Cold Starting (Kangaroo Blue C2)
07-09-2003, 10:33 AM
#16
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Good info - Thanks.
No prob. with pointers.
To answer your question on the full throttle switch. A lot of cars seem to have this miss positioned - perhaps to avoid unintentional DME flash. I had to reposition mine so that it would make contact.
Has the Airflow meter had the cable fix?
Ade
No prob. with pointers.
To answer your question on the full throttle switch. A lot of cars seem to have this miss positioned - perhaps to avoid unintentional DME flash. I had to reposition mine so that it would make contact.
Has the Airflow meter had the cable fix?
Ade
07-09-2003, 01:17 PM
#17
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I’ve heard about a flow-meter wiring mod where the cable is doubled back on its self and ty-wrapped but I’m not clear on what it is for. I can only assume it acts as strain relief. Can you shed any light on this?
07-09-2003, 01:31 PM
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Hi,
That's pretty much what it does. Apparently the cable rubs against the pipes at the back of the airflow sensor. The correction involves cable tieing the cable and connector together so that the cable is forced away from the back of the housing. There are lots of threads on the archives concerning this.
BTW. There's also a new cable connector part available with gold plated contacts.
That's pretty much what it does. Apparently the cable rubs against the pipes at the back of the airflow sensor. The correction involves cable tieing the cable and connector together so that the cable is forced away from the back of the housing. There are lots of threads on the archives concerning this.
BTW. There's also a new cable connector part available with gold plated contacts.
07-09-2003, 07:46 PM
#19
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Blue
the 964 does not have a mass flow meter. The flap/vane system generates an analogue voltage signal that is proportional to volume flow rate - air mass is then calculated from air pressure (ie density)data. Th e993 introduce the mass flow meter (hot wire I think).
the 964 does not have a mass flow meter. The flap/vane system generates an analogue voltage signal that is proportional to volume flow rate - air mass is then calculated from air pressure (ie density)data. Th e993 introduce the mass flow meter (hot wire I think).
07-10-2003, 05:52 AM
#20
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Ade - C4 91:
<strong>
Firstly - I agree that Jonas is very knowledgeable, but I really wanted to hear some technical knowledge from someone who doesn't have a financially vested interest (with all respect to JZM).
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Why? Has Jonas got controlling share in the O2/Altitude sensor manufacturers? How much money are we talking about here?
Jeez, just pick up the phone to Jonas if you want AN answer. If you just want to debate this, then I am quite happy to do that. And to speculate as well.
The O2 sensor is primarily for emissions. Period. If you don't have to pass emissions, then you don't need one. Your car will not run rough, blow up, give 12mpg or shed all its paint overnight if you don't have one. John FM (96.4mhz) has a catbypass AND an O2 sensor. That's weird because he doesn't need it, perhaps the installers didn't know how to jumper the DME or maybe there is a degree of emotional attachment <img border="0" title="" alt="[Wink]" src="wink.gif" /> At the end of the day, it doesn't matter. I am sorry though I cannot give you a technical explanation of why the O2 sensor is not important providing the above conditions are met.
Have you called Jonas yet?
<strong>
Firstly - I agree that Jonas is very knowledgeable, but I really wanted to hear some technical knowledge from someone who doesn't have a financially vested interest (with all respect to JZM).
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Why? Has Jonas got controlling share in the O2/Altitude sensor manufacturers? How much money are we talking about here?
Jeez, just pick up the phone to Jonas if you want AN answer. If you just want to debate this, then I am quite happy to do that. And to speculate as well.
The O2 sensor is primarily for emissions. Period. If you don't have to pass emissions, then you don't need one. Your car will not run rough, blow up, give 12mpg or shed all its paint overnight if you don't have one. John FM (96.4mhz) has a catbypass AND an O2 sensor. That's weird because he doesn't need it, perhaps the installers didn't know how to jumper the DME or maybe there is a degree of emotional attachment <img border="0" title="" alt="[Wink]" src="wink.gif" /> At the end of the day, it doesn't matter. I am sorry though I cannot give you a technical explanation of why the O2 sensor is not important providing the above conditions are met.
Have you called Jonas yet?
