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Too Much Fuel

Hi all, I've been battling rich on boost situation ever since I got my car.

Everything has been checked, and as far as I can tell, is in spec. But I'm still 9.8-10.0 under boost... all the way to redline.
Only thing not in spec is my boost enrichment.. The disc under the WUR has been adjusteded so far in, that my control pressure only drops about 0.2 bar under full boost. Today I disconnected the boost enrichment line from my WUR, and even that made no diffference.

Car is perfect everywhere else... except on boost.

Car is an 84 and has:
completely fresh rebuild. SC cams, 7200 turbo, MSD probrammable ignition (locked dizzy etc), 3 inch exhaust after turbo, but stock euro headers.

Am currently only running 11psi and wondering if its at all possible that I'm just not running enough boost? Am waiting on a digital boost controller, and have the car set to 11psi, as thats what I want the default spring pressure to be... and will use the EMC to get me to about 14.7 psi

Entire CIS system is an unknow as well... Car came in from japan, and at the time had a manual boost controller but no idea what it was set to. possible the CIS head has been modified, but I have no way of telling.

Any odd tricks I may have missed.. i'm all ears...

Cheers

Chris

Old 10-24-2020, 07:16 PM
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I would remove the WUR, disassemble, inspect and clean. Then replace and test again,

Rahl
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Drive it like you hate it! 1976 930 Turbo Carrera, Mostly stock...Lightly sweetened
Old 10-25-2020, 11:35 AM
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No such thing as too much fuel. time for a 1 bar spring! Don't look a gift horse in the mouth!
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82 930 Pearl White 3.3 964 cams, K27 HF, Kokeln, fuel enriched, IA fuel head mod, wur mod, crankfire, 2X plug, Aase worked heads. 1bar, GHL, zork, 23/33 bars, low, loud
Old 10-25-2020, 12:37 PM
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^^^^^^^^^^^
Had a similar problem, As you stated it had a controller so fuel delivery probably modded for more boost before you got it.
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Old 10-25-2020, 12:53 PM
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Cheers for the replies team. Chucked a bigger spring in the Turbosmart gate, and went for a rip. Now hitting 14psi, but still going crazy rich... and still don't have the enrichment connected.

Road was a bit damp so only did a few pulls and only up to about 4500 rpm, but was down to 9.8 on the AFR gauge. WIll have to wait till its dry I guess to see if it starts climbing again as I get near redline.

Am I doing much damage with that much fuel?! Car still hauls even at 9.8... But aware of bore wash etc...

Don't think its the WUR though.. Its fairly static in the equation as far as I can tell. All pressure testing on it has been super consistant. Currently at 3.5bar control. System is 6.1.

Unless I'm some how loosing control pressure on boost, but not sure how that could happen without running out of fuel at the injectors first..

Thanks again
Old 10-25-2020, 02:30 PM
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Make sure the AFR gauge is properly calibrated
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'86 no-sunroof 930 coupe: Emissions removed, FrankenCIS controlling eWUR, lambda, COP ignition. Tial f46P 1.0 bar spring, SC cams, K-27/29, lightweight clutch, TK Longneck intercooler, RarlyL8 headers and dual-outlet hooligan
'14 Jaguar XK-R: Bullet proof windscreen, rotating number plates (valid all European countries), martini mixer, whatever you do don't press this red button!
Old 10-25-2020, 02:56 PM
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Re calibrated numerous times.... even swapped out sensors a few times...
Old 10-25-2020, 03:26 PM
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I'm not sure how the fuel pressure is able to decease under boost with the signal line disconnected. With the boost signal line disconnected, at atmospheric pressure the engine should run slightly rich at idle and lean on boost. Does your WUR have a vac hose connected to the top (atmospheric reference) port as well as the boost port? Would make sense if you are pulling off the reference hose instead of the boost hose.
A drop of 0.2bar fuel pressure under boost shouldn't drop AFRs into the 10's.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 10-25-2020, 05:55 PM
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Quote:
Originally Posted by RarlyL8 View Post
I'm not sure how the fuel pressure is able to decease under boost with the signal line disconnected. With the boost signal line disconnected, at atmospheric pressure the engine should run slightly rich at idle and lean on boost. Does your WUR have a vac hose connected to the top (atmospheric reference) port as well as the boost port? Would make sense if you are pulling off the reference hose instead of the boost hose.
A drop of 0.2bar fuel pressure under boost shouldn't drop AFRs into the 10's.
Correct... it shouldn't.. but unfortunately it does...

I have the boost reference connected correctly... Though at the moment, it seems to make no difference if its connected or not..

Checked it with pressure gauges so many times... All seems to work as it should. Control pressure is rock solid at 3.5 bar.

Adding 4-5 psi activates the boost enrichment, which I currently have set at 3.2 bar

It seems like the metering plate is just moving too far.

