dropping out of VTEC when shifting
03-20-2007, 07:38 AM
#1
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dropping out of VTEC when shifting
Hi,
I tried searching threads related to the Hondata ECU, but was unsuccessful in finding an answer to my question below.
I have test driven a few used AP2s, and find that on upshifts at/near redline, the car temporarily drops out of VTEC (revs drop below 6k apparently). Now, I'm not reving the car to fuel cutoff, so perhaps if I was, the change in gear ratios and VTEC engagement point would synch up perfectly? Or is this a "flaw" of the AP2? (I've never driven an AP1, so don't know if the same was true there as well)
Looking at the Hondata reflash for an otherwise stock car, the redline gets bumped to 8500, and VTEC engagement occurs at 5600. I would think this combination of nearly 1000 rpm would result in some flexibility of shift points w/o dropping out of VTEC. Is this correct?
Thanks,
Phil
I tried searching threads related to the Hondata ECU, but was unsuccessful in finding an answer to my question below.
I have test driven a few used AP2s, and find that on upshifts at/near redline, the car temporarily drops out of VTEC (revs drop below 6k apparently). Now, I'm not reving the car to fuel cutoff, so perhaps if I was, the change in gear ratios and VTEC engagement point would synch up perfectly? Or is this a "flaw" of the AP2? (I've never driven an AP1, so don't know if the same was true there as well)
Looking at the Hondata reflash for an otherwise stock car, the redline gets bumped to 8500, and VTEC engagement occurs at 5600. I would think this combination of nearly 1000 rpm would result in some flexibility of shift points w/o dropping out of VTEC. Is this correct?
Thanks,
Phil
03-20-2007, 07:40 AM
#2
If you shift at redline or near the rev limit, you are well into VTEC in the next gear. You weren't upshifting at a high enough rpm.
03-20-2007, 07:43 AM
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Originally Posted by QUIKAG' date='Mar 20 2007, 07:40 AM
If you shift at redline or near the rev limit, you are well into VTEC in the next gear. You weren't upshifting at a high enough rpm.
You will not drop out of VTEC unless you are not shifting at a high enough RPM or shifting really slowly and letting the RPM's fall.
03-20-2007, 08:24 AM
#5
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Isn't OEM Vtec engagement at 5,900-6,100 for AP1 and 5,400-5,600 for AP2? Are you sure you're actually out of Vtec? I think not many people actually know Vtec engagement points differ between AP1s and AP2s...
And, as Vtec offers the best breathing at certain rpms, you have to pay attention to where you set the Vtec point, dropping out of Vtec doesn't mean the engine doesn't work as well. I can see lowering the Vtec engagement a few hundred rpms, but any more than that and you'd be hurting performance. I have heard of FI AP1s engaging Vtec at as low as 4,400 rpms though...
And, as Vtec offers the best breathing at certain rpms, you have to pay attention to where you set the Vtec point, dropping out of Vtec doesn't mean the engine doesn't work as well. I can see lowering the Vtec engagement a few hundred rpms, but any more than that and you'd be hurting performance. I have heard of FI AP1s engaging Vtec at as low as 4,400 rpms though...
03-20-2007, 08:39 AM
#6
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ive been trying to tell people that ap2 always drop out of vtec. not much you can do except swap to a ap1 ecu. you guys who claim it, check the spec ratio sheet. ur doing the impossible or are mistaken about something.
03-20-2007, 09:49 AM
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Originally Posted by dyhppy' date='Mar 20 2007, 11:39 AM
ive been trying to tell people that ap2 always drop out of vtec. not much you can do except swap to a ap1 ecu. you guys who claim it, check the spec ratio sheet. ur doing the impossible or are mistaken about something.
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03-20-2007, 09:58 AM
#8
Originally Posted by dyhppy' date='Mar 20 2007, 08:39 AM
ive been trying to tell people that ap2 always drop out of vtec. not much you can do except swap to a ap1 ecu. you guys who claim it, check the spec ratio sheet. ur doing the impossible or are mistaken about something.
03-20-2007, 11:21 AM
#9
Registered User
Originally Posted by dyhppy' date='Mar 20 2007, 11:39 AM
ive been trying to tell people that ap2 always drop out of vtec. not much you can do except swap to a ap1 ecu. you guys who claim it, check the spec ratio sheet. ur doing the impossible or are mistaken about something.
