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Turbofrog
 
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Thanks, that was a load of info.

I have followed closely every CIS related thread and I have learned alot. I'm in Europe so I need to think twice weather to invest more money on US modded fuelhead + control stuff or go straight to EFI.

My 930 is a 79 US model with a alu fuel head and I think no O2 as its non catalyst vehicle.

I will check the flows too. I have 2 new fuel pumps installed (dunno if stock though) but I have a spare 044 to try if nothing else works. If I get more fuel somehow I would like to try a frequency valve ala Stup (greddy emanage?) or Thierry (split second+aem).

I might try a pressure relief valve in the wur manifold line just for kicks (before the CIS pressure kit arrives) and to see if it makes any difference on 3rd or on 4th gear. I really need to watch those AFRs though to stop if it goes too lean on spool.

BTW: I think I still have the air injection system on the engine? Driver side in front of the head there is a big junk and a line to driver side exhaust. I think it if its functional it does not pump air on boost or does it? My WB sensor is right after the turbo.
Old 06-10-2010, 12:07 PM
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Yeah thats the air pump.
I think it blows air into the exhaust ports for the first couple minutes after a cold start and then a vacuum solenoid triggers the 2 air pump diverter valves to send air to the catalytic converter the rest of the time including full throttle but I'm not sure.

The odd thing is you say you have a 1979 car...
The catalytic converter (if you have one), air pump, and aluminum lambda fuel head all came out in 1986 to meet USA emission standards at that time so Porsche could sell the 930 in the USA again.
As far as I know none of that stuff existed before '86 so if it's there I'm guessing it was installed in your car later.
Old 06-10-2010, 12:20 PM
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Turbofrog
 
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The door plate says non catalyst but the fuel head is alu. I'm sending a pic from my phone in a minute.

IIRC the air pump has a line to one spot in the header too on the driver side? Where should the lambda bung be?
Old 06-10-2010, 12:36 PM
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Turbofrog
 
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Here is a pic of the engine bay.

Old 06-10-2010, 01:06 PM
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The lambda bung in the origonal exhaust is in the long pipe on the drivers side near the wastegate pipe before the turbo, and in B&B headers it's right before the turbo just below the turbo mounting flange.
Old 06-10-2010, 01:06 PM
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Yeah thats an aluminum lambda fuel head but the lambda pulse valve has been removed so none of that system is doing anything now.

You can see the banjo fitting where fuel comes out of the lower chambers just to the right of the large rubber fuel inlet line and from that low rez pic it looks like someone pulled the rubber hose off it and soldered or welded the fuel hole shut instead of putting a plug there.

The long banjo bolt where the WUR and the lambda pulse valve returned fuel has been replaced with a shorter one and only the WUR return line banjo fitting is there now.
Old 06-10-2010, 01:26 PM
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Turbofrog
 
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Ok, the line I was talking about is about that area you just descriped. I need to lift the rear tomorrow and check the possible lambda sensor and spray some lithium grease to the TOB as the clutch is sticking like hell to the floor. Very annoying on traffic lights.

Can the center bolt on the MP be removed without any problems?

Oh, I need to buy some fuel system cleaner as I had huge problems trying to start the car after it was 2 months in a container. Fuel was drained empty so there might be some sheisse in the system now?

EDIT: Read you other reply and I must say that this is one hot rod as far as getting rid of original stuff is concerned. Some good, some bad like the idiot switch delete or the overboost delete (unless the yellow relay is other vice managed?)

Last edited by smurfbus; 06-10-2010 at 01:34 PM..
Old 06-10-2010, 01:29 PM
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I'm still just trying to understand how these things work, so this is more of a question and an answer.

If he has a lambda control fuel head that has just been hacked to close off the frequency valve passages, that means the pressure in the lower chambers is going to be way too high, right? If so I think that explains the near linear rise in his AFR's with RPM once the WUR's boost enrichment control pressure is all the way in.

Is this logic right?
Old 06-10-2010, 03:02 PM
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You're right.

The fuel pressure in the 6 lower differential pressure chambers in the bottom half of the fuel head will be higher if the pulse vale is unplugged (not the oxygen sensor) or removed and that will make the diaphram that seperates the upper and lower half of the fuel head raise upward a real tiny amount from the increased lower chamber pressure and that will reduce the amount of fuel that can get by the small clearance between the top side of the diaphram and the 6 orifices in the 6 upper differential pressure chamber leading upwards toward the banjo fittings for the injector lines.

