C409

iTrader: (5)

........ I'm scratching my head on this one ... the car - 87 Vette Tuner Pro $32B - runs best when the fuel pressure is cranked to 65psi ..... the INT will hover around the 122 mark with occasional dips to 118 ... but the BLM pegs at 108 ( as low as it goes ) ........ if I reduce fuel pressure it runs like crap and I get a LOT of lean indicators ....... INT 125-144 and BLMs 120's with Lambda ranging between 1.10 - 1.55 .......... 409ci ... 230-236 cam ... single plane ... 32# Bosch III injectors ..... 2800 stall ......

Ronny

iTrader: (1)

I wonder if you are excessively rich fooling the WB sensor. I have read that can happen. Same on a misfire.

Have you locked OL and then tune with WB ignoring the NB?

C409

iTrader: (5)

........... Spark plugs come out pure white ... almost new looking ... no smell of fumes ... the higher the AFR / Lambda reading the jerkier the ride ... just not smooth at all under 2500rpm EXCEPT when the WB indicates an AFR under 1.00 Lambda .............. I have tuned open loop only but still get some lean cruise and lean light throttle apps - low load light acceleration - that I can't tune out ... vac gauge is reading 16 inches at 900 rpm idle ... MAF shows 11grams/sec at same idle ............ I have tried three different intakes and another set of injectors 30# Fords ... another MAF sensor ... changed fuel lines , pump , filter , plugs , wires , etc and so on ........... also tried different fuel pressure settings and fiddled with the constant ...... tried chips burned off ARAP.bin $6E .... new alternator , battery , relays , O2S NB and WB ...... there are NO exhaust leaks .......... ............

Ronny

iTrader: (1)

And your plugs show lean-OK. I would suspect the deffinition file?

From TC:

The definitions that TunerPro supports are created by TunerPro users around the world. As a result, there are few assurances to the accuracy of definition files that can be found in various places on the web, etc. It should be understood that in some cases you can do harm to your engine if you tune using an inaccurate definition file. I have made every effort to validate the accuracy of the General Motors $6E definition file and only the $6E definition file, as that's what I use to tune my own vehicle. All definitions are to be used at your own risk. Some available XDF files were originally imported from ECU files.

xch3no2

Plugs ain't lying, a lean miss sends unburnt fuel into the exhaust.

C409

iTrader: (5)

......... Yeah ... but its more of a flutter than a miss ... and a miss sends unburned fuel along with unused oxygen ... and I can't seem to force it rich ... with 32lb/hr injectors at 65-70 psi the BLM is 108 and so is the wide band ... Lambda 1.08 ............. at 40-45 psi the BLM is 122 and so is the wide band .............. of course the afr is ranging but the blm is not .............

Ronny

iTrader: (1)

Would not unburt fuel show lean as far a BLM ? He is showing fuel being pulled at 108.

C409

iTrader: (5)

..... I do believe I have this one figured out ... today I ran a separate wire from the heated O2S signal wire to the ECM and now the INT and BLM are agreeing with the wide band ... I did not have a lot of time to test drive this theory due to uncooperative weather ... plus I'll need to re-direct the tune to the corrected 02S signal ....... but preliminary testing indicates that there was a problem with getting accurate sensor info back to the ECM ... I'll need to check the schematics to see where the guilty connection might be .........