CIS + Big turbo = too lean. Advice for more fuel?

[WinRice]

Originally Posted by Ringmaster

One discovery that I found interesting is that the car goes open-loop at +/-3000rpm which means that the fuel mileage really suffers if you try to cruise at higher speeds. I wonder if the Lambda controller could be tricked to stay in closed-loop operation at light throttle until +/-4000rpm?

I'm not sure if the Lambda controller reads RPM to help determine when to go into open-loop, but what looks like a throttle pot on the throttle body is just a switch that triggers open-loop at a certain throttle position. You could try to re-clock it and see what happens.

[turbo owner]

Originally Posted by WinRice

5 bar for an NA car, which also used a single fuel pump. Turbo cars are higher, and why Porsche went to two pumps in series so each would step up the pressure, and one pump wouldn't have to take the full pressure load.

System pressures (adjusting values) from the Porsche Tech manuals:

1980 SC - 4.7-4.9 bar
Non-lambda Euro Turbo - 6.2-6.5 bar
US lambda Turbo - 6.9-7.1 bar

Porsche changed the pressure trying to force more fuel through too small a hole, to much back pressure reduces pump efficiency requiring a second pump.

Fuel starvation should not be a problem if the nozzles are sized correctly on a 400 HP engine, fuel requirement can be calculated based on HP. Nozzle sizes can be determined by fuel requirements.

75 PSI is plenty for proper fuel atomization.

[WinRice]

Originally Posted by turbo owner

Porsche changed the pressure trying to force more fuel through too small a hole, to much back pressure reduces pump efficiency requiring a second pump.

Fuel starvation should not be a problem if the nozzles are sized correctly on a 400 HP engine, fuel requirement can be calculated based on HP. Nozzle sizes can be determined by fuel requirements.

75 PSI is plenty for proper fuel atomization.

True, but also remember that 75 PSI above manifold pressure gives proper atomization, you have to compensate for the boost pressure by increasing system pressure.

NA engine - 5 bar
Turbo at 1 bar boost requires 6 bar system pressure minimum to maintain 75 PSI at the injector.

[Thierry25]

Originally Posted by WinRice

I'm not sure if the Lambda controller reads RPM to help determine when to go into open-loop, but what looks like a throttle pot on the throttle body is just a switch that triggers open-loop at a certain throttle position. You could try to re-clock it and see what happens.

Yes the lambda regulation is triggered by the (3 positions) throttle switch. ( as you said no RPM reading)

As soon as the throttle butterfly is opened by more than 6°, the lambda regulation is triggered off and the freq valve duty cycle is fixed to 50%.

[turbo owner]

Originally Posted by WinRice

True, but also remember that 75 PSI above manifold pressure gives proper atomization, you have to compensate for the boost pressure by increasing system pressure.

NA engine - 5 bar
Turbo at 1 bar boost requires 6 bar system pressure minimum to maintain 75 PSI at the injector.

6.5 on the graph above is where back pressure starts showing more sever flow issues, 6 should not be a problem, it might run fat using the Euro injectors.

USA and Canada cars had smaller injectors to meet EPA regs, cars with serial numbers WPOZZZ have the proper injectors for a stock or mildly modified engine.

[Ringmaster]

Originally Posted by Thierry25

Yes the lambda regulation is triggered by the (3 positions) throttle switch. ( as you said no RPM reading)

As soon as the throttle butterfly is opened by more than 6°, the lambda regulation is triggered off and the freq valve duty cycle is fixed to 50%.

Thierry25

Cool, this is good to know! You called it a 3 position switch. I assume the 3 positions are closed (idle), 6 deg for open-loop crossover and open (WOT)? If so there would be no simple way to raise the open-loop threshold.

Can you tell me the part # for the fitting you bought from Summit to install the 044 pump up front?

Ahhh, the joys of CIS tuning - most of my WOT testing has been in ~60F ambient temps. Today it is ~80F and I can't get the car to go leaner than 12.0 above 60000rpm, which IMO is perfect! The boost level is almost exactly the same.

Once I burn through this tank of 94 octane w/10% ethanol I will try a tank of Shell 91 octane (no ethanol).

