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Engine Specific Info and Questions => IDI Engine => Topic started by: 92EcoDiesel Jetta on July 13, 2009, 10:44:42 am
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I wanted to check my idle rpm but that's kinda hard to do w/o a tach. I have all the Tach parts from a Mercedes 300D so decided to hook it up to the Jetta as test equipment. Circled in red is the magnetic pickup, in green is the tooth to generate the signal for the pickup. It's just a small magnet with a dab of crazy glue.
(http://i574.photobucket.com/albums/ss184/EcoDiesel/tachpickup_071309_001.jpg)
Here's a video of it running. I will see if it is possible to trim the tach down and fit it in place of the clock. If it won't fit, I'll neaten it up and mount everything in a box and leave it as test equipment and look for another tach from another car that will fit.
(http://574.photobucket.com/albums/ss184/EcoDiesel/Video_071309_001.flv)
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ps. the pickup is mounted to a bracket mounted to one of the power steering pump bolts. The "tooth" magnet is on the crankshaft pulley.
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the most important part...
DOES IT WORK?
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In case you don't know, click on the pic below and the video will play.
(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_Video_071309_001.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=Video_071309_001.flv)
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Nice
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Sweet that's pretty cool. Why not just use the stock tach though?
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What stock tach? Mine didn't come with one. I've read about using the alternator with the W terminal. I don't really like that idea because it needs to be calibrated for pulley size and I don't have any of those parts and I'm not about to look for them and buy them. I know the Mercedes tach is pretty accurate and no calibration is necessary.
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Very nice!! I wonder what the signal is from Merc box to the gauge itself... I used a similar setup using 2 teeth on the crank pulley, magnetic pickup, and an aftermarket gasser tach.. Needed some way of converting the trigger pulses to a tach signal.. I used a GM HEI ignition module but it isn;t so accurate unless there is something wired in to simulate the coil.... For now it's an 1156 light bulb, but they burn out frequently...
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All you need is to find the cluster from a mk2 diesel with a tach. Match up the wiring style, CE1 or CE2 and that's about it. I've always thought that no calibration was needed but I could be wrong.
Either way though, I like what you've done and my truck will probably get something like that
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maxfax, the Merc box puts out a square wave pulse signal to the gauge, which also has a chip in it.
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Thanks for that info.. Might just be easier to stick with my a/c pulses than try to calibrate everything to work with anything.. Not to mention I have get to find a complete working Benz diesel tach in the boneyards around here...
Burn, take a look at the housing for the IP gear on your truck.. There should be a plug either at the 12 o clock or 2 oclock postion.. That's where they screwed in a magnetic pickup for the factory tach....Although I can;t remeber for sure if there were specfic teeth to trigger it, or if it just used the teeth on the IP gear... If it used the teeth on the gear it would probably be easier to trigger it off the crank for calibration sake...
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Most mag pickup tachs I've seen triggers on one tooth (that 's one per rev) of the crankshaft. That tooth must stick out from the rest. If you try to trigger of the starter gear of a crankshaft with it's many teeth, you will get a very very high reading (if the tach can process it at all)!
Here's my latest tach. Click on the pic to play the video. It's a one piece self contained unit that needs just power and the mag pickup wired to it.! I hope I can fit it in place of the clock. If not I'll make it a stand alone unit.
(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_Tach_071609_001.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=Tach_071609_001.flv)
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Thanks Maxfax. I've often wondered why that hole was there
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fixed the video link above, should work now.
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At idle the Mercedes tach says it was 1000 rpm, this one says 750. Not sure which is correct. I should be able to calibrate it with a 60hz 120 V AC motor. I think I have one that's 1725 rpm and one that's 3450 rpm that I can glue a tooth to the pulley on the motor and calibrate the tach with.
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Thanks for that info.. Might just be easier to stick with my a/c pulses than try to calibrate everything to work with anything.. Not to mention I have get to find a complete working Benz diesel tach in the boneyards around here...
Burn, take a look at the housing for the IP gear on your truck.. There should be a plug either at the 12 o clock or 2 oclock postion.. That's where they screwed in a magnetic pickup for the factory tach....Although I can;t remeber for sure if there were specfic teeth to trigger it, or if it just used the teeth on the IP gear... If it used the teeth on the gear it would probably be easier to trigger it off the crank for calibration sake...
no.
vw never put a tach there.
they used the w term on the alt.
and for the people who build the photo eye tach,
theres a disk of metal on the front of the injection pump pulley. 2 quadrants are painted black, and 2 are left un painted.
they never used a magnetic pickup on the teeth of the pulley.
plus, most of the older engines dont even have the hole next to the ip in the cover.
