Thanks for the additional information ... helps to sort things out ... mentioned your speedometer to not accurate .. this will effect the pulse generator output. Mentioned it was out by "10 MPH" ... looking for a percentage to figure out proper values ... 10 MPH at 60 MPH (ie. shows 60 MPH when the actual vehicle speed is 70 MPH) ? Tire diameter is exactly 38 inches per the manufacturer ?
Will then try and come up with values to improve VSS accuracy.
Regards,
Taz
the speedometer in the truck is 10 mph fast so when im doing 60 according to my speedo im actually doing 50 and the actual tire size is 38 inches tall and 40-14.50-17 is the size written on the sidewall
I attached several tunes below … potential for none of them to be accurate, until you arrive at an accurate displayed speed of the cable driven speedometer.
When properly calibrated (drive & driven gears) the cable speedometer will receive 1000 cable revolutions per mile. Your “pulse generator” is driven off the speedometer cable – designed for 8000 pulses per mile – but only if the cable accurately provides 1000 revolutions per mile. This is equivalent to 8 pulses per revolution, or an 8 tooth VSS pickup.
Displayed speed (or error) is a ratio - if the speedometer reads 10 MPH too fast at 50 MPH, it will read 20 MPH too fast at 100 MPH. For your speedometer to read 10 MPH too fast at all speeds, as you described, is unusual. If true, then there is a problem within the speedometer itself in the gauge cluster.
The next issue is that the software won’t accept 8 pulses per revolution (H0102) - 10 pulses appear to be the minimum acceptable value. While maintaining a tire diameter of 38 inches, this meant adjusting the gear ratio to 4.11 to correspond to 10 pulses per revolution (same output as 5.13 gears with 8 pulses per revolution). “Fudging” this data should provide the PCM with an accurate VSS input - but you can no longer use the speedo calculator function to appropriately adjust the transmission shift points - have to calculate these values externally and import them.
Took a quick look at your tune - “spikes and holes” in your Main VE Table (B0101) and in your MAF Sensor Calibration (B5001) - these would benefit from further tuning.
The tunes below:
2002 Camaro OS - VSS & shift speeds reset.tun
- this is the tune you posted (truck 3)
- modified VSS parameters (to work with cable driven 8K pulse generator)
- modified shift speeds from a base Camaro tune - to work with 5.13 gears and 38 inch diameter tires
2002 Silverado OS - VSS & shift speeds reset - Z06 VE.tun
- this was a stock tune
- modified VSS parameters (to work with cable driven 8K pulse generator)
- modified shift speeds from a base Camaro tune - to work with 5.13 gears and 38 inch diameter tires
- added a 2002 Z06 VE table - definitely not a perfect match for your camshaft – but closer than the stock table
Stock - 2002 Silverado 1500 LM7 5.3 L 4L60E 4 x 4.tun
In the end none of these may work right for you … hopefully one will, or hopefully this assists you in finding a solution.
- stock tune - as a reference
Regards,
Taz
ok i didnt get a chance to try it till late last night, it is still getting a slow signal whereas its only reading maybe 5 mph when the truck is going about 20 mph. it also runs whole lot better but its still stalling out. i wonder if there is a diferent setup i should try maybe a diferent pulse generator? im not sure though and thanks again
Sorry to hear VSS speed is still way off ... looks like a magnitude of 4 ... had to set it to 10 pulses ... any possibility that your pulse generator is a 40K setup ?? May want to double check with the manufacturer regarding the exact number of pulses per speedometer cable revolution. If it ends up being a number different than 8 pulses per revolution, or 8K per mile (1000 cable revolutions) ... let me know and I can adjust the settings.
You mentioned it ran "better" - what tune did you end up using ??
Once you get an accurate VSS speed, the idle should improve - then you could move on to tuning the idle.
Regards,
Taz
EDIT: applied the math in reverse - if VSS speed was 4 times too fast then 40K generator. Given VSS speed is 4 times too slow, perhaps 2K or 4K generator.
Last edited by Taz; October 26th, 2010 at 10:41 AM. Reason: - bad math !
ill give them a call just to double check to make sure and i ended up using the tune with the z06 ve table.
ok i talked to them and they said that it was defenitly 8k pulse generator
Give this tune a try ... the solution may have been in logic, not tuning ...
Regards,
Taz
ok ive been working on it all day i have the speedometer in the truck within 2 mph of the actual speed and i had to put the h0104 to 1000 and now its shifting but it is showing a very low speed signal for example at 50 mph the computer is showing around 25 mph. its shifting but its not quite right. its also still stalling out while coming to a stop unless you keep on the throttle, but seems to do it with which ever tune i try im wondering if its something wrong with the truck ive checked for vacuum leeks and didnt find anything. does a 4.8 have the same injectors as a 5.3? what books anyone recommend for a beginner? thanks for all the help
ok ill that one a try tomorrow thanks taz
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