New problem this summer. 2008 Sport Auto, 148K, A/C on, when I come to a stop, engine runs rough. Check engine light came on, codes showed power loss and misfires on each cylinder.

If I turn off AC, or shift into neutral and rev it up a bit, it's okay.

What should I check?

Thanks.

 

List of causes:
Worn spark plugs and or ignition coils
valves are too tight (loss of compression & torque)
A/c line is restricted
ECU did not see that A/c is on and did not command to throttle body motor to increase engine RPMs

 

Honestly, I would probably change all the coilpacks, seems to be the most common reason for misfiring. Get all 4 for about 250$ from RockAuto Parts Catalog . Get the Hitachi ones. If you've never changed your spark plugs, I would go ahead and do that too.

While you've removed the coils and plugs, you could go a step further and remove the valve cover and check the valve clearance like the above poster mentioned. Some valves could be out of spec. New plugs and coils and a valve adjustment and I bet it'll run like new!

Perhaps try cleaning your condensor also? Check ErictheCarGuy's tutorial on cleaning the AC condensor. Apparently, a dirty condensor can lead to increased pressure inside the condensor and poor AC performance. Linky:

 

Thanks for the replies.

All 4 for under $65?
Would you buy them from ebay?? The local auto parts store wanted $65 each - $85 each for Hitachi.

New 4 Pack 07 08 Honda Fit 1 5L L4 Ignition Coil on Plug Coils Pack 30520PWC003 | eBay

 

No, i've read of people buying cheap ebay or amazon coils and they fail even quicker, some within 5k miles! I'd get the Hitachi from rockauto, about 55$ each and they should last much longer, hopefully for the life of the car. I would consider purchasing dielectric grease to use on the boot of the coils.

 

Thanks. I've read up on some of the coil pack threads. Hitachis are on order.

 

I have this problem every now and them, I solve it by spraying throttle body cleaner in the throttle body. I guessing its the cheap gas I use... And the idle air valve that is getting gummed up. idk, but it does solve my problem!

 

I just fixed this exact same problem with 4 new Beck Arnley coil packs from Amazon for $46 apiece. I read through a bunch of threads on here regarding this issue and the Beck Arnley seem universally acceptable as OEM replacements but for half the cost.

 

Beck-Arnley brand used to have great reputation