The fuel going to those lower chambers has to go through a very small orifice just like the fuel going to the control pressure area on top of the control plunger cylinder so system pressure still remains relatively steady and higher, and the fuel pressure in those seperate areas can be varied by the external devices: the control pressure regulator and the frequency valve.
The fuel used for control pressure and lower differential chamber pressure is being used as hydraulic fluid not fuel, and once it goes through the orifces leading to those areas it never goes near being injected into the engine on that trip from the gas tank to the fuel head. Instead it is returned to the gas tank for the next time.

Because of this people that know what they are doing when removing the frequency valve or unplugging it increase the spring tension on the top side of the diaphram to push it down with the 6 individual spring tension adjuster screws I mentioned in an earlier post up the page to compensate or over compensate, and increase the system fuel pressure if it needs it by shimming the fuel pressure regulator spring.

Hope all that makes sense...
CIS is complicated and two of the 3 seperate fuel pressures: control pressure and lower differential chamber pressure seem to be the opposite of what you would think they are until you learn that the fuel pressure in those areas is used as hydraulic pressure and not for fueling the motor.

System pressure is supposed to stay the same and steady at all times as long as the pumps are running but I hear from Keith/911st that according to Larry at CIS Flowtech it does drop a little at high rpms with the stock 930 fuel pumps.

It's difficult to expalin whats going on without fuel flow diagrams through the internal passageways of the fuel head.
Old 06-10-2010, 04:19 PM
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Turbofrog
 
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Good info. Todo list

1. Measure the pressures and adjust accordingly
2. Try some fuel system cleaner in the meantime and stay out of high rpms

Fuel tank was emptied before shipping and I had really hard time getting it started after it had stayed in a container for 2 months (dead optima too). It started only after I used some 'start gas' straight to the TB several times and then put the IC back on. There might be some nasty sfuff in the fuel head from the bottom of the gas tank?

3. Lift the rear to get a better look of the airpump and lambda stuff and spray some 'drylube' on the TOB (the clutch pedal is sticking like cracy)

Last edited by smurfbus; 06-11-2010 at 03:12 AM.. Reason: #3
Old 06-11-2010, 12:56 AM
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Turbofrog
 
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Fuel system cleaner used, no help

Measured fuel pressures:
System 6.35bar
warm was 3 bar raised to 3.4 bar
enrichment 1.2bar (remember, I dialed max fueling) and still lean!

Fuel delivery on the wur line only 147g/min (147 equals only 109ml )? Spec is 160ml-240ml IIRC
What is the best way to measure fuel pump delivery? Fuel return line as per manual? Spec is 1170cc in 30 seconds

EDIT: Ok, measured the fuel delivery on the return line and it was only 1liter per 30sec, spec being 1.170 L. Then I tried to measure the pressure between the pumps but the CIS kit from pelican does not have AN adapters so I desided to try my spare 044 at the rear. But no go here either as the 044 has 18m*1.5 threads and the bosch that was at the rear was much smaller dia. Freeeck. At this point I was already loosing vision (gas fumes) so I had to quit.

So hopefully I find some adapters today so I can try the 044 which is half way installed already. If it does not help then I will measure the pressure between the pumps if I find a adapter for AN to CIS-kit fittings. That should tell if the front pump is Ok.

Checking fuel pumps from manual:
Pressure between pumps must be between
2 and 4 bar. If less than 2 bar, the first pump
(front) is defective. If more than 4 bar, the
second pump (rear) is defective. Replace
defective pumps and recheck pressure.

Last edited by smurfbus; 06-17-2010 at 10:36 PM.. Reason: Fuel delivery info added
Old 06-16-2010, 11:52 AM
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Turbofrog
 
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Put the 044 at the rear and still lean. Also measured the pressure between the pumps (1.6bar) but the joint was leaking (could not find real good adapters) so I figured a test drive would show any differences. The front pump over the front sheild looks like it needs tank siphoning to remove so I postponed it for later.

Result: A bit richer but not enough.

I'm not sure which these 'new bosch pumps' that were installed before I bougth the car are as there are no marks or labels on them? Next I'm going to swap the rear bosch(?) for the front and see if that makes any difference. I think I'm going to install a new 044 for the front too if there is enough space. The rear one took some effort to fit too bt it was not too bad.
Old 06-18-2010, 02:01 PM
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If you're saying there are no pressed in numbers or letters on some fuel pumps you have, that sounds like the fake chinese bosch pumps that you see for real cheap from some ebay sellers.
they are junk.

