Hello friends !
I would like to make a "relative compression test" on a diesel car (diesel Ford Focus 1.6 TDCI III), with my Picoscope.
To do this, according to the Picotech instructions, I have to prevent the engine from starting, looking for an easy way.
What could I do ?
- disconnect the electrical connectors of the piezo injectors and then start the engine ? (the ECU may not appreciate, isn't it ?)
- disconnect the electrovalve connector from the high pressure pump ?
- find the fuse of the diesel pump (but cannot be found) ?
Any ideas ?? I dare not do anything at the moment...
Thanks a lot !
Take care !
Nico
How to prevent an engine from starting? :-)
Re: How to prevent an engine from starting? :-)
Enable start relay without ignition on?
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R8évolution
- OneWave
- Posts: 14
- Joined: Sat Aug 15, 2020 7:30 pm
Re: How to prevent an engine from starting? :-)
Disconnect the camshaft sensor
Re: How to prevent an engine from starting? :-)
In general terms - not this specific carzebraone wrote: ↑Sat Mar 12, 2022 2:25 pm
What could I do ?
- disconnect the electrical connectors of the piezo injectors and then start the engine ? (the ECU may not appreciate, isn't it ?)
- disconnect the electrovalve connector from the high pressure pump ?
- find the fuse of the diesel pump (but cannot be found) ?
- you could, but NEVER disconnect a piezo injector with the engine running.
- Don't do this as some engines (- Ford Durartorq for example )default to max pressure in the rail - 1800 bar and you may blow the pressure release valve which can be single or 3 uses only.
- Engine driven pump often without a low pressure tank pump so no fuse. You don't want to starve the HPP of fuel anyway.
- Cam/Crank sensor often will not work as most cars will start on the the other if one is missing. Need to pull both.
Relay bypass as suggested would probably be safe - though may trigger "attempted theft" - also sometimes (Jags for example) the start relay is solid state on the board so not possible.
If you disconnect the rail pressure sensor that should be OK, as ECU should see it out of range (0.5-4.5v) and shut the injectors down. However it may have a limp strategy to run the rail at minimum pressure so no guarantees.
Interested to hear others input on this .
Re: How to prevent an engine from starting? :-)
Some have a compression test function available with the diag tool.
Re: How to prevent an engine from starting? :-)
ok, I’m going to do a synthesis as I go along:
1- "Disconnect injectors BEFORE starting": it seems that this is the best solution, but are you sure that the ECU can support it? (of course no question of making this engine running, thanks Picowight)
2- "Unplug the cam shaft sensor" (R8evolution thank you): it seems a good idea (can anyone confirm it?) but Picowight says it may not work. Is there a risk of trying that?
3- "Enable contactless start relay" (liviu2004 thank you): but I don’t understand how to do it. Is it to activate the starter solenoid without touching the key?
4- "Unplug the solenoid valve connector from the high-pressure pump": delete, this is not a good idea (thanks Picowight!)
5- "Cut the low pressure pump": we delete, it is not a good idea, Picowight is right I looked, there is no primary pump.
6-"Disconnect the rail pressure sensor": thanks Picowight, but is there a risk of trying this?
As a reminder, in all cases, for the relative test, the car must not start...
Many thanks for all your messages!
Nico
1- "Disconnect injectors BEFORE starting": it seems that this is the best solution, but are you sure that the ECU can support it? (of course no question of making this engine running, thanks Picowight)
2- "Unplug the cam shaft sensor" (R8evolution thank you): it seems a good idea (can anyone confirm it?) but Picowight says it may not work. Is there a risk of trying that?
3- "Enable contactless start relay" (liviu2004 thank you): but I don’t understand how to do it. Is it to activate the starter solenoid without touching the key?
4- "Unplug the solenoid valve connector from the high-pressure pump": delete, this is not a good idea (thanks Picowight!)
5- "Cut the low pressure pump": we delete, it is not a good idea, Picowight is right I looked, there is no primary pump.
6-"Disconnect the rail pressure sensor": thanks Picowight, but is there a risk of trying this?
As a reminder, in all cases, for the relative test, the car must not start...
Many thanks for all your messages!
Nico
Re: How to prevent an engine from starting? :-)
3. I pull the start relay out a bit, use a test light connected to battery minus and touch the minus terminal of the relay coil. Of course, this is determined previously by the wiring diagrams or test.
I only need a test light. See scannerdanner on youtube.
I only need a test light. See scannerdanner on youtube.
-
R8évolution
- OneWave
- Posts: 14
- Joined: Sat Aug 15, 2020 7:30 pm
Re: How to prevent an engine from starting? :-)
The 1.6l TDCI is a PSA engine, if it has the same ECU strategy as on the Peugeot it will not start without the camshaft sensor, there is no risk in disconnecting it apart from finding it a transient fault in the ECU once reconnected.
Re: How to prevent an engine from starting? :-)
There you are, an easy solution for this engine!
Re: How to prevent an engine from starting? :-)
Good job 
!!
I think we have found the easyest way.
I will try it this week, and I will be back to confirm.
Great thanks you three !!
(Liviu has said somthing interesting too, i will remember)
!! I think we have found the easyest way.
I will try it this week, and I will be back to confirm.
Great thanks you three !!
(Liviu has said somthing interesting too, i will remember)