Dip in torque curve

[Nazul]

Since my car has been tuned there has been a dip around 4200 -4700 rpm.
My tuner tried everything to get this away but did not succeed. He told me this is caused by the 16 valves effect.
Though VTEC engages at 3500 in open loop, torque does not mount immediately after it.

I wonder if this is normal behaviour on my mods?



My mods are:

ITG maxogen box
RBC manifold
Hondata heat gasket
Hytech header
3 inch exhaust

The calibration:

calibration.kal

[keto06]

I'll have to look at the kal when I get home, but yea, that sounds about right.

[keto06]

Not the best map Ive seen, but certainly not the worst. Could it be tuned out? Maybe...but its not worth messing with a tuned map. Especially with no log or dyno AFR reading.

[Nazul]

Dyno AFR was tuned, but just not showing on the map, AFR was 12,8 above 3000 rpm and 12,5 near max RPM.
What can be better in your opinion? Do you believe the dip can be removed by mapping or is it a setup limitation?
AFR was fine around 4500 rpm btw. And what about oil consumption, can it be caused by this map? I have a consumption of 1 liter every 2000 km on high load on the engine i have to admit.

If u think u can make it better and gain higher HP on 4500 rpm and above 8000 maybe its worth it for me to make some logs.
But I dont have a wideband sensor since i have PRA ecu.

[keto06]

what were the first 2 lines in this graph?

[Nazul]

Red is before tune grey after

Top curves is torque
Others horsepower bhp and whp

[Nazul]

Any thoughts Keto?

[rikitaun]

Try it

Vtec point 4500rpm with OEM cams

rpm VTC
3000 35º
3500 30º
4000 30º
4250 35º
4500 40º

advance ignition to 30º in this range and adjust a/f 13.00-13.5

[Nazul]

Where did u get this info then?

[keto06]

13.5 is a little high for my taste (my car made best power in the high 12s on the dyno) but other than that, his suggestion could work. It will require you to put some work into your low cam tables though and without a dyno theres no guarantee it would work.

Post a log with the new cam angles and the AFRs logged and fixed.

[Nazul]

I have a PRA ecu with narrowband, there is no way in logging the AFR without me installing a wideband first i'm afraid :(

[keto06]

then I wouldnt mess with it.

If you want to wire in a wideband you might be able to fix the issue, but doing it blind is silly.

[Nazul]

Ok thanks for the help then anyway :)

[rikitaun]

Where did u get this info then?

I have made around 16 cars in spain.
If you have gasoline 95 or 98 ron put this values in LOW-CAM without problem.

DIP is caused by low VTEC point and agressive VTC from OEM cams.

[Nazul]

But i believe my cams are at 30 degrees around those rpms.
I'll check when im home.
We believe the dip is from the 3 inch.
But i can test, normally i should feel the difference.