Tom DM

Update 2.

New battery 12 V/75 Ah installed (the battery is actually 2 cm lower than the faulty 12V/70Ah unit).

I started the car, start motor cranks the engine but no joy.

Them I remove the air inlet tubes (Thx Nicole) and ... the car starts!
Engine at 1500 RPM. I check the alternator : 14.2 rock-steady Volts at 2500 RPM.

But after some 2 minutes the engine is warm: idle drops to 1000 RPM and soon after the engine dies. No way to get it started again.

Well: I wait for the filters and new spark plugs to arrive and I'll search the forum and older messages for "vacuum leaks and solutions".

CU,

Tom

Bryan

Make sure the vacuum line on your fuel pressure regulator is still connected. If this vacuum line broke or fell off, you'd get both a vacuum leak (although minor) and fuel deliverly problems. Essentially, you'd have maximum fuel pressure all the time. This would be problematic during warm starting and at idle. During a cold start, the engine needs extra fuel anyway so the excess fuel may not cause problems. But during warm start, the engine would "flood", to use a carburettor term, because the engine doesn't need much extra fuel to start when warm. At idle, high vacuum lowers the fuel pressure for proper idle. If this fuel pressure reduction isn't happening, you're getting way too much fuel at idle, even more than the O2 sensor system can compensate for. But the engine would probably be OK at higher rpms and when the engine is under load, because those situations create less vacuum and raise the fuel pressure.

This problem would also cause poor fuel economy.

Bryan

Tom DM

Update 3.

I've taken out the air filter and its base in order to check the vacuum connections (there are 2 at the rear of the engine and 2 at the front).
Those at the rear need special hands and some acrobatics!

After unplugging them (they all were in good shape), I connected them again, installed all items again and started the car.

It took 3 times to get it started but I didn't crank the engine more the 10 sec. The third time it fired. Aha, now we are cooking with charcoal

Idle was correct at 1500 RPM and when temperature settled it dropped to 1000 RPM but remained slightly rough. Good enough to do a test drive

Compared to my others cars the 928 feels big and not very powerfull. It starts only to live at over 3000 RPM but then it goes. Suspecting foul sparks I did some acceleration tests (hey it was night anyway and the industrial complex deserted ). The car was OK but fuel consumption (on the computer) stayed high (30 l/100 km) even when cruising . I had the impression that fuel consumption went once again up at towards the end of the test (75 l/100 km on hard acceleration).

Any thoughts on how getting the vacuum lines fixed? Maybe glue them with a supple glue? I think plastic straps won't hold.

Can't wait to receive the ordered filters and stuff...

Cheers to all and special thx to Brian and all other replies.

Tom

Nicole

I think the only way to fix broken or leaking vacuum lines is to replace them with new ones. Everything else won't last longer than a few days, especially given that there are vibrations and heat cycles involved in there.

Vacuum leaaks are a little tricky to fully diagnose and fix at home. The Porsche procedure requires you to put a cap on the Mass Air Flow Sensor under the air filter box, and also close the exhaust, I believe. And if you have leaks under the intake you have to be quite "handy" with tools, or take it to the mechanics.

Just remember one thing about repair projects on the 928: Most of the time when you do a repair, there is some other preventative maintenance you should do at the same time. The guys on this board are very good in pointing such things out to you. It will save you a lot of money in the long run - more than the Rennlist Membership costs you.

Tom DM

Update 4.

Well, I checked all wires and connectors.

The car was rather hard to start (4 attempts of ±10 sec cranking) but then it fired. RPM settled immediately at 1000 rpm, very cleanly.

Well: a test drive then. No problems with acceleration although it does not feel like 350 Horses kicking. Fuel consumption is still astronomical: 20 liters/100 km when walking around at 60 kph@2000 RPM, 75 l/100 km when WOT acceleration... I should be looking for an oil pit

I left the car for the day and this evening tried again: now it fired up immediately! Hmmm, is the car playing with me? But then no: 20 l of fuel have disappeared in less than 30 km driving...

Hello at the guys and girls at Devek: check your mail please, I need the parts rather urgently

Upon reception and installation of the parts I will do some timed runs (I 've got a logging system which takes GPS-data to calculate the speed and acceleration. As it only needs a 12 V source it will be hooked up easily).

If the fuel consumption persist, I have the car inspected at Porsche (which is 3 km down the road).

All tends to lead to a very rich running engine, torque is everywhere. Maybe blocked cats? Maybe the Temp II sensor Bernard 94 suggested (ordered at Devek so waiting for it)?

To all who replied or read these lines, thanks and best regards from Brussels.

Tom

Tom DM

Update 5 (those numbers keep going up )

Well not much: a CD containing the manuals for the 928 has not arrived yet, nor the parts from Devek (the 3-4 days delivery time seem to drag on)

I tried to start the car again: no joy as the (new) battery was as dead as a dodo. 0 V on it...

I took a conventional loader and it refused flatly (what 's in a name?) to charge. Luckily a 50A-shock of a jump starter convinced the new battery to load again.

After the battery was charged again, I checked the losses. 3 A ! Well, that's a fine reason why the battery empties...

Checking the fuses one by one (Thanks 928 Specialists!) I found (with the car parked and without the key engaged):

Fuse 18: window/Sunroof Regulator : loss of 100 mA
Fuse 21: Radio-Amplifier, Glove box Light: loss of 10 mA
Fuse 22: Electric seat adjustment Left : loss of 700 mA
Fuse 25: Diagnostic Connector, Int Lights, instrument cluster : 1000 mA

Total of losses found: 1810 mA, so some 1190 mA are still unaccounted for.
Probably alternator or rectifier diodes?

Tried to start the car: no joy. It tried to fire a few times but died. Smell of unburned fuel form the exhaust...

Well that's it up till now: I hope the Devek-stuff arrives this week, because I get a bit bored polishing the car

Greets to everybody!

Tom

Tom DM

Update 6... ladies and gentlemen: we have a runner.

The Devek-stuff arrived (sparks, TempII sensor, filters etc). Got everything installed but the car still refused to start.

Porsche Brussels being 2 km down the road I towed the car to the dealer... without license plates. Cops came by but let us through . Ouf...

Anyway: It took a qualified Porsche technician 21 Hr to find a faulty mass. He replaced also the in tankfuel pump and fuelfilter. Big bill but I was well received at Porsche and they found the hitch. I was glad the fault was not in the ECU or the MAf-sensor.

The car fires now after a 1-2 seconds. Me a happy bunny

Less happy was I when I saw the list the mechanics drew up ( I also asked for a complete checkup): busing buying brake components now. Insurance and registration is on its way and with a little luck a black GTS will be on the road within two weeks. Must remember to drill for oil

Time flies .... I bought the car end August and it 's nearing December now.

I'll keep you posted and to all: thanks for the received support.

Tom

sweanders

Great news Tom! Congrats!