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Change in VTEC after repair


HareBrain

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I just got my bike back from the shop after three months, repairing cosmetic damage from it being knocked over in a parking accident. Like my previous 8th Gen, the bike had always had a marked VTEC transition, especially the first time each ride when it was a definite "lurch". (I understand not everyone has this.) Now there's nothing. Not only is there no lurch at all, but I can't detect the increase in power and noise that I thought was there before. But I might be imagining that, especially since it's been a while since last riding it. I've watched a couple of youtube reviews but the wind noise makes it hard to tell.

 

So, I'm sure this is a stupid question, but I'm assuming there's no way for the VTEC to "switch off"?

 

And assuming there's not, anyone got any idea what could have made the transition so much smoother? I'm not complaining, but it makes me wonder if the shock of the fall did something I should be aware of.

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Can’t switch VTec off. 
 

Does bike feel weaker in the upper revs? If not then you’re golden. 
 

Could the shop have installed some sort of factory ECU update while it was in there? 

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14 minutes ago, Stray said:

Can’t switch VTec off. 
 

Does bike feel weaker in the upper revs? If not then you’re golden. 
 

Could the shop have installed some sort of factory ECU update while it was in there? 

And even if the VLC Solenoid was unplugged it would flag up a DTC of 27.

VTEC transition has been improved over the 6gen, but you should still feel a noticeable increase in power when you're in the zone.:wheel:

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2 hours ago, Grum said:

And even if the VLC Solenoid was unplugged it would flag up a DTC of 27.

 

Ah, thanks, that sounds pretty conclusive.

 

It does feel stronger in the upper revs, but more gradually than I thought I remembered (almost like my old CBR600F). But maybe what I remembered was the lunge forwards after the "drop". It's odd that both my 2014 VFRs had this "drop" but from the sound of it, it shouldn't have been there and isn't very common.

 

Anyway, I'll keep an eye on it but it sounds like it was a freak improvement. I'm sure the shop didn't adjust the ECU.

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5 hours ago, Grum said:

And even if the VLC Solenoid was unplugged it would flag up a DTC of 27.

VTEC transition has been improved over the 6gen, but you should still feel a noticeable increase in power when you're in the zone.:wheel:

I am not familiar with fault detection strategy on this bike. Open in drive circuit detection for the solenoid is a pretty basic function. Just because solenoid is being energized it doesn’t confirm it actuates. Is there a other one that will detect malfunction or the vtec system or just a bench test of solenoid?

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43 minutes ago, Magneto said:

I am not familiar with fault detection strategy on this bike. Open in drive circuit detection for the solenoid is a pretty basic function. Just because solenoid is being energized it doesn’t confirm it actuates. Is there a other one that will detect malfunction or the vtec system or just a bench test of solenoid?

Service Manual shows how to check the valve off the bike. The solenoid seems to be extremely reliable, have never heard of one failing on a 6 or 8gen. 

Guess a dyno check would also verify vtec ops.

You could also try unplugging the valve test ride the bike and then compare how it performs with it plugged in.

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This probably doesn't apply but could be of use.......

 

Back in the late 90s-early 00s I owned a few Honda autos with VTEC. iirc oil pressure and coolant temp must reach a certain level or it won't engage. Also vaguely remember an oil screen to keep any debris from reaching the solenoid but that might be a different car or bike. If the system did not engage it would throw a code

 

Obviously these are different VTEC systems but checking the oil and confirming temp before reving into the zone are super easy to do.

 

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1 hour ago, jim v said:

iirc oil pressure and coolant temp must reach a certain level or it won't engage

 

I think that's the case, I was reading about it earlier.

 

Just done another ride with lots of hard 2nd and 3rd gear pulls, and the VTEC is there, but again, always really smooth transition. Though it used to feel a bit clunky, I kind of miss how it was.

 

Why it's changed I guess will remain a mystery, but at least it seems to be working fine.

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5 hours ago, Grum said:

Service Manual shows how to check the valve off the bike. The solenoid seems to be extremely reliable, have never heard of one failing on a 6 or 8gen. 

Guess a dyno check would also verify vtec ops.

You could also try unplugging the valve test ride the bike and then compare how it performs with it plugged in.

 

I don't know about 8th gens, however IIRC on 6th gens if the ECU does not see the spool valve solenoid plugged in it results in a no-start condition.  That connection is underneath the throttle body and is not easy to get to. 

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3 hours ago, Cogswell said:

 

I don't know about 8th gens, however IIRC on 6th gens if the ECU does not see the spool valve solenoid plugged in it results in a no-start condition.  That connection is underneath the throttle body and is not easy to get to. 

According to DTC 27 for the valve, engine ops are normal.

20210228_073250.jpg

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