Regardless of what other steps I take, the front fuel pump will be replaced with an 044. Mine is already 19 years old so I don't mind spending the money to replace a part that will die one day. Maybe this change alone with get me enough extra fuel for the 1/2 point of WOT fuel I am looking for

Water/meth is a very interesting option with quite a few benefits but I am always reluctant to add another "system" to a car. Just more stuff to go wrong... Having said that, a simple kit with a small nozzle that activated @ WOT above 5500rpm would surely cure my issue.

[Thierry25]

Originally Posted by RarlyL8

Bosch P/N 0437 502 017 is for the USA injectors, the Euro injectors are P/N 0347 502 009.
I would be interested to know if the -057 will out flow the -009. It is known that the -009 will outflow the -017.

Brian, I think the- 017 is stock for both EURO & US 964 3.3 C2T . ( maybe it was different for 930)

I never tested the - 009. But once again, I am 100% sure the 057 outflow the 017.

Attention, the 057 provide more fuel everywhere on all the RPM range.

[turbo owner]

Originally Posted by turbo owner

Porsche changed the pressure trying to force more fuel through too small a hole, to much back pressure reduces pump efficiency requiring a second pump.

Fuel starvation should not be a problem if the nozzles are sized correctly on a 400 HP engine, fuel requirement can be calculated based on HP. Nozzle sizes can be determined by fuel requirements.

75 PSI is plenty for proper fuel atomization.

I found the formula, 400 brake HP at the crank needs 42 LBS of fuel per cylinder per hour at WOT or about 5 gallons per hour per cylinder. These are forced air induction fuel calculations.

Pump and nozzle requirements can be figured from there

[Thierry25]

Originally Posted by Ringmaster

Thierry25

Regardless of what other steps I take, the front fuel pump will be replaced with an 044. Mine is already 19 years old so I don't mind spending the money to replace a part that will die one day. Maybe this change alone with get me enough extra fuel for the 1/2 point of WOT fuel I am looking for

I am pretty sure this change alone will bring you the last ml of fuel you want to get ! ( again not saying 11.5 @ 6500 is need with your SC cams under 1b ) ....

However, if you have some tools (pressure gauge etc) in your hands, you could do some investigation prior to buy it. At least you could check your usual "static" fuel system pressure. If still @ 6.8 or 7 b , you can try to add a single washer to the fuel pressure regulator, rise about 7.6b in static and see what happen.

By the way, are your injectors new or professionnaly cleaned recently ? if not, this is a "must do" prior to do anything else ! If your injectors are not flowing correctly, the entire range of RPM , fuel saving and even the reliability of the engine are compromised.

[Ringmaster]

Bonjour Thierry25

I am pretty sure this change alone will bring you the last ml of fuel you want to get ! ( again not saying 11.5 @ 6500 is need with your SC cams under 1b ) ....

I hear you I do want to run a solid 1bar of boost which I think should be safe, given that I have JE forged pistons, Supertec head studs and the conservative 964T/EZ-69 timing curve.

However, if you have some tools (pressure gauge etc) in your hands, you could do some investigation prior to buy it. At least you could check your usual "static" fuel system pressure. If still @ 6.8 or 7 b , you can try to add a single washer to the fuel pressure regulator, rise about 7.6b in static and see what happen.

I have the correct pressure gauges so I will check to make sure the fuel pressure is no lower than 7bar.

By the way, are your injectors new or professionnaly cleaned recently ? if not, this is a "must do" prior to do anything else ! If your injectors are not flowing correctly, the entire range of RPM , fuel saving and even the reliability of the engine are compromised.

The injectors are brand new Bosch # 931 110 225 00. These are listed as fitting 1986 - 1992 US-spec 911 turbo. I don't know how this part number crosses over to OE injector numbers that you and RarlyL8 posted.


In an earlier post you said:

Yes you can lower the PC to 2.0 b. There is no basic problem to reach this PC. However you will certainly get more fat mid and you will increase the PC recovery time. ( if PC is too low , the transient response during gear shifting and throttle off response are affected ). Past a certain value, you can lower PC to whatever value.......... you don't get any additionnal fuel on very top end.

I noticed that when the Enrichment Pressure was lowered from 2.8bar to 2.45bar that it didn't help much with the fuel up top, however the recovery/response time betwen shifts seems really bad. The car bogs quite a bit and takes a long time to start pulling hard after a shift. Would setting the pressure back closer to 2.9bar help this situation?

