Misfire, popping, sputtering after broken spark plugs was replaced with a Heli coil and plug

ERICKOOL

MEMBER
2010 DODGE CARAVAN
3.3L
6 CYL
2WD
AUTOMATIC
112,000 MILES

Van listed above is the Grand caravan SXT model. Brought it to garage after spark plug broke. They bored out the hole and put in a heli coil and plug. After doing so it runs horrible. Immediately starts missing, popping, surging up and down. Never had an issue before plug broke. It does start but if you put foot on the gas it gets no more power, just surges and the point it started. Can you please tell me what's causing the surging, missing, and popping? The popping is very loud and sounds like it's close to the location of the replaced spark plug. Thank you.

2 Replies

SCGRANTURISMO

MECHANIC
4,897 POSTS

Hello,

I would take the vehicle back to shop where you had the work done. This sounds like you have a major vacuum leak. I would have them double check the heli coil and make sure that it was properly done. Please keep us informed.

Thanks,
Alex
2CarPros

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Friday, January 31st, 2020 AT 4:24 PM

KASEKENNY

MECHANIC
18,907 POSTS

Run a compression check on that cylinder. More than likely the coil is not holding and you are loosing compression through the plug. It is very common for people to repair the head this way but it is not recommended for the reason you are experiencing.

What happens is the coil does not allow the plug to stay tight to the head and it allows pressure out which is the popping you are hearing. Then the poor running is caused by the misfire due to low compression.

This test will confirm it. It could be other things but I am confident this is the issue based on what you told us.

https://www.2carpros.com/articles/how-to-test-engine-compression

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Friday, January 31st, 2020 AT 4:25 PM