Thom

My humble impression is that the Motec may be oversensitive to some parasitic noises that only appear in particular conditions while they should not actually affect engine operation.

This could be checked by unflagging one by one those 9 signals and see if it makes any difference in engine operation.

reno808

Where you logging when you where driving to the dyno?

Did it detect errors when you were making boost?

333pg333

You could be right Thom. It's beyond my pay grade at this stage. The Wheel is here and it will go on and be done with it. I've got a very thin hope that somehow we can be tuned and ready by next week to still make one of the Shakedown days. It won't happen, but I'll try.

Reno, the car was trucked to the dyno not driven. It's not a road going car anymore. The errors were in higher rpms. No boost yet.

reno808

Hmmm normally the errors start on the higher loads. Why didn't they re-set the thresholds on the sensors? Thats what we started to do and its working so far. Next week its going back to the dyno to do final pulls and go for max hp and tq

333pg333

I don't think that's necessarily the point...to reset the thresholds until you get an uncorrupted signal? To my way of thinking that's allowing the possibility of misfires to get through the net so to speak. Once we have a good read off the Clewett wheel, then we know that we can seek the best possible tune...or at least that's what I think. Hand up as a non expert in these matters so this is only my uneducated opinion.

Duke

The engineer is (of course) correct. The stock 132 is just a speed signal and does not give a reference to the actual engine position. The reference is handled by the stock reference sensor which is just a single pin on the flywheel.

So when running a cam sensor AND the stock 132 trigger the ECU has to determine the engine position off the cam sensor and as the Pat's engineer writes that can cause timing errors due to belt stretch etc.
Using a crank trigger with a missing tooth enables the ECU to determine the exact engine firing position of the crank and use the cam to just determine what cycle the engine is in.

Thom

When using the 132 ring gear for speed reference and a CAS for timing reference, belt stretch means that the TDC angle value referenced by the ECU takes place slightly later than actual piston TDC.
This should be easily compensated for by increasing timing, at least when the tuner is able to the push the timing curve right to the edge of detonation.

Duke

Detonation might not be a problem but I can see from a technical point of view that it might not be accepted by some ECU's.

Thom

Yes...

The way I see it is that adding another reference sensor on the crank may help the Motec run better, while the engine might not perform any better than if some flexibility on the actual TDC ° variance was allowed.

The signal from the CAS still has to be offset somehow for belt stretch.

Duke

Not sure it can handle 3 speed and angle sensors, I've never seen that on any other systems.
Several systems just use the cam angle sensor only to know which phase the engine is in, not the actual angle.

reno808

Its sounds like he didnt set the offset timing correctly or calibrate the triggers correctly. When you set the trigger calibration it must be done twice. once just cranking the engine over and the other up on the rpm range. As the RPMs goes up the timing moves. So you set it so when the rpm goes up engine timing does not move. once you get that all sq away you start to move the arming thresholds when you start to get trig errors. just my .02 cents i am not a expert as this is just a hobby for me
I can go on all day about this since that is what i am doing right now.

ausgeflippt951

Patrick -- I just discovered your thread and blew off an hour's worth of work to skim through it all. Awesome car; it looks phenomenal.

Sorry to hear about the slight issues -- you're almost there!

333pg333

Well much smarter men are working on my car than me. I'm sure it's not just a matter of they forgot to do something.

From what I've been told the sensor on the Clewett kit isn't the best and needs to be gapped much closer than they stipulate. Does anyone have any knowledge of this?

Thanks Collin...hope we're not too far away from take off!

reno808

Yes they are a completely right. It is literally paper thin airgap.

Duke

The Clewett setup is very nice and sturdy but remember you cannot use it later on when you have the dry sump setup. The teeth is pretty small so that combined with the sensor give low voltage. I would start with 0.2 mm gap right away.