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Fuel control via WUR + rpm boost switch
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Wed Jul 13, 2016 6:52 pm    Post subject: Reply with quote

Job done. Zeitronix ZT-2 rpm input now works with a potentiometer reducing the noisy signal so it can be used and logged. ZAVT switch and relay now works with the Pierburg boost pressure switch/solenoid. Initially tested on lower rpm and boost, but final log below shows switch opening the boost signal at 4600rpm

Marker 1 - On cruise at 3600rpm the AFR is low 14's
Marker 2 - gas pedal is floored and AFR goes to mid 11's, so enrichment is happening somehow as boost rises?
Marker 2 to 3 - this would normally drop to 10 AFR due to full boost enrichment, now mid 11's which is a 1.5 point improvement
Marker 4 - at 4600rpm the switch opens and AFR goes to low 10's as before
Marker 4 to 5 - these AFR bumps will be me letting off the throttle slightly and can be seen in the second bump with boost reducing.

Throttle response before the 4600rpm fuel enrichment is far crisper. Car leaps forward in all gears.

Conclusion is I need to lean off the WUR by half point AFR across the whole range. Then check and maybe lift the rpm switch threshold to 4800 or even 5000rpm before enrichment for higher rpm

Fuel threshold is not my limiting factor for more power. I have more than enough and need to trim it back a touch. My guess is the 2660 compressor and 8.4-8.5 CR will be my limitation in using up all the available fuel by raising boost whilst staying away from detonation.


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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Fri Jul 15, 2016 11:52 pm    Post subject: Reply with quote

You guys know you can take your WUR apart and adjust the boost sensing diaphragm to adjust the on boost enrichment right?

You can set cold warm and on boost control pressure separately to whatever you want..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Fri Jul 15, 2016 11:53 pm    Post subject: Reply with quote

You guys know you can take your WUR apart and adjust the boost sensing diaphragm to adjust the on boost enrichment right?

You can set cold warm and on boost control pressure to whatever you want..
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Sat Jul 16, 2016 12:14 am    Post subject: Reply with quote

Fasteddie313 wrote:
You guys know you can take your WUR apart and adjust the boost sensing diaphragm to adjust the on boost enrichment right?

You can set cold warm and on boost control pressure separately to whatever you want..


Yes. But what do you think triggers on boost fuelling regardless of the pressure setting
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Sat Jul 16, 2016 1:29 am    Post subject: Reply with quote

Carrera RSR wrote:
Fasteddie313 wrote:
You guys know you can take your WUR apart and adjust the boost sensing diaphragm to adjust the on boost enrichment right?

You can set cold warm and on boost control pressure separately to whatever you want..


Yes. But what do you think triggers on boost fuelling regardless of the pressure setting


Intake pressure triggers it on another diaphragm under the spring
but it's not like your changing the trigger point.. I'm pretty sure it's not like a "trigger" either, it's variable depending on the pressure that is acting on it.. Where it maxes out I don't know but it's not an on/off thing...

What you can adjust is how much it enriches for x amount of pressure change.. Move the whole enrichening curve more or less richer on boost..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Sat Jul 16, 2016 1:36 am    Post subject: Reply with quote

Carrera RSR wrote:
Fasteddie313 wrote:
You guys know you can take your WUR apart and adjust the boost sensing diaphragm to adjust the on boost enrichment right?

You can set cold warm and on boost control pressure separately to whatever you want..


Yes. But what do you think triggers on boost fuelling regardless of the pressure setting


Intake pressure triggers it on another diaphragm under the spring
but it's not like your changing the trigger point.. I'm pretty sure it's not like a "trigger" either, it's variable depending on the pressure that is acting on it.. Where it maxes out I don't know but it's not an on/off thing...

