2.0 injectors: early vs late model cars

[rjames]

I notice that there are different 2.0 liter engine injectors for the early and late ('75-'76) model year cars. Is there really a difference between the two? Can they be interchanged?

Thanks!

[Dave at Pelican Parts]

Jeff Bowlsby, one of the most knowledgeable D-jet people out there, says that there is.

I checked a set of early ones vs. a set of late ones for resistance, and they were all in the same range. When I had them cleaned and tested, the listed flow numbers when they came back were all in the same range.

I was hoping for more info from Jeff, or anyone else who knows conclusively.

I doubt that Bosch or Porsche would put a different part number on the 75+ ones with no reason...

--DD

[bowlsby]

Dave you are WAY too kind...I hope you are doing well on other fronts.

The flow rate specs on the 75-76 2.0L injectors were posted on the Club site about a month ago...by whom I don't recall...

It probable though that Bosch would not create yet another set of injectors or an ECU or anything, without justification.

My hunch is that the 75-76 2.0L ECU is different enough from the 73-74 2.0L ECU that they needed different injectors too. A careful study of Brad Anders site on the ECU characteristics would probably tell us what the differences are, I just have not gone there yet.

[rjames]

hmmm.... so the most important thing might be to make sure the injectors match the ECU?


I have a '75 2.0 car and am not having any issues with my current setup, just found a deal on early model injectors and wondered if they'd work. I know my ECU probably isn't original (somebody wrote 'KNOWN GOOD' on the backside of it) but I should probably verify what model (late or early) the ECU is.

[lapuwali]

If the resistance (actually impedance) of the injectors is the same, and the flow rate is the same, then they are the same as far as the ECU is concerned. No need to match the injectors to the ECU.

My guess is that the later injectors are different only because Bosch learned how to change the design to manufacture them more cheaply, or to improve reliability, or both. This was early days for EFI injectors, and I'm sure they were still learning a great deal about how to mass-manufacture them during this period. They were also experimenting with things like pintle shapes and types, and exact spray patterns.

[pbanders]

The output stage of the 052 ECU's is the same as all the other ECU's, it's not an electronic difference. If the flow rates are the same, perhaps the difference is an improvement of some kind - e.g. harder pintel seat, better gas seal, etc.