03 4.8 Heavy missfire on Bank 2 HELP???

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11-26-2009, 06:02 PM
classic_speed_and_customs

03 4.8 Heavy missfire on Bank 2 HELP???

I start my truck and it will run great for a minute or so. Then the whole right bank starts to misfire. Manifold will barely evaporate water. Will ocassionally pick back up around 4000 rpms but die off again instantly. Coils are good and getting power. Changed ECM, MAF, wires, plugs, and checked intake for cracks. Kind of out of ideas. This started when I hit a puddle with the right front tire. Instantly started to miss. Thought I found why when I found my Bank 2 Sensor 1 o2 unplugged but this seemed to have no effect. Any ideas?
11-26-2009, 06:30 PM
mean05

You have catalytic converters still on the truck? If so you may have a clogged verter on that side
11-26-2009, 07:01 PM
classic_speed_and_customs

There are no catalytic converters on the truck.
11-30-2009, 09:42 AM
farmtruc

When you start your truck it's in open loop, o2 sensors not really being used, but then when it warms up (after a minute or so) it goes into closed loop. If the o2 is bad or reading incorrectly, it'll cause lots of trouble, just like you're describing.
Keep it in open loop and see if it helps, if so, it's your o2 sensor.
11-30-2009, 03:58 PM
bangbangskeetskeet

Quote:

Originally Posted by classic_speed_and_customs

I start my truck and it will run great for a minute or so. Then the whole right bank starts to misfire. Manifold will barely evaporate water. Will ocassionally pick back up around 4000 rpms but die off again instantly. Coils are good and getting power. Changed ECM, MAF, wires, plugs, and checked intake for cracks. Kind of out of ideas. This started when I hit a puddle with the right front tire. Instantly started to miss. Thought I found why when I found my Bank 2 Sensor 1 o2 unplugged but this seemed to have no effect. Any ideas?

If the O2 was unplugged when you hit the puddle it could have caused the sensor to read incorrectly thus causing the issues explained by Allen. I think replace the O2's and then check it out. :thumb:
11-30-2009, 04:08 PM
farmtruc

Quote:

Originally Posted by bangbangskeetskeet

If the O2 was unplugged when you hit the puddle it could have caused the sensor to read incorrectly thus causing the issues explained by Allen. I think replace the O2's and then check it out. :thumb:

Don't quote me, lol, but there was a turbo truck we did, it had the same issue, so i unplugged the o2's, I think it put it in open loop all the time, and problem solved, obviously a temp solution, but it fixed it.

might wanna try it, i don't recommend racing with it in open loop though, cause it's not tuned for it, but it'll lead you in the right direction.