Revcounter Mod For Aftermarket Ecu's

[Vili 18]

This is simple and easy modification to make your OE tachometer to work with signal from ecu tacho output.

 

Idea is to remove the signal conditioning and voltage suppressing components (capasitor and 1k resistor). And replace the signal suppressing 15k resistor with smaller one. You want to leave the second capasitor (not marked in the picture) in the signal line because it protects the IC from DC currents. Disclaimer: I'm not a electronic guru so don't mind my possibly incorrect terms.

 

After this mod my revcounter worked beautifully with the DTA ecu. Except the reading was way out. I fixed the reading by adjusting the brass weight screws behind the meter. Now it reads very close (+/- 50 rpm) to true value. There is a bigger error roughly 150 rpm at 3200 rpm, but it is close enough for me.

[Sandy 191]

Nice one

[brian j 32]

Just to say I have done this mod on mine and it is working fine with MP 3.1 management too.

 

 

 

(null)

[chipstick 382 1 Cars]

Came across this during a search as I am having rev counter problems with my DTA.

 

My clocks have just a wire bridged, with no other visible modifications to the rev counter. The wire isn't in the 'usual' place common with GTi6 conversions, it's a longer length - unfortunately I didn't get a bloody pic. Il have to demolish my dag again.

 

Thing is, it works fine sometimes, but occasionally drops off to 0 and then will fly back up to the presumably correct RPM.

 

I wondered if anyone had a similar issue.

[stef205 92 1 Cars]

I have the same issue here dan, I'm using a omex tho, mine over reads or under reads, despite using omex tacho driver unit and other rev counter mods. I plan to use the racetech rev counter and possibly speedo to for better a accuracy.

 

(null)

[Vili 18]

Came across this during a search as I am having rev counter problems with my DTA.

 

My clocks have just a wire bridged, with no other visible modifications to the rev counter. The wire isn't in the 'usual' place common with GTi6 conversions, it's a longer length - unfortunately I didn't get a bloody pic. Il have to demolish my dag again.

 

Thing is, it works fine sometimes, but occasionally drops off to 0 and then will fly back up to the presumably correct RPM.

 

I wondered if anyone had a similar issue.

 

Bridging over the capasitor has probably fried the chip on the board.

[Vili 18]

I have the same issue here dan, I'm using a omex tho, mine over reads or under reads, despite using omex tacho driver unit and other rev counter mods. I plan to use the racetech rev counter and possibly speedo to for better a accuracy.

 

(null)

 

You can try to adjust the brass weight screws in the clock. That's how I got mine to read correctly (or at least close enough). Wouldn't mind proper a proper revcounter though.

[chipstick 382 1 Cars]

Bridging over the capasitor has probably fried the chip on the board.

 

It just strikes me as odd that it works 50+% of the time yet occasionaly drops out to 0 and flies back up to the correct reading.

 

It's not something I really require, but I like things to be sorted. Having it disconnected completely would annoy me I think.

[CaptainK 11]

Came across this during a search as I am having rev counter problems with my DTA.

 

My clocks have just a wire bridged, with no other visible modifications to the rev counter. The wire isn't in the 'usual' place common with GTi6 conversions, it's a longer length - unfortunately I didn't get a bloody pic. Il have to demolish my dag again.

 

Thing is, it works fine sometimes, but occasionally drops off to 0 and then will fly back up to the presumably correct RPM.

Dan, are you using my old clocks on your GTi6 or did you convert your clocks to use my DTA? I'm not sure of the exact "fix" to the rev counter mine had, but it sounds similar to what the OP stated. It worked flawlessly for me in my 205 except that on ignition on (before start the engine) the rev counter needle would twitch slightly. After that it worked perfectly. Might be worth using my clocks if you still have them ?

[EZ Tutty 7 1 Cars]

Hmm, i might have to give this method a try on my GTi6... I've used the single link method, and whilst it seems to read something like, it's a little over excitable... it shoots round to 7krpm on start up for example :-\ (just the clocks not the engine lol)

[chipstick 382 1 Cars]

Dan, are you using my old clocks on your GTi6 or did you convert your clocks to use my DTA? I'm not sure of the exact "fix" to the rev counter mine had, but it sounds similar to what the OP stated. It worked flawlessly for me in my 205 except that on ignition on (before start the engine) the rev counter needle would twitch slightly. After that it worked perfectly. Might be worth using my clocks if you still have them ?

