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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 6953
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Misfire after changing plugs and leads, steady, its a 2002

Customer Question

misfire after changing plugs and leads
JA: How many miles are on the car? Is it a steady misfire? Or random?
Customer: steady
JA: What is the model/year of your Mitsubishi?
Customer: its a 2002 magna v6 and 190k
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: the battery died so put a new battery in and since then it has started
JA: Anything else you think the mechanic should know?
Customer: it was runing fine till we changed the plugs and leads
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mitsubishi Mechanic about your situation and then connect you two.
Customer: and the battery died
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.


Are you actually getting misfire faults or is it just running rougher than normal?
If I understand right, the problem originally started when you changed the battery? If that is correct, when you changed the plugs/leads did it affect the situation in any way (for better or worse) or was there no change?

Customer: replied 1 year ago.
the problem started when we serviced it. we changed the battery as it dropped cells and now it has a misfire for some reason after changing the fuel filter and the plugs and leads
Customer: replied 1 year ago.
its worse since we touched the fuel filter being honest
Expert:  Doug replied 1 year ago.


With regard to the plugs and leads... did you use either NGK or Denso direct replacement plugs? These engine management systems are extremely particular about the plugs and run absolutely terribly with gimmick plugs as well as many generic brands (Bosch for example barely run these cars).

With regard to the fuel filter... can you put the old one back in and see if there is any change in case there was something wrong with the replacement?

Customer: replied 1 year ago.
changed it all back to how it was and its still the same
Expert:  Doug replied 1 year ago.


How about the plugs, were they NGK or Denso direct replacements?

Customer: replied 1 year ago.
Ngk long life as the books said they were required to be
Expert:  Doug replied 1 year ago.


If the condition formed specifically after the tune up work was done (not after the battery but before the tune up), have you checked for intake leaks with propane or brake cleaner?