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Most mag pickup tachs I've seen triggers on one tooth (that 's one per rev) of the crankshaft.
Yeah most diesel setup I have seen used one tooth on the crank and some variety of electronics to convert the signal.. I used a standard ole Sunpro gasser tach set to 4 cyl.. So for calibration 2 teeth were much easier.. One rotation of a distributor = 2 crank revolutions.. So 2 teeth on the crank would give the same result...
Finally I got my hands on a factory gasser tach so I swapped that in with no mods required to the tach (plus I have no W terminal on my Alt).. But of course the Tach itself took a poo recently, so it's back to the dorkey 5" sunpro tach for now..
no.
vw never put a tach there.
No they didn;t... But I was referring to the diesel in his Ford.. ;D
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While I certainly commend your ingenuity and resourcefulness, I have to mention that the Merz 300 series tachometers are notoriously unreliable. I've fixed them before because they fit in the Merz cluster, but there is no way I'd use any parts from one on a VW. I am most fond of the Ford probe method that Jimbote outlined in the FAQ. Similar or possibly less complicated install, uses a stock gas VW tach, inexpensive, fits the cluster perfectly, etc...
I just read Jimbote's method. Thanks for pointing out that thread, Andrew. Certainly having a VW tach that fits in the cluster without modification is the way to go. When I saw the "Ford probe method" in your post I thought it was a tach from a Ford Probe car at first lol. But it's actually a magnetic pickup from a Ford, the same type of pickup as used in the Mercedes and many other diesels with a tach. Magnetic pickups are easy to make. All you need is a short 1/8 dia. iron bar core , magnet wire, epoxy and an electric drill. Just wind the wires over the iron core with the drill and bring the leads out and encapsulate it with epoxy. I had to make one once and it worked fine.
I will look for a VW gasser tach and use the Mercedes mag pickup which is already installed which I think will work but won't know for sure till I try it. I just have to add another tooth 180 degree from the tooth that's already there.
As far as the Mercedes tach being unreliable. Are you referring to the tach amp? If so I agree. I've repaired a few of them. But once repaired properly, it is as reliable as any other tach.
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The problems I've seen with the Merz tach have been either the amp or the large multi-pin connector in the engine bay.
I like that the magnetic pickup when used with the VW tach doesn't need any amplifier at all.
Andrew
The location of the Mercedes tach amp high up in the engine compartment and its circuitry being potted certainly does not help. Heat and poor solder joints is what causes them to fail. The second video I posted is a self contained tach, but it probably won't physically fit into the VW cluster without modification. Would you know if Mark II gasser tachs works the same as the one Jimbote used (I think his came from an 83 GTI )?
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All you need is to find the cluster from a mk2 diesel with a tach. Match up the wiring style, CE1 or CE2 and that's about it. I've always thought that no calibration was needed but I could be wrong.
Either way though, I like what you've done and my truck will probably get something like that
Does anyone know if its possible to swap the tach from a CE1 turbo diesel cluster into a CE2 diesel cluster with the clock in it? I have a spare CE1 TD cluster but it won't work in a CE2 car.
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All you need is to find the cluster from a mk2 diesel with a tach. Match up the wiring style, CE1 or CE2 and that's about it. I've always thought that no calibration was needed but I could be wrong.
Either way though, I like what you've done and my truck will probably get something like that
Does anyone know if its possible to swap the tach from a CE1 turbo diesel cluster into a CE2 diesel cluster with the clock in it? I have a spare CE1 TD cluster but it won't work in a CE2 car.
time for a wiring harness swap! CE2 has 1 plug and CE1 has 2 plugs. its kinda a *** to pull the whole dash to swap the wiring.
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All you need is to find the cluster from a mk2 diesel with a tach. Match up the wiring style, CE1 or CE2 and that's about it. I've always thought that no calibration was needed but I could be wrong.
Either way though, I like what you've done and my truck will probably get something like that
Does anyone know if its possible to swap the tach from a CE1 turbo diesel cluster into a CE2 diesel cluster with the clock in it? I have a spare CE1 TD cluster but it won't work in a CE2 car.
time for a wiring harness swap! CE2 has 1 plug and CE1 has 2 plugs. its kinda a *** to pull the whole dash to swap the wiring.
