I bought a piezo guitar microphone, clamped it on the #1 inector hardline of my 85 300D and took the pic below on my oscilloscope. There is a lot of noise (which is to be expected) but you can see the 2 disctinct pulses which are 40 milli sec apart (25 hz). The engine RPM is probably somewhere around 650 to 700.

Is this signal plausible? I don't know the relationship of RPM vs injector pump firing rates on a 5 cylinder 617.952. I don't want to waste my time trying to amplify and filter this signal if it is garbage.

This is my first step in attempting to come up with a timing light triggered by injector line pulses. Wish me luck.

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Ok. 4 cycle engine. Each cylinder should fire ever other rev, so at 700 rpm idle, thats 350 fires/minute.

25 hz * 60 sec/min = 1500 cycles min.

350 fires/minute is about 6 hz or 170 millisecond. Looks like you have 10ms a division, change your setting to 20 or 50 ms.

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Bosch had injectors with inductive sensors in them back in the 1990's. basically the last of the motors with injector pumps. They used the pulse signal & a crank position sensor to electrically adjust the injector timing, no timing device needed on the IP drive. You can probably find one of these injectors in EU & then just use the body with a tip that suits a MB injector.

These are some part numbers that may help you find out about the sensor injector


the no.1 injector. check connector with a multi meter, i think under 80 ohms is good.

Injector #1 0986430248 or 0432217249 maybe 0430211091 or 0432217249
IDZ1023 equivalent to 15 06 2022F, 15 06 2026F There are 2 different blow pressures ~ 150 & 165 bar

KCA30S82 boschowski number is 0432 217 246

0432217303

GERMANY 060 KCA 30 S 82 369 150


The sensor detected the pintle movement. Have you tried your sensor attached to the side of an injector?

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^^^ THIS

I've seen a few of these pop up on Ebay in europe for Peugeot and Citroen engines, XUD engine I think. They look very similar to MB injector holders with an EFI pigtail coming out.

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Can you hook up a timing light and read the crank pulley?

Sixto
87 300D

Thanks for the replies and suggestions. Doesn't the injection pump rotate twice for every rotation of the crankshaft?

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85 300D turbo pristine w 157k when purchased 161K now
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80s idi BMW cars with the trip computer had a needle lift sensor. So does my 1999 jetta




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I think it seems reasonable as there is a pulse when the delivery Valve opens and pressurizes the Fuel Injection hard Lines and opens the Injector and there is another Pulse that goes back towards the Delivery Valve when the Injector closes.

The reverse pulse is one of the things that can cause a hole in the Fuel Injection Hard Lines and the collar that is around the Delivery Valve and sometimes how the Delivery Valve is cut is designed to alter the pulse some.

If I can find a pic where I can point out the Delivery Valve Collar I will ad it later.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

What is the duration of injection (open close)? Can it be 40 milli sec long?

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85 300D turbo pristine w 157k when purchased 161K now
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Not exactly related, but look-up my post on my electronic pop tester. I recorded pressure oscillations in the tubing upstream of the injector as it popped. When I pump by hand (fairly continuously) it is different than when the IP forces a fixed volume of fuel each pulse. The faster I stroked, the higher the frequency of the nozzle pulses. You can also see them on the mechanical gage. When pop-testing, I expect the injector pops, the line pressure drops, the injector closes, then line pressure increases until it pops again. Anyway, I think it helps demonstrate that the injector design is such that they tend to pop open and snap shut, i.e. positive feedback. As it opens, more area on the under-side is exposed to the high pressure, which forces it open faster and the reverse situation when closing. I think the two pulses you see are the sound of the stem slamming against the rear stop and then slamming closed, all in a single injector pulse. As mentioned, if you increase the time range you might see the pulse for the next engine cycle. Of course, if you have the square clamps between all the fuel tubes, you will likely measure sounds from adjacent cylinders as well.

The injection pump rotates at exactly half the crankshaft speed. Same for the camshaft. So one rotation of the crank gives you one half turn of the injection pump.

Or think of it this way. The bottom sprocket would have to be larger than the sprockets on the injection pump and cam to turn them faster than the crankshaft.

The only approach I can think of quickly is to get the pickup device to fire a strob or timing light. There may be a serious issue as your signal indicates it may fire it twice. This would take a signal amplifier and probably a strong one at that.

There to me are also some technical issuers unless an attempt was made to engineer a comparison system with a twin trace scope and a reference pulse from the crank pulley as well. A small magnet affixed there and a pickup for it as well.

The camshaft and the injection pump speed of rotation is indeed half that of the crankshaft.

However as you are looking at the point of release of fuel in an injector line it is probably best to think about it in terms of four stroke engines...

...for every "bang" / point of release of fuel in the injector line the crank makes two complete turns because we have an

1) induction stroke - piston moves from TDC down to BDC
2) compression stroke - piston moved from BDC to TDC

THE FUEL PULSE HAPPENS TOWARDS THE END OF THE COMPRESSION STROKE

3) power stroke - BANG!!!! - piston moves from TDC to BDC
4) exhaust stroke - piston moves from BDC to TDC

{No fuel is added to the cylinder on this "upwards" stroke}

This relationship exists for all four stroke engines no matter how many cylinders it has. Only more modern fancy fuel saving things would complicate the firing order - but we're talking old school technology here so the simple relationship applies.


(For clarity - and just in case TDC = top dead centre; BDC = bottom dead centre of piston movement within cylinder)

So if your crank is turning at 600 rpm - that's 10 revs / second - that's 10Hz so you should then see pulses that occur at 5Hz.


You could think of the system in terms of camshaft speed or IP speed however, but as you're looking at the engine as a whole and not an IP on a test bench - perhaps this way round is best?

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Don't leave that there - I'll take it to bits!

This isn't aimed at anyone in particular...

...I've always found this method to be helpful particularly if it is late at night and your head hurts...

...it stops you from getting confused with units.

So converting from rpm to Hz =>

Start off with the value you have. In this case 600 rpm.

That's 600 revs per minute (per means "divided by")




You know that one minute contains 60 seconds and that one Hertz is one cycle per second. So you arrange the units so that they divide through to give the value you want.

Attached Thumbnails

 

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Did you really intend to say the pulses are 20 hz apart? If it fires every other round, wouldn't that be 5 hz? Please forgive me if i am misunderstanding. It is the middle of the night for me.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!