Cruise, VSS, electronic throttle question
02-19-2008, 06:51 PM
#1
Cruise, VSS, electronic throttle question Looking for an answer on this one, and it seems to have most people I have talked to stumped. I am running a 5.3 w/ electronic throttle in a 79 Jeep. The trans is a Th400 and there is a transfer case as well. The speedometer drive is a cable coming from the back of the transfer case. I want to retain the cruise control. I know I will need a VSS and this is where the question is.
I have found a 20 pulse per rev VSS that will hook onto the speedometer cable. Will this be sufficient for the cruise to work? I think this will put the pulse per mile at about 20K. The trans functions in the PCM will be turned off since I am using a TH400. Is there anything else that needs to be considered in the programming?
Thanks guys!
I have found a 20 pulse per rev VSS that will hook onto the speedometer cable. Will this be sufficient for the cruise to work? I think this will put the pulse per mile at about 20K. The trans functions in the PCM will be turned off since I am using a TH400. Is there anything else that needs to be considered in the programming?
Thanks guys!
02-20-2008, 09:54 PM
#6
Yes, the sensor puts out a sine wave. The only problem I see is this. From my calculations, the driveshaft turns 2.5 times for the speedometer to turn 1 turn (still have to test this). This would mean you'd need to program the ECM for 8 (20/2.5) pulse per rev and divide your calculated pulse per mile by 2.5 as well. Does that make sense? Am I out of my mind?
02-21-2008, 06:33 AM
#7
The programming will be for driveshaft revolutions. The T400 is direct drive in third, so I don't understand what you are talking about on the 2.5 turns. You will need to program for a 20 ppr vss. What is the p/n of the vss? I am making some changes to my setup and will need a different one.
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02-21-2008, 05:54 PM
#8
The programming will be for driveshaft revolutions. The T400 is direct drive in third, so I don't understand what you are talking about on the 2.5 turns. You will need to program for a 20 ppr vss. What is the p/n of the vss? I am making some changes to my setup and will need a different one.
Here's my math:
The driveshaft turns 2.5 times for the speedometer cable to turn 1 time. So, if the sensor is mounted on the cable, it is really turning 2.5 times slower than the drive shaft. So, 20 is really 8. Pulses per mile would be the same thing.
02-22-2008, 09:32 PM
#9
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You two are making my head hurt! See if this helps...http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf
02-23-2008, 03:58 AM
#10
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I am using the same combo (5.3/th400). On mine I ordered the pass through pulse generator from summit. It allows you to keep your cable driven speedo and have vss. I didnt need the cable driven part so it is blocked off on mine. To correct the ppm I also ordered a speedometer reccalibrater from dakota digital. It has multiply outputs so it should have what you need to run cruise. On mine the toyota gauge and cruise require differnet ppm's so it made it easy for me but if you are using a cable driven speedo you wouldnt have that problem.
02-23-2008, 10:02 AM
#12
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Did you ever think of mounting a 40 tooth gear of some sort on the output shaft of the transmission/transfer case. I know that the Dodge 2.2/2.5 (
) upper timing belt gears are 40 teeth and could be rigged up in some fashion to work on a driveshaft yoke. Cheap and effective, you could trim some of the gear away 'cause all of it is not needed for the sensor to read on !
Mike
) upper timing belt gears are 40 teeth and could be rigged up in some fashion to work on a driveshaft yoke. Cheap and effective, you could trim some of the gear away 'cause all of it is not needed for the sensor to read on !Mike
02-23-2008, 04:59 PM
#14
Did you ever think of mounting a 40 tooth gear of some sort on the output shaft of the transmission/transfer case. I know that the Dodge 2.2/2.5 ( ) upper timing belt gears are 40 teeth and could be rigged up in some fashion to work on a driveshaft yoke. Cheap and effective, you could trim some of the gear away 'cause all of it is not needed for the sensor to read on !
Mike
) upper timing belt gears are 40 teeth and could be rigged up in some fashion to work on a driveshaft yoke. Cheap and effective, you could trim some of the gear away 'cause all of it is not needed for the sensor to read on !Mike
I bet it would turn out something like this:
I call that a 40 ppr reluctor ring!
02-23-2008, 06:00 PM
#15
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