I'm not looking to do a whole dash wiring harness swap. To clarify, all I was asking was can you use the tachometer from a CE1 cluster in place of the clock on a CE2 cluster. Maybe someone would WTT a CE1 for a CE2 tach or whole cluster.
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man, i've been looking for a ce1 cluster for awhile now. all I got is a ce1 gasser cluster(in the car now) with tach. :'(
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What year & model MK II diesels came with a tach? What is CE1 and CE2? Please explain.
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How do they read RPM when they dyno A diesel? Seems like that would need to be pretty accurate.
Also is there any concern with the weight of the magnet throwing the already fragile crank pulley off balance? Especially since it is located as far as possible from the center causing the greatest moment? Or is it so small that the effect is negligible? Since we expect hundreds of thousands of miles from these engines I can't help but ask
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The problems I've seen with the Merz tach have been either the amp or the large multi-pin connector in the engine bay.
I like that the magnetic pickup when used with the VW tach doesn't need any amplifier at all.
Andrew
Andrew, have you successfully duplicated jimbote's method? I got hold of a MKI gasoline tach and did a bench test with it and was not able to get a reading from it. I didn't have a Ford probe and that may be the problem. The magnetic pickup I was using was putting out only 300 milivolts and that may not be enough for the SAK215 chip in the VW tach. I'll keep working on it.
The bench test setup was a 1725 rpm AC motor that I added 1 or 2 trigger "tooths" to. I used this same setup to check the calibration of the Mecedes tach and it was spot on.
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Andrew, I read on another forum you found a Ford probe for $15. Where can I get one for that? :)
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the same place you can get running driving cars for $250 bucks.. craigslist!
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if anyone can find a probe such as the one mentioned i'd be interested. I have a dead tach in my dash that does nothing.
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Anyone know if this tach originally ran off the ignition coil or the W terminal of the alternator? Per the data sheet, the SAK215 needs 0.5 volt minimum to trigger, max 20 v. I tried bypassing the RC network at the input and wired the pickup direct to pin 2 and it still wouldn't work. So I momentarily touched pin 2 direct to +12V and got the needle to jump slightly, which confirms the tach is not dead, just need the proper amplitude to trigger it. I found a pickup from a CIS distributor which puts out just around 0.5 v per my measurement. If I can set a small enough gap, maybe it will put out enough voltage to trigger.
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Of course Andrew, it would never work otherwise. Can you measure the resistance of your Ford probe? I am curious how it compares to the Mercedes pickup at around 70 ohms.
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I didn't mean any offense, it's usually something little. You're sure you haven't gotten the 12+ and ground reversed?
Can you measure the resistance of your Ford probe? I am curious how it compares to the Mercedes pickup at around 70 ohms.
1,130 ohms.
Andrew, no offense taken. :)
I am 100% sure I didn't reverse the + and ground since that would have fried it. As I said earlier I was able to make the tach needle move by manually pulsing the input with 12V. I think the problem is I need a higher voltage from the pickup. I'll see if the distributor pickup will be good enough. It is 1.1k ohms, close to your Ford probe.
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Finally got around to test the new distributor mag pickup with the Mk I tach and it's working!!!!! ;D
Here's a pic of the pickup temporarily installed. Note that I changed the "tooth" to a small round super magnet in hopes of getting a higher output. I epoxied the magnet in place so it does not fly off at high PM (ask me how I know ;D ). I bypassed the RC network on the input of the tach which attenuates the input signal and went direct to pin 2 which is the input to the chip and it worked!!!
(http://i574.photobucket.com/albums/ss184/EcoDiesel/tachpickup_080709_001.jpg)
Here's a video of it under test. Click on it and it should play. I also took out the clock in my MK II cluster to see how the tach will fit and it looks like I have to cut a big round hole in the back of the cluster plastic housing in order for it to fit. There's also the empty space of the fuel gauge which I will have to cover up, or, if it'll fit, I will put the LCD clock from the MK I cluster there. Oh yeah and I have to spray paint over the "unleaded fuel only".
(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_VWtach_080709_002.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=VWtach_080709_002.flv)
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Andrew, can you be more specific on which gasser tach will fit my cluster better?
I forgot to mention that in the video, there's only one "tooth" rather than two. I was surprised that the rpm was correct when it should have been 1/2 of that with only one tooth.
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Hi Andrew, sorry I' been busy and have not done much with the tach. My cluster has 1 connector like the pic you posted. Maybe it's easier to swap the speedo instead of the tach like I am trying to do. I am wondering what else will not work other than the glow plug light and whether I can safely plug in the connector without frying anything?
