

I could be way off, it could be something stupid like resetting your computer, or a bad fuel filter. Just some stuff to think about......
Keep us informed.


BTW, I think its hella cool that you(a chick) has an F-Body, and is into it enough to post stuff on this forum. Rock ON!!!

 

Thanks for the help guys, I have my car fixed now, it was the fuel pressure, my old fuel pump wasn't putting out enough pressure, The mechanic hooked a gage to it and only got 9lb. and it's supposed to be higher, and after a new pump the car runs great now. Thanks again.

 

I hope he changed the filter also?

I know my FP is on the way out.

Some days my car will drop its ***** at 4000 RPMs, and some days it'll fly up to 6000 RPM.

But my entire car's dead now anyway. A big '39 Plymouth hit it.

Looks like it's time for AJ to buy a Z28 or an IROC!!

 

Ouch!!! Sorry about your car AJ, that's a beautiful color, hope you find one as nice, how did the 39 fare? It's pretty unusual to get hit by an old car like that, they usually drive pretty safe with them.

 

That isn't too bad AJ. You only need like 4 body parts and some paint to fix that.

Then take the rest of the money (if it was his fault) and make the car go faster.

 

Thanks for your condolences.

I wish it was that easy. You should see the inside. Remember, the spare tire is behind that qtr panel. It did some damage as well.

Plus the RF fender got some to. It was hit by the guy that flew by my car after the coupe hit him.

For complete details, click here.

 

Is there any way I can turn up the fuel pressure without having to go somewhere to have it done??? My car seems to be suffering from the same problem after putting on a Hooker Cat Back.

 

If your handy with tools you can modify your regulator to get more pressure, here is the tech article on how to do it...
Pressure regulator modification