Thanks for all the replies. I love to get it running as an LH jetronic .

I know mechanic injection is simpeler, my old benz also has it and it never lets me down.

Hereby a picture of the engine bay.







I have disconnected the temp II sensor, than it starts fine and keeps running. I have the Bosch 0280130069 in it. Dual signal (checked it to be sure).

I will try and disconnect the MAF tomorrow, see what it does then.

 

Actally, the "L-Jet" used in the US 80-84 cars was the first electronic injection. A variation was used on 944s, where both injection & ignition are controlled through the DME box. That used the 'barn door' Air Fuel Meter.
LH used the hot wire MAF. A big improvment. But not without it's faults.

However, both are a significant performance improvement over CIS. While CIS had it's day, electronic has too many advantages. And even CIS is better than a carb. Mind you, I'm an old school gear head. I prefer a Holley 4 barrel over Webers, but that's because I can tear one down in my sleep. I need to be at least mostly awake to get it back together correctly. Webers are something I never had an opportunity to get into.

One of the advantages of electronic is tuning via programming.

The LH (and EZK) can be really fine tuned. Mixture & spark advance adjusted at any given RPM. I don't know the details/fine points, but a good tune can bring out the best in electronic engine management.
Not so easy to do with CIS. Impossible with a carb.

John Speake (I had a funny feeling he'd show up) is the one to talk to about tuning & setting up the LH cars. He's also a very good source for parts.

 

So I came to testing the car without MAF today.
Starts fine, runs fine, just doesn’t really pick up real good.

Also starts fine when warm.

So could it be the MAF?

 

Many variables.

You can do some basic testing of the MAF with a multimeter, but its best to have it rebuilt. They are more often than not out of calibration.

Also, be aware that on the S2 you set the mixture on the maf. Both mixture and idle speed is set manually.

The S2 LH jet is a really easy to diagnose and fix.

 

when i had my BMW 850 running on 1 bank of cilinders , i switched the MAF's to see that the dead bank also switched . So i had a "bad" MAF. ( a 850 doesn't start/run without the MAF )
I compared both MAF's with a multimeter , even the signal voltage by using a leaf blower.... but i could not find any difference between the "good" and "bad".
So yes, i believe you cannot do much on a MAF with a multimeter....i bought 2 new ones and problem solved , but on the 928 i would have it rebuilt , as it's a very expensive part i assume…..?

 

Hi guys,

so I’m back after I have had the MAF revised.
More or less a necessary move, so no regrets as it seemed to be way off.

But still it doesn’t keep running, too bad.

When I disconnect the temp II sensor it does keep running. And runs smoother than before!

I will be making a DIY pressure tester for the inlet system. As I suspect it is a vacuum leak somewhere.

Any other suggestions?

 

Problem solved!!
As I was looking to disconnect the TPS and check if this was in the right position. I found a loose intake pipe 😬.

when the rubber sleeves were connected the pipe looked fixed. But as soon as I disconnected the sleeve the pipe was loose.

Can’t remember I loosened those after re-install. But I feel stupid for not checking. and man are some of them in difficult spots!

So I tightened all the intake pipe bolts to the engine and it runs great!

Now some carefull idle and throttle cable adjustment and get it ready for the APK(MOT).

Thanks for all the help.