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9m Motec M84 upgrade on non-Varioram

 
Old 09-27-2011, 07:14 AM
  #16  
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Hey Macca, your idle hunting between 600 to 1.3k is too wide. No wonder you were so disappointed with the build. Try and have the tuner fix it! Your cam is very mild so I dont see it linked to the cam profile. My brother has a similar cam on his 964 with a SW chip and no problem at all.

Mine doesnt hunt. On the other hand, it needs some work in cold start. When cold, idle is lower than when its hot. No problem when the AC is on. But other wise, it purrs like a cat.

Colin, a 320 degree cam confirms what I suspected My cam is only 292 in duration. I thought a 305 was too big but I guess I was wrong. Hmm...but that is your race car right?

Last edited by camlob; 09-27-2011 at 08:05 AM.
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Old 09-27-2011, 08:28 AM
  #17  
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Hi Camlob. Yeah. Its only for a handful of seconds before it levels off and tappers down to approx. 1100. Ive just looked at the "live" stored files and it appears to be 700-1200 so I may have exaggerated a bit....

Ive only tuned it cold start in 10-16 Celsius conditions (middle of winter) so I suspect it will improve a bit with warmer days. Ive got the table set up so that once the head temps get to 90 is backs down to around 1000 rpm. Its easy to play with - you could probably adjust yours yourself (sounds like your tables are reversed).

I find the higher idle with the sportier cams requires a different smooth launch technique.

That would be Colins competition car. Youd want to check the spec on that though as Im sure he had his trick heads, lifters etc with a number of other modifications to make it reliable. From what I understand thats been a test bed mule and has had many 100s of hours of development to get it making excellent power....
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Old 09-27-2011, 10:10 AM
  #18  
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Originally Posted by Macca View Post
Thanks Colin. Really appreciate the input. That heads me in the right direction.

My programming seems to be in line with what you have suggested (alpha N base tables etc). I idle warm at 1100. Idle is stable but first gear clutch balance at this idle isn't as easy as a lower idle speed. I have adjusted this down to 1000 rpm but have found that below this with electrical loads/air con clutch on that the engine may stall in certain situations.

Im pretty sure the cam may have something to do with this. That in conjunction with the LWFC etc. Since the cam (993SS) install the first 10-20 seconds cold idle produced wild hunting (600-1300 rpm) before it settles down (as soon as it can latch onto a head temp reading). I think this may be partly mechanically induced and possibly difficult to eliminate (it did this on Motronic as well as aftermarket ECU).

I will check with the tuner re the ISV based on your comments.

Looking at my programming console I have ISC set "open loop sol/stepper". Type = Unipolar (6 terminal) then a "max clamp" set at 70% and a "min clamp" at 5%. These mean nothing unless reverting to the base fueling alpha N tables and "idle base position table", but on the idle base position table I use the solenoid (%/DC) field to tune the idle for varying cylinder head temps by varying the % for each temp mark.

The tuner has installed 100s of these ECUs but I must confess mostly to race cars and almost never to 911s. Obviously there are some peculiarities to setting up a 911/993 on LINK ECU which they have no anecdotal experience in (although they did get LINK HQ in Christchurch to check their theory). I could find no other 993s running aftermarket ECU in a street application (drive ablility, electrical and air con loads etc being primary concerns).

I should think we almost have it as good as we can make it but will investigate the PWM vs PID angle and associated programming....

Shame you couldnt make it down for the Rugby World Cup. I could have shouted you a quarter final ticket for a few hours of your time on the dyno :-)

Cheers


The truth is that a non-race engine runs at less than full throttle for 99% of its life, hence the time you spend on the mapping and set up should reflect this balance. The problem you face is that most ecu manufacturers & tuners put 99% of their efforts to the performance at full throttle which is why you end up having to accept a compromise in driveability and idle control. I cannot comment on your Link system as I have not worked with it, however even though the M48 made a very reasonable job with idle control the M600/800 and new M84 is in a whole new league and as a result I have probably put more time into sorting this out than on dialling in the main fuel table.

