Braking: where is that big motor?

[Tom Friend]

We all gripe about the lack of brakes, and many spend money (in varying degrees) to fix the problem. I would contend that part of the problem stems from the ECU itself. When I get off the throttle, I expect the engine to provide some braking, yet that doesn't happen for at 2-3 seconds. Almost as if there is something keeping the throttle plates from closing completely.

I haven't seen this little engine braking since I raced rotaries. With those beer keg motors, you had to rely 97% on the brakes, as there was almost no braking provided by the motor. My GTS feels almost that bad, but the throttle plate closure is so unpredictable that I must use clutch & brakes 100% of the time.

Is this normal? Does the Mopar "performance" ECU do the same thing?

 

[JonB]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Tom Friend:
When I get off the throttle, I expect the engine to provide some braking, yet that doesn't happen for at 2-3 seconds. .....Is this normal? Does the Mopar "performance" ECU do the same thing? <HR></BLOCKQUOTE>

Your ECU is indeed "doing the Two-Step." NORMAL.

As you may recall, I picked up the first retail-delivered GTS. A few days later I was on the racetrack at PIR, and when I lifted going into (then 7, now 10) I was surprised at the idle-lag. Scary ! When I lift, I want LIFT!

I called Team Viper via Ron Smith from the pits, and was told: NORMAL ! 'We programed the ECU to ask the ISM to drop to idle in 2 steps, to avoid backfiring and minimize off-throttle driveline clunk.' The ISM has 25 or so "steps" and the first drop is to "step 7" or some such, and the final drop 2.5 sec later is to idle. That 2.5 sec is a LONG time when you are entering a corner at speed! While they kindly took the complaint under advisement, nothing changed. A T.V. engineer was flown to PIR the following week to examine some other minor GTS "birthing" bugs, and we also examined that idle program. It could not be changed at that time. I have learned to live with it, but not like it.

I am pretty sure the Mopar ECU also has that 2.5 sec lag. We also discussed this at the T.V.Tech Sessions at VOI-4. To no avail.

You asked about on-motor braking: With an aluminum flywheel, less rotating mass gives you faster deceleration as well as acceleration

 

[Tom Friend]

That rots.
Hey Sean- how about a fix for this in the VEC-2?