frankmarroquin

iTrader: (31)

My truck is a 03 Silverado with a 4.8... It is pretty much stock except for a 4500 PI Converter and Borla XR1 I recently added. By the way it does still have the CATS and stock manifolds. It drove perfectly fine after the in stalls but then i noticed my CEL on after while but it wasnt blinking. The problem there was that I had forgot to re connect B2S1 Oxygen Sensor. OK after a day or two I finally reconnected the sensor cause it had finally dried up outside. Right then is when it started driving bad... What I first noticed from the Scanner is that B2S1 Stayed all the way up and LTB2 stays all the way down in the negatives.

I have already replaced the Spark Plugs and the 02 sensor but I was thinking maybe could be the Cats??? Looked perfect when removed and it doesnt give a bad odor as some usually do when they going bad.

Funny thing is if I go to "Closed Loop", "Fuel Trim Learn" and set them to on and switch them to off as well as delete the DTC's my truck drives perfectly fine and everything works as should but as soon as I turn off my truck I need to redo this again. You guys have any ideas? Ill post up the Scan as soon as my truck does it again because its like a kid at the doctor... Get better as soon as you get to the office. My truck misfires then I just connect the MPVI and it starts to work fine.


*Cylinders 2,4,6 & 8 are all mis firing... But if I press "Reset Fuel Trims" it smoothes out. Any ideas guys?

*Update... Weird thing is the driver side CAT is Really Hot but the Pass Side Warm to where I can actually keep my hand on it.

Ryan K

iTrader: (11)

ITs the torque converter... you need to disable misfire detection. The torque conveter weighs less and the computer dosen't know how to calculate for it. Do a seach for converter randomly unlocks.

Ryan K

iTrader: (11)

https://ls1tech.com/forums/pcm-diagn...domly-fix.html

jpracing01

You don't have to totally disable it... U can adjust the values in the missfire tables to "tune" it out

bighaas79

Ryan K, I read the other thread you had posted and I had a question. Will doing just a crankshaft relearn not work with this? As I understand it the pcm should be able to use whatever parameters it sees as a baseline when the relearn is performed, therefore should be able to automatically compensate for the lighter t.c. Is the stock pcm not able to compensate far enuf for this? I've seen a couple that would set a 300 code for the simple reason that they drove it long enuf with an actual miss that after they changed plugs or whatever it took to correct the problem, and did not perform a relearn that the pcm was actually looking for that erratic signature because it had learned it as normal. Is this something you have even tried or does just not work? Just curious casue if this is something that would work would be much simpler to do i would think. Your thoughts?

rpturbo

iTrader: (47)

Why such a big converter on an almost stock truck? Am I missing something?

frankmarroquin

iTrader: (31)

Should be getting a stroker within the month...

jimmyblue

iTrader: (11)

A one-side imbalance is abnormal. But I guess you have
enough randomness to cylinders misfiring that it hits the
300 code and not 0302, 0304, 0306, 0308. Sounds like
there's something messed up on the passenger's side
injectors, maybe one stuck on or drooling. The system is
trying (and failing) to pull it lean. That or there's an
unusual O2 sensor fault that has stuck the sensor high.
Which may be the case since resetting trims improves
things. Maybe somebody chafed the sensor harness while
installing the converter and you got heater shorted to
signal, or something. Usually when that screwup happens
it's short-to-ground just because of greater "opportunity".

frankmarroquin

iTrader: (31)

Sorry I never got back but I just had to tune out the Misfire Detection and it drove perfect.