Speed limit on M1 Vitviper package. Can't limit the engine speed after 4th gear .

Hello everyone!

I having hard time trying to limit the engine speed after shifting in to 4th gear, lower gears works. I checked al the limits , I tried adding more limits and nothing sims to work, unfortunately, I had tried to contact Vitviper and no luck , he is not reciving any DM, etc.

I can attaching some screenshots videos , or team view also the monitor always showing MAXIMUN, and the max speed engine its setup for example 7200 rpm for testing, sometimes I tried 6500 rpm, and always the same , all good until flatfood shifting in to 4th, then rev limiter goes at 9k rpm aprox .

If you do just a pull in 4th gear rev limiter reach the target.

The only sims to work its if I setup fuel cut, but the last time i did that it blew the head gasket..

Thank you in advance

Is this a mechanical overrev? The ECU Rev Limit will never help you with that. The Ignition Cut is 100%, so the maximum limiter is active.

I suggest you overlay "Engine Speed Limit" with "Engine Speed", so you can see what the currently used Speed Limit is at all times.

Just FYI , Vit works for MoTeC USA now, he had a buddy doing the support for his older packages.

Hello David,

No no course is not a money shift or mechanical over rev.. This is flat foot shifting.. I setup the rev limiter lower for testing, because at that engine speed plus gear its too fast for do testing.. I reduced the rev limiter , and every time i shifting let say : rev limiter setup at 7000 rpm , I do the shifting at 6800 rpm, WOT, no lift gas , Clutch ( RPM shoud go at 7200 max during clutching ) and then engage next gear.. it could go slightly higher? yes course coud go maybe 100 more rpm but not 1000 or 2000 rpm above..

Well that is great news.. I ran out of ideas, I already check all the limits, I tried to implements whatever limitations for testing such as tempereture etc..

all the same so far..

So is it possible the Gear Shift Cut doesn't happen until after the clutch has been depressed (disengaged)? Is your clutch switch at the top of the travel, or the bottom? It needs to be sensitive enough to trigger the cut before the clutch actually disengages. If you're using a pressure switch, trying to decrease the trigger value to something very low.

If you can post a logfile (you will need Level 2 Logging to debug most shift - related tuning) with Engine Speed, Engine Speed Limit, Gear Shift, Gear Shift Engine Speed Limit, Gear Shift Type, and whatever switches or inputs you use to trigger the upshift. Log as much as possible at 100 or 200 hz, or whatever max is allowed for the channel.

The configuration of ''No lift shift '' on this software is triggered by a stroke sensor located in the pedal clutch, also has a swtich activated when the pedal reach the bottom or all the way down. But is configured at 50% (before the clutch is disengaged ) the estrange thing is all works good until you shifting in to 5th, 1, 2, 3, 4 no problem.

I have some datalog ,I thing it doesn't have that resolution but ill try to post what I have.

Alex it looks like the clutch is being disengaged. That will allow the engine to over rev.

If that the case why the ignition cut, limit the engine at the setup speed ( I have tried 6500, 7200, 8000 rpm ) on 1 to 2 , 2 to 3 rd ,3th to 4 th gear no issues but it does not shifting from 4 to 5th doing FFS?

Perhaps due to the torque load in 4th gear, the clutch starts to slip at a different point, so your 50% value isn't correct. Try changing the sensor to 40% to see if that changes things.

Yes I did, but unfortunately it didn't solved the issue.

I'm trying to put toguether the car today so I can download some logs i did , I'm replacing the turbo now.

If the clutch physically disengages it's going to momentarily over rev like that. If you're using a multiplate the engagement point moves a lot as it gets hot, like after a launch and going through a couple gears.

Bit of a long shot, but could it be auto-igniting under the compression pressure from a hot spot, such as a spark plug?

Mike , I understand that, my question is, why its doing this consistently just after 5th gear? if your point would be the case it would be doing the issue at any gear?, 1, 2, 3, or 4th gear?

Hello Gord, If this is the case, why it does' not doing this issue in 1, 2, 3 and 4th gear? the amount of boost is the same on 4th and 5th gear.

I have the car together I'm going to plug the laptop and retrieve some logs .

I 've tried to see each area and the most relevant is the no lift shift triggers way after it is programmed , on screenshot B the clutch pedal is in about 78% and clutch activation its at 25%.

There will be more heat soak under the longer loading in the higher gears. If, and it's an "if", there is a marginal issue, or multiple issues, close to the edge, that might tip it over.

Re-reading the thread, you don't seem to mention a low-to-high rpm pull in the one gear, or several different gears, that might point things in the right direction.

It's unlikely, but it is possible for some diaphram clutches, which pretty much every one is nowadays, to "hang up" slightly if over-travelled, as the centrifugal forces on the spring 'fingers' can keep it dis-engaged. In some extreme cases the clutch will physically stick to the floor - it's happened to me, and a stop had to be fabricated to prevent it. Some vehicles are equiped with a "helper spring" as part of the linkage, and this makes it worse.

Yes course mechanicals limitations always been there, I'm running a X-Clutch twin disc organic, . So what I ended up doing for fix the issues goin from 4th to 5th was using the fuel cut again, but this time I the strategy is fuel cut first , and ignition after, that did the trick limiting the speed engine at the point I want it. long time before I was using the fuel cut but after the ignition cut. Strategy was ignition cut, then fuel cut , that was working good but for some reason was damaging the head gasket.

Now my issues are from 2 gear to 3th gear, looks like I can't win lol, the speed limit is doing the job but stills too much torque and doe not fully disengage, it's like the ignition cut patter is too fast , and I cant change that also sometimes it does work the ''no lift shifting'' and other does not.