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RPM Limit activated

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I did a power run on the dyno today, and realised that the engine could not go beyond 6872rpm.

The RPM Limit warning was activated.

I looked at my RPM limit table and it was set to 7400rpm after ECT reaches 50degrees celsius.

The MAP limit is also set to 285KPa.

Looking at the log, the max MAP recorded was 245KPa, and max RPM was 7098rpm on PCLink.

The RPM limit is set to Fuel %cut, 2D table and Advance Mode "OFF".

What else should I check to see why the RPM limit is lower than that set in the RPM Limit table?

Thanks.

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Check to see what the Limit control range is set to. If it is set to like 300 or 400 rpm this is most likely why it is cutting early. It will vary time to time as it controls the rpm range that the limiting operates over. This is most likely what is happening.

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With the advanced mode OFF the limit control range is 200, which you are not coming within (7200 RPM). When you encounter the problem have a look at the 'Triggers/Limits' tab of the Runtime Values Window (F12 key to open). Are the fuel or ign cut being applied? If yes, which limit is active?

Scott

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Possibly you have a limit that is set for ECT temp and you are not noticing this either. I would assume it is something silly and you will find it very soon.

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Hopefully someone can help with a similar issue I've encountered with my G4+ Fury. It's fitted to a straight 6 with crank sensor and cam sensor and cop ignition  

 

 

When mapping the car wouldnt rev above 7000rpm despite the rpm limit being above that (7400). The 'rpm limit' comes on on the Eculink although it's obviously not at it  

Advanced mode is off so the control range should be 200, and the revs won't rise if we raise the limit above 7400rpm. 

 

Ive had a look through all the map and found the following tables that do not go above 7000 rpm, but would these cause the ecu to limit the rpm?

 

Accelerate clamp table? (Reading of 0 at 7&8k)

Afr lambda table (although Lockout limit is at 5k)

Charge temp approx table (can't change axis?)

Ignition dwell control

Trigger 1&2 arming threshold table (again can't change the axis)

 

 

the obvious tables like Fuelling/ignition/dbw are populated upto 8k. 

 

 
Edited by Sparkystav

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The tables that have an RPM axis that stops before the normal redline will just hold the same value from the last cell at any higher RPM so none of those listed are part of your problem. 

The fastest way to get to the bottom of it is to do a PC Log with all parameters recorded, email that and a copy of your .pclr to BGfzSPG.png  Please include a link to this thread so we know what its about.

How to do PC log: https://www.youtube.com/watch?v=_P1LRANeO4A

Also if you can do a trigger scope at idle that might give some clues too.

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Just a suggestion. 

Might be worth setting engine speed sampling frequency to 100hz for ecu logging. This will allow you to see any noise which may be present.

I was having a similar issue of limiting before it should, and found that at higher rpm the trigger signal was a bit noisy and causing the ecu to see spikes in rpm. One spike into the limit range is enough to trigger rpm limiting.

There are filters that can be applied to the triggers which may help if this is the issue.

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