I have been given some good advice that the stock fuel filter might be a restriction when trying to get max flow out of the high-pressure CIS system. Has anyone successfully fitted a billet race-type fuel filter in place of the stock fuel filter? Any improvement?

[Thierry25]

Originally Posted by Ringmaster

I have been given some good advice that the stock fuel filter might be a restriction when trying to get max flow out of the high-pressure CIS system. Has anyone successfully fitted a billet race-type fuel filter in place of the stock fuel filter? Any improvement?

Yes I also think the fuel filter is a restriction. ( Attention, the 964 NA fuel filter should not be used ). As I want to keep the setup as stock as possible , I never investigated in this direction.

[Ringmaster]

Originally Posted by Thierry25

Yes I also think the fuel filter is a restriction. ( Attention, the 964 NA fuel filter should not be used ). As I want to keep the setup as stock as possible , I never investigated in this direction.

I am attempting to find a high-flow race fuel filter than will replace the stock 964T fuel filter and connect using the M14x1.5 fittings - not easy!

We've had some nice mid 80F weather this week and the WOT AFRs are spot-on but when it gets below 50F it is too lean above 6000RPM. Since lots of 911 turbos only venture out in nice warm weather maybe this is why some owners don't need to get as creative with the CIS system as others?

Still hoping that installing an 044 pump up front to work in conjunction with my rear 044 pump will do the trick

[JFairman]

Well I have to eat all the words I said earlier in this thread and I admit my opinion was wrong because with internet searches I found a definately genuine new bosch made in czech republic 044 pump in the sealed plastic bag inside the black multi language box with the usual bosch red multi folded sheet of paper instructions in many different languages for $188 shipped from a genuine Bosch dealer and installed it.

I already have the CIS Flowtech 20% over modified fuel head and Brian Leask adjustable control pressure regulator installed and the CPR is adjusted well for my car and the AFR's I want.
I have the innovate MXT-L AFR gauge with built in controller installed and it is accurate and consistant.

I did nothing else other than install the bosch 0 580 254 044 pump in place of the front bosch 0 580 254 967 pump that was installed around 40,000 miles ago by the previous owners mechanic and the AFR'S went from about 12.5:1 at 1.1bar boost around 6400 rpms down to around 11.8:1
I havn't logged AFR's, I just glance down at the AFR gauge while driving.

At idle I had the CO screw adjusted so it was around 13.5:1 with the old front pump and idle went down to around 12.8:1 with the 044.
A small adjustment to the CO screw put it back to 13.5:1 at 750-800rpm idle speed.

Steady warm cruise AFR at 75mph on flat Florida interstate moves around between 15 and 15.2:1 and it runs great.
I'm also glad to find the new 044 pump is no louder than the little bit smaller one that was in there.

[WinRice]

Originally Posted by JFairman

Well I have to eat all the words I said earlier in this thread and I admit my opinion was wrong because with internet searches I found a definately genuine new bosch made in czech republic 044 pump in the sealed plastic bag inside the black multi language box with the usual bosch red multi folded sheet of paper instructions in many different languages for $188 shipped from a genuine Bosch dealer and installed it.

I already have the CIS Flowtech 20% over modified fuel head and Brian Leask adjustable control pressure regulator installed and the CPR is adjusted well for my car and the AFR's I want.
I have the innovate MXT-L AFR gauge with built in controller installed and it is accurate and consistant.

I did nothing else other than install the bosch 0 580 254 044 pump in place of the front bosch 0 580 254 967 pump that was installed around 40,000 miles ago by the previous owners mechanic and the AFR'S went from about 12.5:1 at 1.1bar boost around 6400 rpms down to around 11.8:1
I havn't logged AFR's, I just glance down at the AFR gauge while driving.

At idle I had the CO screw adjusted so it was around 13.5:1 with the old front pump and idle went down to around 12.8:1 with the 044.
A small adjustment to the CO screw put it back to 13.5:1 at 750-800rpm idle speed.

Steady warm cruise AFR at 75mph on flat Florida interstate moves around between 15 and 15.2:1 and it runs great.
I'm also glad to find the new 044 pump is no louder than the little bit smaller one that was in there.

