SOLVED: Are these VTEC engagement points reversed? | AEM
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sammy
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SOLVED: Are these VTEC engagement points reversed?

 

So, just to make it clear, I'm a newbie looking at these programs, and I'm the owner of the car, not the tuner. So, not sure if I'm looking at this correctly. The tuner is on vacation, so I can't ask him.

I'm thinking that the VTEC rpm engagement points are reversed, which is what's causing what seems to me to be real peaky whp dyno results.

This is a 2004 Honda S2000, recently supercharged and tuned using a AEM EMS v2.

The whp dyno results show a huge increase in power, very suddenly at about 5500-6000rpm. About a 300hp jump from 200hp to 500hp. It's running about 17lbs of peak boost at about 8400rpm. SOS Stage 2 with a 3in pulley. Tourqe jumps from about 200 to 310 lb-ft. 

The tuner told me that he set the VTEC rpm engagement point at about 4500rpm. But the hp graph and my butt dyno show nothing really at that transition.

Using AEMTuner for the first time for me I added a channel for VTEC to view the running parameters as I was driving the car. It's just a channel that says ON and OFF for VTEC. It would come on at about 6000rpm more or less at WOT acceleration. It's sort of hard to tell exactly 'cause I'm driving. I tried to record a PC log (not the built in AEM EMS log), but for some reason it didn't record anything, or I don't know how to view it on AEMData.

Here's the question about the reversed rpm settings for VTEC. It's set as follows when I view the calibration (the throttle and engine load settings seem normal):

VTEC On above 4300rpm

VTEC Off below 4500rpm.

AEM's definition of the fuctions say:

VTEC On means the engine speed must be above this value for VTEC to become possible.

VTEC Off means the VTEC turn off threshold is if the engine speed falls below this value the VTEC function will turn off. Normally this is set about 200rpm LESS than VTEC speed ON.

But, it seems the tuner reversed these...it's set 200rpm MORE than VTEC speed ON. I looked at some built in tunes that AEM provides, and they seem to follow the explanation, opposite of what mine seems to be set at.

So, is mine reversed? Is this what is causing the huge jump in power and torque, instead of being a smooth increase? Is VTEC really engageing at about 6000rpm as I saw, or is that some sort of malfunction in the viewing because of this. 

Engine load settings are set to VTEC On above engine load 7.3PSI, and VTEC Off below load 3.9 PSI.

Thanks for anyone who can help in this.

AEM_NS
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Last seen: 14 min 33 sec ago
Joined: 06/06/2014 - 09:31
Yes, VTEC Off should be lower

Yes, VTEC Off should be lower than VTEC On but having Off above On shouldn't really do anything.  Remember that VTEC won't turn on until MAP is at least 7.3 psi.  At what rpm do you hit this boost?  You could easily make VTEC Off lower than On and see if there's a change.  Or wait until your tuner gets back from vacation. 

sammy
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Last seen: 4 years 6 months ago
Joined: 12/02/2015 - 22:00
The huge boost in HP occurs

The huge boost in HP occurs at about 6000rpm, about the same time VTEC is engaged. I don't know exactly what the boost is at that point. 

Give me a little education here...the parameter of VTEC not turning on until the MAP says 7.3psi...is that the 'boost" from the supercharger? Or, is there more to it than that?

He didn't give me a graph of boost level vs RPM, but is that something I can see on AEMTuner, or with a log from it?

AEM_NS
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Last seen: 14 min 33 sec ago
Joined: 06/06/2014 - 09:31
Honestly, this is a tuning

Honestly, this is a tuning issue that you should really be communicating with your tuner. The last thing we want is for something bad to happen due to inexperience with the EMS and performance engine tuning in general. 

sammy
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Last seen: 4 years 6 months ago
Joined: 12/02/2015 - 22:00
No offense, but that's sort

Oh...come on now,  that's sort of a cop out. winkYou're getting nervous that I"m going to go into the calibration and change something which damages my engine.

Don't worry, that's not going to happen.  I'm simply trying to learn about tuning. You have to start somewhere. I'm smart enough to know that I don't know much at all about tuning yet, but don't worry, I've been told by  many people, dozens of times to not change anything.

In fact, you yourself earlier told me that I could change some settings and it probably wouldn't affect anything, but I didn't.

So, I just asked about how the engine load psi related to boost levels. I don't think they are one and the same thing, but I want to learn. This wasn't a question about my tune specically, just a general one.

 

Thanks guys

PS, wanted to mark this a solved, but is there a way to do it in this forum?

sammy
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Last seen: 4 years 6 months ago
Joined: 12/02/2015 - 22:00
Problem is SOLVED. Got it

Problem is SOLVED. Got it eTuned to fix the VTEC issue