Mechanical Injectors Tests

Technician · Post by **Technician** » Mon Mar 09, 2020 5:50 pm

I don't know if there is any value to this type of test or not! A Ford Transit 2.0 Di with mechanical injection. I found an old snap on diesel pulse adaptor and now using it with the aid of a current clamp I have scoped the vibration pulses from all four injectors. Reading through the buffer two of the injectors tend to spike up to about 200 ma whereas the remaining two seam not to. I can't see at the moment if there is any value in this test?

Iver · Post by **Iver** » Mon Mar 09, 2020 7:29 pm

I can't see at the moment if there is any value in this test?

That would depend on how that engine is running. If it is running smoothly then you have a waveform from a "Known Good" In this case you have quite likely uncovered a testing error, on the basis that if it is running right and fuelling correctly then we would expect the pulses to be even.

Would be interesting to see what pulses you get from running well to cracking off an injector pipe, or causing a blockage with a cap or ball bearing.

That is on Bosch Esi from a Mondeo but the same or similar Bosch VP30/44 pump and clearly shows that it is capable of adjusting fuel for each cylinder to achieve smooth running. any variation there could and would have an impact on your results.

Are we comparing apples with apples ??

Can you get directly onto the piezo and bypass the Snap on box and the Amp Clamp ? - Raw Data ?

Could this be one of those cases where Measured Values can give more than a Scope ??

Technician · Post by **Technician** » Mon Mar 09, 2020 11:08 pm

Ivor, this is a Transit Di. The injectors are not electronic controlled, they are pure mechanical hydraulic pressure operation only. If the Bosch pump did not deliver enough fuel pressure the injectors would not lift their nozzles to spray fuel. This is the really early stuff from around 2003/4 model year. Interesting about the idea of cracking off an injector to see what happens, but that really would depend upon the design of the distributoe head of the Bosch pump. Just doing a little research regarding the distributor head designs in conjunction with the delivery valves, I see they are operated by a cam plate that pivots to increase fuel pressure to each delivery valve in turn, but back in the day I remember something a lecturer once said about cracking off injectors, something about the Bosch pump metering devices were designed such that the control pressure in the metering head controlled two injectors at once. I can see now that what was said back in the day comes across as incorrect now, but I've lived with that idea for probably 30 years!

I'm reasonably confident that these injectors are worn and causing poor spray formation and smoke with misfires when cold, which clears about 30 seconds down the road and the misfires seem to stop also, hence wanting to see if a test could be carried out to confirm this. New injectors are about £500 so would like to be sure first before firing the parts cannon.

Iver · Post by **Iver** » Thu Mar 12, 2020 3:12 am

this is a Transit Di. The injectors are not electronic controlled, they are pure mechanical hydraulic pressure operation only

.

Understood !!!

In this case then I'm guessing it does not have CKP either ?

However, if you do have a bee in your bonnet then perhaps get an abs wheel and inductive sensor then attach it to one of the pulleys to get smooth running on a waveform.

The price of injectors is possibly not economically viable and we still don't know if the pump has wear too.

I have and will always argue that an injector cannot be tested properly on a bench (removed from the combustion chamber)
However in this case, with the lack of alternatives ..............................?

You have differing readings on your previous testing using the Piezo (timing light adaptor)

Perhaps move the injectors into different holes then look to see if the problem stays with the cylinder or moves with the injector.

Technician · Post by **Technician** » Thu Mar 12, 2020 1:37 pm

Iver wrote: ↑
Thu Mar 12, 2020 3:12 am

this is a Transit Di. The injectors are not electronic controlled, they are pure mechanical hydraulic pressure operation only
.

Understood !!!

In this case then I'm guessing it does not have CKP either ?

The price of injectors is possibly not economically viable and we still don't know if the pump has wear too.

I have and will always argue that an injector cannot be tested properly on a bench (removed from the combustion chamber)
However in this case, with the lack of alternatives ..............................?

You have differing readings on your previous testing using the Piezo (timing light adaptor)

Perhaps move the injectors into different holes then look to see if the problem stays with the cylinder or moves with the injector.

Thanks Ivor for your support. Yes the engine has a CKP sensor. AD list it with the engine code ABFA 2.0 Di 2003/4 year model so you can see what is fitted. Back in the early days I used to be able to buy nozzles etc but not too sure about that these days without some digging!

Before I remove them and put new ones in I wanted to be sure of good scope settings etc to record the results for the before and after test.

Technician · Post by **Technician** » Thu Mar 12, 2020 7:00 pm

Was going to do some more testing this evening after work but the Pulse diesel injection unit has now failed. I seem to get no end of problems with equipment. I won't be buying another. What I'll do is look more in detail at the NVH kit and see how I can test the vibrations from the injectors with it.

Iver · Post by **Iver** » Thu Mar 12, 2020 11:18 pm

I digress.

That piezo clamp has uses away from the the old mechanical diesels.

I have found some used for it on common rail and Hydraulic brake pipes on ABS.

Can be used to catch a stuck / not activating valve in the abs pump.

Is it the amplifier that had popped or as #picoben said in another post you can directly scope the piezo.

Technician · Post by **Technician** » Fri Mar 13, 2020 1:12 pm

Thanks Ivor, maybe I misunderstood what Ben was saying, but now I'll try and use the piezo with a BNC lead connected and see what results I can get.

Technician · Post by **Technician** » Fri Mar 20, 2020 6:06 pm

Ford Transit diesel injector test cylinder 1.psdata: Injector 1; (25.32 MiB) Downloaded 366 times

I've done some more test using the Piezo directly connected to the injector pipes and a x1 probe. I think it looks like three injectors are failing. I'd appreciate your views.

It seems that the forum can't accept the size of the files so the other three cylinders I've had to copy.

The first image shows cylinder 2 injector operation at idle. Comparing all four cylinder injectors and understanding how the delivery valves work in conjunction with the pressure increase to lift of the injector pintle, to me it looks like the best cylinder injector operation is cylinder 4.

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