John Speake

Porsche 928 Diagnostic Tester – your help appreciated !

JDSPorsche is developing a diagnostic tester for use with the 928 and other Porsche models. This will have a 2 line 40 character display, and a simple user interface.

This can be used with any 928 from 1988 onwards, and the early 1987 S4 cars can be easily made “diagnostic ready” with a simple change of EPROMs.

It will come with suitable plugs to connect either to the early 12 way rectangular connector, of the later 19 way circular diagnostic connector.

It will be able to diagnose the LH, EZK, PSD and airbag ECUs, plus a functional test of sensors and actuators (throttle switch, injectors, idle stabiliser control, tank venting solenoid, knock sensors, flywheel pulse sensor, Hall sensor)

It can also be used to reset the idle speed to the correct value, and measure detonation “knocks”.

In order to estimate the possible demand for such a device, and hence set a price, I would appreciate it if you would answer a couple of questions:

1) Would you consider buying a diagnostic tool as described ? YES /NO

2) What is the maximum price would you consider it worth to you ?
$300/$400/$500


Thanks ! (and thanks to Randy for allowing me to ask)

Z

I've been thinking about some kind of diagnostic reader too. I was thinking more along the lines of something that would output the fault codes like the engine management computers in the Saab and Volvo cars do, by flashing a "check engine" type of light. Something like what you're talking about would be a whole lot better.

Yes. It would be more functional than what I was thinking, and then I wouldn't have to work through making my own either.

Price is hard to say. Since my car is one of the earlier ones that the unit would be usable on, I wouldn't really be able to get as much of a benefit from it like those with later cars would. I don't have PSD, airbags, and some of the other stuff that the tester would be capable of, and I don't think that there's as much of an engine diagnostic capability in my car as there is in the later cars either, is there?

Cameron

John,

If what you are saying is that if there is a higher demand, there will be a higher price - then my answer to number 1 is NO.

Now, where do I send my deposit to reserve one!?!?!

.....Cameron

SteveG

Z: I don't think that is limited to Saab and Volvo. If I understand what you describe correctly, my '86 Prelude computer can be read by the shop. Of course the shop said my O sensor had to be replaced years ago when the ck engine light came on and I didn't and it gets the same mileage as before.
the light clears when shutting off the ignition.

John: The question is moot since I have an '85, but I would love to have one for the GT I will someday own, hopefully less than $500.

Z

It's not limited to those, but the Saab and Volvo use Jetronic 2.2 and 2.4 engine management which is basically the same as in a 928. They have the same connectors, many of the same pin assignments, and yes, they have the same commonly failing Bosch chip in the LH computer as we do.

John Speake

OK Cameron, your's will be $1000 !!

The price will be set by demand, I've incured some high fixed initial costs for this project. The more I think I can sell, the lower the price.

"Z" I assume your car is pre S4 ? The LH 2.2 used on the early cars is quite different to the LH2.3 used on S4 and later.

The LH 2.3 and LH 2.4 were designed at much the same time, and both have diagnostics, but the hardware is very different.

The LH 2.2 in Porsches has no diagnostic capability that I know of.

Nathan Valles

It might be easier to build a computer program and a serial adapter cable to hook up to your computer or laptop than to design a stand alone system. Especially if you are looking at making adjustments to the system.

In any case I would have trouble justifying more than about $300 for this kind of purchase.

JE928Sx4.

For $300.00, yes. I'd save a bit or wait for some problem to develop when I needed it if it was higher.

JE

John Speake

Thanks for the feedback - keep the comments coming. At $300 I would need to sell plenty !

JE928Sx4.

OK $350.00, but then I'd wait til I was stumped and needed it otherwise. :-)

JE

Scott M.

John;

I would be moderately interested.

Keep me abreast.

Dave H.

i think an adapter cable and an emulator to run on a laptop would be a better way to go

maybe.

the factory 9268 tool is ~$300. so maybe. it would have to more intuitive. VAG-COM diag software for VW/Audi is $200, that might be a better target.

$400-500? not a chance...

John Speake

Hi Dave,
The 9268 is no longer available, and with the leads you could double the price you mention.

I did consider a laptop solution, but decided that a small, handheld box with an intuitive display would be easier to use for may people.

Thanks for the feedback, it's very useful !

aaron3

John,

Absolutely interested. $300 if I'm not in urgent need. $500 if I'm desperate. $300 goes pretty quick if I have to take the shark into the shop.

ErnestSw

Hi John,
I'm sure you're familiar with the built-in diagnostic capabilities of the 89 and newer models with a simple jumper in the plug. How much more information would this instrument provide than the dash read-out? Would it be comparable to the "Hammer"?