part throttle stumble
Thread Starter
Teching In
Joined: Mar 2010
Posts: 12
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part throttle stumble I recently installed a 5.3(L33) with 5.7(LS6) accessories, intake, headers with computer and harness from LS1. When I first start it, it will run fine with good throttle response. The problem is when it gets up to temp. it will still idle fine, but at a steady part throttle, it stumbles, and comes back, like galloping. fuel pressure at rail is steady at 60 psi, I've checked for vacuum leaks by spraying carb cleaner around every thing with no results. I also have a wideband o2 sensor and gauge that is telling me that it is running really lean at idle like 15.5-16 afr, maybe higher, only reads to 16. No codes are being set either. So my guess is that i need to get the computer retuned because of difference in displacement? Sorry i dont have any data logs because the geniuses at painless sent me the wrong software
I have searched this, but haven't come up with same situation. Any ideas/opinions?
I have searched this, but haven't come up with same situation. Any ideas/opinions? 
Thread Starter
Teching In
Joined: Mar 2010
Posts: 12
Likes: 0
OK so I unplugged the wideband, and the problem went away, plug it back in and it does it again. So is it safe to say that the o2 sensor is bad? It only has about an hour of run time on it in the garage. So with this unplugged does it mean that it is running in openloop? If so, is this a bad idea? Well, either way Im sure that I need to get a tune. Oh btw, when I plug the sensor back in, the wb is reading in the upper 14s but soon maxes out the gauge and does its stumble thing again.
Yes, when the O2 is not plugged in, it runs strictly off the computer program. When the sensor is plugged in, it makes adjustments iaw the O2 sensor to try to keep the afr at stoich. So, it makes me wonder if the sensor is bad, or not calibrated. Or if the program is not recognizing the wideband properly. ......interesting.
