Wierd LTFT readings after car sat for 2 months
03-16-2011, 05:14 PM
#1
Wierd LTFT readings after car sat for 2 months My car sat for 2 months while I redid the entire suspension and brake system. I finally finished yesterday and drove it around the block. It ran ok (it's never ran GREAT) for the first 5 minutes or so, but after that it started surging at all RPMs while driving. I figured it might be bad gas since it sat, so I filled it up and still got the same thing. The weird part is that it doesn't do it until about 2-3 minutes after the car is started, every time. Maybe a closed loop issue?
So I plug in the ole Predator to look at my O2 readings, and my Bank 1 LTFT is 25% and Bank 2 is -15%. This is idle-3000 rpm. After a while, Bank 2 settled down a bit but Bank 1 was still high. Also, the mV on Bank 1 was only changing from 085-105, but Bank 2 seemed to be cycling normally from 210-810.
So my question is, do bad O2 sensors actually cause erratic LTFT readings, or do the sensors just read them and not affect them? Any other ideas of what the issue could be here?
Mods are H/C/I LS6, LS6 MAF, 42/lb injectors, tuned w/ HPT about 5 years ago, haven't touched the tune since.
So I plug in the ole Predator to look at my O2 readings, and my Bank 1 LTFT is 25% and Bank 2 is -15%. This is idle-3000 rpm. After a while, Bank 2 settled down a bit but Bank 1 was still high. Also, the mV on Bank 1 was only changing from 085-105, but Bank 2 seemed to be cycling normally from 210-810.
So my question is, do bad O2 sensors actually cause erratic LTFT readings, or do the sensors just read them and not affect them? Any other ideas of what the issue could be here?
Mods are H/C/I LS6, LS6 MAF, 42/lb injectors, tuned w/ HPT about 5 years ago, haven't touched the tune since.
03-18-2011, 02:51 PM
#3
I am probably not the person to ask because I am new to this, but I know of a couple of guys who did swaps, and one of them wired an O2 wrong. His LTFT's were way off and it did not run right. Once he got it fixed, cleared and was all good. My guess is it's just a bad O2, but I don't KNOW $h1t yet on these.
03-18-2011, 10:28 PM
#5
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yes they will affect ltft's they i believe are the main factor in determining ltft's. i would say its just a bad o2, after sitting for that long its probably just corrosion or sumthing in the o2, how long did you drive it for? could get better with a little more driving time. i would try replacing that o2 if it doesnt, ive seen o2 really affect afr's and fuel trims. IMO get a new o2 and it should be fixed, anyone else agree?