From pictures I've seen the word BOSCH in red letters is going the wrong way on the boxes they come in.
Old 06-18-2010, 02:26 PM
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I'm in the same place with it running out of gass after 4k rpms I have already have the modified fuel head but the higher displacement and compression is a little too much for it so when i talked to brian leask about it he said the heavily modifed 930's like mine need the system pressure raised to 7.5 bar. which is 110 psi. mine is a 3.4 with 7.5 to one compression and a waste gate set at 1 bar.
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88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's.
05 Cayenne S lapis blue
Old 06-18-2010, 03:12 PM
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Quote:
Originally Posted by xbmwguy View Post
i don't think i have quite that to the rear wheels 964 cams, 7006, some head work, running about .9 bar boost right now. fairman and i checked system pressure and it was at 98# seems a little high but not crazy. this morn i have pulled the enrichment control out to its max to see what happens. i never see the afrs in the mid to upper 11s as i did even with my stock wur., but jim said, like you brian, that maybe i am running out of fuel at the top. he has a few fuel heads, one a brand new modded, that maybe i will yry and then buy but i am starting to think megasquirt, as i will be approaching those $ as i keep trying to better the crappy design of cis, which by the way does translate into CONTINUALLY IRRITATING SH#T
Frank, you need the modified fuel head. my afr's were really good with 1 bar boost until I upped the compression ratio and displacement. Brian told me even with the modified head i have the larger displacement and compression ratio need the system pressure higher. even then i might need bigger lines and injectors. So I ordered the shim kit to bump the system pressure. it will be here next week. I still have a spare set of heads and a 3.2 intake in the garage for my swap to efi. I have the heads apart but not ported yet. Not dating the russian girl any more so i might be able to afford it in a few months. I was going to pick Juans brain and Eddie Bello a little more though before i decide what efi system to go with
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88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's.
05 Cayenne S lapis blue

Last edited by Ken911; 06-18-2010 at 03:36 PM..
Old 06-18-2010, 03:26 PM
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Turbofrog
 
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No pressed prints on the pump so it's a fake.

EArlier my AFR went above 13 at 5000 rpms and the last log I checked it was 5300. I have tried a releif valve in the wur manifold line to help with the overly rich midrange and now I tested lower pressures. Too low and it was pig rich at 9-10AFR AFTER 2nd gear WOT for some time (8sec) in 3rd gear

Is there a intank filter before the front pump?

Last edited by smurfbus; 06-18-2010 at 10:37 PM..
Old 06-18-2010, 09:58 PM
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Turbofrog
 
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Logged the new setup with two Bosch 044 fuel pumps with system pressure at 96psi and BL WUR at max fueling and it still goes over 13AF now at 5440 rpms.




I might try and raise the system pressure to over 100psi as it seems to be the only way to get more fuel with my current setup and fuel head plus I still need to check the injector flows too.
Old 06-28-2010, 11:51 AM
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As stated previously, the lambda fuel head expects the frequency valve circuit to be present and operatign at 50% duty cycle to bleed off pressure in the lower chambers and allow more fuel to pass to the injectors. Your symptoms and images seem consistent with that control circuit having simply been plugged without the required adjustment to the springs in the upper chambers. This should result in proportional lack of fuel exactly as you are seeing in your graphs.

The next step seems to be swapping out the fuel head with a non-lambda unit, installing the lambda circuitry and valve (yuck!), or getting your fuel head recalibrated so that it will work with the frequency valve removed.
Old 06-28-2010, 02:01 PM
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Ok, this should show as inadequate flow from injectors so that is the next test when I find suitable little bottles so I don't bend the lines too much. I hope the adjustment screws are not too stuck. I have the CIS manual to read in the mean time.

No parts for the lambda valve or any other valve so going thierry/stup/st is not going to happen yet plus I would like to see enough fuel before even thinking of managing the fat mid range. On 4th gear the AFR goes to under 10 if I go WOT at 3000rpms so I don't have a rpm switch/solenoid either and the releif valve I have in there can't handle it but that scenario does not happen much at normal driving.

I need to think other ways to lower the lower chamber pressure too like a small orifice bypass line. Has anyone tried that before? IIRC there is a limit on how much the fuel line screws can be adjusted.

The PO said the car runs 12.5 at WOT so there might be some other problems too.

EDIT: I also need to check if my FH is one of the CIS flowtech ones which have the lambda ports plugged. They have a cleaner plug in the lambda port though.

Last edited by smurfbus; 06-29-2010 at 01:52 AM..
Old 06-28-2010, 09:26 PM
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