What is the process for testing the older '79 type injectors? Did a search and saw John's method for testing newer injectors.

(I've done it with my Lister, but I'm not going to be able to use that technique on the 928.)

 

The only experience I've had on the topic is with my boats diesel engine and all you can do is measure the spray pattern by firing each injector towards a piece of cardboard (at a specific distance) and measuring the spray pattern and ensuring that all of the target area is covered.
Don't know too many who actually do this rather than just having them tested and cleaned by a qualified shop.

 

I took mine all out, cleaned any "crud" of the outsides, soaked them overnight in carb cleaner (upside-down so "micro-crud didn't foul the screen in there), rinsed them in clean carb cleaner, allowed them to dry, dropped water the inlet of each; and using a nozzle w/rubber tip, sprayed thru at 70 psi to check pattern (using water may sound odd, but I thought it wiser than spraying a fine mist of flammable liquid across the shop), re-rinsed in cleaner & re-installed.

Mine were all pretty good, but I soaked them 2X as above to get perfect cone-patterns.

 

Gregg,

To visually test your injectors, you need to remove them from the intake tube and place them in a small container. I would remove all of them for this test or you could flood or hydrolock the engine. After they are all removed, jumper the 30 and 87 relay connections just long enough to pressurize the system. Check each injector for dripping fuel. To check the spray patterns (should be conical), depress the air sensor plate while the system is pressurized. If any are leaking or have bad patterns they need cleaned or replaced. A slightly irregular spray pattern can usually be fixed by running Techron through your fuel system. Before having them shop cleaned, keep in mind that they can be purchased new (Bosch OEM) for about $25 each. BTW the same instructions apply to the cold start valve except that you will need to apply 12 volts to check the spray pattern.

Dennis

 

Who's selling them for $25?

 

http://catalog.autosportvolkswagenparts.com/

Just rechecked and the price has gone up to $26.04.

Dennis

 

Apparently that price is for select years. The injectors for my 81' are $75.00 each. I was ready to buy a set of new ones. Darn!!

 

Sorry G Man. The older ones are purely mechanical. Guess that's another advantage of owning an OB.

Dennis

 

I'd still like to know how to test them, but thanks for the link. No disrespect to those selling on this forum. That's a great price!
I like doing my own work. They make a nice car, but they don't write a very nice manual. At least from my experiences with it so far.

 

Gregg,

The manual was actually written for Porsche trained mechanics so a lot of information is assumed. Most of the CIS testing instructions can be found in other manuals. Besides the 9 volume manuals, I recommend you purchase UpFixin Vol V from the PCA and a fuel injection manual that includes the CIS such as Haynes (the big one). Don't waste your money on Chiltons.

Dennis

 

Yes, like it appears that the injector sleeves arre held in by an aluminum screw in plug. But nowhere do I see that that is the case. I've worked on power steering assemblies on vehicles where the information wasn't in the book. I've custom machined parts and put in my own springs and plugs, but only if I were willing to kiss the parts goodbye. I'm not willing to goof with my 928 that way. So I sit here wondering, scratching my head.

PCA? What does that mean? Sorry, but once I get my feet on the ground, I don't ask questions, I get to work.

 

Gregg,

The injectors have a hex that should enable you to unscrew the whole assembly. I would pretreat the screw in cap with PB Blaster or WD-40 prior to removing. If they have been in there a long time the injector may strip out the hex hole in the screw in cap. If that happens, get a pair of pliers and twist it as you are turning the injector. New ones are normally available from the big three. When reinstalling them use a little antiseize.

PCA stands for Porsche Club of America. The UpFixin manuals can be purchased from their site at www.pca.org . Not sure if you have to be a member to purchase.

Dennis

 

Wow, thanks. Yep, I'm a big user of antiseize. Almost never is it a mistake.

 

hmmm, I'm confused. When I went to that autosportvolkswagenparts.com site and entered 81 928, the injectors they showed have an electrical connection. The injectors on my 81 euro do not. Did the euro 81's have pure mechanical injectors and the US 81's, have the electrical ones?

 

Exactly Don, US models went to elec. injectors in '80; Euros models kept mech. injectors thru '83.