No boost leaks... car runs awesome (well... as far as I can tell)

AFR's are 14.5-14.7 on cruise, 12.8ish at idle.

just got back from a rip, and it bottoms out at about 9.8AFR, and by redline, climbs up to about 10.4

There's a lot of fuel going into this thing! I'm lost .. will try and get a fuel pressure gauge fitted permanatly so I can see whats going on while driving. Not sure what else to try!
Old 10-25-2020, 07:34 PM
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So with the engine off and the pumps running, if you add 5psi boost to the WUR the fuel pressure drops from 3.5 to 3.2bar. And with the engine running this equates to 10:1 AFR, even if the boost signal is not connected to the WUR?
The only thing I can think of is that the fuel distributor piston and/or air meter arm have been modified to travel further at full throttle. This could flood a stock engine. To test this remove the injectors and measure the volume at full throttle for 30 seconds.
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Old 10-26-2020, 06:25 AM
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Quote:
Originally Posted by Chris_chch View Post
Correct... it shouldn't.. but unfortunately it does...

I have the boost reference connected correctly... Though at the moment, it seems to make no difference if its connected or not..

Checked it with pressure gauges so many times... All seems to work as it should. Control pressure is rock solid at 3.5 bar.

Adding 4-5 psi activates the boost enrichment, which I currently have set at 3.2 bar

It seems like the metering plate is just moving too far.

No boost leaks... car runs awesome (well... as far as I can tell)

AFR's are 14.5-14.7 on cruise, 12.8ish at idle.

just got back from a rip, and it bottoms out at about 9.8AFR, and by redline, climbs up to about 10.4

There's a lot of fuel going into this thing! I'm lost .. will try and get a fuel pressure gauge fitted permanatly so I can see whats going on while driving. Not sure what else to try!
You could ditch the WUR and some of your other components, install FrankenCIS with eWUR. Then with the mixture control in place you can continue to up your boost to take advantage of all that extra fuel (jealous lol)
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'86 no-sunroof 930 coupe: Emissions removed, FrankenCIS controlling eWUR, lambda, COP ignition. Tial f46P 1.0 bar spring, SC cams, K-27/29, lightweight clutch, TK Longneck intercooler, RarlyL8 headers and dual-outlet hooligan
'14 Jaguar XK-R: Bullet proof windscreen, rotating number plates (valid all European countries), martini mixer, whatever you do don't press this red button!
Old 10-26-2020, 07:11 AM
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Quote:
Originally Posted by RarlyL8 View Post
So with the engine off and the pumps running, if you add 5psi boost to the WUR the fuel pressure drops from 3.5 to 3.2bar. And with the engine running this equates to 10:1 AFR, even if the boost signal is not connected to the WUR?
The only thing I can think of is that the fuel distributor piston and/or air meter arm have been modified to travel further at full throttle. This could flood a stock engine. To test this remove the injectors and measure the volume at full throttle for 30 seconds.
Appreciate the feedback... and yes... it all operates exactly as you describe. Will get a permanent fuel pressure gauge installed first... if that comes back without anything obvious.. I'll just make use of this extra fuel I guess... good excuse to get some headers and a bigger turbo....

Thanks again!
Old 10-26-2020, 10:38 AM
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Originally Posted by flightlead404 View Post
You could ditch the WUR and some of your other components, install FrankenCIS with eWUR. Then with the mixture control in place you can continue to up your boost to take advantage of all that extra fuel (jealous lol)
I haven't really followed the eWur developements... Always thought I'd just go full EFI if it got to that... Does the system actually work well? I'm kinda interested now...
Old 10-26-2020, 10:40 AM
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Quote:
Originally Posted by Chris_chch View Post
I haven't really followed the eWur developements... Always thought I'd just go full EFI if it got to that... Does the system actually work well? I'm kinda interested now...
Works very well afaiac. I see mixture adjustments being made within 0.1 sec. You can use as much or as little of the system as you like

I have a 60-2 toothed flywheel and am controlling ignition as well as mixture with both the eWUR block as well as lambda valve.

I'm limited by fuel constraints but with SC cams, 1.0 Tial WG, Brians headers and mufflers, and a K27/29 turbo I must be pushing 400 to the wheels. I had 365 to the wheels with 0.8 bar WG and it was lifting early. The 1.0 bar doesn't lift early so not only am I getting higher boost, its actually slightly earlier and faster too

According to some resources "The general rule of thumb is that, not accounting for temperature-induced power losses, a turbo will increase horsepower by about 7 percent per pound of boost over a naturally aspirated configuration"

I wish I had more fuel though, because more fuel = more boost
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'86 no-sunroof 930 coupe: Emissions removed, FrankenCIS controlling eWUR, lambda, COP ignition. Tial f46P 1.0 bar spring, SC cams, K-27/29, lightweight clutch, TK Longneck intercooler, RarlyL8 headers and dual-outlet hooligan
'14 Jaguar XK-R: Bullet proof windscreen, rotating number plates (valid all European countries), martini mixer, whatever you do don't press this red button!
Old 10-26-2020, 02:18 PM
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Where do you have your O2 sensor mounted?

Rahl
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Old 10-27-2020, 12:52 PM
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Where do you have your O2 sensor mounted?

Rahl
Just after the turbo... but before the muffler
Old 10-27-2020, 09:21 PM
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That should be the recommended location. So that is probably not contributing to your issue.

Rahl

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Old 10-28-2020, 11:04 AM
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