Anyway I tried the tach again and it stopped working! Turned out the magnet I glued onto the crankshaft pulley was missing! I will clean the mating surface better and try again with crazy glue and epoxy. If that doesn't work I will get 2 studs welded and use a nut to secure the donut magnets.
I also tried to calibrate the tach with a 1725 rpm ac motor. At first I tried to cut a v notch in the motor pulley for the mag pickup but it didn't work- it did not generate enough voltage. So I bolted the magnet to the pulley and the tach works, but was reading only 1400 rpm. I tried adjusting the potentionmeter but could only get it to go lower than 1400 rpm but not higher. I need to get another magnet and add it 180 degree apart then do the calibration again.
Once itcalibrated, I am going to try to fit it in my current cluster and see how that goes. If it's not physically possible then I will look for a CE1 cluster as you suggested.
Can you post a picture of your cluster? I imagine it's like this:
(http://i13.photobucket.com/albums/a269/libbybapa/BVQ9cpBWkKGrHgoH-CcEjlLlyiyvBKRod7p.jpg)
How about swapping out the whole cluster for one like this? (http://cgi.ebay.com/ebaymotors/85-92-MK2-VW-JETTA-GOLF-GTI-INSTRUMENT-CLUSTER-GAUGES_W0QQitemZ160353236700QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item2555cc36dc&_trksid=p4506.c0.m245)
You could swap in your speedo. You might need to adjust the wiring in the connector and add the glow plug led.
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Here's my calibration setup:
1725 RPM motor with 2 donut supermagnets as the "trigger tooths" I turned the adjustment pot till I got 1725 RPM. The range of adjustment was 0 to 2400 RPM.
Now it's just a matter of fitting the tach into my cluster and attaching the 2 donut magnets to the crankshaft pulley so they don't fly off again. lol
(http://i574.photobucket.com/albums/ss184/EcoDiesel/?actionPhoto_081409_003.jpg)
(http://i574.photobucket.com/albums/ss184/EcoDiesel/?actionPhoto_081409_004.jpg)
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so they don't fly off again. lol
(http://i574.photobucket.com/albums/ss184/EcoDiesel/?actionPhoto_081409_003.jpg)
(http://i574.photobucket.com/albums/ss184/EcoDiesel/?actionPhoto_081409_004.jpg)
THAT is the key. Anyone have any ideas? i doubt a glue of any kind would work?
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I have glued a magnet to a flywheel before with just crazy glue and it stayed. I think I just have to do better surface prep before apllying the glue. I will sand it down then clean with solvent and see if that'll do it. If it still don't stick, I will either weld or tap two 6-32 studs in the flywheel and put a nut on the donut magnets.
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ah! good idea!
Where again does one find the sensor that counts the magnets passing? I know someone said off of a different car but any examples so i can narrow my search in the junk yard?
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ah! good idea!
Where again does one find the sensor that counts the magnets passing? I know someone said off of a different car but any examples so i can narrow my search in the junk yard?
Mine is from a distributor from a gasser but I do not know which car it came from. I think your best bet is just find one and try it, or get the Ford probe that Jimbote recommends. It seems having a higher resistance correlates to higher output. The tach needs a certain level before it will trigger. The one I used did not put out enough voltage with a ferrous "tooth" but I was able to increase it by using donut magnets instead.
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Yeah using magnets is definitely the way to go. I have an external tach i'd like to drive with it. You know, like one of those ricer tachs but its not massive and its not in front of my face on the dash.
So im looking for a photogate type deal that will either be actually on a distributor? I was thinking it would be on one of the spark plug wires? If anyone has any pictures I'd really appreciate that! :D
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I haven't updated this thread because I haven't been working on it lately. Anyway, I bought a CE2 gasser cluster a few weeks ago and been trying to get the tach in it to work the last few days. I connected the 28 pin connector on the dash to the cluster, connected the hall effect sensor to pin T28/10 tach signal. The hall effect sensor was driven by 2 magnets on the pulley of a 1725 RPM AC motor and the tach didn't move. This was using the same setup I used to get the CE1 tach working. I kind of expected the CE2 tach not to work because I have not bypassed the RC network on the tach circuitry on this CE2 tach like I had to do with the CE1 tach. The tachs on the CE1 and CE2 cluster use the same chip but the layout is different. The CE1 tach has its circuitry on a small round PC board on the tach itself while the CE2 tach has its circuitry on the same board as the rest of the electronics for the cluster. So I went ahead to trace out pin T28/10 and it went no where near the tach chip on the PC board. Not wanting to waste time to figure why pin T28/10 does not go to the tach chip, I soldered a wire directly to the input of the tach chip and made the same mod as I did to the CE1 tach. It works!!! In the video, as I turn the key on, the tach jumps to 1725 RPM reading the speed of the AC motor, then I started the engine and the temp and fuel gauge registers and oil pressure comes up. Oh, how do you like the location of my oil pressure gauge? I still have more work to do such as fastening the 2 trigger magnets to the crank pulley, hooking up a glow plug light which I will do when I move the glow plug relay out of the fusebox and into the engine bay. I will connect the glow plug LED directly across the glow plugs instead of to the glow plug relay.
