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Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
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 Posted: Sat Dec 18, 2010 3:57 pm Post subject: Trigger wheel testing?? |
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Anyone know of a way to test whether the vr sensor is mounted square and at the proper distance from the trigger wheel. Mechanically I could spin the motor (currently out of the car) and use a 1mm feeler gauge on each of the 36 teeth.
I'm looking more for an electrical method such as oscilloscope testing. Just how precise does the vr sensor distance have to be from the trigger wheel tooth ?
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1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Sat Dec 18, 2010 5:43 pm Post subject: |
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Sensor should provide a square wave output. Should be able to spin the motor and at the scope.
I think MSnE might even allow you to watch the sensor input as well.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Sat Dec 18, 2010 6:21 pm Post subject: |
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EDIS rocks, I wouldn't worry about it to much. It does not have to be precisely mounted at all. Set it at 1mm and spin the motor, if it doesn't hit the sensor, your good to go. Make sure your bracket is sturdy enough that it doesn't flex during vibration, we destroyed a VR sensor that way once (rev the motor up and the bracket starts vibrating then hits the trigger wheel, oopsie)
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
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| Posted: Sat Dec 18, 2010 7:43 pm Post subject: |
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So min how far off is too far? 2,3,4,5 mm?
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Sat Dec 18, 2010 7:51 pm Post subject: |
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It's supposed to be <1mm if your trigger wheel is mounted OK then this should be easy to achieve.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
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| Posted: Sat Dec 18, 2010 7:56 pm Post subject: |
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| Rich H wrote: | | It's supposed to be <1mm if your trigger wheel is mounted OK then this should be easy to achieve. |
I read that on the manual might just use a feeler gauge to test each tooth as I spin the motor just to ensure concentricity, just curious what margin of error the edis etc can tolerate in terms of sensing the spinning tooth from over 1mm
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Sat Dec 18, 2010 10:54 pm Post subject: |
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As long as it's under 2mm it'll probably work, but I'd aim for .7mm if you can.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Sun Dec 19, 2010 1:45 am Post subject: |
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| fiat22turbo wrote: | | Sensor should provide a square wave output. |
Bullshirt!
It`s a VR sensor and will output a SINE WAVE.
Ideally you want a CONSISTENT 0.5mm gap but more will work, as others have found. The important aspect is that the wheel be mounted concentrically, ie. an EVEN gap all round. Any eccentricities will result in timing variations, then lost/ dropped tooth counts if severe.
Apparently EDIS tolerates quite a poor/ irregular signal. Realize you only have MS1 and am more or less stuck with EDIS. Personally would suggest upgrading to the MS2 processor (plug in daughter board) sooner rather than later. Then you can piss off the EDIS and allow the MS, running the extra code, to decode the wheel directly. Regardless what the Ford fans say, that is the preferred option. V3.0 board has integral VR processing but is an easy add-on to earlier PCB`s. MS2 allows for more inputs, outputs, and features that MS1 simply can not provide with it`s limited capabilities. Obvious one that comes to mind is integrating your A/C comp clutch, so it disengages when you need all the power, say at 80% TPS.
Easiest and cheapest way to determine toothed wheel signal, if you don`t have a scope, is to use the trigger logger feature of Tuner Studio. Free D/L. Note how you want all the graph, representing individual tooth voltage, to be even. This indicates all teeth are read and a consistent gap.
http://www.efianalytics.com/TunerStudio/#triggerLogger
In all honesty Scorp, you are much better off posting these sorts of MS question on the MS forums. You will get an accurate answer, and any erroneous posts will soon be corrected by those who have the experience and know WTF they`re talking about. At least RTFM as much as you can, and then search the forums. Very unlikely you will experience any unique issues that have not occurred to others previously.
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World`s quickest 924 2L slushbox
| Allan @ DTA wrote: | | I have no issue with superchargers, they are for guys who want to drive a car rather than talk about horsepower with their baseball cap on backwards |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Sun Dec 19, 2010 9:29 am Post subject: |
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| Scorpio wrote: | | So min how far off is too far? 2,3,4,5 mm? |
Last time I did it, I just stuck two dimes together and put them on the VR sensor to space it out so whatever that comes out to for distance. Keep it less than 3mm and you should be fine. I'd err closer than farther away.
Concentricity of my trigger wheel is fairly terrible, its a late sunday night installation job that I haven't bothered fixing yet. Doesn't seem to be causing any problems that I can notice, been running the car the whole time with it like that. First time we fired up my buddies toyota truck his EDIS ring ate his VR sensor for lunch due to the vibration issue I noted in my previous post, he continued to use that munched up sensor for 8-10 months afterwords anyways.