07-10-2003, 06:03 AM
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BTW
I have called Jonas probably 4 times since owning my Car. On all 4 occaisions, I told him I am up in Leeds & probably will never be able to use him. On all 4 occaisions, he spent 20 minutes or so going through possible causes/solutions to my problem. He is not overly commercial in this regard.
Pinstripes
cat bypass was a previous owner job. My car has rock solid idle etc etc, so I don't feel the need to change anything.
I have called Jonas probably 4 times since owning my Car. On all 4 occaisions, I told him I am up in Leeds & probably will never be able to use him. On all 4 occaisions, he spent 20 minutes or so going through possible causes/solutions to my problem. He is not overly commercial in this regard.
Pinstripes
cat bypass was a previous owner job. My car has rock solid idle etc etc, so I don't feel the need to change anything.
07-10-2003, 09:10 AM
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Hi JohnFM
Mass flow / volume flow…hmmm. My understanding is that the 964 flow meter outputs an analogue signal based on the position of a wiper arm on a ceramic disc. The position is dictated by the mass flow of air and the force generated by the flow meter return spring. I believe the 993 has a hot wire type meter where the cooling effect of the air flow over the wire is used to determine mass flow. I know people call hot wire type flow meters “mass flow” and moving flap type “volume flow” but surely mass flow is what is being measured by both types? I may be being pedantic here but without mass flow, what force is acting to hold the flap open against the return spring? Volume flow is irrelevant as the chemistry of combustion is determined by air / fuel ratio on a mass basis. Whatever…interesting it may be but this is not fixing my cold start issues. Back to work.
Mass flow / volume flow…hmmm. My understanding is that the 964 flow meter outputs an analogue signal based on the position of a wiper arm on a ceramic disc. The position is dictated by the mass flow of air and the force generated by the flow meter return spring. I believe the 993 has a hot wire type meter where the cooling effect of the air flow over the wire is used to determine mass flow. I know people call hot wire type flow meters “mass flow” and moving flap type “volume flow” but surely mass flow is what is being measured by both types? I may be being pedantic here but without mass flow, what force is acting to hold the flap open against the return spring? Volume flow is irrelevant as the chemistry of combustion is determined by air / fuel ratio on a mass basis. Whatever…interesting it may be but this is not fixing my cold start issues. Back to work.
07-10-2003, 12:02 PM
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You aren't being pedantic, but the fact is the analogue signal output from the vane type meter is useless to engine management without the other parameters to enable the DME to CALCULATE mass flow. The vane type meter measures volume flow rate. The hot wire signal is detemined by mass flow. AS you say, this isn't fixing your cold start problem, but it helps if we are all singing off the same hymn sheet!
07-10-2003, 01:48 PM
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OK, how does the vane type meter exclude the effects of air density to record just volume flow rate?
Any volume flow meter I've used in the past is only calibrated for use with a liquid or gas of a given density. Fact.
Any volume flow meter I've used in the past is only calibrated for use with a liquid or gas of a given density. Fact.
07-10-2003, 07:53 PM
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Christer - You are partially correct in saying that the O2 sensor is used for emissions (it is) - but its main purpose is to determine the enrichment and correct fuel delivery.
There's really good book describing Bosch Motronic Fuel injection;
Ulrich Adler, Combined Ignition and Fuel-Injection System with Lambda Closed-Loop Control - Motronic Technical Instruction
Robert Bosch GmbH ISBN 1-85-226009-2
quote:
By means of the Lambda closed-loop control, the air-fuel ratio can be maintained precisely at Y=1.00. ["Y" == "Lambda"] This control principle is based upon the measurement of the exhaust-gas oxygen by the Lambda sensor. The exhaust-gas oxygen is a measure for the composition of the air-fuel mixture supplied to the engine. The Lambda sensor acts as a probe in the exhaust pipe and delivers the information as to whether the mixture is richer or leaner
than Y=1.00.
In case of a deviation from this Y=1.00 figure, the voltage of the sensor output signal changes abruptly. This pronounced change is evaluated by the ECU which is provided with a closed-loop control circuit for this purpose.
Tolerances and the ageing of the engine have no effect whatsoever. At values above Y=1.00, move fuel is metered to the engine, and at values below Y=1.00, less.
This continuous, almost lag-free adjustment of the air-fuel mixture to Y=1.00, is one of the prerequisites for the efficient after treatment of the exhaust gases by the downstream catalytic converter.
