Injectors and electrics

[drmike]

A bit of a vague question but ...

Is there a way I can safely detect the pulse going to the injectors using a digital multimeter?

I assume I can just bang one end on earth set to volts and find the right cable to probe?

I'm an optimist.

Mike

[drmike]

No-one?

[landydan]

What engine is it? If a TD5 then there are ways, if 200tdi or 300tdi then the only way is to get them out & tested by a diesel specialist.  :?:

[drmike]

Thenaks 200 TDI but all I want to do is know that the pulse goes to the injectors which as far as I know are fine.

Mike

[Porny]

Mike...

Have you got one of those ultra rare, prototype, made from gold plated rocking horse manure 200Tdi's???

Or a multi meter that can measure diesel flow    :D

Unless you have, your injectors have absolutely nothing electrical in them!!! So you will not be able to measure any signal/pulse!!

A 200tdi is all mechanical!!

What do you want to test??



Ian

[landydan]

Mike...

Have you got one of those ultra rare, prototype, made from gold plated rocking horse manure 200Tdi's???

Or a multi meter that can measure diesel flow    :D

Unless you have, your injectors have absolutely nothing electrical in them!!! So you will not be able to measure any signal/pulse!!

A 200tdi is all mechanical!!

What do you want to test??



Ian

Indeed i think he must have. the way he was saying was as though it was a TD5. I would love to see how to test a mechanical injector with a multimeter?? :lol:  :lol:

[drmike]

All right, all right bottom of the class for me! I am truly an idiot given that I have had to mess about with the diesel pump so I really should have known.

I got seduced by the Tiny Tach in the states which uses the pulse from the injector circuitry to log to a digital tachograph but as a spin off gives RPM. I just want to lash up a temporary tacho on teh 200 TDI so I have some idea what RPM I am doing at sundry speeds.

I have a non standard geardox probably it is felt from an early 110 for a TD. The gearing is quite low. The previous owner claimed to 'cruise at 85' - yeah right. It would pull it but, as he found, you blow engines.

Thus I'd like to know with some certainty what the RPM is at various speeds etc. No I am not going to buy one as they seem devilishly expensive hence a lash up using something that pulses in line with the engine. I would like to use the W terminal (assuming I have one) on the alterantor but I don't know how to and have no understanding of what comes out of it!

Let me know when I can remove the dunce's cap please.

Mike

[Porny]

All right, all right bottom of the class for me! I am truly an idiot given that I have had to mess about with the diesel pump so I really should have known.

I got seduced by the Tiny Tach in the states which uses the pulse from the injector circuitry to log to a digital tachograph but as a spin off gives RPM. I just want to lash up a temporary tacho on teh 200 TDI so I have some idea what RPM I am doing at sundry speeds.

I have a non standard geardox probably it is felt from an early 110 for a TD. The gearing is quite low. The previous owner claimed to 'cruise at 85' - yeah right. It would pull it but, as he found, you blow engines.

Thus I'd like to know with some certainty what the RPM is at various speeds etc. No I am not going to buy one as they seem devilishly expensive hence a lash up using something that pulses in line with the engine. I would like to use the W terminal (assuming I have one) on the alterantor but I don't know how to and have no understanding of what comes out of it!

Let me know when I can remove the dunce's cap please.

Mike

Lol..... you can stop standing in the corner now  

If you only want a tempory set-up....  I have got a brand new tacho/rev counter for tdi... which I stil haven't got around to fitting.

If you wanted - and if you've got a 'w' terminal on your alternator - should be marked (or a spare spade) - you could always borrow my gauge - if I can remember where it is!!  Have got a hand held digital pick up we can use to set it up at idle (i.e. get the correct idle speed).

Shame you haven't got a Td5 as that's very easy... I'd just plug my lap top in!!!


The 'w' output basically gives out a small voltage... not sure if you could make sense of it using a multimeter or a scope - well you could but you need to know the voltage output at set speeds.


Ian

[drmike]

It's nice and quiet in the dunce's corner though - I sort feel at home here.

That's a kind offer of the loan of the tacho which as you're fairly local I may take up if nothing else turns up.

Somebody wittered on about setting up a strobe on a petrol engine which you run at 2000 RPM say and then mark the belt on the diesel and point the strobe on the diesel then rev engine until mark stays still so diesel at 2000 RPM. Then at least I'd know what it sounds like at 2000 RPM!

(Shall I get the dunces cap again?)

Mike

[stageonesimmo]

The 'W' terminal gives a raw AC voltage as it is tapped from one of the coils in the gene before the AC is smoothed to DC by the regulator.  You can pick it up with a very low setting on a multi-meter equipped to do AC, but as porny points out, you'd need to know how to interpret the signal....  I reckon its: get the frequency then divide it by the number of phases in the gene = RPM.... but maybe not, as you have the ratio of the crankshaft pulley to the alternator pulley to take into account

Anyway, you can buy electronic pick-up s that detect the pulse in the injector pipe as the injector triggers - theres a kind of shock-wave that piezoelectric thingamajigs can detect.  they aren't cheap though, and again, you need to be able to interpret the signal and turn it into something useful.....

Phew, I off for a lie down now.....