As mentioned EDIS is very tolerant, get your trigger wheel mounted as concentrically as is feasible, and then set your VR less than 3mm. There are plenty of other things you can worry about, this shouldn't be one of them. I've installed EDIS on every one of the car's I've megasquirted because of this, I don't need the additional spark control that letting megasquirt run it would give. If I did I'd just upgrade to a CNP or similar setup.
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Sun Dec 19, 2010 8:40 pm Post subject: |
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Irrespective of the various pros and cons of running EDIS, and individual personal opinions, here is a screen shot of the TS wheel logger. Taken a month or so ago, it helped me finally resolve a persistent tuning problem that no one here, and less than a handful of MS experts, are even aware of.
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World`s quickest 924 2L slushbox
| Allan @ DTA wrote: | | I have no issue with superchargers, they are for guys who want to drive a car rather than talk about horsepower with their baseball cap on backwards |
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Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
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| Posted: Sun Dec 19, 2010 9:27 pm Post subject: |
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what problem was that? sounds complicated
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Mon Dec 20, 2010 6:42 am Post subject: |
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Had ignition timing retard with increasing RPM. Was easily, but not accurately, compensated for in the tune, adding additional timing per RPM bin. The root cause however was indeed complicated and became a source of frustration to identify and eliminate.
TBH, my cam driven tach wheel is not ideal and a dual crank AND cam wheel is preferred. However with the dual 6PK belt drive for the accessories and blower there are practical mounting and pickup issues, leading to another compromise. Initially thought timing belt stretch at higher RPM was to blame but could not measure any more than 1* variation on an excessively slack belt. The cam always lags, valve train tension ensures this.
The MS2 extra has a spark hardware latency setting that permits up to 170 microseconds compensation, dramatically reducing the retard but not eliminating it. Biggest variation is during fast acceleration, since from the time the wheel count is processed and spark outputted the crank has gained more momentum. Steady state is not a problem. Put simply, the ECU can not predict the future.
Using a dual trace scope, one channel with actual spark from an inductive pickup and the other channel syncing from the crank via an optical pickup, could measure the equivalent of 2* lag. Bugger all for most people really. even if they could measure it. Even on my basic little engine 2* is the difference between detonation and not. To most pro tuners though 2* is a major concern and for me personally became a technical challenge. No MS`s were aware but EFI experts and top tuners were and the issue was raised on EFIU board. Modifications to the VR input circuit fixed my issue although a code change is preferable IMO, but i`m a hardware man.
Getting back to EDIS, this similar problem will occur, (and others) albeit only half as bad since the tach pickup is crank (VS cam) driven. Depending on the configuration with MS this particular issue is compounded. The EDIS clock speed is only 250KHz. Reasonable for the 90`s though, just like analog brick phones were. IIRC MS1 runs at 4MHz and MS2 @ 20MHz.
http://www.dainst.com/info/edis/edis.html
http://www.vems.hu/wiki/index.php?page=EdisIgnition%2FFaQ
Yes, (Why do I think Min will jump in here???  ) I know any fool can simply add an extra bit of timing or chewing gum here or there to tune it out. Again, it was the technical issue that concerned me. You will never know though Scorpio and not let something you don`t know about be a problem for you. Enjoy your MS, EDIS, boost and all the hot chickybabes you pull.
_________________
World`s quickest 924 2L slushbox
| Allan @ DTA wrote: | | I have no issue with superchargers, they are for guys who want to drive a car rather than talk about horsepower with their baseball cap on backwards |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Mon Dec 20, 2010 11:17 am Post subject: |
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| RC wrote: | | Yes, (Why do I think Min will jump in here??? ) |
We both have ... strong personalities. I like you RC, you post good stuff, I try to refrain from needless conflict with you.
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Scorpio
Joined: 05 Jul 2007
Posts: 1957
Location: Brisbane, Australia
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| Posted: Mon Dec 20, 2010 3:13 pm Post subject: |
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Only understood a fraction of that rc, ignorance is bliss as long as my engine doesn't blow up!! Hahaha
_________________
1979 NA
MS1..EFI..
GARRETT T25 TURBO
BILSTEIN SHOCKS
GT BASED CUSTOM BODYKIT
Brisbane , Australia
Think mean think fast
all youll see is
my Porsches Arse!!! |
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macBdog
Joined: 16 Aug 2004
Posts: 1111
Location: Brisbane, Australia
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| Posted: Mon Dec 20, 2010 5:50 pm Post subject: |
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I mounted my trigger wheel to an electric drill and tested varying distances. Evene >2mm worked on the bench but I got it as close as possible on the motor to account for noise.
The first time I ran the car there was a slight "tink tink tink" as one of the trigger wheel teeth must have been slightly oversized and hit the sensor. It went away after a minute or so 
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1979 931 with a 350 chev
1973 911E with EFI
| p-talk wrote: | | I'm still convinced the word 'Porsche' makes people crazy in all kinds of ways |
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