HIGHWAY MODE QUESTION
10-05-2010, 09:03 PM
#1
Junior Member
Thread Starter
Join Date: Oct 2010
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
HIGHWAY MODE QUESTION
Just joined the forum, and have found a huge amount of helpful info. I have a 1979 El Camino that I have converted over to TPI using an aftermarket unit from Affordable Fuel Injection. It is based on a 1990 SD system and uses the same ECM and MemCal. I have been burning my own chips for the past month or so and have the car pretty well tuned. My BLMs all average between 125-131. My car has no VSS (T5 tranny and mech speedo). I was wondering if I can still invoke HM without a VSS. If so, what changes do I need to make on my chip to get it to work? Thanks in advance for any help!
10-06-2010, 12:29 AM
#2
Supreme Member
iTrader: (1)
Join Date: May 2004
Location: houston
Posts: 2,262
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
Re: HIGHWAY MODE QUESTION
welcome to the best DYI chip tuning fourm there is.
the ECM will stay in cell 4 without a speed input and you won't see the full benefit with what you have. also without good speed input you'll have no hiway mode, no canister purge, and no EGR.
surging or dying when coming to a stop can be a problem too.
there are a few ways you can get a speed input to the ECM.
with using a speedometer cable, an in-line speed sensor will work just fine.
jags that run is one source for an in-line sensor, and there are some others sources too.
once you get a speed sensor, you can tune the ECM to use the signal the sensor outputs.
the ECM will stay in cell 4 without a speed input and you won't see the full benefit with what you have. also without good speed input you'll have no hiway mode, no canister purge, and no EGR.
surging or dying when coming to a stop can be a problem too.
there are a few ways you can get a speed input to the ECM.
with using a speedometer cable, an in-line speed sensor will work just fine.
jags that run is one source for an in-line sensor, and there are some others sources too.
once you get a speed sensor, you can tune the ECM to use the signal the sensor outputs.
10-06-2010, 08:55 AM
#3
Junior Member
Thread Starter
Join Date: Oct 2010
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
Re: HIGHWAY MODE QUESTION
Thanks for the reply. My car has no EGR or other pollution controls. My wiring harness was custom built by Affordable Fuel Injection and has no inputs for EGR or VSS. The car runs great with no surging or dying so far. If I were to get an inline VSS, how would I hook it up so that the ECM can get inputs from it? Thanks again!
10-07-2010, 12:04 AM
#4
Supreme Member
iTrader: (1)
Join Date: May 2004
Location: houston
Posts: 2,262
Likes: 0
Received 0 Likes
on
0 Posts
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
Re: HIGHWAY MODE QUESTION
if the harness doesn't have the wiring for a VSS, you can add the wires pretty easy.
a couple of terminals to go into the ECM connector and enough quality wire to go from the ECM to the VSS and back.
twisting the 2 VSS wires together helps with RF interference.
depending on which speed sensor you get, you can make a couple of changes in the bin so the ECM can understand the speed input signal.
magnetic or non-magnetic is just checking or unchecking a box. IIRC, depending on which sensor you use, one of the inputs to the ECM goes on different terminals. its been a while since i've messed with the speed input on my car, so i forget.
pulses per mile is a little harder, drive it and see if the ECM speed closely matches the speedometer. if not then change the the PPM setting up or down and check it again.
it doesn't have to be exact just close.
a couple of terminals to go into the ECM connector and enough quality wire to go from the ECM to the VSS and back.
twisting the 2 VSS wires together helps with RF interference.
depending on which speed sensor you get, you can make a couple of changes in the bin so the ECM can understand the speed input signal.
magnetic or non-magnetic is just checking or unchecking a box. IIRC, depending on which sensor you use, one of the inputs to the ECM goes on different terminals. its been a while since i've messed with the speed input on my car, so i forget.
pulses per mile is a little harder, drive it and see if the ECM speed closely matches the speedometer. if not then change the the PPM setting up or down and check it again.
it doesn't have to be exact just close.
Thread
Thread Starter
Forum
Replies
Last Post