 

I took your rev counter unit out and placed it in my existing clocks so the mileage was correct.

 

Perhaps it's a loose connection. I will remove it and have a nosey.

[chipstick 382 1 Cars]

This ones been done completely differently.

 

 

No loose connections noticeable.

[EZ Tutty 7 1 Cars]

 

 

Just for future reference.... this method works flawlessly on the GTi-6 ECU

Thanks Vili

Edited September 16, 2012 by EZ Tutty

[chipstick 382 1 Cars]

This ones been done completely differently.

 

 

No loose connections noticeable.

 

Put this back in mine yesterday and it's spot on.

 

I can only assume I didn't have the plug pushed home or something.

 

The yellow wire is the only change. So a simple mod for people using a DTA.

[JoshGti 8]

Did the resistor mod to mine last week with my mp3.1 works a treat all the way to the limiter, no need to play with the screws as the limiter cuts in at the right time.

[Vili 18]

This ones been done completely differently.

 

 

No loose connections noticeable.

 

This one is the dangerous mod. You have bypassed all the filtering components and connected the signal directly to the chip. There's a good probability that DC will fry the chip eventually. The only needs to be a small potential difference between the ground and the signal line and there is enough current to fry the chip over time.

Edited September 17, 2012 by Vili

[chipstick 382 1 Cars]

It's been like that for a couple of years now.

 

I haven't bypassed anything. That's how it was modified for the previous owner some time go as above.

[CaptainK 11]

This ones been done completely differently.

Apologies Dan, my bad then. I was just told that the rev counter had been altered to allow the GTi6 revs to work on it, by soldering and resoldering wires etc. Hope you find the problem with it. (if this problem was happening on an FTO, then it'd be the IFS being silly - replace and all fixed )

[chipstick 382 1 Cars]

Apologies Dan, my bad then. I was just told that the rev counter had been altered to allow the GTi6 revs to work on it, by soldering and resoldering wires etc. Hope you find the problem with it. (if this problem was happening on an FTO, then it'd be the IFS being silly - replace and all fixed )

 

The way it's been done works well now, so I will leave it be. The problem must have been a plug connection when I fitted it. Out of interest, who did it and when? The fact it's lasted so long without 'frying' the chip gives me no reason to change it. Unless people have seen them done this way fail often?

[welshpug 1,661]

I'm glad I just did my £1's worth of resistors trick, doesn't seem worth the hassle of this faffing with the tachometer itself

[chipstick 382 1 Cars]

I'm glad I just did my £1's worth of resistors trick, doesn't seem worth the hassle of this faffing with the tachometer itself

 

Care to enlighten me of the resistor trick for use with a DTA?

[welshpug 1,661]

It can be used with any wasted spark or sequential spark system, doesn't use the DTA trigger at all.

 

Haven't got the bookmark to hand as I'm at work now, but its what Spiky sells, I have made a couple up myself and all you need is to attach a wire to each coil trigger, one to an earth and the signal to the tachometer, I stick them next to the ecu or ignition amp.

 

edit, found a linky

 

http://forum.205gtid...showtopic=60239

 

if you have more coils just add another diode, i.e two for wasted spark 4 cyl, 4 for sequential spark 4 cyl etc.

 

further info on this thread too

 

http://forum.205gtidrivers.com/index.php?showtopic=56806&st=40

Edited September 17, 2012 by welshpug

[chipstick 382 1 Cars]

Thanks for those. Having a single coil pack and leads setup I always thought that option wasn't available. Surprised Sandy doesn't add that into his looms.

[Anthony 1,003]

I'm glad I just did my £1's worth of resistors trick, doesn't seem worth the hassle of this faffing with the tachometer itself

Until one of them begins to break down and causes a misfire, or if you're really unlucky, fries a coil driver.

 

Tacho converters are a nasty bodge as far as I'm concerned, but each to their own.

[welshpug 1,661]

can't see how it'll cause a misfire

 

its been on for 20k miles now!