vtec from around 4k rpm on part-throttle

[Asbjorn]

So I have had this issue for the longest time. If I accelerate part-throttle from low rpm to high rpm, torque sometimes increases suddenly from around 4k. It won't do it every single time, but quite often. It feels as if the car has VTEC that kicks in at around 4k.

Here is a log example of the issue

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If I go WOT, the car becomes super smooth, and there is never any "VTEC" kicking in and out. I can request any torque below 100%, and the problem might be there as rpm increases. But it is never there at WOT. The car is also super smooth at low rpm and in daily driving.

Has anyone had a similar issue, or can point me to where I might look for a solution?

 

[langsbr]

Maybe log vanos? Possibly clogged vanos solenoids but not enough to throw a code?

 

[Asbjorn]

Maybe log vanos? Possibly clogged vanos solenoids but not enough to throw a code?

Let me try and report back. The solenoids are less than 2 years old though, and I have done the "N55" camshaft seal maintenance, where the teflon type from N55 is installed instead of the metal N54 type. No vanos codes since then.

 

[RSL]

You're also entering boost around there, not sure if that's cause or effect. Could just be something causing throttle plate to move too aggressively when transitioning conditions, but kind of surprised not to see load or much else jump with it. Should pay attention to see if that only occurs in that 0-2psi range, if spool mode is involved (fuel mode), RPM/pedal positions, speed, etc.

 

[iminhell1]

I'm just going to go with the load table (Load to Torque) in that area needs work / isn't correct. Add tq requested to the stuff you're logging.
Maybe chop that area by 10% or so and see what the change is. If it improves chop another 10%. Find a bottom and then work back up, bottom is going to be a point where the throttle is so flat you need to add peddle to accelerate or hold speed. You want that middle ground area.

 

[Asbjorn]

Alright I added all the logging channels you suggested and did a few logs. Below log was the worst example. The so-called "vtec" turned on and off several times at higher rpm. Seems to happen every time the throttle opens, but I'm no expert. Really need your input on what is going on.

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[iminhell1]

Ya that's sorta what i thought I'd see. The TQ request stuff is basically maxed out all the time. That leads to odd and sometimes uncontrolled behaviors. It works fair for WOT stuff. But when it comes to drivability it's not a good option.

if you want, post the tune file and i'll poke around later tonight. You have to add a ".txt" to the end to post the file here.

 

[Asbjorn]

Ya that's sorta what i thought I'd see. The TQ request stuff is basically maxed out all the time. That leads to odd and sometimes uncontrolled behaviors. It works fair for WOT stuff. But when it comes to drivability it's not a good option.

if you want, post the tune file and i'll poke around later tonight. You have to add a ".txt" to the end to post the file here.

Thank you so much for this feedback!

I assume the map is locked, but attached it is. If you can't open it, I would just need a very precise sentence to forward to my tuner. I am not sure if I can just tell him: "Please adjust the TQ request stuff so my car becomes drivable, thanks!" ?

Its been like this for as long as I can remember. Every time I have asked about it, I have been told to go look for leaks. And in his defense, 99% of the time there has indeed been a leak, and focus changed.

 

[iminhell1]

Map is locked.
And now that I see who did the tune, I'm not going to step on any toes. Dimitri knows what he's doing. But I'd send him logs so he can see what's going on. It should not work like that.

I was thinking it was some other yahoo doing the tune and hacking something together.

 

[RSL]

Torque request is a setpoint monitor for a torque that MHD doesn't log. I can't say I've ever had issues with it stock or maxed, but probably don't tune the same.

Part of the problem may be in even having it setup where you can get to 6300rpm at only 20% pedal in 3rd. I tried today out of curiosity and could only reach about 4300 at 30% pedal.

 

[Asbjorn]

Oh that's interesting! Thanks for checking.

I have forwarded your comments to Dimitri. Will keep you posted. Hopefully he agrees it isn't a hardware issue this time. Otherwise I will just have to go WOT all the time.

 

[Asbjorn]

Torque request is a setpoint monitor for a torque that MHD doesn't log. I can't say I've ever had issues with it stock or maxed, but probably don't tune the same.

Part of the problem may be in even having it setup where you can get to 6300rpm at only 20% pedal in 3rd. I tried today out of curiosity and could only reach about 4300 at 30% pedal.

I am marking this as the best answer and solved. I was getting almost 100% torque at 50% throttle for some reason. Six map revisions later, and it no longer does the vtec thing, and I don't get full power until acc pedal is at around 80%. Tuner also changed vanos and some other stuff he didn't specify in detail.

Here's a log with 55% acc pedal.

datazap.me | Asbjoern | v43L - 55%

datazap.me

 

[doublespaces]

You have to add a ".txt" to the end to post the file here.

I've added .bin to the list of allowed attachments.

 

[langsbr]

I think it was an .mhd file which is a locked custom tune file. Probably won't make much sense to allow them really. But good idea on bin if people share unlocked maps.