mis-fire after heater core replacement

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stealth

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First post but avid lurker.

I have an 03 Liberty Sport with just over 100k on it. As it got cold i noticed the heater was only blowing slightly warm air. So I replaced the thermostat which did nothing. Took it to the local shop and they said it needed a new heater core after they tried flushing it. Had a second opinion at another close by shop and they said the same. So I decided to have it done there. I picked it up today and noticed right away that it was sputtering. I live about 7 miles from this shop and needed to get home to get ready for work.

Halfway home the check engine light started flashing and the part time 4 wheel drive light came on and off, the Jeep was sputtering pretty bad. I made it home and shut it off. Then started it again a few times, took it down the road again and it ran better one of those trips. It also died a couple times after starting. The codes it showed were for misfire in I think 3 or 4 cylinders, I can't remember exactly and it is late here now.

Before I took it to the shop there were no lights on. It ran pretty strong. I called the shop right away and they seemed surprised. They told me it sounds like a coil gone bad and to bring it in on Monday to have it scanned. I am pretty aggravated at this shop. I do not think they did anything more than start it up to see if the heat worked, which it does now. Could they have not hooked up a vacuum line somewhere? Somehow got anti-freeze into the plugs? Maybe the computer needs time to reset? All I know is that it ran fine with no lights on when i dropped it off.

Thanks for any suggestions or comments
 

LibertyTC

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My first thought- Good possibility that coil packs may have got wet..
Remove coil packs and look for coolant/ water down in coil & towards spark plug bore.
Make sure all is dry...
Used compressed air to blow it out, & die-electric grease along seal & bottom of coil pack for re-installation.
 

stealth

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Thank you very much. I was looking for something to do or try today, before I had to take it back to the shop. I will look into your suggestion. Hopefully it is something minor since it ran fine before this work. Wonder if I should expect the shop to fix it with no charge if this is the problem?
 

LibertyTC

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Chances are they are wet.
I hope they used the right coolant...."HOAT" !!
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Hopefully after all is dry, & jeep runs again fine, you can just call em & let em know what you found...
But die-electric grease should be used as previously mentioned.
 

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HoosierJeeper

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I'm guessing that's the issue, check out the passenger side specifically. x2 on the HOAT but it sounds like this shop doesn't care, so I'd just take it to the dealer for a flush.
 

M38 Bob

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Likely they did get coolant around the coil/plug area.

As an aside, though, one of the most difficult things in the auto repair business is when something totally unrelated to the issue one's been hired to fix goes to $chit while it's at your shop.
 

stealth

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Thanks for all the advice. I did tell them before they started the work to use only HOAT coolant, it is orange in color. I will check on the coils today. Also thanks for the link to the video. Much appreciated.
 

LibertyTC

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Likely they did get coolant around the coil/plug area.

As an aside, though, one of the most difficult things in the auto repair business is when something totally unrelated to the issue one's been hired to fix goes to $chit while it's at your shop.

Ya I often wonder about the shops qualifications & who's doing the job!
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jeepop

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This happened to mine after I flushed my heater core. I pulled out both ignition coils in the back on that side. Both where dry. I used some spray cleaner I have for electrical sockets on the clips, and wiggled the fuel injector electrical connector too. Cleared it up.

If I was in your shoes, I would first try unclicking the connectors from the ignition coils, and even the fuel injectors, clean them and reconnect before pulling the ignition coil. Mine did not get any water into it.

Once is runs smooth again the check engine light will clear in about a day.
 

stealth

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UPDATE. It ended up being a couple bad coils so far. I replaced them all myself, using electric die grease and contact cleaner and it has ran fine since. Thank all for the suggestions!
 

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