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(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_Video_090309_002.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=Video_090309_002.flv)
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When I started this tach project, I first used a tach from a Mercedes, then one from a Peugeot, then a tach from a VW CE1 cluster and finally the CE2 cluster. I have a lot of parts I have bought for this project and they are for sale. The Mercedes and Peugeot tach will work on any engine once you have a trigger set-up and sensor installed. The Mercedes and Peugeot tach comes with the tach, mag pickup, and whatever electronics so it is complete. The CE2 cluster from my Ecodiesel has the CE1 gasser tach installed, an LCD clock has been put in place of the vacant temp gauge under the tach and the unleaded fuel decal has been sprayed over with flat black paint. It looks pretty good. I have no need for it since I have a CE2 gasser cluster in my car now so it is also for sale. If you want a cluster with a tach and LCD clock here's your chance. Send me a PM if interested. I will post some pics later.
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I've got the 2 trigger magnets installed. I used a Dremel flex disc and hit the crankshaft pulley down to the bare metal, then use crazy glue on the magnets. After it's dry, I added JB Weld to the hole of the donut magnet and also the outside of the magnet so it's well supported by epoxy. Click on the pic below to play the video (in case you don't know). I tried to not rev it too much since the epoxy won't be fully cured for 24 hours.
(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_Video_090309_003.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=Video_090309_003.flv)
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Andrew, thanks again for telling me about the Jimbote method otherwise I'd still be trying to fit a Mercedes tach in the cluster lol. I am curious what size is the Ford probe? The square hall effect pickup I'm using is about a 3/4" cube. Gasser tachs that run off the ignition coil is seeing pretty high voltages and has circuitry to attenuate that voltage. I had to bypass that circuitry and also use magnets for the triggers to get higher voltage to the tach chip in order for it to work with the pickup that I am using. My guess is the Ford probe pickup must put out a much higher voltage than what I'm using, thus my question to its size.
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Thanks for the pic Andrew. Is the Ford probe magnetic? i.e. if you put an iron screw on it, does it stick? Have you installed the tach yet? I'd suggest getting the tach and probe working on the bench with an AC motor of known RPM, before wiring it up in the car.
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Andrew, magnetic is GOOD! They have higher outputs than non magnetic. Let us know when you get yours working.
I've not driven the Jetta much till today, so the epoxy's been curing all this time and I've rev-ed the engine a bit and the magnet triggers on the crankshaft pulley hasn't fallen off lol. Here's a pic at 55 it's doing 2500 rpm. Is that about right for a 92 Ecodiesel?
(http://i574.photobucket.com/albums/ss184/EcoDiesel/Photo_091009_001.jpg)
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Sounds reasonable. Have been here (http://www.vwdiesel.net/forum/index.php?topic=16504.0) and done the math?
Not sure if I did it right but per GolfJettaTransRatio.xls , I plugged in 2500 rpm on the row for the AVX transmission got 82 km/h in 5th which is 50.95 mph. About 3 to 4 mph slow.
But from http://scirocco.org/gears/ I plugged in tire size 185 65R 14, 4.25 final drive, 0.75 gear ratio, 2500 rpm and got 54 mph, which is what I am seeing on my speedo.
Here's a video of me shifting gear merging into highway traffic. (click to play). Video starts with 2nd gear and ends in 5th.
(http://i574.photobucket.com/albums/ss184/EcoDiesel/th_Video_091009_002.jpg) (http://s574.photobucket.com/albums/ss184/EcoDiesel/?action=view¤t=Video_091009_002.flv)
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The end of the video shows at 3000 rpm it's doing 65 mph. I plugged the numbers into http://scirocco.org/gears/ and got exactly 65 mph. ;D