Macster

Here's a pic of my Turbo's stock exhaust manifold. Similar construction as your description. My eyes are no longer precision measuring instruments so I can't say with any degree of confidence those tack welded together manifold flange plates are 5mm thick or 10mm thick, but they do not look like they're 10mm thick but 5mm thick (or closer to 5mm than 10mm).



Sincerely,

Macster.

pete95zhn

I do not know what I'm missing here, but the problem is very consistent. Yesterday's situation:

At start lambda 0.8-0.9.
When warm-up enrichment cease lambda rises to 1.0.
After few minutes of idle lambda 1.1.
Increasing revs idle-4000 rpm, car stationary, lambda rises to 1.2-1.3
Over 4000 rpm ( exact switching point unclear ) lambda drops to 1.0!

Now, when all leaks have removed from the equation, this happens whatever the combination of parts is, ie.
-no matter if it's blow-through or std location MAF ( Hitachi used )
-no matter which set of WBO2's I use ( have two ), NBO2 voltage seems to follow WBO2 indications
-TB used now is 996 turbo std
-Forge DV's are used as BOV's but they're before the MAF and don't leak.
-exhaust has 100 cell HJS cats, new flanges and seals
-there's no fault codes
-connection from oil tank vent to intermediate piece ( that T-piece ) is blocked, all vacuum connections are checked
-997 GT2 aluminium intake distributors, gaskets checked, rubber sleeves connecting them to intermediate piece OK, intake side pressure tested
-aux air passages at heads blocked
-switching off cam lift or valve timing via Durametric affect engine's idle, so I assume that all solenoids are operational

Could it be possible that fuel tank vent line valve or it's check valve is damaged? I'll disconnect it during the weekened for trial anyway...
Where the possible leak -if any- could lay? Forge DV's are used as BOV's but they're before the MAF and don't leak.
How about N75 valve:



Atmospheric Pressure is now connected to, well, athmosphere while the F-pipe hassle is deleted. IMO it can't flow "backwards", from Y-pipe to atmo, or can it? ( Actually I've once disconnected the whole valve without success. )
How about some sensor problem, like either IAT or MAP? Once again, no fault codes...

Any help appreciated!

Kevin

You have not posted any engine run logs so we are all in the blind.

So if you are running a Hitachi BLOW thru MAF setup, why isn't your tuner helping you>> what has he told you. From the looks of it, your injector "value" is incorrect. However, this has varying degree of input from your MAF diameter and MAF values which are entered into the Motronic code...

Post your logs from a few runs and we will quickly see the direction of your fueling.

pete95zhn

Well, the response from AZ has sometimes bee quite slow...so I decided to use also this way to get new ideas...
But, it did run properly during the winter's freezing days, OEM TB, Y-pipe and that Hitachi at std location.
Below latest Durametric logging, car stationary. Haven't been on the road for a while because the state inspaction date has passed...

pete95zhn

High-resistance short circuit to B+. Will renew wiring to both sides.

pete95zhn

So, while there were no mechanical causes to this I started to look for electric ones. What makes fault finding difficult is that I have reprogrammed Motronic and I really do not know which fault codes have been blocked. I asked just NBO2's to be blocked, but so far I haven't got info if all oxygen sensor related were...
So I started with OBD Manual's code P0130...:

Work instruction:
1. Check reference voltage on component. OK
2. Check reference voltage on control module. Unable without that test adapter

4. Check wiring for short circuit to ground. OK
5. Check wiring for open circuit. OK

But 3. Check wiring for short circuit to B+. Measured following voltages:
Pin II/9 and gnd 2,5V
Pin II/15 and gnd 2,96V
Pin II/2 and gnd 0,35V
Pin II/5 and gnd 0,35V

Right bank shows similar values. According to work instruction all of these should be 0V. ( Although I did measurement with cold engine... ) Corrective action is to repair wiring & correct the cause of damage.
Now the million dollar question:" Where that short to B+ may be?", if it's not in the WBO2 wiring, which I have just replaced without any help. Or is my Motronic toast? If yes, why?

EDIT: Did some more fault seaching.
According to fault code P0103 MAF B+ check OK.
According to fault code P0112 & P0237 ( or 0238 ) IAT & MAP B+ check not OK, found +5V.

Disconnecting connectors ( breaking points ) X59 1/2/3 ( = separating the engine ) does not help, ie. the fault is not at engine wiring loom.
Disconnecting Motronic connectors C/D/E and leaving only A & B, power feed and WBO2,, does not help.
Removing fuse C1, engine electronics does help...

Is there a way to get the Motronic tested for internal faults? And also repaired?

Macster

There is a company located IIRC in FL that advertises in PCA Panorama that it repairs/rebuilds DMEs.

Sorry, but I have no copies of PCA Panorama magazines at work to provide you with any more detail...

But I just did a quick google search and came upon this link:

http://www.porschedme.com/

Do not know if this is the place though.

Do your own google search. I used:

porsche dme repair

and got a couple of interesting hits.

Sincerely,

Macster.