The Lambda closed-loop control operates in a range between Y=0.8...1.2, in which normal disturbances (such as the effects of
altitude) are compensated for by controlling Lambda to 1.00 with an accuracy of +-1%.
This book's worth a read.
Ade
There's really good book describing Bosch Motronic Fuel injection;
Ulrich Adler, Combined Ignition and Fuel-Injection System with Lambda Closed-Loop Control - Motronic Technical Instruction
Robert Bosch GmbH ISBN 1-85-226009-2
quote:
By means of the Lambda closed-loop control, the air-fuel ratio can be maintained precisely at Y=1.00. ["Y" == "Lambda"] This control principle is based upon the measurement of the exhaust-gas oxygen by the Lambda sensor. The exhaust-gas oxygen is a measure for the composition of the air-fuel mixture supplied to the engine. The Lambda sensor acts as a probe in the exhaust pipe and delivers the information as to whether the mixture is richer or leaner
than Y=1.00.
In case of a deviation from this Y=1.00 figure, the voltage of the sensor output signal changes abruptly. This pronounced change is evaluated by the ECU which is provided with a closed-loop control circuit for this purpose.
Tolerances and the ageing of the engine have no effect whatsoever. At values above Y=1.00, move fuel is metered to the engine, and at values below Y=1.00, less.
This continuous, almost lag-free adjustment of the air-fuel mixture to Y=1.00, is one of the prerequisites for the efficient after treatment of the exhaust gases by the downstream catalytic converter.
The Lambda closed-loop control operates in a range between Y=0.8...1.2, in which normal disturbances (such as the effects of
altitude) are compensated for by controlling Lambda to 1.00 with an accuracy of +-1%.
This book's worth a read.
Ade
07-11-2003, 04:47 AM
#27
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Ade - C4 91:
<strong>Christer - You are partially correct in saying that the O2 sensor is used for emissions (it is) - but its main purpose is to determine the enrichment and correct fuel delivery.
There's really good book describing Bosch Motronic Fuel injection;
Ulrich Adler, Combined Ignition and Fuel-Injection System with Lambda Closed-Loop Control - Motronic Technical Instruction
Robert Bosch GmbH ISBN 1-85-226009-2
quote:
By means of the Lambda closed-loop control, the air-fuel ratio can be maintained precisely at Y=1.00. ["Y" == "Lambda"] This control principle is based upon the measurement of the exhaust-gas oxygen by the Lambda sensor. The exhaust-gas oxygen is a measure for the composition of the air-fuel mixture supplied to the engine. The Lambda sensor acts as a probe in the exhaust pipe and delivers the information as to whether the mixture is richer or leaner
than Y=1.00.
In case of a deviation from this Y=1.00 figure, the voltage of the sensor output signal changes abruptly. This pronounced change is evaluated by the ECU which is provided with a closed-loop control circuit for this purpose.
Tolerances and the ageing of the engine have no effect whatsoever. At values above Y=1.00, move fuel is metered to the engine, and at values below Y=1.00, less.
This continuous, almost lag-free adjustment of the air-fuel mixture to Y=1.00, is one of the prerequisites for the efficient after treatment of the exhaust gases by the downstream catalytic converter.
The Lambda closed-loop control operates in a range between Y=0.8...1.2, in which normal disturbances (such as the effects of
altitude) are compensated for by controlling Lambda to 1.00 with an accuracy of +-1%.
This book's worth a read.
Ade</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">OK I give up. I wanted to share information with other owners about what is perfectly possible and works well if you are in the position of not having to pass emissions tests.
I understand how the O2 sensor works in basic terms - i.e. as per above. However, as our cars can run perfectly OK without them - indeed mine runs a lot better I cannot see what the point of this conversation is. So I retract my statement that an O2 sensor is there mainly for the car to pass emissions (even though IMHO that statement is true) just so I can get some peace. Perhaps we can have a look at the cold start problem that somebody mentioned?
p.s. that book looks very boring.
<strong>Christer - You are partially correct in saying that the O2 sensor is used for emissions (it is) - but its main purpose is to determine the enrichment and correct fuel delivery.
