Has anybody looked at their 78mm to see if it opens any more than the LS2 TB?
Played around with both today and this is what I saw. I also logged PIDs for the APP sensors and TP sensors. The logged values did not reflect the described operation of the sensors as per the service manual. So I believe that all of the interpretation of sensor inputs is done in the TAC module.

http://media.putfile.com/78mm-vs-90mm-Throttle-Body

 

Nice! I like the comparisons all in one video. Thats funny how the stock 78 ready 100% but doesn't really open full horizontal.

I agree with you on the TAC. If its truly programmed to look for a certain voltage range that is not the same as the LS2 TB, then thats probably where the answer lies. What I'd like to see now is someone with an electric throttle body from a 02 vehicle do some logging and list their sensor voltages at various levels. Has anyone with an 02 vehicle with electric TB done the 90mm swap? Do they see the same results?

 

and looking at that, the 78 does not open anymore than the 90 @ WOT. Kinda makes the theroy of not getting 100% TPS go out the window!

The one thing we will never understand is the explenation of what the OE calls 100%. To me the 90mm TB is still a good mod that works VERY well.

 

BLOWN364 did an 02 Denali 90mm conversion and it opened 100%

 

I would like to see a picture of what he called 100%......I think the mystery has been solved IMO, the stock 78mm was open approx the same in the video and the 90mm at the 100% TPS reference.

 

Nice vid

Your LS2 throttle body makes the same noise as mine does

The 1st third of my throttle response just isn't there. I'm wondering if guys with 04-05 trucks are having the same issue as their foot pedals are different part numbers than the 02-03 model I have in my truck. I will log some APP versus TPS and see where I'm at probably Wednesday or Thursday.

Grippy, can you post up those 02-03 foot pedal resistances I gave you? Anybody with an 04-05 truck could you post up your resistances too?

Bill

 

have you changed this information?

 

Below are the foot peddle resistances I measured for the 02-03 Foot Pedal I purchased this morning… attached is the TAC circuit that includes pinouts for the 3 APP (Accelerator Pedal Position) circuits in this particular foot pedal. If you can obtain the same APP circuit schematic (either through DrX, Grumpy4.8, or your source) for your foot pedal then measure the resistances this will tell you, well all of us, that the 02-03 foot pedal is indeed different than the 04-05 foot pedal. The reason why I suggest obtaining the schematic is to confirm whether or not your foot pedal is “wired” the same as the 02-03. I checked my 06 (2) APP circuits and they measure open across the pins… tells me power is required to complete the circuit… I would have to rig something up with a power supply and measure voltage drops with a known current in order to calculate resistance. Too much damn work for something I know is not working anyway J





Idle = foot pedal in idle position

WOT = foot pedal fully depressed



APP 1 (pins E & F) Idle = 2.680 kOhms , WOT = 4.52 kOhms

APP 2 (pins B & C) Idle = 3.382 kOhms , WOT = 1.506 kOhms

APP 3 (pins A & K) Idle = 5.98 kOhms, WOT = 4.05 kOhms



For the record… this is the pedal part and year info I obtained from my parts guy… more/less info for GENIII apps in ½ and ¾ ton… other applications may apply…



02-03 foot pedal – 15177923 – 02-03 Gas only, 04-05 Diesel only

04-05 foot pedal – 15120405 – 04-05 Gas only

06 foot pedal – 15107594 – 06 Gas only

 

Blown Chevy, I haven't changed anything since the 90mm TB install. I'll do some logging, make the change, do some more logging, and report back hopefully no later than Thursday.

Thanks for the help

Thanks for posting up the info grippy

Bill

 

My UMIracing throttle body has always opened 100 percent.