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andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 251

2014 Defender 110 Puma 2.2 CSW Aintree Green

Vcv valve traces..

After playing with the injectors and establishing they were piezo operated I wanted to have a look at the much mentioned vcv valve..
My reading on here suggests that the 2.2tdci engine isn't as prone to problems with it as the 2.4 but I took a look anyway..
After a bit probing I got that it was a duty cycled or pwm operated valve but at idle and putting on a few revs it was impossible to see any real change to the cycle..
I'm guessing I will need to be able to see it under load conditions to notice the difference.. At least I know, the signal wire now and I'll get a remote lead into the cab at some point and try again..
Best I could do today was alter the time base to view one cycle and watch the difference between idle and revving the engine..
The difference in the square wave or duty cycle alters by about 154 micro seconds I think it was..

Click image to enlarge

Click image to enlarge

Eventually I'm hoping to be able to look at the vcv valve against the rail pressure..

24th Apr 2024 5:20pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19620

Could do with a set of connectors to make a parallel test lead from it, plug and play just take into account the losses from the wiring length.

I expect the connectors can be tracked down, what they are though I don’t know but I would imagine they are available as they are generic with other manufacturers too. Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

24th Apr 2024 5:41pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3214

2012 Defender 90 Puma 2.2 CSW Santorini Black

All very interesting

I think you mean milliseconds ms rather than microseconds μs. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

24th Apr 2024 5:48pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 251

custom90 wrote:
Could do with a set of connectors to make a parallel test lead from it, plug and play just take into account the losses from the wiring length.

I expect the connectors can be tracked down, what they are though I don’t know but I would imagine they are available as they are generic with other manufacturers too.

That's what I'm on about.. Getting a lead into the cab that has been tapped off the signal wire and has a connector for the scope..
I already have multiple leads of various sensors in the cab that allows connection of the scope while driving..
The length of the leads isn't an issue for the signal.. Many automotive scope leads are 3meters and can be extended.. As long as you don't pick up a load of electro magnetic interference it's fine👍

24th Apr 2024 5:55pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 251

Dinnu wrote:
All very interesting

I think you mean milliseconds ms rather than microseconds μs.

No.. The width of the section of the square wave when it drops from 15.6v down to zero volts is 0.446 mili seconds at idle
On the second trace when reved that portion of the pulse drops to 0.292 mili seconds
A difference of 0.154mili seconds or 154micro seconds👍

24th Apr 2024 6:15pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3214

Ahh right

I need specs

The one that sits on the nose, not numbers

1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

24th Apr 2024 7:51pm

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