Today I just dyno tuned another couple of very hot F7s from MA/ NH. One
had too much HP, 93 lb/hr fuel flow (compared to 110-115 expected at
this temp here). The other has almost as too much HP, 96 lb/hr. I will
try to post some of these hotrods this weekend.
I have purchased an Arctic Cat TPS tester, and it appears that after
using the Cat tester there is something wrong with the TPS’ on these
sleds (and the one we tested Wednesday).
Regardles of what the Cat manual suggests, normal TPS’ idle at @ 2.8vdc and at WOT are 0 vdc.
The last three gonzo hotrod stock F7s appear to idle at correct
voltage, but at WOT they are MORE THAN 0 VDC. I won’t say what voltage
they show, but these anomalies appear to have correct voltage at idle,
1/4,1/2,3/4 but then instead of dropping to zero volts they seem to
hold 3/4 throttle voltage to WOT! This could explain the wicked
lean fuel flow of the hotrod F7s, combined what appears like advanced
iginition timing! I want one of those for myself.
I believe this is a glitch in these particular TPS’, not adjustment!
The last two hotrods (brought here by custom tuner Mike Chudzik
of Gill MA) had apparently perfect TPS voltage from idle to 3/4
but mysteriously that voltage locked there from 3/4 to WOT instead of
dropping to 0! So at WOT the ECU probably thinks the throttle is at
3/4…giving us crisply lean fuel and advanced timing that explains the
148 + HP we recorded on these bone stock sleds!
But remember before you roll back your TPS to similarly fool your ECU–
if you do that , then when you roll back to a true 3/4 throttle after a
long lake blast the ECU wil think you’re at 1/2 and you will
likely be toast. Normal TPSers are way better off with timing keys and
PAC-like restrictors. But if you have one of the strange but too often
recurring hotrods, beware of adding timing or dropping fuel pressure!
SHOOTOUT!!
Committed Trail Mods are coming from Bender, D&D, Crankshop,
Hooper, HTG, DynoPort, Bikeman and hopefull more will drizzle in..
LIVE STREAMING VIDEO!!
The two cameras have arrived, and if my tech support people do their
jobs you wil be able to watch the Dynotech certification live on the
internet Monday, Tuesday, [I’m going for a colonoscopy on wednesday].
We’re planning to have one camera/ sound in the control room, one
camera/ sound in the dyno room so you can watch either or both? Then
the Bikeman is hoping to dyno tune his two F8s live on Thursday AM
before we head up to Old Forge on Thursday for the Shootout on Fri AM.