I changed sparkplugs in my 07; H3 yesterday. When completed, I cranked engine and it was missing badly at first and after it ran a few minutes it cleared up a little. As a precaution I removed all 5 coils and made sure all plugs were properly tightened. Replaced coils and cranked with same results.I slowly increased rpms and miss cleared up around 1500 rpm. I reved engine several times and check engine light came on. Code shows random misfire on #2 cylinder. Any suggestions to correct this problem?

 

You have to make sure that the coil pack is correctly and completely on the plug before you tighten the coil pack retaining bolt. Check the wiring to coil pack #2 for, make sure it is properly connected and shows no signs of cracks or missing insulation.

If it still persists, swap coil pack #2 with #1, see if the miss follows the coil pack. If it does, get a new coil pack.

What spark plugs did you put in? Stick with the OEM AC Delcos, aftermarket plugs are never a good idea for the I5s.

 

thanks, I will give this a try

 

I replaced all 5 coil packs and engine is still missing. new codes: 300 random misfire. 302, # 2 cylinder misfire. 102 MAF circuit low output. 352, coil b primary/secondary. I had no problems what so ever until I changed plugs. Any other suggestions??

 

What plugs did you put in?

 

And.... did you gap them???

Clean the connector to the MAF with CRC electrical contact cleaner, that has to be snapped on fully and have a good constant contact.

 

AC Delco 41-103. Gap .43

 

AC Delco 41-103. Gap .43 the only issue remaining is code 352. I will get contact cleaner and do as suggested. All help greatly appreciated.

 

OK on the plugs.

Your P0352 and P0302 are telling us that you have an intermittent fault in the wiring to your coil #2. There is a primary circuit (battery) and secondary circuit (PCM coil fire control and monitor) which is grounded by the PCM every time the coil needs to fire.

Most likely caused by, like I said before, a wiring problem to the coil. This could be a harness short, an incomplete connection (the connector is not fully snapped in or its connector/lock is broke), dirty connectior to the coil, or a PCM fault. The PCM fault is least likely, and something you did not disturb when changing plugs.

 

thats .043 huh?!