Hugh, Motronic (moronic) question

ronin · 10-29-2003, 09:21 PM

I've been wondering if it would be reasonably possible to retrofit a 1987 951 with the newer (88 and up) DME. as of 1988 the DMEs have self-diagnosis (trouble code) capability and I had considered retrofitting if it's not too difficult or cumbersome.

I suppose it's all a matter of how many sensors need to be added or replaced, or if that's even possible but I really would like to give it a go if it is. any ideas? perhaps signore Audaces might want to take a swing at this one too

thanks guys

SoCal Driver · SoCal Driver's Garage

Need to compare the schematics. Can't attest to any differences in the programming. Maybe Wilk's can jump in here.

ronin · 10-29-2003, 10:20 PM

that would be a good start. I'll have a looksee over the weekend when I have a bit of time. good point, I forgot about mr. Wilk. he'd be a good candidate for information on this one

btw: any idea on the price of a used '88 (or thereabouts) DME?

plandy · 10-30-2003, 05:46 AM

Quote:

Originally posted by ronin
I've been wondering if it would be reasonably possible to retrofit a 1987 951 with the newer (88 and up) DME. as of 1988 the DMEs have self-diagnosis (trouble code) capability

Self diagnosis really?...and how would one view these trouble codes?

SoCal Driver · SoCal Driver's Garage

Quote:

Originally posted by plandy
Self diagnosis really?...and how would one view these trouble codes?

There is a plug in the engine compartment that either has a diode that flashes or you string a diode between two of the terminals. Or may be only with a reader.

Bet the first code is "Clean the Grounds!".

1.2gees · 1.2gees's Garage

My 86 has the mentioned code read out plug in the engine compartment. Do you know what specifically the later DMEs add? I was told by a mechanic in carrboro (nc) who owns two 88 turbo s' btw, that later DMEs would swap in. I have no personal experience though.
Ahmet

TCMdocs944 · 10-30-2003, 09:09 AM

__________________________________
"Bet the first code is clean your grounds"
__________________________________

Bet the second is check your vacuum lines

ronin · 10-30-2003, 05:15 PM

Quote:

Originally posted by SoCal Driver
There is a plug in the engine compartment that either has a diode that flashes or you string a diode between two of the terminals. Or may be only with a reader.

there is the Porsche diagnostic tool, but you can also do the check with the throttle pedal method: depress throtlle and hold (WOT)- turn ignition to on - after check-engine light goes out and comes on again, release throttle pedal and the next light on0off period will be the first trouble code

Quote:

Originally posted by FR Wilk
If I had a copy of the 88 code, I could make you a copy. EPROM duplication fee is about $25. I believe Porsche sells an 88 951DME for over $2000.

I'd really like to get a copy of that. what would you need to get the code? a sample ECU? I suppose I could look around to see if I could "borrow" one from somewhere and ship it to you

ronin · 10-30-2003, 05:20 PM

Quote:

Originally posted by 1.2gees
My 86 has the mentioned code read out plug in the engine compartment. Do you know what specifically the later DMEs add? I was told by a mechanic in carrboro (nc) who owns two 88 turbo s' btw, that later DMEs would swap in. I have no personal experience though.
Ahmet

according to the Porsche FM, self diagnosis wasn't supposed to be available until '88 but if the plug is in there...

I'm going to check my car to see if it'll do the trouble code test

ronin · 10-30-2003, 10:12 PM

that sounds doable. I'll check here locally and perhaps we should post a new thread to ask others if they have a set that they would be willing to volunteer for temporary duty

ronin · 10-30-2003, 10:13 PM

p.s. good thing you don't need the whole dang ECU

plandy · 10-31-2003, 05:52 AM

Quote:

Originally posted by SoCal Driver
There is a plug in the engine compartment that either has a diode that flashes or you string a diode between two of the terminals. Or may be only with a reader.
Bet the first code is "Clean the Grounds!".

Well yes, but I thought this feature was already available on earlier models. So I was wondering what was different on '88 and later units. You do string a diode across terminals then watch it blink in morse code patterns. Not exactly my idea of self diagnostics

ronin · 10-31-2003, 08:33 AM

well, whether it flashes a bulb or reads out on a digital display (as with my scantool) the end result is the same. I still have to do the check to see whether it works on the earlier models. the FM says that this was only available from '88 on but we shall see

AFJuvat · 11-01-2003, 07:02 PM

the tool is (if memory serves) a 9226 or 9228. It has a red LED for interpreting trouble codes and a SPST switch to bypass the Idle stabilizer valve for idle adjustment.

Downside: the DME from that year does not "store" trouble codes once the engine is turned off - you need to read them with the car running.

AFJuvat

ronin · 11-01-2003, 07:07 PM

hmmm. you sure? the DME is supposed to store the codes and only clear them when the battery is disconnected. or do you mean pre '88 DMEs?

AFJuvat · 11-02-2003, 03:06 AM

The DME on the 968 stores codes after the car is off, but the DME fir the 944 does not store codes.

AFJuvat

Britwrench · 11-02-2003, 06:45 AM

AF, don't forget that late 89 and onwards S2 and Turbos have the diagnosis plug for using the Hammer. The blink tester for the old cars was virtually never connected when I worked at the dealership. We just used to connect the car to a "big box" (Bosch) tester. The point of loosing information by turning the ignition off is, to say the least, not ver clever.

ronin · 11-02-2003, 10:57 AM

sooo, Mark. you got a few stock '88 chips laying around??

AFJuvat · 01:50 PM

Agree on the not too clever thing.

You are absolutely right the 89 - 91 do have the provision for the hammer

Yes, I have an 88 chip, already making arrangements to ship it to FR

Britwrench - seen PST3 yet?

AFJuvat

ronin · 11-02-2003, 01:43 PM

you da MAN!! (sorry, it just came out) thank you very much. how may I repay you?