Mk2 Scirocco 1.8 20vt with DTA ECU - Tacho/ Speedo questions

OK I finally have a proper update for this thread, the tacho converter is installed and working...sort of lol

See video below - It looks to me like the tacho is only displaying half of the revs. Could this be to do with the ECU sending half the amount of pulses that the tacho is expecting? Really hope this is something that can be fixed, so close now.

Also on another note at the end of the vid you can see the dash lights are working! Thanks Jon, like you said I had to wiggle the dimmer wheel around until it lit up, is very fragile though. Is this a new switch jobbie or something that can be repaired maybe?

 

In the DTA software, to General Engine Settings, and check the Tacho Pulses per Rev is set to two.

 

Ok so I've just got in the car with my laptop and USB-Serial adaptor ready to change the settings...but the connector on the ECU is a 15-pin VGA connector!?

I'm guessing I need a specific cable to talk to it; Sparrow can you let me know how I go about getting hold of one.

Cheers

 

We sell them, call the office on 01926 889121. We only sell robust dealer versions, MEF Motorsport sells cheaper versions that may suit.

 

Cheers Alex I'll give you a call Monday and get one on order.

 

Ok almost 4 months later I finally got around to connecting to the ECU and changing the tacho pulse settings..

- I took a backup of the map before doing anything
- Then went to general engine settings, changed the Tacho Pulses Per Rev setting to 2, then hit save. But the rev counter was still only giving half of the output?
- One thing that seemed strange was the Tacho Pulses Per Rev setting was originally set to 0 before I changed to 2

Any ideas on what I'm doing wrong?

 

Change it to more than 2 and see if the actual engine speed on the DTA window matches the rev counter.

 

Ok I've changed from 0 to 2, and 2 to 3, but the tacho is still reading around half the RPM. Have checked the real time mapping window and the software is reading correctly at ~900rpm.

Just to be sure - I connected to the ECU, unlocked the map, made the change to 'tacho pulses per rev' setting, then locked the map again. Am I doing anything wrong at this stage?

Here is a screenshot of my settings:

 

Nope, that's correct. You could try 4, it's not going to damage anything.
If that doesn't change the RPM, you'll need to contact the seller and see if there's anything else required.

 

So I've tried going up as far as 4 and still nothing changes, the tach still reads 50% of the RPM.

One thing I've noticed is that when I disconnect from the ECU and then reconnect and go back into General Engine Settings the tacho pulse setting is reverted back to 0.

This is exactly what I'm doing: Connect to the ECU, unlock map, change to 'tacho pulses per rev' setting, lock map. Is there anything else I need to do?

 

Is the tacho definitely driven from the ECU?
Some cars are wired to run directly from the coil. If one of those wires is broken, it will read 50% of the actual RPM.

 

From Jon's earlier advice it sounds like the original setup would have been coil to D/26 being a single wire, so I've just replaced the coil with the ECU. I still can't work out why the software doesn't hold the general engine settings when I amend the tacho pulses setting?

 

That should work at all. The ECU doesn't output a high enough voltage to drive the clocks.

You need to drive them directly from the coil pack using this post, or get a tacho converter and fit that inline between the ECU and the coils.

 

Sorry my mistake, didn't mention I do have a tacho converter wired up so it's, ECU > Tach converter > clocks

 

I'm not sure then.
You can send the ECU here if you want me to check the settings?

 

Possibly a daft question, but are you unlocking the ECU before making the changes?

 

This is exactly what I'm doing: Connect to the ECU, unlock map, change to 'tacho pulses per rev' setting, lock map.

And thanks for your offer of checking the settings, I'm running out of options so may have to send it your way. Any final suggestions?

 

After changing tacho pulses per rev, are you pressing F4 to save the changes?

 

Nope

Will do that as soon as I get home tonight and post an update!

 

I was going to say the only bit I could see missing was the "save" part before re-locking. Mine is wired up via the diode method so can't help any further i'm afraid.