Hello everybody I'm new to this site and I need some major help. I have a 06 h3 with 115000 on it and the service engine soon light has come on and it scanned misfire #5. So I changed plugs cleaned throttle body cleaned mas and it didn't go away. So I changed coil pack on #5 still didn't help. I did a compression test and it ranged from 190 to 150. #5 is the lowest. Could this be my problem? Thanks

 

Is the engine missing or running rough?

 

With that many miles I would guess possibly faulty injector or wires to cyc. #5 on fritz. If the difference was large in compression I'd lean toward that 1st. Also is the C.O.P. locked down tight and did you use a lil silicone in the plug boot? Ya know carbon build up in the boot could also be to blame.



Chris

 

The engine runs a little rough at idle. I replaced boots and used the silicone and everything is tight. Not sure what to do next





Dingeray

 

You can do a noid test on the injectors. Conversely you could just sawp in a new injector on 5 and test that way. But with everything apart I'd just do em all.

Have you cleaned MAF and TB?
Chris

 

Thanks for all of your help! I cleaned mas and tb no change. I Will get the injectors checked and let you know. Thanks again for your help!!




Dingeray

 

Whats the diagnosis?

Chris

 

Had this happen on my '07H3 recently, (72,500 miles) only when @idle, for a few minutes or longer. Never misfired off idle! I had already replaced the sparkplugs, insulators, & coils, within the last 2k miles (got a great deal on ACDelco parts).
I did a decarb and injector clean, and misfire @idle is gone. I used seafoam and lucas, great stuff.... 2500 miles since I purchased it and I only use premium fuel, however, I have no idea what kind of fuel the previous owner used?

 

I had that issue with similar mileage on my 06, but it was a faulty coil.

 

Had the same issue. Cleaned the TB and MAF and light went away. Did you take the TB completely off to clean it? Or did you just clean it while it was still on the motor?