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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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

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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1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
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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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^^^ 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 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

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.

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 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

I have no idea there.
The Element Plunger always has the same lenth of stroke on inline Fuel Injection Pumps.
It is how the Helix on the Plunger is Cut that determins what is called the "Effective Stroke" of the Plunger. Effective meaning the amount of the Stroke that is actually delivering Fuel.

As an example when the Element Plunger is rotated to the Shutoff Position the Plunger is still moving up and down as the Engine Rotates but the Plunger is rotated so the Helilx/Cut in the Plunger always exposes the Fuel Feed/Inlet Hole in the Barrel of the Element.
So in this case the Plungers effective stroke is zero and the Fuel that went into the the Element and is actually displace by the Plunger going up is expelled out of what I called the Fuel fill Hole (this violent expelling of Fuel is one of the reasons a Fuel Pressure Gauge Needle jumps).

The Time that the Helix covers the Fuel Feed Hole determins the length of Injection time (and amount of Fuel Injected) as does the rpm the Fuel Injection Pump is turning.

Simply put the amount of Injection Time is going to vary with the amount of Fuel Injected and the rpms of the Fuel Injection pump.
Someone who knows a lot about Physics and Math with the right measurements could calculate the speed of the Plunger moving up during Engine Rotation.

But, it is way easier to do the Measuremt as you are doing it now.

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84 300D, 82 Volvo 244Gl Diesel

If I try to apply this on the VE type pumps then this entire fuel increase deal is handled by the "spill sleeve"

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It is somewhat similar as the Plunger on the VE also has the same stroke all of the time and the Metering Sleeve sliding on the Plunger adjusts the effective Stroke of the Plunger.

There is a lot of info on the Internet for the VE Pumps at VW and TDI sites.

However the VE Plunger rotates.
Some Fuel Injection Pumps used by Caterpillar also use the Sleeve Metering.

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84 300D, 82 Volvo 244Gl Diesel

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.

When I was in Trade School I was told there is an actual Hydraulic Pressure wave/s going on inside of the Fuel Injection Lines so He is not just picking up Sound.

(Think of the more well know "Water Hammer" Pressure wave that happens when something explodes next to a Ships Hull.)

Although Sound can also cause a pressure way I doubt if it can do so with much magnitude in this situation.

Also not commented on is that the Fuel Injection Hard Line is going to expand during pressure and contract back to size during periods of no pressure.

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84 300D, 82 Volvo 244Gl Diesel