Porsche 2.0 Start but Stalls

Good Day,

Our Porsche 2.0 USA with a D-Jetronic system starts but stalls inmediatly.
This problem is allready keeping me busy for few weekends and i dont have any more ideas.
i am stuck at this moment.

This are the things i have allready look through with the help of this website.

Measured the whole wiringloom.
12V on pin 16 and 24, power supply.
12V pin 18, start signal
Air temperatuur sensor 378 Ohm
Engine temperatuur sensor 2,8 KOhm

Throttlevalve 10 steps 0 Ohm, stationair checked

Injectors
Pin 3 3,2 Ohm
Pin 4 3,7 Ohm
Pin 5 3,0 Ohm
Pin 6 3,6 Ohm

MAP sensor
Pin 7 - Pin 15, 90 Ohm
Pin 7 - ground, Open
Pin 8 - Pin 10, 330 Ohm
Pin 8 - ground, Open
Vacuum 100%

Engine starts but stalls inmediatly.
when i take of the MAP sensor vacuumhose and plug of the manifold, the engine starts and runs.
Put back the MAP sensor vacuumhose, the engine stops inmediatly.

is it possible that there is a problem with the ECU.

Type ECU 280 000 044
Type MAP sensor 280 100 043

With kind regards

Erik

Hello Erik,
did you check the fuel pressure? Greetings Michi

Michi

Yes i checked the fuel pressure it is 2 Bar.

Erik

Hi Erik,

did you also checked the Auxiliary Air Regulator / the hose ?
If it is closed or the engine don‘t get additonal air while it is cold, it won‘t run very well or it will stop. So, if you disconnect the hose to the AAR, what will happen ?

Best Regards,
Marc
(I just tried that at my VW 411, which is not much different)

Hi Eric,
when does the engine stall?

While the starter turns, the D-Jetronic injects without getting the trigger signals.

When you release the key to 'ignition on' position, the trigger signals are needed to keep the engine running.

Therefore: please tell us more about the conditions the engine runs/stalls.

Regards
Norbert

Hi Norbert,

The engine stalls when the key gets back in the ignition on position.

I think that that the trigger signals are oke because the engine runs beautiful stationair when there is no vacuum connect at the MAP Sensor.

This is also the reason that i am stuck at this moment or am i thinking in the wrong direction.

Regards
Erik

Erikkraft wrote: ... the engine runs beautiful stationair when there is no vacuum connect at the MAP Sensor.
...

What happens when you close the hose towards the MPS?
Maybe Marc is right, and the engine needs this extra air...?

Regards
Norbert

Norbert,

When i reconnect the the vacuum at the MPS sensor while the engine runs, the engine stalls inmediatly.

Also when the engine runs and i pull vacuum bij hand (mouth)on the MPS sensor the engine stalls.

Regards
Erik

Hi Erik,

please answer: Do you clogg the hose when you let the engine run and disconnect the MPS or does the engine soak extra air through the hose / the connector?

- pulling vaccuum to the MPS signalizes low throttle, the mixture is leaner than without vacuum -

Regards
Norbert

Norbert,

When i take off the MPS vacuumhose from the manifold i place a plug on the connector on the manifold so there will be no vacuumleak.

Regards
Erik

Hi Erik,
all the readings you posted in your first post are o.k. - injector's resistance way too high, maybe a ground <earth> problem? Should be about 2,4 Ohms. There is a central ground connector at the plenum as far I remember.
Fuel pressure is o.k., did you check it with the engine running, too?

At this point I can mention only one more reason for the effect you describe besides a broken ECU:
- Injectors clogged ???

Regards
Norbert

Hi Erik,

just shortly from holidays: If you remove vacuum line from MAP sensor, your MAP sensor will signal full-load to ECU and thus make mixture rich. Does your MAP sensor hold vacuum? And have you checked your engine for vacuum leaks plus tested igntion timing?

Hi Volker.

The MAP sensor is holding its vacuum , i had to replace it with the same type number because the original had a hole in the diafram.



Timing of the engine has been checked. Stationair spot on TDC and the pre setting by 27 degrees is correct.

Regards
Erik

Hallo Erik,

You mentioned the 0.280.100.043 as being the manifold pressure sensor in your 1973.

As far as i lnow is this for a 1974-1976 type

You should have the mps 0.280.100.037

It will give a different voltage signal back to the ecu

Best of luck, Leo

Hi Leo,
following Volker's list the ...043 MPS was installed from 5/73 on.

Normally all cars built after the summer holidays are the following model year.

Regards
Norbert

Norbert,

Car was manufactured on november 1973 and delivred on februari 1974.
The partnumbers should be correct.

There is one thing i chanced bij rebuilding the engine. The original injectors where leaking allover the place. I replaced them . But i could not find the same partnumber. I placed injectors for a 2 liter aircooled vw engine. Also with the green cap.

Could that give a problem.

Regards

Erik

Hi Erik,
all green D-Jetronic-injectors have the same flow rate and are compatible.


Regards
Norbert

Hi,

yes it is a problem! Porsche 914 1.7 and 2.0 have different injectors, both in color and flow rate. You should have yellow ones.

Volker wrote: Hi,

yes it is a problem! Porsche 914 1.7 and 2.0 have different injectors, both in color and flow rate. You should have yellow ones.

No, Erik. You own a 2.0 and green ones are correct.

Regards
Norbert

This are the of injectors i replaced.