The clamp that you refer to is the duty cycle of the valve, for reference the M84 settings vary from 30% to 80% with a normal setting of approximately 45-50%. For cold start the M84 can set the valve normal position and desired idle rpm for varying engine temperatures, the revised speed is then controlled with the PID functions as it would be when it is hot. Note that to get the 964 idle valve working correctly with any Motec system requires the use of a diode between the terminals, it is possible that your Link system will need the same, however if the Link allows you to test outputs you can check this with the ISV in your hand by observing the valve position from open to closed - this would give you the max/min duty cycle required by your set up.

PID is part of the strategy for duty cycle control which determines how far & fast the valve moves from the normal position to correct the error, in a very simplified terms Proportional is a linear response where you alter the slope of the graph, Integral is an increasing "exponential" response to speed up the change for large errors whereas Differential is the opposite and provides a damping function to prevent control overshoot.
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Old 09-27-2011, 10:11 AM
  #19  
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Originally Posted by camlob View Post
Hey Macca, your idle hunting between 600 to 1.3k is too wide. No wonder you were so disappointed with the build. Try and have the tuner fix it! Your cam is very mild so I dont see it linked to the cam profile. My brother has a similar cam on his 964 with a SW chip and no problem at all.

Mine doesnt hunt. On the other hand, it needs some work in cold start. When cold, idle is lower than when its hot. No problem when the AC is on. But other wise, it purrs like a cat.

Colin, a 320 degree cam confirms what I suspected My cam is only 292 in duration. I thought a 305 was too big but I guess I was wrong. Hmm...but that is your race car right?
Yes, this cam was in the 4.0 litre engine in my race car.
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Old 09-27-2011, 10:19 AM
  #20  
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Originally Posted by evoderby View Post
Interesting input Colin!

On your non-ISV race car do you run some sort of ignition timing idle control? I use this on my Cooper S with pretty nice results: programmed the DTA (Alpha-N) ignition map for the desired idle RPM as well as a 200RPM window around this increasing advance when the engine undershoots the desired RPM and vice versa.

Works rather well, especially considering it runs quite a lumpy cam (286 scatter) and the time honoured weber 45 to take care of fueling (injection is next to useless on siamese intake ports). In fact my 964 with modified ISV to prevent stalling doesn't do a much better job (70-100rpm hunting).

Then again didn't Porsche who had a big hand in designing the Harley V-Rod watercooled engine specifically (counter)map the engine to give the characteristic lumpy Harley idle? ;-)
With ITB's and no ISV you can only run ignition timing idle control but that said good idle performance needs perfect balance of the throttle plates (to each other and side to side).

On a stock 964 or 993, the only reason the Motec system makes a better job of idle control than a standard Motronic is when you get the parameters of the valve perfect and combine it with MAP correction of the main fuel table you get a rock steady mixture at iand below normal idle speeds, whereas with Motronic it hunts as the mixture cycles rich & lean with valve opening. On Motec, the 993 engine in my 3.2 would happily run at 920rpm within a 30rpm control window (deadband); if you ran the car in gear on the idle map the revs would drop to 700rpm & the engine would accelerate the car back up to 900rpm on the flat, although it did struggle to pull more than 700rpm uphill in 4th....

Last edited by NineMeister; 09-27-2011 at 10:35 AM.
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Old 09-27-2011, 12:25 PM
  #21  
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Originally Posted by NineMeister View Post
With ITB's and no ISV you can only run ignition timing idle control but that said good idle performance needs perfect balance of the throttle plates (to each other and side to side)....
I understand that, not everyone is using ignition to control idle however....

....a while ago I exchanged ignition maps with a person in the UK who hillclimbs his mini quite succesfully in the up to 1400cc class. Believe it or not when looking at his map it was an exact copy of a non vacuum advance cooper s distributor plot....the advances of modern management;-)
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Old 09-27-2011, 04:55 PM
  #22  
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Hi Colin. Im starting to understand the system more and more whereby what your saying is starting to make sense. Interestingly although I have the duty cycle for ISC/ISV set to 5 min 70% max almost all the operational parameters I have set fall between 37-55%.

We will spend some more time on this and get it as good as can be.

I really want to thank you for your contributions on this board. I know how long it takes to write a detailed response to a question like mine and given you also have a business to run and family life its a really unbelievable thing you do to give back a lot of free time not to mention invaluable experience to this board for nothing more than intrinsic benefit. I really take my hat off to people like yourself and other on this board - I really dont think you get enough praise and thanks from the rest of us!