There's really good book describing Bosch Motronic Fuel injection;
Ulrich Adler, Combined Ignition and Fuel-Injection System with Lambda Closed-Loop Control - Motronic Technical Instruction
Robert Bosch GmbH ISBN 1-85-226009-2
quote:
By means of the Lambda closed-loop control, the air-fuel ratio can be maintained precisely at Y=1.00. ["Y" == "Lambda"] This control principle is based upon the measurement of the exhaust-gas oxygen by the Lambda sensor. The exhaust-gas oxygen is a measure for the composition of the air-fuel mixture supplied to the engine. The Lambda sensor acts as a probe in the exhaust pipe and delivers the information as to whether the mixture is richer or leaner
than Y=1.00.
In case of a deviation from this Y=1.00 figure, the voltage of the sensor output signal changes abruptly. This pronounced change is evaluated by the ECU which is provided with a closed-loop control circuit for this purpose.
Tolerances and the ageing of the engine have no effect whatsoever. At values above Y=1.00, move fuel is metered to the engine, and at values below Y=1.00, less.
This continuous, almost lag-free adjustment of the air-fuel mixture to Y=1.00, is one of the prerequisites for the efficient after treatment of the exhaust gases by the downstream catalytic converter.
The Lambda closed-loop control operates in a range between Y=0.8...1.2, in which normal disturbances (such as the effects of
altitude) are compensated for by controlling Lambda to 1.00 with an accuracy of +-1%.
This book's worth a read.
Ade</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">OK I give up. I wanted to share information with other owners about what is perfectly possible and works well if you are in the position of not having to pass emissions tests.
I understand how the O2 sensor works in basic terms - i.e. as per above. However, as our cars can run perfectly OK without them - indeed mine runs a lot better I cannot see what the point of this conversation is. So I retract my statement that an O2 sensor is there mainly for the car to pass emissions (even though IMHO that statement is true) just so I can get some peace. Perhaps we can have a look at the cold start problem that somebody mentioned?
p.s. that book looks very boring.
07-11-2003, 06:38 AM
#28
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Without having seen the internals of the vane type flow meter used on a 964, I will take a rough guess at its operating principles. I would suggest that the vane can only move as a result of a pressure difference acting across it. Bernoulli principle and all that...I'm sure you are familiar with it.
I would suggest that the density of the air before and after the vane can be taken as a constant (well, you need to assume this to apply Bernoulli anyway).
I guess the only terms of interest will be the velocity of the airstream (which is determineed by the volumetric flow demand of the engine at the time and the cross sectional area of the throttle body) and the pressure of the airstream.
Unlike the thermodynamic priciples underlying the hot wire or hot film mass flow meters, the vane type plapper operation is based on pressure & velocity of hte air stream.
I am sure someone with more recent application of Bernoulli (its over 12 years since my mech eng degree!) can clarify this.
I would suggest that the density of the air before and after the vane can be taken as a constant (well, you need to assume this to apply Bernoulli anyway).
I guess the only terms of interest will be the velocity of the airstream (which is determineed by the volumetric flow demand of the engine at the time and the cross sectional area of the throttle body) and the pressure of the airstream.
Unlike the thermodynamic priciples underlying the hot wire or hot film mass flow meters, the vane type plapper operation is based on pressure & velocity of hte air stream.
I am sure someone with more recent application of Bernoulli (its over 12 years since my mech eng degree!) can clarify this.
07-11-2003, 06:51 AM
#29
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Back to the cold start problem - doesn't the flow meter (mass or volume who cares!) have an air bypass? COuld there be a problem with this or the ISV which is temp related??
HAve you tried removing the ISV and giving it all a good clean out?
HAve you tried removing the ISV and giving it all a good clean out?
07-11-2003, 09:54 AM
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The ISV is coming off as soon as I have the chance and will get a good clean.
I've just checked and adjusted the idle switch as it was going open circuit with only the slightest hint of throttle pedal or floor mat movement.
I've made a 3 pin mintimer plug test lead rather than trying to get the Fluke meter on the pins and the full throttle switch is working and if anything comes on a bit early.
I'll post any findings as and when.
I've just checked and adjusted the idle switch as it was going open circuit with only the slightest hint of throttle pedal or floor mat movement.
I've made a 3 pin mintimer plug test lead rather than trying to get the Fluke meter on the pins and the full throttle switch is working and if anything comes on a bit early.
I'll post any findings as and when.