67C10BUB

I put an 08 5.3L and a 4L60E in my 67 C10 pickup. It runs great except for one annoying issue. Sometimes at a constant light throttle the RPM will raise and lower over and over by about 300 RPM and give a bank 1 and 2 lean code (P0171 and P0174). If I let off or get on the throttle the surging stops and it drives normally. I took a freeze frame of when the issue occurs and got the following:
Fuel sys 1 CL
Fuel sys 2 CL
Calc load 74.5%
ECT 92 deg C
STFT B1 1.6%
LTFT B1 29.7%
STFT B2 1.6%
LTFT B2 29.7%
MAP 78 KPA
RPM 1924
Speed 54 Km/H
IAT 45 deg C
MAF 55.39 g/s
TPS 40%
Run time 443 sec
Command Evap 100%
Warm up DTC clear 9
Dist 115 km
CAT1 420 deg C
CAT2 420 deg C
ECU volts 12.6
Load value 54%
EQ ratio .999
Rel TPS 25.5%
Ambient 28 deg C
TPS B 39.6
ACC pedal D 34.5%
ACC pedal E 17.3%
Command TAC 37.3%
Evap up 1875 Pa

Any help would be greatly appreciated. John from Speartech thinks that it may be that I have an E85 tune on a non-E85 engine. Is this a possible reason for this issue?

deuce4935

iTrader: (2)

You probably should copy and paste this in the pcm tuning section, you'll get better help there.

pearceleather

misfire codes?

67C10BUB

Nope, the lean codes are the only ones I am getting.

67C10BUB

I'll try that, thanks.

67C10BUB

Anyone else have any ideas?

67C10BUB

Nobody has any insight into my issue?

busta9876

iTrader: (3)

Your long term fuel trims are maxed out. if its programmed for E85 injectors, and you DO NOT HAVE E85 injectors, the pulse width will be much smaller, causing computer to have to ADD to the pulse width to get correct air/fuel ratio. This might be why you have 29.7% correction on long term fuel trims. This could defiantly cause a drive ability issue.

Or you could have low fuel pressure.
Or the mass airflow sensor could be incorrect for application (as far as how ecm is programmed)

67C10BUB

Thanks so much for your help. I guess I will send my ECM back to Speartech and have him change it. This just seemed like such an odd way to "feel" this issue, since it drives perfectly other than this issue.

busta9876

iTrader: (3)

what is the injector part# that is on your engine? 8 digit part# on the side of each injector. This info will tell you what injectors you have, then have Speartech tell you what its programmed for, this can at least confirm if you have the correct injectors programmed.

12580681 non flex fuel 07-08
12594512 flex fuel 5.3L

67C10BUB

busta, thanks so so much for posting. I have the non-flex part number, so I will definitely be sending my ECM back in to be reprogrammed. I will also give John at Speartech these part numbers, since he said that he was unaware of a way to tell which motor I have. Maybe this could help someone else in the future.

ModMuscle

was there a fix for this? Any outcome?