jpitman2

If you do a mixture test (CO?) you might know whether to make them all leaner or richer? Even a sniff at the exhaust and test for sooty would give you an idea if it was too rich.
My car's distrubtor looks like the black non-adjustable unit in pic above. It also has an electrical connector on its inner side that I believe is something to do with hot starts, that I have not seen on any other 928.
Note also that some 911s used an 8 port distributor with 2 ports unused, but the ones I have seen were black bodied units.
jp 83 Euro S AT 53k

gbgastowers

I have that same electrical connector and I think it is for the mpg gauge. I am trying to figure out where to go from here. I don't have a way to check the CO. I can inspect some spark plugs to get an idea whats going on(I just cleaned them before todays startup). It does seem like it's running rich but I am thinking my symptoms are indicating fuel starvation? I have several WUR's and the one I first tried was pressure set up perfectly then I tried the lower pressure WUR I have and it didn't help. I am thinking I will try to shim the fuel disributor pressure regulating (bypass) valve as mine has no shims on it now. I am pissing in the wind again.

Fogey1

+928. It's the injector output that counts.

jpitman2

When I got my car it had a bad hot start problem. When i found a disconnected lead down the side of the engine, I found it would plug into the distributor. Hot start problem went away. My car doesnt have any sort of mpg display - no vacuum gauge or whatever it might be.
Have you checked system and WUR pressures, and delivery rate? Without these you are truly pissing in the wind.
jp 83 Euro S AT 53k.

gbgastowers

system=70 psi
cold control=19 psi
warm control=44 psi

and it holds pressure for 25 min

I have a new CIS specific fuel pump but I have not checked the delivery rate.

here are the plugs which I cleaned before todays start up. I only ran the car for about 20 min.

dogleg

off subject here ,but did you ever check and confirm cylinder compression ? i cant start to get my head round this one till i know the basics are right!

gbgastowers

yes - I did. It was a limited test starting with the #6 cylinder that had the spark plug that always looked new. It had plenty of compression so I did not test the others. I am not using any oil (no smoke)and there are no signs of bad rings(which I replaced a few months ago).

dogleg

when you say plenty of compression what was the reading?still think its worth checking all 8 to be able to compare to each other and get an overall picture of condition in this area.

jpitman2

The pressures look in the ball park - cold control will vary with ambient temp. Cyls 1 and 8 look worst, but if it spent some time idling before shut off, not terrible. The other 6 dont look bad at all. Initially mine was lean - popping on the overrun, and white plugs. Are you sure the cam and spark timing is OK? Is the throttle opening fully?
jp 83 Euro S AT 53k

993turbo

Well, doing a compression test of one cylinder does not tell you much about the engine Im afraid.

The engine needs 3 basic things to run: Fuel (Gasoline) - Spark (at the ''right time'') - and sufficient compression.



Not saying compression is your problem, it is still well worth checking all 8 cylinders. Check them cold, on WOT.
Should you have any cylinders which are below the average of your engine, check with oil to rule out piston rings.

Its well worth the time!

Roy928tt

F.A.C.T.S.

Fuel

Air

Compression

Timing

Spark

gbgastowers

Since I have all the plugs out now I will go borrow the gauge and do it right just to rule it out. The car runs/ran fairly good with one of the WUR's I have. This WUR is set up with lower pressures and the car likes it to where the power loss in minimal.

gbgastowers

A lot of the plugs are a little wet(fuel fouled?). 1 & 8 at least were dry. Cam and spark timing are triple checked and a lot of money was wasted chasing non existent ignition fears. Throttle has been adjusted to 1mm play and the action was visually inspected yesterday.

Dennis Wilson

IIRC 4 bar (60 psi) is too high for injector pressure and will flood the engine. Try turning them down to 45 psi. The injector pressure should be equal to the system pressure, minus the control pressure, as adjusted by the position of the air sensor plate. Don't have the charts here at work so going from memory.

Dennis

gbgastowers

Thanks Dennis,
The 60 I referenced was how many mililiters I measured after a certain time. I will check the psi to the injector and go from there. Good info. Gunar