I currently have MS2 v3 in my fiero, i also have a quad 4 in it, I'd like to get my speedo working. I used to use the factory ECU and rockcrawls circuit to get a reading but since removing the factory ECU i haven't had a working speedometer. Whats everyone else doing?

What transmission are you using/what type of VSS?

The ECU doesn't need to be there for the speedometer. The VSS wires go through the C203 to the speedometer. Depending on the VSS, you may need a dakota digital converter.

it is mildly possible you could slide in a fiero VSS and have it output nearly correct.

In the mean time, a gps is cheap.

LOL Currently I'm really good at guessing my speed base on RPM, I'm using a 90 beretta transmission i believe the speedo signal is 4000 pulses per min and is a triangular wave, it's been so long i cannot recall properly, it's was converted in the past by rockcrawls cap circuit to trim the waveform output from the ecu to (1200 PPM square wave???) for the factory speed gauge, however the ecu doesn't work without everything else plugged into it.

Why not drive the speedo off the VSS like factory and see what happens?

If the Beretta VSS outputs a 4000 PPM signal, then just connect it directly to the Fiero speedo.

Why would Megasquirt have a VSS input?
I'm running version 3.110 (the latest) of the Bowling & Grippo code with my MS2 V3.0 and there is no feature requiring a VSS.

If you want traction control or something, it's pointless to use the VSS on the driving wheels.
The only thing it might actually be useful for is a shift lamp.

VSS is actually rather important for a lot of the ECU functions.

It makes sense that it doesn't have an OUTPUT, however.

Any "typical" MegaSquirt 2 installation will not have a VSS input.

With normal MS2 Bowling & Grippo code, the VSS is not taken into account for any fueling/ignition algorithm.

*Other* ECUs may require a VSS input, but not MS2.

[This message has been edited by pmbrunelle (edited 03-13-2010).]

Thats interesting. It seems to me like you'd really be limiting the capability of the MS without it.

i would think it would be more concerned with the engine speed than the actual vehicle speed. I'm no expert tho.

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I can't find any reason to put VSS into the MS other than for Traction or boost control. But if you did then make a MS digidash.
http://www.turbododge.com/f...t-gauge-cluster.html

Hmm, fair enough. Although those two features are important to me, lol. I'd think it'd also be nice to have for data logging.

As far as the OP, looks like you can skip the MS and just go to the speedo.

I tried connecting all the ground and hot terminals on the factory beretta ECU and then running the VSS through the factory ECU and connecting it to the speedo, I guess that because the rest of the components are not connected to the ECU (because all engine sensors are run off megasquirt) it will not function properly.

Before megasquirt I used the beretta quad 4 ECU and attached fiero addition circuit from the output of the ECU to the fiero speedometer. Now the factory ECU does not function and I'm lost at how to get the signal conditioned from the Quad 4 transmission VSS to the factory FIERO SPEEDO.

here is the product i had used before

http://www.fieroaddiction.c...ath=2&products_id=12

quote Originally posted by Comealongway: I'm using a 90 beretta transmission i believe the speedo signal is 4000 pulses per min and is a triangular wave

The Fiero speedo is 4000 PPM. What's keeping you from connecting it directly?

quote Originally posted by pmbrunelle: The Fiero speedo is 4000 PPM. What's keeping you from connecting it directly?

The 90 Getrag uses a reluctor based VSS and is about 24600 PPM. Hook it up directly to the speedo and before you get out of your driveway the speedo needle will fall off (learned the hard way).

Only 2 fixes:
Take the tranny apart and install the Fiero style VSS ring and gear - then hook VSS directly to the speedometer like stock.
Install the SGI-5 Dakota Digital speedometer interface on the yellow wire coming from the VSS before it goes to the speedometer.

I am suprized MS doesn't use a VSS... without it you lose the ability to trigger event based on vehicle speed (like turning off fans above 35 mph, setting a higher coast idle speed or enabling a lean crusie mode).

Another possible fix would be to modify the Fiero speedometer for a 24600 PPM input.

People have been modifying their tachometers' capacitors/resistors/crystals for their 4/6/8 cylinder engine conversions, so this should be doable as well, by replacing the proper components.

quote Originally posted by fieroguru: I am suprized MS doesn't use a VSS... without it you lose the ability to trigger event based on vehicle speed (like turning off fans above 35 mph, setting a higher coast idle speed or enabling a lean crusie mode).

Yes but a lot of those things can be accomplished without VSS... the fans aren't on if the engine temp doesn't warrant it, lean cruise mode is kind of a bandaid... it can be done in the tune, you really can do a lot if you know the RPM and MAP at any given time. Things like the Fiero TCC can be used successfully because all the ECM does is set it to on when the engine is up to temp, the rest is handled by the brake switch and third gear switch in the tranny.

The MS-General Purpose Input/Output board has a VSS input, as one of its primary uses is as a trasmission controller and you can program the MS to do what ever you want based on any input it has access to either locally or from the GPIO board via the CAN bus. It is just(only) limited by what people choose to develope it for. The MegaSquirt/II/III series was designed to be an engine controller, the BCM and TCM type functions are really outside the scope of the design, hence the developement of the GPIO board.

No reason lean cruise should be related to vehicle speed. Why wouldn't you want lean cruise at 40 km/h? The mixture table is referenced to RPM and MAP. Doesn't matter what gear you're in.

You can run whatever mixtures you like.

[This message has been edited by pmbrunelle (edited 03-15-2010).]

Nice to see some MS users on the forum… I plan on using it for my project and am curios how well a daily driver responds to MS???

My brother installed MS on his maximum effort (25 psi now and going higher) Mustang turbo v6 car and I must say I am impressed with his results….

The install was a pain in the a$$ but the tuning was super easy…

I have not seen a daily driver with MS perform yet, but if my bro’s Mustang is any indication it should work quite well.

In fact it works so well on my brothers Mustang I wonder why anyone even messes with the stock ECM and trying to re-program it for their needs (turbo 3.4 project ect…)

I’m always reading someone’s dyno results using a modified factory ECM ending with something like “with a better tune I could…” or it made X amount of HP with a poor tune…

Anyway good to see some guys messing around with MS here at PFF

I’m sure this post will bring the wrath of many stock ECM users with tuning software that cost twice as much as the whole MS setup…

Thanks for the post… Good stuff!

quote Originally posted by Scoobysruvenge: Nice to see some MS users on the forum… I plan on using it for my project and am curios how well a daily driver responds to MS???

The driveability will be as good as the person who tunes it.

I installed it summer '09 on my daily driver Fiero 2.8 L with manual transmission, so once the weather got cold, driveability was crappy... Popping, stalling and generally not pleasant. Can't tune for winter conditions in the summer though.

As a brand new inexperienced tuner, it took me a good part of the winter fiddling with cold start cranking pulse widths, cold enrichment, etc, to get it right.

But now I can turn the key in cold weather and drive immediately.

Fuel economy isn't spectacular at 12.2 L/100 km for my last tank, but that's without EGR, rush hour traffic and idling, and a lead foot. A more experienced tuner could probably improve upon this, but I'm just an amateur.

[This message has been edited by pmbrunelle (edited 03-15-2010).]