What you can adjust is how much it enriches for x amount of pressure change.. Move the whole enrichening curve more or less richer on boost..
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Sat Jul 16, 2016 2:58 am    Post subject: Reply with quote

The fuel enrichment is triggered circa 0.6 bar boost. Fine on a stock turbo running stock boost and no IC. For modified turbos running higher boost and especially IC's it makes the AFRs too rich in the mid range. Something you can't dial out by internal control or threshold pressures alone. If you could, then the Brian Leask solution derived from similar CIS setups on 930's would be worthless. I've emulated this solution. After today's adjustments and logging I'm going to leave the WUR alone as its now lean enough up to the rpm trigger at 4800rpm. Fuel enrichment after this appears to help cool things down according to the EGTs


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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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morghen  



Joined: 21 Jan 2005
Posts: 8163
Location: Romania

PostPosted: Sat Jul 16, 2016 3:14 am    Post subject: Reply with quote

I just did a test run with the boost restrictor before the WUR.
It does make a difference and there is a noticeable improvement but it think either my WUR needs a refresh(diaphragm seems to hold vaccum tho, as i tested it) or at this point this turbocharger cant be fed with this fueling system anymore...or there is something else that i'm missing.

What happens is that at 70% throttle, AFR values are quite good, boost is 1bar and with this before WUR boost restrictor AFRs are in the 12.X up to 5000RPM (i havent tested further)....however if i go 100% throttle, no additional power is delivered insted power delivery becomes jittery as it probably detonates and mixture leans dangerously to 14AFR and probably further so i instantly lift the pedal.

For me this is it, i'll be selling my GT DITC, two sensors and will be installing VEMS this winter.

https://www.youtube.com/watch?v=XfHsqMBvLoI
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Last edited by morghen on Sat Jul 16, 2016 3:50 am; edited 1 time in total
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Sat Jul 16, 2016 3:48 am    Post subject: Reply with quote

Not enough boost signal is getting through to trigger the WUR to enrich the fuel I would guess Ciprian.

If you are starting from scratch the a standalone ECU and EFi makes sense. Also makes sense to go to Raceboy as he knows these cars and should be able to offer you a plug and play solution. I'd suggest getting him to set the final tune would make sense too. 300bhp+ should be easy
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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morghen  



Joined: 21 Jan 2005
Posts: 8163
Location: Romania

PostPosted: Sat Jul 16, 2016 3:56 am    Post subject: Reply with quote

Hm, This could be the case as a small nipple on the TB is feeding the boost gauge, the decel valve and the WUR and with the T pieces and the actual nipple being less than 3mm in diameter it might have too little signal.

I'll try a single line from the manifold to the WUR just for checks.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1912
Location: MI

PostPosted: Sat Jul 16, 2016 6:16 am    Post subject: Reply with quote

Maybe you could put a MBC boost controller on your WUR like you would a WG single port style to only let your WUR see like 8 psi when your actually making 15 or so to try to trick it into enrichening less..
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morghen  



Joined: 21 Jan 2005
Posts: 8163
Location: Romania

PostPosted: Sat Jul 16, 2016 6:34 am    Post subject: Reply with quote

Had that idea a while ago, yes sounds interesting but MBC will mostly delay the moment the WUR gets full boost. A digital MBC would be better but not sure worth it without full EFI.
I'll have to do some re-routing but next week as we're having storms here this weekend.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Mon Jul 18, 2016 5:45 pm    Post subject: Reply with quote

morghen wrote:
Had that idea a while ago, yes sounds interesting but MBC will mostly delay the moment the WUR gets full boost. A digital MBC would be better but not sure worth it without full EFI.
I'll have to do some re-routing but next week as we're having storms here this weekend.


A digital MBC is just a replacement for the MSD rpm switch and boost pressure solenoid. Probably the same money. Save your time + money and invest it in VEMS this Fall
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1970
Location: Somerset, UK

PostPosted: Mon Jul 18, 2016 5:51 pm    Post subject: Reply with quote

With 3 100+ mile drives on Friday, Sat and Sunday I'm happy with the results of the rpm switch. AFR's are all good. Full boost/WOT is a touch rich over 4800rpm, but happy with that safety and it helps cool the EGT's. Happy days
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CÚdric  



Joined: 27 Aug 2004
Posts: 1973
Location: Sweden

PostPosted: Mon Jul 18, 2016 7:21 pm    Post subject: Reply with quote

Nice solution, do you have an afr curve for a full load run?
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