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daniel
Joined: 18 Jun 2009
Posts: 686
Location: Sydney, Australia
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 Posted: Mon Jun 18, 2012 8:41 pm Post subject: CIS leaning out in mid rpm range |
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After recent dyno testing I have noted that the CIS leans out between about 3000rpm to 4000rpm. I have no idea why... I have though of some possible causes/solutions, would like some comments:
1) Possible WUR problem? Now might be the time to convert to one of the electronic versions?
2) Is there some form of electronic controller that can trigger the cold start valve to fix this?
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Tue Jun 19, 2012 12:31 am Post subject: |
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Vacuum leaks eliminated? System & control pressures within spec? Fuel flow rate within spec?
How lean is it going?
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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daniel
Joined: 18 Jun 2009
Posts: 686
Location: Sydney, Australia
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| Posted: Tue Jun 19, 2012 11:26 am Post subject: |
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Vacume leaks ok,
Fuel pump tank ect is all new so I imagine its ok, plus it come back to way rich at high rpm's
I checked control pressures with the last engine and all were ok.
This thing that bothers me is that the mixture seems to be dependant on revs?
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Tue Jun 19, 2012 2:53 pm Post subject: |
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| daniel wrote: | | I imagine its ok |
Your imagination is better then mine.
So, how lean at midrange? How rich at high rpm? Gotta graph?
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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Arvidw
Joined: 20 Sep 2009
Posts: 227
Location: The Nederlands (Europe)
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| Posted: Tue Jun 19, 2012 3:47 pm Post subject: |
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Yes, CIS leans out slightly at mid-rpm. (0.5AFR point lower)
Yes, CIS runs ridiculously rich at the redline. (2+AFR point higher)
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl) |
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daniel
Joined: 18 Jun 2009
Posts: 686
Location: Sydney, Australia
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| Posted: Tue Jun 19, 2012 4:55 pm Post subject: |
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Hi Rasta, I have a graph but I always have a lot of trouble posting pics here. Can I email it to you?
Here is a run down of the figures:
at 2500rpm13.5
sits at 14.8 from3400rpm to 4000rpm than drops to 12.2 at 6000rpm (peak power)
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet |
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Tue Jun 19, 2012 6:24 pm Post subject: |
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could be one or all of your injectors aren't firing properly,
first I would do a quantitive system pressure test... post results
second control pressure cold and warm test... post results
last quantitive injector test of each injector and check spray patterns whilst your at it... post results
the thing about wideband sensor is it just measures fuel from all injectors,
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress... |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Tue Jun 19, 2012 11:20 pm Post subject: |
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| leadfoot wrote: | | the thing about wideband sensor is it just measures fuel from all injectors |
The thing about wideband sensors is they don't measure fuel at all. They measure air. Could be rich misfire. btdt
Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Cedric
Joined: 27 Aug 2004
Posts: 2809
Location: Sweden
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| Posted: Wed Jun 20, 2012 1:54 am Post subject: |
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My afr is rock steady all way through the rpm range, within afr0,5 if i remember correctly. Can post a plot later. Checked the wur?
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1980 924 Turbo
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Wed Jun 20, 2012 5:26 pm Post subject: |
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| Min wrote: | | leadfoot wrote: | | the thing about wideband sensor is it just measures fuel from all injectors |
The thing about wideband sensors is they don't measure fuel at all. They measure air. Could be rich misfire. btdt
Min |
well actually they don't measure air either because that contains nitrogen and other gases. Oxygen levels in air are about 21% and this is compared to the oxygen level in the exhaust manifold, they sample the oxygen levels outside the exhaust but do not care what the nitrogen is doing.
So realistically, they measure fuel levels just as much as the measure air!!! The point I was making was it factors all injectors and can't differentiate between cyclinders. Also how would a rich misfire cause a lean condition?? you might have to explain that one to me?
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress... |
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Min
Joined: 04 Nov 2002
Posts: 2368
Location: Vernon, British Columbia, Canada
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| Posted: Wed Jun 20, 2012 11:08 pm Post subject: |
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| leadfoot wrote: | Also how would a rich misfire cause a lean condition?? you might have to explain that one to me?
Stu |
Somehow you've managed to make me lose all desire to share my knowledge. Have a good one.
Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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Arvidw
Joined: 20 Sep 2009
Posts: 227
Location: The Nederlands (Europe)
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| Posted: Thu Jun 21, 2012 7:25 am Post subject: |
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Misfire = no combustion
no combustion = no oxygen burned
no oxygen burned = loads of oxygen in exhaust
loads of oxygen in exhaust = lambda sensor reading loads of oxygen (a lambda sensor measures the residual amount of oxygen in the exhaust gasses)
lambda sonde concludes: a lot of air is not used during combustion so there was too much air, too little fuel = lean mixture
Megasquirt thinks: lean mixture, add more fuel !
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Porsche 924 2.0 Kompressor 136.1wHp @ 5650rpm / 201.9wNm @ 3900rpm (dyno @ dp-engineering.nl) |
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leadfoot
Joined: 11 Dec 2002
Posts: 2222
Location: gOLD cOAST Australia
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| Posted: Thu Jun 21, 2012 10:12 pm Post subject: |
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ArvidW, thanks for the clarification, makes sense, misfires though are pretty easy do diagnose so far as the engine generally struggles to get rpm, similar to timing issues... to much fuel... just never really though about it that way.
Min: If only you'd use your powers for good instead of evil...
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress... |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Fri Jun 22, 2012 2:46 am Post subject: |
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| leadfoot wrote: | | Min: If only you'd use your powers for good instead of evil... |
No sheet.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Fri Jun 22, 2012 3:09 am Post subject: |
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| Rasta Monsta wrote: | | leadfoot wrote: | | Min: If only you'd use your powers for good instead of evil... |
No sheet. |
I thought Canadians were supposed to be such nice people?
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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