Where is my Throttle Response
Thread Starter
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
Where is my Throttle Response I have 377 cu in with a 233/239 cam, SD tuned, with a FAST90 intake and an aluminum flywheel with dual disc clutch. Mechanically it has all the right stuff, but it won't rev up fast. When I am cruising at 2500 or 3000 rpm and I give it some gas, it's like it has turbo lag, it just fells lazy. Stomp it to the floor and it hauls, but it just is slow to take the gas at mid throttle. When I heel and toe downshift, it is hard to get the revs right because it just won't rev quick.
I have the VE table and LTFT pretty close, the wideband is always around 14.2-14.7 and 12.7 at WOT. Timing at 28. If this car had a carburator, I would say it needs an accelerator pump. It needs a shot of gas when I hit the pedal, how do I get that with a tune. Thanks for any ideas of what to try next.
I have the VE table and LTFT pretty close, the wideband is always around 14.2-14.7 and 12.7 at WOT. Timing at 28. If this car had a carburator, I would say it needs an accelerator pump. It needs a shot of gas when I hit the pedal, how do I get that with a tune. Thanks for any ideas of what to try next.
Enrichment rate set to fastest? Be careful which way you set it. You usually enter the highest value the table will accept IIRC.
Have you turned off all the throttle ****-blocking tables that are set up to "maintain traction"?
You may need to add some fuel to the mid range, higher load cells. Blipping the throttle to downshift sometimes hits some weird cells that you might not hit during normal VE tuning. Your PE thresholds may also need to be set lower so that you can get some fuel down the pipe a little earlier. If you are already in PE in those areas, the scanner may not have logged any error in those areas, thus not allowing you to correct them. But, you saying going WOT kicks it up there quick tells me the PE threshold may be set to high.
Have you turned off all the throttle ****-blocking tables that are set up to "maintain traction"?
You may need to add some fuel to the mid range, higher load cells. Blipping the throttle to downshift sometimes hits some weird cells that you might not hit during normal VE tuning. Your PE thresholds may also need to be set lower so that you can get some fuel down the pipe a little earlier. If you are already in PE in those areas, the scanner may not have logged any error in those areas, thus not allowing you to correct them. But, you saying going WOT kicks it up there quick tells me the PE threshold may be set to high.
Try and observe whether the drive-by-wire TB
actual angle / position swings abruptly, or is being
done slowly and matches the rev-up ramp rate.
There are settings for opening rate I believe (don't
mess much with electric throttles).
Also look for KR on abrupt throttle events, this might
result from a too-lean light throttle SD tune or from
late enrichment allowing knock. With stock KR settings
you can accrue a big retard from a little knock and
see a long time before it decays back out. You may
want to use burst knock to control tip-in ping, if you
are convinced that the airflow / fueling are right. But
generally I've gotten rid of tip-in ping by watching
the O2 sensors and making sure there is no "lean
blip" on throttle transients.
actual angle / position swings abruptly, or is being
done slowly and matches the rev-up ramp rate.
There are settings for opening rate I believe (don't
mess much with electric throttles).
Also look for KR on abrupt throttle events, this might
result from a too-lean light throttle SD tune or from
late enrichment allowing knock. With stock KR settings
you can accrue a big retard from a little knock and
see a long time before it decays back out. You may
want to use burst knock to control tip-in ping, if you
are convinced that the airflow / fueling are right. But
generally I've gotten rid of tip-in ping by watching
the O2 sensors and making sure there is no "lean
blip" on throttle transients.
TECH Fanatic
Joined: Aug 2005
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From: Sunny London, UK
Timing at part throttle is real important for throttle response, if it looks ok from the logs with no BKR or KR etc.
Actually if you see BKR being logged you may want to consider zero'ing out the table. If timing is tuned right, stock BKR will be too agressive.
Actually if you see BKR being logged you may want to consider zero'ing out the table. If timing is tuned right, stock BKR will be too agressive.
Thread Starter
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
OK, I will work on the PE in the lower rpm range to see if I can improve there. Do I have to be in OL for the PE to kick in??
I have not seen any knock with this new motor. It's dynamic compression is 7.95, should be good with 28 degrees.
Blur, you are referring to those max torque settings that the traction control uses, it is set to 639.
Opening rate for TB mmmmm that sounds interesting.
Thanks, I will try it out on Sunday AM. I usually go for a cruise, that's my church.
I have not seen any knock with this new motor. It's dynamic compression is 7.95, should be good with 28 degrees.
Blur, you are referring to those max torque settings that the traction control uses, it is set to 639.
Opening rate for TB mmmmm that sounds interesting.
Thanks, I will try it out on Sunday AM. I usually go for a cruise, that's my church.
Thread Starter
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
OK, I just made my Sunday morning "church run". I tried to free rev it several times to see what is happening. There is no knock, and the wideband is at 12.5 The only thing I see on the scan is that it is dropping timing. As the TPS makes a peak, the timing makes a peak down. The timing table is pretty flat at 28, what would make it drop when the TPS spikes up.
Jimmy; where do I find that throttle opening table. If I could get my hands on that thing I would open it to 100% Thanks
I attached a screen shot as a .doc
Why is the wideband reading pretty rich for closed loop, and the LTFT is adding fuel??
Jimmy; where do I find that throttle opening table. If I could get my hands on that thing I would open it to 100% Thanks
I attached a screen shot as a .doc
Why is the wideband reading pretty rich for closed loop, and the LTFT is adding fuel??
