worf928

60k miles over 7 years is *driving*! Good for you.

Yes, I would expect a Mass-Air Sensor to degrade over that many miles. Degradation of the hot-wire is, effectively, proportional to the number of times the car is started and driven to operating temperature. The OE units typically last roughly 60k miles before going out of spec.

However, the running symptoms you describe are consistent, not with normal degradation of the hot-wire, but with the 'hardware' failure of the early units.

BTW, I send off three or four MASs for rebuild each year. Most come from 928s with less than 100k miles and 5 of 6 (in general) are out-of-spec or just-barely within spec.

Now that I know that you've put 60k-miles on your 928 since you bought it in 2012, I highly suggest that you pull the LH and take a look at the back for previous 'rebuild stickers'. If it has none, then you should have it tested and rebuilt even if it tests 'good.'

When you e-mail Rich about the MAS, ask him if he can test your LH. I'm reasonably certain that he has at least one working 928 in which he can stick your unit. Also, Rich was the first rebuilder in the 928 community of LHs in the US and can rebuild yours.

Rich (Andrade) is Electronik and is based in Arizona.

John (Speake) is JDS Porsche and is in England.

Both offer MAS and LH rebuilds. And I use services from both.

Kiln_Red

Rich is on the same continent as the OP.

OP, if you don't have a full picture of your car's service history, then you are way ahead to recognize that needing to start with a good MAF and LH module is imperative for "baselining" your car. It's not too much work to rule out faults in your wiring, leaving you with the realization that one or both of these parts may be defective, or marginalized. Send them both off. *I* would send them to England. But, as you are aware, you have more than one choice.

It does bother me that the car was working as it should before the very recent intake R&R job. A massive enough vacuum leak could be so disruptive that MAF behavior could go unchanged (disconnected), as high volumes of unmetered air would make it impossible to judge MAF performance. Rule out vacuum leaks. Check that the new dampers and FPR will hold vacuum and the vac lines going to these parts for presence of fuel. Verify your LH wiring. The next step, for me, is MAF and LH.

Timetrader22

Hi,

LH ECU is out of the car and the seals have been broken but no indication of who had it open and what if anything was done. I spoke on the telephone with Rich at Electronik Repair today and I'm sending both the LH ECU and the MAF to him tomorrow and I'll wait for the results of his testing.

In the interim I plan to test the fuel pressure and the vacuum pressure and rule out any issues there.

I'll update with any information I get back from Rich and any findings/discoveries I uncover while I'm poking around while I wait for my electronics to come back.

Thank you to everyone here who contributed... I feel closer to a resolve

Tim

worf928

So it has anti-tamper stickers but no company name?

I will throw my dice and bet on Autothority chips.

Mrmerlin

I would put the stock chips back in after you get the LH rebuilt
Or get a set of Porken chips

Timetrader22

Hi Mrmerlin,

Will it be easy to identify if aftermarket chips are installed in the LH?

I just searched for the Porken chips and it looks like they are available for 85'-86' 5.0 motors only.

Are they available for 87' 928s4's

Are they substantially better than factory chips?

Thank you,
Tim

Mrmerlin

Just get stock chips or buy a sharktuner

worf928

There is usually a sticker on each EPROM. The stock chips have Bosch part number stickers.

Rich can probably identify the chip in your LH. He may be able to provide stock chips if, indeed, your ECUs have non-stock chips. However, that is conjecture only at this point.

PM Porken and ask.

Garth S

Friendly 'bump' for this thread. \

I am intently interested in the resolution for Tim's car, as one of the S4's I've worked on recently ( '88 auto) arrived by flat bed, and amongst many other issues in part attributed to non operation for 3+ years, it suffered the stalling at slightest touch of throttle. It also had many other symptoms that appeared during the process ( high idle, too rich, misfire, apparent loss of fuel, yadayada ....

With a handful of relays and a fresh MAF, I had the S4 purring, and running at full power as it should. That was then .... as it again started indicating signs of fuel starvation/missing as the owners Cheshire wide smile began to evaporate: it is again on the hoist .....

Timetrader22

Hi All, I just received the rebuilt MAF and successful tested LH ECU with original chips back from Rich at Electronik Repair. They were in my mailbox when I got home late this afternoon and I'm anxious to fit them and report back.

I'm going to attempt to install them tomorrow night but its probably more realistic that I'll report back on the weekend.

Anyway, I'll update as soon as I can.

Best regards, Tim

Timetrader22

Ok, after much delay I finally have a positive update for my problem(s). I was able to re-install the MAF and the LH ECU and after several restarts and a bit of idling time and the car is running better than it ever has, since I've owned it.

As it turns out Rich from Electronik Repair identified that the wire was broken in my MAF and he replaced it as well as a damaged screen that may have allowed a foreign object to enter the MAF and ultimately break the wire.

I was able to drive the car the other day for approximately 200 kilometers or 120 miles and it really feels strong and solid.

Thank you everyone who tried to help me work through this, I'm very thankful for your insights!

Best regards,
Tim

worf928

Mrmerlin

thats a great thanksgiving / Christmas present