Motronic ECM - New, Used, Rebuilt?

[Harold_89_911]

I posted about my no-start condition earlier last week. Spent a little more time with my car on Saturday and I'm afraid that it is the computer. Everything described in the Bentley seems to check out. Shortening lead 30 and 87b, the fuel pump runs fine but when I crank the engine, lead 87b never goes to 12V and there is no spark. Also tried a new DME relay.

I will get the car to my mechanic on Wednesday but have started to look for ECM costs on the internet already to prepare myself. What are my options? Should I play it safe and buy new (appr. $900), get a used one (where?), or can one get rebuilt ones (how good are they?).

From my understanding, the Motronic ECM is pretty solid and failures are rare. Any info would be helpful. Trying to get my car back on the road before April 17 when I'm supposed to have my first track day at Willow Springs.

Thanks

[Harold_89_911]

Any Motronic experts out there?

Thanks in advance

[Porcupine]

Harold check prices with Hendrick Porsche 1-800-315-8193.
They have the best prices for OEM stuff. They should have new or factory rebuilt units.
For example I bought a new 964 twin plug distributor from them complete with caps and rotors for $460.00 + shipping. Much cheaper than e-bay or used/rebuilt stuff. Figure about 20-30 off list price. I used to buy from the local dealer but they seem to have adjusted there list prices up about the same as the PCA discount they give.
Martin

[Decolliber]

I bought brand new one from Hendrik Porsche for about $1000. If you want a rebuilt one you need to supply a DME that has never been opened up and you also can get one only for the same year as the one you submitted. I found that my 88 Carrera had a DME from an 84. So my only option was a brand new one. I sold the old one on Rennlist; it sold instantly at $250, so I obviously underpriced it. Even if you can get a rebuilt one, my inclination would be to get a brand new one. Consider the analogy with computers. The electronics eventually begin to fail, and with all new components you know its going to be working properly for a long time. Put slightly differently, would you want to buy a reconditioned 1988 286 computer, with some new bits and some 14 years old?
The brand new DME made a dramatic difference to the running of my 88.
Keep in mind that the 84-86 Carreras have a different DME from the 87-89 Carreras. The differences may not be very significant, since an 88 will run with a DME from an 84. One difference is that the 87-89s have an idle speed of 880 rather than 800.

[KTL]

Keep in mind also that the older (84-86) have 24 pin chips and the newer (87-89) have 28 pin chips, some of which are socketed and non-socketed (soldered to the board). Just thought i'd add that in case you have a desire to upgrade the chip.

[john walker's workshop]

for a rebuild call loren, manhattan beach, ca, @*** *** ****

Moderator's note: Contact information removed at owner's request.

[Harold_89_911]

Great info guys. Thank you so much.

I checked with Hendrick Porsche. They will sell the new unit for $1402 and a Porsche rebuilt for $768. Would take about a week to get the unit. They have the identical warranty so he suggested to get the rebuilt.

I had looked before at EuroWebParts.com. They had a list price of close to $1500 but were selling it for $979. Based on the list price, I assumed it was new but when I called, they told me it was a Bosch rebuilt one and I had to send in the core.

Then I called Loren and he asked me to describe the failure more. I told him that the fuel pump relay wasn't being grounded and therefore the pump wasn't turning on during cranking. He told me that the Motronic does not fail that way and it was most likely the pickup sensors. I told him that I diagnosed the sensors according to the Bentley and had the right resistance. He told me to do the signal check. So maybe I will get lucky on this one. I have a lot of faith in my mechanic (Jason Duarte) so I will know more on Wednesday night. At least I feel a little better prepared for this.

[Harold_89_911]

That's why we pay the Porsche mechanics the big bucks. It was the alarm box. The DME relay powers up when the contact is on but then the voltage drops. I only measured the lead at static, not during dynamic conditions. Car is running fine without the alarm box. New box will cost about $150. Lot better than $1000 for the ECU!

Thanks again for the great advice from all. As usual, was a good learning experience, even thought I had to swallow my pride and get the flat-bed truck to pick up the car this morning

[88911coupe]

Sorry. wrong thread.

[Mifintifin]

Ahh...at the risk of Wayne blowing a server fuse ********** has rebuilt ones with warranty for $549 net, $150 core. I've had good luck with them.

Mifintifin,

82 SC Coupe
83 SC Cab