Escort Cosworth - Fury ecu - Tachometer

[B.Edmonds]

I have a 1992 Escort Cosworth with a new engine harness and Fury ecu. I have the car running and have driven it quite a bit.

I managed to get the tachometer operating accurately by adjusting duty cycle and multiplier however I'm having 2 problems:

* When I 1st start the car, the tach does not operate ( it's in the 0 rpm position with the engine running ). It will only begin to operate after about 10 min of driving. Will remain operational until I shut the car off. When started again, everything repeats.

* My adjusted duty cycle and multiplier randomly revert back to what the maker of the base map made and I have to reset.

Any help would be greatly appreciated.

[Adamw]

The settings "reverting back", would most likely be that you are not performing a "ECU store" before switching off.  Whenever you make a change it is only stored in temporary memory, you need to do a store to write it into permanent memory.  Ctrl-S or F4 is the keyboard shortcut to do this.

This is not a car I know much about but if the tacho is still intermittent after you have stored these settings properly then my next suspicion would be that the tacho may be a high-level device that was originally designed to be driven off the higher voltage coil signal.  It may need a "tacho booster" circuit added.

[B.Edmonds]

Hi Adam,

Thanks very much for your reply. I didn't know to permanently store the change and will do so on Monday. 

Hopefully that also cures the intermittent tach operation. Will report back.

[B.Edmonds]

On 8/4/2018 at 3:47 PM, Adamw said:

The settings "reverting back", would most likely be that you are not performing a "ECU store" before switching off.  Whenever you make a change it is only stored in temporary memory, you need to do a store to write it into permanent memory.  Ctrl-S or F4 is the keyboard shortcut to do this.

This is not a car I know much about but if the tacho is still intermittent after you have stored these settings properly then my next suspicion would be that the tacho may be a high-level device that was originally designed to be driven off the higher voltage coil signal.  It may need a "tacho booster" circuit added.

Thanks for your help Adam.

I went ahead & bypassed a resistor on the back of the cluster & presto, it works perfectly.

[B.Edmonds]

After driving the car for a week or so I have started to experience a strange symptom.

While driving, intermittently, the rev counter will drop to the 0 position. When it does this, it will cycle between 0 & +/ 5rpm for a few seconds & the stop completely.

Engine running quality never changes. If I shut down the engine & restart, the rev counter does not come back to life. If I leave it over night it starts working again.

I have checked the following:

* All electrical connections good

* Swapped in a known good cluster. Same symptom

* Checked ECU for RPM on laptop, good. No faults present with the engine running & the tachometer gauge reading 0.

** When I was 1st trying to get the car running I had a "block 3" fault. This was before I got the engine running. Have not seen this fault return since the one time I saw it.

Possible ECU fault ?

Any help would be greatly appreciated. 

 

 

[Brad Burnett]

Which auxiliary output do you have the tacho configd on?

[B.Edmonds]

The tacho is configured to A4.

Tacho output is pin 18A, socket A.

[Brad Burnett]

would you post a copy of your calibration?

[B.Edmonds]

25 minutes ago, Brad Burnett said:

would you post a copy of your calibration?

If you can message me your email address I will send it to you to look at.

I would prefer not to post it publicly as it is a product of a company in the UK. They asked me not to share it.

[Adamw]

On 8/8/2018 at 9:01 AM, B.Edmonds said:

I went ahead & bypassed a resistor on the back of the cluster & presto, it works perfectly.

This doesnt always work.  You usually have to change the value of several other components to convert a high-level tach into a true low-level compatible tach.  So my feeling is this is still more likely your issue.  I cannot think of any ECU settings that would change the tacho output signal from the ECU over time.  

[B.Edmonds]

1 hour ago, Adamw said:

This doesnt always work.  You usually have to change the value of several other components to convert a high-level tach into a true low-level compatible tach.  So my feeling is this is still more likely your issue.  I cannot think of any ECU settings that would change the tacho output signal from the ECU over time.  

Thanks. I completely get what your saying but I'm struggling to understand why it will be fine for a few days and act up suddenly. There's also no pattern to how it will act up.

I've also spoken to a few friends with Escort Cosworths. In each case, these people have done the same cluster modification with good results. The ecus range from Pectel to Emtron to many others. Anything else possibly worth checking ?

Attached is someone else's picture of the tacho modification. Same as mine.

[Adamw]

20 minutes ago, B.Edmonds said:

but I'm struggling to understand why it will be fine for a few days and act up suddenly. There's also no pattern to how it will act up.

I could think of a few different explanations, but arent going to bother explaining them all.  Here's one example:  Lets say with that bypass mod your tacho needs to see a minimum 6V pulse to work (this is just a guess as an example, originally it was designed to have 50V+). The ECU aux outputs are pulled up (1.5Kohm) to a regulated 12V, so the normal ECU tacho output signal with nothing connected is 0-12V - you would think this should be heaps right?  Now, depending on the input impedance of you tacho that will act as a voltage divider and pull that down, lets be optimistic and say it is 2 Kohm so that will straight away reduce the ECU tacho signal down to 6.8V.  Now, remember your tacho is grounded to the chassis which due to 30 year old wiring probably has a significant voltage offset compared to ECU/Engine and this will also change depending on electrical load.  A 0.5V offset may be normal in a car like this with just the engine/fuel pump running.  Now lets say the electric fan turns on and you get a further 0.4V offset, so your tacho is now only seeing a 5.9V pulse - less than the 6V it needs... 

 

If you want to confirm the ECU aux output is always working, you can just jumper/splice that into a DI as below, set up the DI function to frequency.  You can then log/display the signal coming off aux 4.

 

[B.Edmonds]

Thanks as always for the detailed reply !

I'll do a bit more investigation with what you have told me.

B

[B.Edmonds]

After doing some investigating inbound my alternator charging voltage often dropping, sometimes to 11.9v. Replaced the alternator, no more tacho problems.

Thanks for the support !

[augusto]

Use this circuit connected to the auxiliary output of the rev counter.
This relayed circuit will generate a high voltage to make the revs turn.
Sorry my poor english
Augusto