Switch Tachimetric relay

[Ruben 0]

Hi there again! I found out that my tachimetric relay is not making good contact , and i would like to know if it is possible to change the relay for a on and off switch like in rally cars?

 

 Best Regards

 Ruben Figueira 

Edited December 12, 2020 by Ruben

[DamirGTI 342]

It is possible but that's dangerous way of doing it .. if you end up in a crash/collision/roll over , wired like so you'll be likely up in flames too ... as there will be nothing to stop the fuel pump from running .

 

Wouldn't really recommend that for a track/race car either .. as in split second before the crash occurs you'll not be able to react and switch the fueling off .

 

OE Tachymetric relay has this safety feature built inside of it  , to cut off power supply from the entire EFI system when the engine revs drop below 400rmp in "state emergency" i.e. possibly upcoming crash event or general cause rapid de-acceleration .

 

 

D

 

 

Edited December 12, 2020 by DamirGTI

[Ruben 0]

2 hours ago, DamirGTI said:

It is possible but that's dangerous way of doing it .. if you end up in a crash/collision/roll over , wired like so you'll be likely up in flames too ... as there will be nothing to stop the fuel pump from running .

 

Wouldn't really recommend that for a track/race car either .. as in split second before the crash occurs you'll not be able to react and switch the fueling off .

 

OE Tachymetric relay has this safety feature built inside of it  , to cut off power supply from the entire EFI system when the engine revs drop below 400rmp in "state emergency" i.e. possibly upcoming crash event or general cause rapid de-acceleration .

 

 

D

 

 

So , you recomend using the relay , i get it , in therms of safety its not the most correct thing to do! In this case , this is a road car , but still im curious about how can it be done. Anyway i will buy a new relay , i have seen the prices of them and they seem quite rare and expensive!

 

Best Regards!

 Ruben Figueira

[DamirGTI 342]

In the past , i've had race cars being towed to me to help clear up the ("custom") wiring mess and get them up and running .

Stuff that i have found on them with various on/off manual switching bypassing OE electric/electronic system was shocking and outright dangerous by means of connecting things up properly , the quality of the work itself , and the lack of any added safety feature with the original bypassed (like in this case inertia switch for the fueling , or any means of fuel cut off by speed/tacho signal , oil pressure , alternator etc.) .. not to mention how hard is to work on just a two color bundle of non original wiring with no wiring diagram whatsoever .

 

 

The OE Tacho relay system is not as complex as it might seem , so yes i recommend keeping and fixing the OE system rather than digging into the wiring and connecting some additional circuits relays fuses wires switches etc. , if you're stuck and need the car mobile asap and only as an short term solution to "keep you moving" then maybe , otherwise simply no . 

 

Tacho relay , as most of the parts for the 205 , has gone up a bit in price nowadays .. but you can still find them at reasonable price (look away from ebay and the likes) .

Or , look at the scrapyards for used/second hand one , as other car brands/makes from the 80's-90's (Audi/Alfa/Fiat/Lancia/Citroen/Iveco/VW/Seat...) had identical type of relay it's not a 205 Gti "item only" .

 

It can also be repaired , cracked solder joints are common fault on them and easy to fix .. i fixed a few of them in the past , by re soldering joints , replacing burnt diodes , fixing/soldering broken relay coil winding wire .. much of the stuff can be fixed so no need to throw away and search/buy new at once .

 

 

D

 

 

 

Edited December 13, 2020 by DamirGTI

[Ruben 0]

On 12/13/2020 at 6:28 AM, DamirGTI said:

In the past , i've had race cars being towed to me to help clear up the ("custom") wiring mess and get them up and running .

Stuff that i have found on them with various on/off manual switching bypassing OE electric/electronic system was shocking and outright dangerous by means of connecting things up properly , the quality of the work itself , and the lack of any added safety feature with the original bypassed (like in this case inertia switch for the fueling , or any means of fuel cut off by speed/tacho signal , oil pressure , alternator etc.) .. not to mention how hard is to work on just a two color bundle of non original wiring with no wiring diagram whatsoever .

 

 

The OE Tacho relay system is not as complex as it might seem , so yes i recommend keeping and fixing the OE system rather than digging into the wiring and connecting some additional circuits relays fuses wires switches etc. , if you're stuck and need the car mobile asap and only as an short term solution to "keep you moving" then maybe , otherwise simply no . 

 

Tacho relay , as most of the parts for the 205 , has gone up a bit in price nowadays .. but you can still find them at reasonable price (look away from ebay and the likes) .

Or , look at the scrapyards for used/second hand one , as other car brands/makes from the 80's-90's (Audi/Alfa/Fiat/Lancia/Citroen/Iveco/VW/Seat...) had identical type of relay it's not a 205 Gti "item only" .

 

It can also be repaired , cracked solder joints are common fault on them and easy to fix .. i fixed a few of them in the past , by re soldering joints , replacing burnt diodes , fixing/soldering broken relay coil winding wire .. much of the stuff can be fixed so no need to throw away and search/buy new at once .

 

 

D

 

 

 

Yes i understand! I actually found a relay and i fitted it in and it works just nice!!! Thanks for the advice!