Car seems to have no throttle response?
12-09-2003, 03:15 PM
#1
Staging Lane
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Car seems to have no throttle response? OK heres the deal ive been tuning for a few days. whta ive done so far is
1.) tune from the reccomend HC tune
2.) set idle air to 8.6
3.) *PN Airflow decay by 95%
4.) reduced Main VE another 95% from 1200 down
5.) multiplied IFR table by 95%
Heres what happening...The car runs great but when i first take off and at every gear change it want to "chug chug chug" then it pulls away fine. Its like i have NO initial throttle response? If i were to nail the gas while it gear it would sit there for a split second then say "oh $hit lets roll" and be off. It pulls like a raped ape up top except for that hesitation at take off and gear changes. Anyone know what could be causing this??
1.) tune from the reccomend HC tune
2.) set idle air to 8.6
3.) *PN Airflow decay by 95%
4.) reduced Main VE another 95% from 1200 down
5.) multiplied IFR table by 95%
Heres what happening...The car runs great but when i first take off and at every gear change it want to "chug chug chug" then it pulls away fine. Its like i have NO initial throttle response? If i were to nail the gas while it gear it would sit there for a split second then say "oh $hit lets roll" and be off. It pulls like a raped ape up top except for that hesitation at take off and gear changes. Anyone know what could be causing this??
12-09-2003, 03:33 PM
#2
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Your mixture calc is probably bent and only closed loop
is making it right (with some lag, hence poor throttle
response).
Need to log O2s, long & short term trims and see what
is uncovered on throttle & RPM transients.
is making it right (with some lag, hence poor throttle
response).
Need to log O2s, long & short term trims and see what
is uncovered on throttle & RPM transients.
12-11-2003, 11:09 AM
#5
I don't know, you have to ask someone with a cam the size of yours. 230 on both sides is getting there, but I don't think it's huge enough to cause your problem. I used to have a 270/270 that was pretty slugish below 3000 rpm.
It almost sounds like your injectors are plugged up.
It almost sounds like your injectors are plugged up.
12-11-2003, 12:16 PM
#7
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I'm fighting the same issue here.. 238/240 .605/.609 112+2 cam on a small motor, and it has a hesitation right off idle if you tip into the throttle more than about 15% .. Once you break 2500 RPM it flies.
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12-11-2003, 12:46 PM
#8
Originally Posted by Brains
I'm fighting the same issue here.. 238/240 .605/.609 112+2 cam on a small motor, and it has a hesitation right off idle if you tip into the throttle more than about 15% .. Once you break 2500 RPM it flies.
No guru here - but, I have a fairly stout cam (239/251). I increased my VE just off idle ( idle = 1200 RPM @ 70 kPa).... It's decreased 10% @ 1200, 20% @ 800, 400 RPM. Added a few percent 1200 RPM below 60kPA . Then added 10% 1600 RPM @ all kPa. So basically it's leaned out, at idle, and then as it drops kPa, as throttle transitions, it gets richer.
The real/best way to deal with (I think?) this would be to Rescale entire VE using NoGo's tuning for VE. I'm going to scan this weekend and try it. I'll let you know how it turns out. I hope I can figure out how to use ChrisB's Tuning software.FWIW.
NoGo is the Man joel
12-11-2003, 06:33 PM
#9
Originally Posted by binksz06
No guru here - but, I have a fairly stout cam (239/251). I increased my VE just off idle ( idle = 1200 RPM @ 70 kPa).... It's decreased 10% @ 1200, 20% @ 800, 400 RPM. Added a few percent 1200 RPM below 60kPA . Then added 10% 1600 RPM @ all kPa. So basically it's leaned out, at idle, and then as it drops kPa, as throttle transitions, it gets richer.
The real/best way to deal with (I think?) this would be to Rescale entire VE using NoGo's tuning for VE. I'm going to scan this weekend and try it. I'll let you know how it turns out. I hope I can figure out how to use ChrisB's Tuning software.FWIW.
NoGo is the Man joel
12-11-2003, 10:15 PM
#11
A 230+ cam is not made for good low rpm operation on 346's.
You need to play around with the VE table and low rpm/idle timing tables to get it better.
I've adjusted my VE tables to 2400rpm and made drastic timing changes.No problems with off idle operations but took a while to get there.
You need to play around with the VE table and low rpm/idle timing tables to get it better.
I've adjusted my VE tables to 2400rpm and made drastic timing changes.No problems with off idle operations but took a while to get there.
12-11-2003, 11:12 PM
#12
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VE helps the throttle response. I still need to work on idle VE, but using the methods learned here my car pulls like crazy compared to stock VE. Its probably not any faster but it feels like it.
Eric
Eric