Hey Jim, don't feel bad, I pretty much had the same results. My 967 had 35K-40K on it, swapped to a 044 and dropped roughly 0.5 in AFR. Being the analytical type, shook my head a few times, checked my past notes and it was correct. Checked the before and after system pressure and it was 7.1 bar both times. I can believe the additional fuel flow at WOT, but can't explain why the idle AFR went down when the system pressure remained the same.

Must have been one tired 967?

[Ringmaster]

This...

I did nothing else other than install the bosch 0 580 254 044 pump in place of the front bosch 0 580 254 967 pump that was installed around 40,000 miles ago by the previous owners mechanic and the AFR'S went from about 12.5:1 at 1.1bar boost around 6400 rpms down to around 11.8:1
I havn't logged AFR's, I just glance down at the AFR gauge while driving.

At idle I had the CO screw adjusted so it was around 13.5:1 with the old front pump and idle went down to around 12.8:1 with the 044.
A small adjustment to the CO screw put it back to 13.5:1 at 750-800rpm idle speed.

And this...

My 967 had 35K-40K on it, swapped to a 044 and dropped roughly 0.5 in AFR. Being the analytical type, shook my head a few times, checked my past notes and it was correct. Checked the before and after system pressure and it was 7.1 bar both times.

...is good news for me


JFairman and WinRice, are you running dual 044 pumps or just the 044 up front?


Thanks

[WPOZZZ]

Originally Posted by JFairman

Well I have to eat all the words I said earlier in this thread and I admit my opinion was wrong because with internet searches I found a definately genuine new bosch made in czech republic 044 pump in the sealed plastic bag inside the black multi language box with the usual bosch red multi folded sheet of paper instructions in many different languages for $188 shipped from a genuine Bosch dealer and installed it.

I already have the CIS Flowtech 20% over modified fuel head and Brian Leask adjustable control pressure regulator installed and the CPR is adjusted well for my car and the AFR's I want.
I have the innovate MXT-L AFR gauge with built in controller installed and it is accurate and consistant.

I did nothing else other than install the bosch 0 580 254 044 pump in place of the front bosch 0 580 254 967 pump that was installed around 40,000 miles ago by the previous owners mechanic and the AFR'S went from about 12.5:1 at 1.1bar boost around 6400 rpms down to around 11.8:1
I havn't logged AFR's, I just glance down at the AFR gauge while driving.

At idle I had the CO screw adjusted so it was around 13.5:1 with the old front pump and idle went down to around 12.8:1 with the 044.
A small adjustment to the CO screw put it back to 13.5:1 at 750-800rpm idle speed.

Steady warm cruise AFR at 75mph on flat Florida interstate moves around between 15 and 15.2:1 and it runs great.
I'm also glad to find the new 044 pump is no louder than the little bit smaller one that was in there.

I just had my Innovate installed and steady cruise gets me a 15.5-15.6 AFR. When I get on boost and go WOT, it dips down to about 10.5 @7000. She pulls really hard to redline with the mods listed in my sig.

Do I back off the fuel enrichment 1 notch? And richen up the idle?

[smurfbus]

Bryan: Yes, you leave a lot on the table running 10.5AFR. Mine almost dies when that rich but I have my spark plugs at 0.4.

15.3AFR is the best for fuel economy so maybe aim for that. IIRC it also run cooler that 14.7AFR.

RM: I think the front 044 is enough. I'm running two 044s but then again I had major lean running problems that I tried to cure with pumps to no avail.

I now have 11.5AFR at 4th gear 6000rpms (shorter gears) and 1.1bar boost. It does still seem sluggish at speeds (compared to my audi) so I'll finally add the WMI pump with a simple pressure switch I've had in the shelf for two years. I wanted to get the fueling sorted first.

[WPOZZZ]

Thanks, I'll richen up the idle and turn down the fuel enrichment a notch. I'm also thinking about getting WMI as well. Any recommendations?

[smurfbus]

My BL WUR enrichment didn't do much on upper rpms and I have it blocked now that I run AIC1.

[WinRice]

Originally Posted by Ringmaster

JFairman and WinRice, are you running dual 044 pumps or just the 044 up front?


Thanks

044 front, stock rear at that time. I'm currently upgrading the fuel system for EFI and the potential use of E85, so I have another 044 on the shelf for the rear.