On inspection of my exhaust system I noticed several holes in the mufflers and pipes. Its the original exhaust system so its nearing 30 years of use. Im wondering if the holes in the exhaust could be whats causing my misfire?

 

very much so.

 

Thanks! I was going to be replacing the exhaust for something a little more free flowing to free up a few ponies under the hood anyways, so I hope this solves my problem!

 

I'm a little curious as to how a hole in a muffler can cause an engine misfire....


Cheers
DD

 

Muffler..not so much. BUT, as he also mentioned... PIPES. He did not mention where. But, holes in pipes especially towards the front can most certainly cause misfires.

 

Yeah, a hole ahead of the oxygen sensor could cause running problems, yes.

Cheers
DD

 

Before we get lost in some long debate, what sort of problems do you have? What have you checked up until now?

 

Well the holes are in the pipes as well as the mufflers. The problem is it sputters when accelerating and it feels like it has no power and wants to die. The problem goes away above 2500-3000 rpm's where it'll run smooth as silk

 

Oh and I forgot to mention that the holes in the pipes are throughout the entire exhaust system. I didnt check though if it was before the oxygen sensor. I also think that there is a leak in the manifold. However one of the bolts that is holding the heat shield on is seized and no amount of penetrating fluid can free it. So I have to cut the head off the bolt to remove the heat shield to inspect it as well. Because it could be as simple as a gasket for the manifold or something less simple.

 

Sputtering:

Could be an old fashioned ignition misfire. How are your plugs, plug wires, cap and rotor?

Could also be a fuel issue: clogged fuel filter, incorrect fuel pressure, dirty fuel, partially clogged injectors.

The fact the it improves at higher rpm is a bit odd but, still, the basics mentioned above are worth considering.

Is the problem engine-temperature sensitive? Any black smoke from the exhaust? Are the spark plugs black? Do you have a fuel pressure guage by chance?

Cheers
DD

 

I think Doug is on to it. Sounds to me like you are falling under load. We you hit the higher RPM's and it smooths, are you still accelerating as hard? I like Doug's first suggestion. Check cap, rotor, wires, plugs, and even coil.

 

Well the spark plugs are in good working order. The wires may be another story. Im not sure when they were replaced last, however the distributor appears to be new. I will be replacing the fuel filter though soon. Ive also run an injector cleaner through the system as well with no obvious improvements.

Going back to the distributor though, this is uncharted territory for me. Im not sure how to tell if its firing correctly or if the timing is off. I dont have one of the timing strobe lights to tell (im not sure if I could rent one from a parts store or not) and if the timing was off, how to adjust it properly

 

These cars typically don't suffer from timing issues, but it never hurts to check. I would think you could rent a timing gun from a parts store. Of course, it's old school so they may not carry them for rent anymore. Most cars cannot be adjusted now days. You may want to check the contacts in the cap and on the rotor as well.

 

Thats the part Im unfamiliar with is checking the contacts or anything to do with the distributor. But to answer the previous post: it does sputter under load. It definitely isnt as noticeable when Im very very light on the throttle, and it hardly does it at all when its in neutral or park. But it still sputters a bit in both scenarios

 

Remove the cap, leave the wires attached or find a way to mark them so they go back to the same place. Inside you will see brass contacts where each wire connects. Check these contacts for signs of wear or corrosion. The rotor will remain on the center of the distributor where you removed the cap. Check the brass or metal at the end of the arm for the same thing.