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Car misses with popping noise

I have a 2000 Plymouth minivan. About a year ago it would occassionally miss. I thouight it was bad gas and began adding alcohol with every fill up. This hasn’t worked and the problem has gotten worse. Now, whenever I accelerate it misses and I get a popping sound that seems to cvome from the engine compartment or under the drivers seat. When I get up to speed it seems to run okay. The problem is worse when the engine heats up. Any ideas??

Is the Check Engine light on/flashing?


The check engine is not flashing

But is the check engine on? If so, can you get the codes read ? most auto parts stores will do this free.

PS: on but not flashing indicates a problem with the engine. Flashing means a serious problem.

+1 to @Tester and @BillRussell , is the check engine light on? If it is most auto parts stores will read the codes for free.

How many miles on the van? Which engine? What type of maintenance has been done over the years. If your plugs and wires are original or old, they need to be replaced.

I’m assuming you were you adding the alcohol b/c you thought there was water in the gas, but you’ve since decided this isn’t a gasoline problem. So what’s causing it … hmm …

Popping sounds are often exhaust noises. If you have a leaky exhaust system, that could explain both symptoms, the sound and the poor performance. On modern fuel injected cars using engine computers the exhaust system has to be air tight for the computer to set the correct fuel to air mixture. Wrong f/a mixture can causing missing.

Another guess, you could be hearing backfires into the intake manifold. That could be caused by valve problems. To test for that, a compression check-up would be the first thing to do probably.

Okay guys, this is the story. In spite of the fun people make of minivans, i love them. Over the last twenty plus years, I’ve had three. I move lots of merchandise and building materials and these vans are much more comfortable and get better gas mileage than work vans which I had previously. I’ve bought only used ones, the present one with 185000 miles on it. It’s now at 276,000 miles. I’ve always serviced them regularly and used only synthetic oil.
More on the problem: First, the check engine light is not on. It’s a 3.3 liter engine. The mechanic (he has good reviews on mechanics files) has discouraged me from having him troubleshoot it. He thinks the high mileage and the cost of troubleshooting means I should let it go the way of the sunset and buy another one. But, like I said above, it runs fine when I get up to speed. I just drove it on an 800 mile round trip and it got a little over 21 miles per gallon. So, I appreciate your feedback and will share it with the mechanic to see if I can get it to 300,000 miles before I kiss it good-bye.
Thanks guys.

@wildeted I have to agree with your mechanic. If the van is reasonably reliable and has decent gas mileage, just keep driving and do regular maintenance.

My sister is a retired cost accountant and her formula is precisely the same. Drive it into the sunset and “shoot it in the head” when the time comes. Cowboys did not really enjoy doing that but they had to be realistic!

My only caveat would be not to drive an UNSAFE vehicle!

Misfires under load are usually caused by failing spark plug wires on this engine, how old are the spark plugs and wires?

Popping sound with a misfire is usually a backfire. On older engines backfires came from misdirected spark. A bad distributor cap, and old dirty plug wires often were the culprits. Is this issue worse when the weather is damp? If yes, that is another clue leading towards a bad cap and wires.

I’m not familiar with the ignition system on this motor. But if it uses a distributor cap and traditional spark plug wires I’d change the cap and rotor first, then the wires if there is still a problem.

If you have a coil on plug set up, then you can change the “boots” that go between each coil and the plug.

These parts are not that pricey and with your miles on this car it’s worth a shot.

With that many miles on the engine, misfire/popping noise might from a stretched timing chain.

Tester specializes in Fiat-Chrysler. I have had lots of help over the years from that site. There is a discussion group devoted to Minivans/Pacifica, with many avid and expert participants.

I agree that minivans are versatile, comfortabe and enjoyable. I have my wife to thank for urging one on us years ago. No regrets, only kudos.