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Exhaust question

My '94 Econline van has had a manifold leak for a while (almost a year). It’s too costly a repair for a work van so the noise doesn’t bother me.

Recently, it has begun to sputter pretty bad while accelerating and I am wondering if a leaky manifold would cause performance problems. What do you guys think? Thanks.

An exhaust leak bypasses the O2 sensor(s) and is a safety hazard. Over time, the leak can cause erosion of the mating surfaces.

…and could bypassing the O2 sensor cause sputtering?

Yes. It could an inaccurate reading to be sent to the ECU. But the vehicle is 15 years old. There are moore likely causes of sputtering that should be checked out before making this assumption.

One suggestion. If the leak can be accessed, there are muffler repair materials available in the parts stores that can successfully withstand high temperatures and may be a good plaster repair for the leak. I’m not suggesting that this is as good as a replacement, but it’s better than doing nothing.

A manifold leak can expose the exhaust valves to excessive fresh air and oxygen, causing the valves to erode.
A compression test will show this.

Will eroding valves cause sputtering?

Yup. Anything that causes erratic ability of the cylinders to hold compression will cause erratic operation.

An intake manifold leak would also affect the proper metering of fuel to the cylinders, as well as affect manifold vacuum, a variable in the formula that he ECU uses to meter fuel. This would definitely cause sputtering. Testing for this can be done with a vacuum gage. Any Haynes manual or the instructions for the gage itself will provide instructions. Basically the needle wobbling at idle is a dead givaway.

An exhaust leak is a safety issue because the exhaust contains carbon monoxide. If you are going to continue to drive this vehicle, take a tip from the dogs–leave the window down and drive with your head out the window.

That’s just it. The speedometer doesn’t work.

…or are you talking about a wobbling vacuum gauge needle?

“or are you talking about a wobbling vacuum gauge needle?”