Dragstrip WB logs
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Joined: Apr 2003
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From: Oz
Dragstrip WB logs
Does anyone have a WB datalog showing their auto trans car going WOT thru a gear change or 2??
I have a new WB and I used it at the strip for the first time last night and think I have uncovered a problem with my tune...
It was rich anyway (11.8-12.2's), but on the gearshifts, it goes 13+ AFR for 1.4secs before recovering.. I know from tuning on the dyno that it loses 25-30hp at AFR's above 13..
This doesn't seem right to me and i'd like to compare to some others..
Thanks.
I have a new WB and I used it at the strip for the first time last night and think I have uncovered a problem with my tune...
It was rich anyway (11.8-12.2's), but on the gearshifts, it goes 13+ AFR for 1.4secs before recovering.. I know from tuning on the dyno that it loses 25-30hp at AFR's above 13..
This doesn't seem right to me and i'd like to compare to some others..
Thanks.
Drifting
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From: Holliston MA
Cruise-In VII Veteran
That's too big of a spike, I don't have any logs to show you, but the engine sees a large load when the transmission engages a gear. That's also usually around peak torque where the engine likes fuel. That's one of those places that isn't very easy to tune on a chassis dyno.
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From: Oz
I did some work on it yesterday and managed to flatten it out quite a bit by playing with the higher rpm VE table (SD). Still not perfect, but getting better..
I was hoping to see how a well tuned car's WB AFR looks on the shifts between gears, this would give me a benchmark standard to aim for..
Someone here must have a WB log they can post, pleeeeeze?
I was hoping to see how a well tuned car's WB AFR looks on the shifts between gears, this would give me a benchmark standard to aim for..
Someone here must have a WB log they can post, pleeeeeze?
Last edited by ben73; Aug 23, 2004 at 08:28 PM. Reason: spelling/addition
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From: Rolling Meadows IL
I have a 4+3 so when I shift I lift off the throttle. I don’t power shift. When I lift it goes real lean until I get back on the gas and the TPS is over %69 percent. At 64 samples / second the lean peak is very visible. Once the TPS hits %69 the A/F goes back to 12.5-13. I wonder if the ECM is cutting back the power when it shifts the auto.
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From: Oz
Thanks Dave.
I would expect that a 4 speed would go lean when you back off for the shift. I suppose the difference is that you then have a bit of TPS AE to help you get back into the 12-13:1 zone pretty quickly..
I have tried modifying my VE tables so the peak is at the RPM's that the engine sees when it hits 2nd and 3rd, but it hasn't really changed a lot. I was hoping that this would add fuel as the rpms fall from ~6000 to the VE peak at ~4000.. Nope. ;-(
As far as I can see, the only thing that could trigger it to pull out fuel is the rapid fall in rpm's between the gears.. The TPS stays the same, as does the MAP.. I'm working thru the hack to see if I can locate anything that may be pulling the fuel out based on rapid rpm drop....
I'd really like to see what some other cars do?? This may even be very common and I am wasting my time?????
I would expect that a 4 speed would go lean when you back off for the shift. I suppose the difference is that you then have a bit of TPS AE to help you get back into the 12-13:1 zone pretty quickly..
I have tried modifying my VE tables so the peak is at the RPM's that the engine sees when it hits 2nd and 3rd, but it hasn't really changed a lot. I was hoping that this would add fuel as the rpms fall from ~6000 to the VE peak at ~4000.. Nope. ;-(
As far as I can see, the only thing that could trigger it to pull out fuel is the rapid fall in rpm's between the gears.. The TPS stays the same, as does the MAP.. I'm working thru the hack to see if I can locate anything that may be pulling the fuel out based on rapid rpm drop....
I'd really like to see what some other cars do?? This may even be very common and I am wasting my time?????
