Montero making popping noise from the exhaust

I have a 1996 Mitsubishi Montero with over 100,000 miles. It has been sitting in the garage for over a year. So a lot of cleaning was done to the engine. I had the oil changed and spark plugs replaced. The wires for the spark plugs were also replaced. The popping noise started when the spark plugs (and wires) were replaced. Ignition coils were also replaced after that which didn’t really stop the popping noise from the exhaust. A smell of “raw” gas from the exhaust is accompanied by white smoke. The noise and smoke only happen when you put the gear on drive. If it’s on park, it is as quiet as a mouse. I don’t really know anything about cars. I am just relating to you what I am told. What could be wrong with this truck? I am driving around with my daughter’s car and don’t have too much extra $ to throw into a car payment. So if I can get this truck to work for another couple of years, it would be great. Help! A NON-DISCLAIMER DISCLAIMER: I am a woman (I was trying to avoid to mention that). I really think women should know basic things about their cars. My mistake not to learn about cars. Frankly, I am intimated by it.

You might want to have the fuel pressure regulator checked to make sure that the rubber diaphram inside hasn’t developed a leak. If it has, gasoline can be drawn into the engine via the vacuum hose to the regulator, thereby causing gas vapors to be expelled out of the exhaust.


No check engine light,car drives normal (no surging,no hesitation) but a misfire (thats what it sound like to me) under the load the transmission provides.

Vacuum leaks will cause this no code misfire condition.

What I am really thinking is one of the cylinders is firing at the wrong time because the wires are not routed correctly (inductivly coupling).

Check plug wire routing, then the work proceeds into less likely areas like engine mechanical condition.

As far as being intimidated don’t be, the layperson is not expected to know what we mechanics call “driveability” issues. We do expect you to not ignore a “check engine” light and regulary check fluids. Don’t ignore odd noises or when your car fells like it’s not driving like it used to. Driveability is not basic car maintiance.

Thank you for your reply.

I neglected to say there is a check engine light on. It comes on and then gets cleared by the mechanic but comes right back. the mechanic says it is a PO705 which is a transmission control sensor. I don’t know what that means either. It’s still sputtering even when the fuel filter was replaced.

Thank you for your reply.
The sputtering noise comes from under the middle of the truck. It idles well but sputters at stop lights. It hesitates a little at 40 MPH. check engine light comes on and off. It says error on transmission control sensor (as what I am told). I am taking it back to the mechanic but want to have an idea of whats wrong with it.

You did not like the idea that the plug wires are incorrectly routed?