Thanks again mate!
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Old 09-28-2011, 12:50 AM
  #23  
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Originally Posted by Jean View Post
Hi SwissSC

Don't hold your breath...and be happy with your engine.

Naturally aspirated engines have characteristics that makes them breathe (pun intended) a maximum certain amount of air that burns with fuel and produce a certain amount of torque. The maximum amount of torque by cubic centimeter of engine displacement (efficiency if you want) is extremely difficult to improve on a production based engine without doing dramatic changes to the engine design itself, I am not talking about exhaust modifications, or air fuel ratios or timing, not even improvements in head flow, I am talking about millions of dollars in R&D of inherent design changes of the engine and its electronic management.

To put things into perspective, it took Porsche 10-12 years of development (from the 993 to the 997) to see this efficiency increase by a mere 15%.. Meaning maximum torque produced by their engines per cubic centimeter increased by 15% only. Add to this, that most of this increase was achieved through an increase in compression on the engine, going to 4 valves and watercooled, and the rest from drastic improvements in engine electronic management.

Your car with specific cams and all those changes had its efficiency increase by 6% based on your max torque reading, and once you adjust for your displacement increase to 3.8, your maximum efficiency increase by 1% only, which is reasonable, maybe very slightly low. The Porsche varioram introduction on the 993 engine which was a great innovation and cost $$$ in R&D had almost similar results.

This engine achieved the efficiency that Porsche achieved with all the above modifications across 3 generations and millions spent in 10-12 years just by slapping a Motec on it

Motec is great, and I would install it on an old generation engine needing help, but dyno numbers like these are totally worthless from a buying decision perspective.

IMO with the amount of money SwissSC already spent he should purchase the motec. The processing speed of the motronic is too slow. Can you imagine even smartphones now have dual-core processors!

We can at least try and bring our engines up to modern spec by installing better ecu's etc. Our heads are also a limiting factor IMO so I am thinking down the road that I will probably change my heads eventually.

But you are correct also that making a decision based on a dyno sheet is not right. I would research and see where it all leads.

A few years ago it was unthinkable for a big displacement car to get 125hp/liter. Now Porsche did it with their RS 4l. Now that is something we certainly cant get!
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Old 09-28-2011, 06:59 AM
  #24  
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Originally Posted by camlob View Post
A few years ago it was unthinkable for a big displacement car to get 125hp/liter. Now Porsche did it with their RS 4l. Now that is something we certainly cant get!

Never say can't. I'm currently working alonside an engine consultant/guru who has achieved a reliable 148bhp/litre from a production based 2.0 litre 16v variable cam engine, so whilst this outstanding level of achievement would definitely not be possible with a two-valve per cylinder fixed timing aircooled engine, there is still a lot more possible than you might think provided you are prepared to try hard enough & have the resources to make it happen. Since the history books tell us that Porsche managed 110bhp/litre with the 3.0 litre RSR, I guess the lesson here is that nobody has (yet) tried hard enough to significantly better it?
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Old 09-28-2011, 07:21 AM
  #25  
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Originally Posted by Macca View Post
Hi Colin. Im starting to understand the system more and more whereby what your saying is starting to make sense. Interestingly although I have the duty cycle for ISC/ISV set to 5 min 70% max almost all the operational parameters I have set fall between 37-55%.

We will spend some more time on this and get it as good as can be.

I really want to thank you for your contributions on this board. I know how long it takes to write a detailed response to a question like mine and given you also have a business to run and family life its a really unbelievable thing you do to give back a lot of free time not to mention invaluable experience to this board for nothing more than intrinsic benefit. I really take my hat off to people like yourself and other on this board - I really dont think you get enough praise and thanks from the rest of us!

Thanks again mate!
Glad to help. Here's a few more numbers to consider from our M84 file:

Aim RPM (hot) = 920
Normal position (set slightly below usual operating duty cycle) = 48%
Initial position (where the valve is before idle control starts) = 55%
Min duty cycle (hot) = 35%
Max duty cycle (hot) = 80%

All of these numbers are set in tables of cylinder head temperature vs duty cycle, so obviously I use slightly larger numbers when the engine is cold to jack up the idle speed with a richer mixture.

