Anyone for a puzzle
 

Used to have an 05 dakota. 2 years ago timing belt broke and it never ran right again. Finally sold at and bought an 06 Mitsubishi Raider. I assume most of you know that the raider is a dakota with a few body modifications.
Recently i started getting what seems like a misfire. My obd showed a random misfire P0300.
It occurs mostly on cold startup. runs very rough especially after high idle drops.
After about a minute when I give the gas pedal a kick it seems to smooth out. It has a lot of pickup after it smooths out an only occasionally at a stop light it will run rough.
On rare occasions especially in the winter it might stall at a stop light.
I have noticed that i can make it break down around 4000 rpm in park, Normal?
Changed plugs with OE champion copper plugs no change in symptoms
Dealers fancy computer says random misfire on cyl 2,4,6,8.
Checked for vacuum leaks, none found.


Performed a compression test all cyl are 175 plus or minus 1 or 2.
Compression on all cylinders on that bank show 175
Check fuel pressure on the rail, steady around 50
A few months ago the 2 high o2 sensors were changed. I dont recall it that was before or after the misfiring started.
Battery test is good.Fuel injector additive added today .not much confidence it will help due to only 1 bank
Important to note that there are no other codes other than the p0300.
Sensors like egr, temp, MAP, all seem like they would effect whole engine not just 1 bank.

Dealer still has my truck and the bill mounts!! They are as baffled as I am.

ANY suggestions?


UPDATE: Before I pulled the heads, I decided to have the ECU checked out, cheaper option! Sent an email to G7 computers in New york.. Asked if a faulty ECU would cause random misfires on one bank. They said yes so I pulled the ECU and sent it to them. They got it and found a software error. reloaded the software and sent it back to me the day after they received it. Paper work included did not definitively say the fix would resolve my problem. I texted with them and they said it would resolve my issue. I reinstalled the ECU and hallelujah my baby runs great, For the first time in the last several years, I am getting 16MPG.

Not all great news though. Now im getting a p1129 error. Im guessing its an o2 sensor problem... Both high sensors were replaced with mopars. Tech damaged one when he put it in. unfortunately he was killed a few days later in a motorcycle accident. I brought to an RMV approved garage and he replaced the damaged one with a bosch. Apparently a lot of folks think Bosch sensors are not reliable in the 4.7..Further, it seems both sensors should be by the same manufacturer. I am going to order another Mopar and ill post another update.

BTW I would highly recommend G7 computers. The were extremely helpful, fast and responded very quickly by text or email.

What brand O2 sensors were installed? Does it run any better if you disconnect the front O2 sensors?

Mopar, New and in packages

Moved to the correct section.

2005 4.7L V8 does not have a timing belt for one....how is the battery on the Raider? Weak batteries wreak havoc on these trucks....

What about the spark system? Coil packs? Distributor? Wires? Just trying to get more information about your situation to help you?

Thanks for the idea but
Battery test is excellent

Thanks for the reply. All have been repalced/checked..

Sounds like everything has been done but an ECM swap.

thanks
 

I am thinking ecm also. Dealer says no? Says it would not effect only one bank? I question that logic. Anyone else think its a possibility?

I question it too. Although I have met some very highly trained and qualified dealership mechanics they are far and in between. I have fixed things on my vehicles that the dealership said it wasn't and it was and it fixed it. Go with your gut feelings!