For some reason my H3 has a misfire at idle, but only sometimes. One minute it will be idling fine and then another it will be a bumpy idle, then the next minute it was be misfiring bad and the check engine light will be flashing. I have attached a long of it being real bumpy at idle. I also noticed that the fuel trims are way off. The tune in this is totally stock, I haven't messed with it a bit.
Any ideas?
Could you attach your config too please? Also, year and 3.5 or 3.7?
Last edited by HawkZ28; 02-27-2010 at 12:34 PM.
Hawk
Sorry about that, I was in a hurry when I posted this up.
This is a 2006 with a 3.5L motor. Here is the .cfg file I used, it is just the same stuff I used for my Corvette I had though. I also managed to log it while the check engine light was flashing and the code for cylinder 2 misfire came up again. It is cylinder 2 every time. I replaced the cylinder 2 coil, but it did not help.
Did you also replace the boot and use some dielectric grease? When was the last time you replaced the plugs? What brand did you use? Also, have you completely removed the TB and cleaned it lately?
Is this a forced induction app? Your AFR looks awfully rich for NA, and your TPS is awfully high for an I5, especially idleing at 550-650.
Mine will do something similar sometimes at the first start up after loading a tune, and then that's it. I still haven't tracked down the cause. Just figured it was a bug of some sort.
If it's an ongoing issue, you may want to do a leakdown test- there was a TSB on the cylinder heads in the 2.8 and 3.5's in regards to valve seats. P0300 was the initial indicator, but typically it was a few cylinders IIRC.
I don't know if it's in this thread, but it was extended each year to include 06, 07, etc...
http://coloradofans.com/forums/viewt...hlight=misfire
Hawk
I did replaced the boot and used dielectric grease. I replaced all of the plugs while I was in there using NGK plugs. The afr is just reading that from where I had it set up on my Corvette, it is not even hooked up on this vehicle. The motor is completely stock. I was reading online about a lot of problems with a clogged injector. I put some fuel injector cleaner in it for now, hoping for the best, even though I highly doubt it will help even if it is a clogged injector. As soon as I get a chance I am going to take out the injectors and get them flow tested and cleaned and do a compression check.Originally Posted by HawkZ28
If the FI cleaner doesn't work, try just replacing that plug w/ either a Delco or Denso Iridium and see what happens.
I looked for the thread and couldn't find it, but there was one where a couple of us were comparing notes in regards to misfires on here. It seems pretty common in the I5 for no apparent reason (as well as KR in weird places).
Hawk
Here it is....
http://www.hptuners.com/forum/showth...hlight=misfire
Hawk
you do realize that the 3.5's have huge issues with the heads and the misfires are the first sign of the head going bad.
Covered in post #4
Hawk
i didn't scroll far enough
carry on batman!
LMAO! I'm captain of that ship most days....fingers faster than the eyes and scolling.
Reminds me of how I answer the phone when an old buddy from high school calls....Gotham City, Batman speaking, how may I assist you in crime fighting this evening.....
Hawk
This link may help...
http://www.hummerxclub.com/forum/vie...p?f=25&t=11414
Good Luck!
Yes. That is possible. See the link in post 7.
Hawk
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