If you are using Alpha-N you must also use a MAP sensor connected to the plenum to correct the fuelling when the valve opens & closes. The MAP correction function is easy to set up:
MAP Fuel correction
0 -100
20 -80
40 -60
60 -40
80 -20
100 0
120 +20
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Old 09-30-2011, 06:02 PM
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Colin

I will come back to you as soon as I am clear what to do first on my project list:

- lsd from a carrera cup car
- 8:32
- uniball, harder bushings and thicker stabilisator (I used to drive impact bumpers and I felt more comfortable creeping around the "dynamical limits" with them)
- rolling road mapping or directly take your motec solution (question of logistics from Switzerland to your place...)
- loosing further weight (car & me...)

And of course: question of budget ;-)

Hakan
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Old 09-30-2011, 06:46 PM
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Hi Colin,

Is there a way to significantly improve idle and cold starts for ITBs, for a street car? Do you ever instal IACV with ITBs?

Thanks!
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Old 09-30-2011, 07:20 PM
  #28  
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Hi Colin.

Ive re read your emails a few times and also looked into my programming software. It appears my idle control settings are set up in open loop. As you indicated this is common practice with tuners like mine who are building race car engines and spending their time tuning the fuel and ignition curves on the dyno rather than spending that same time fine tuning multiple parameters for real world driving (street car) with multiple load factors (lights, radios, air con clutches) etc. A perfect idle doesnt seem to be a focus for these guys when quoting a fixed price for dyno time and tuning, rather just a good idel that doesnt stall. Seems fair enough...

In any case I have now opened the close loop parameters (not connected to vehicle) and I can begin to make sense of the data you have given me. I have taken the liberty to purchase a band new ISV (my one is 18 years old and although it was cleaned a couple of years back I really just want to eliminate it as a potential issue and consider it a wear item).

The open loop system provides much more detail for tuning including target idle rpm. It will require a bit more time to set up but can be done with a bit of trial and error off the dyno so once the new ISV is fitted we will be dedicating a few hours to setting it up and teaching me the relationships between variable so I can perform final tuning over time (cold starts, different scenarios etc).

In order to facilitation a quicker initial set up and eliminate false starts it would be great if you could share your experience with the fillowing settings (on or offline) when you have a moment? May just give me a few clues....

Recommended deadband rpm?
Rpm lockout?
Idle rpm target for head temps (assume LWFC and pulley with mild cam - 993cup style)

Also and importantly do you every make any changes to the stock 993 ISV (i.e. adjust the air bypass screw etc?).

Thanks so much. It wasnt until I delved deep into the settings that I started to understand the approach you have taken and thus how it differs from how my car is currently set up. We are using a 993 ISV three wire and it is set up correctly to ECU (which can handle dual outputs for this).

My tuners original thoughts is that the stock ISV may not have flowed enough air or been fast enough for the application - but its actually probably a matter of more fine detailed tuning with a ISV proven to be in optimal condition....

Cheers
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Old 09-30-2011, 07:35 PM
  #29  
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Oops one last question. On open loop the ISV setting is 200 Hz frequency under auxiliary output settings table. Is this the correct setting for 993 ISV Bosch unit as it seems to be a default setting in the software the tuner hasnt adjusted?

Thanks again
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Old 10-01-2011, 08:02 AM
  #30  
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Macca,
Here are the settings you need:

Frequency = 90Hz

Deadband = 50rpm (I use 30 when the settings are close to perfect)

Suggested Idle speed to cylinder head temp:
0C 1150rpm
20C 1000rpm
40C 980rpm
60C 950rpm
80C 930rpm
100C+ 920rpm

RPM lockout (?) = Switch on point is <2% throttle, <1500rpm

The idle valve is more than large enough for your engine so just fit the new one straight out of the box, no changes required. The only reason it may not be fast enough will be down to the system response of the software, so assuming your software runs PID control strategy, start with zero everything and get the normal or null position about right, add the proportional gain first until you gain some control, add a little integral to speed up the response before finally damping down control overshoots with derivative. Be warned that too much P or I can cause hunting, so don't be fooled to using D to fix bad settings.
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