E38 tuning without VSS
Thread Starter
Teching In
Joined: Feb 2009
Posts: 48
Likes: 0
From: Western Australia
E38 tuning without VSS Hey guys i posted this on HP tuners forum but havent had any replies in a couple of days so thought id try here,
I read somewhere that if the e38 doesn't receive a VSS it will use the base spark table only. Is this true? I am trying to pinpoint a possible reason for my car not responding too well to tuning on the dyno and being consistently low on power. Possibly tuner is adjusting wrong table?
I have a TH400 without a speed sender in it.
Also, does no VSS have any impact on the throttle not staying wide open throughout the rev range or anything like that?
I read somewhere that if the e38 doesn't receive a VSS it will use the base spark table only. Is this true? I am trying to pinpoint a possible reason for my car not responding too well to tuning on the dyno and being consistently low on power. Possibly tuner is adjusting wrong table?
I have a TH400 without a speed sender in it.
Also, does no VSS have any impact on the throttle not staying wide open throughout the rev range or anything like that?
It seems it's a hit or miss situation.
I have seen some with no Vss and they use the high octane table, but if yours is not you have no other options.
However, hooking a Vss is easy. Dakota Digital sells an adapter for TH350/400 to allow cable speedo along with Vss signal. The transmission tail must have the speedo gears to make the adapter work.
It doesn't matter if the gears aren't correct for the tire/rear gear you're using, as long as the PCM sees the car is moving it will switch to high octane table. In fact, you can adjust it in the tune to make the PCM read the correct speed.
I have seen some with no Vss and they use the high octane table, but if yours is not you have no other options.
However, hooking a Vss is easy. Dakota Digital sells an adapter for TH350/400 to allow cable speedo along with Vss signal. The transmission tail must have the speedo gears to make the adapter work.
It doesn't matter if the gears aren't correct for the tire/rear gear you're using, as long as the PCM sees the car is moving it will switch to high octane table. In fact, you can adjust it in the tune to make the PCM read the correct speed.
I've read a number of times about issues folks had with tuning without VSS. From what I can tell it's not really possible. The ECU uses the VSS signal to help calculate load. I think.
