is the 84 motronic still a cis system?
10-22-2002, 07:22 PM
#16
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Just to stir the apple cart a little, both the 84 Carrera Motronic AND the 76 to 89 930 K-Jetronic systems are CIS, i.e. Continuous Injection Systems. There is no comparison whatsoever in how the system continuously injects its fuel, but nevertheless they are both CIS. I think this may be where a little of the confusion is coming from.
Only with the introduction of the 964 in 89 did the Motronic system evolve into Sequential Injection, and as rightly said above the 993TT was the first production turbo Porsche to receive Motronic with its full electronic control over fuel and ignition, the 965's still had K-Jetronic.
Only with the introduction of the 964 in 89 did the Motronic system evolve into Sequential Injection, and as rightly said above the 993TT was the first production turbo Porsche to receive Motronic with its full electronic control over fuel and ignition, the 965's still had K-Jetronic.
10-22-2002, 08:16 PM
#17
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[quote]Originally posted by NineMeister:
<strong>Just to stir the apple cart a little, both the 84 Carrera Motronic AND the 76 to 89 930 K-Jetronic systems are CIS, i.e. Continuous Injection Systems. There is no comparison whatsoever in how the system continuously injects its fuel, but nevertheless they are both CIS. I think this may be where a little of the confusion is coming from.
Only with the introduction of the 964 in 89 did the Motronic system evolve into Sequential Injection, and as rightly said above the 993TT was the first production turbo Porsche to receive Motronic with its full electronic control over fuel and ignition, the 965's still had K-Jetronic.</strong><hr></blockquote>
So, you are suggesting that the batch injection used in 3.2 Carreras is considered CIS? I always thought CIS meant that fuel is continuously injected, but the fuel amount or pressure varies. In both batch and sequential electronic injection, the fuel pressure stays more or less the same, but the injector is opened and closed electrically. Batch injection is when a group of fuel injectors are open for a specific time period during one crankshaft revolution. Sequential injection is when a individual injector is open for a specific time during a camshaft revolution.
The 944 turbo was the first production turbo Porsche to have electronic control of the fuel and ignition. The 959 may have predated the 944 turbo, in which case it would be considered the first.
Just curious, was that a joke about stirring the apple cart? I always find it works better to stir the pot and upset the apple cart.
<strong>Just to stir the apple cart a little, both the 84 Carrera Motronic AND the 76 to 89 930 K-Jetronic systems are CIS, i.e. Continuous Injection Systems. There is no comparison whatsoever in how the system continuously injects its fuel, but nevertheless they are both CIS. I think this may be where a little of the confusion is coming from.
Only with the introduction of the 964 in 89 did the Motronic system evolve into Sequential Injection, and as rightly said above the 993TT was the first production turbo Porsche to receive Motronic with its full electronic control over fuel and ignition, the 965's still had K-Jetronic.</strong><hr></blockquote>
So, you are suggesting that the batch injection used in 3.2 Carreras is considered CIS? I always thought CIS meant that fuel is continuously injected, but the fuel amount or pressure varies. In both batch and sequential electronic injection, the fuel pressure stays more or less the same, but the injector is opened and closed electrically. Batch injection is when a group of fuel injectors are open for a specific time period during one crankshaft revolution. Sequential injection is when a individual injector is open for a specific time during a camshaft revolution.
The 944 turbo was the first production turbo Porsche to have electronic control of the fuel and ignition. The 959 may have predated the 944 turbo, in which case it would be considered the first.
Just curious, was that a joke about stirring the apple cart? I always find it works better to stir the pot and upset the apple cart.
10-24-2002, 08:43 PM
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Steve,
Yes, it was a joke, written in error at first but I kinda liked it so I left it in.
I suppose that what I am driving at is that non-sequential electronic injection is also known as continuous injection. I know that you have a point, but if you look at duty cycles of the Motronic 3.2 engine you will find that the injector is sized such that at if it is held fully open for the entire cycle you would just get enough fuel for 250bhp, so yes, it is continuous.
Funnily enough I do not even consider the 964 Motronic to be fully sequential as it reverts to batch fire at full load full throttle, and like the 3.2 will only deliver enough fuel for 300bhp when open all the time.
Fit an engine with Motec and large injectors, pull the pulse width to 10ms or less per cycle at full load and THEN you have sequential injection. These are is my findings, anyway.
You're right about the 951, it was the first turbo Porsche to have electronic management, guess this was a mental block for all things watercooled, thanks for putting the record straight.
Yes, it was a joke, written in error at first but I kinda liked it so I left it in.
I suppose that what I am driving at is that non-sequential electronic injection is also known as continuous injection. I know that you have a point, but if you look at duty cycles of the Motronic 3.2 engine you will find that the injector is sized such that at if it is held fully open for the entire cycle you would just get enough fuel for 250bhp, so yes, it is continuous.
Funnily enough I do not even consider the 964 Motronic to be fully sequential as it reverts to batch fire at full load full throttle, and like the 3.2 will only deliver enough fuel for 300bhp when open all the time.
Fit an engine with Motec and large injectors, pull the pulse width to 10ms or less per cycle at full load and THEN you have sequential injection. These are is my findings, anyway.
You're right about the 951, it was the first turbo Porsche to have electronic management, guess this was a mental block for all things watercooled, thanks for putting the record straight.
11-06-2002, 10:08 PM
#19
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What will confuse the matter is that K-Lambda 930s have a motronic management module to control the fuel flow bypass for emissions control.
This is not electronic fuel injection it is still CIS however, the pressure is controlled by a electronic bypass value (which is modulated) to control the fuel pressure delivered to the injectors.
This unit is technically a crude EMC. In my 89-930 i couldnt get the car started after i changed over intercoolers because the new boost pressure sensor was not functioning properly. The motronic unit disabled the fuel pump because of bad boost (MAP) input. After i replaced the boost pressure sensor (MAP) with the original it started fine.
This is not electronic fuel injection it is still CIS however, the pressure is controlled by a electronic bypass value (which is modulated) to control the fuel pressure delivered to the injectors.
This unit is technically a crude EMC. In my 89-930 i couldnt get the car started after i changed over intercoolers because the new boost pressure sensor was not functioning properly. The motronic unit disabled the fuel pump because of bad boost (MAP) input. After i replaced the boost pressure sensor (MAP) with the original it started fine.
11-07-2002, 06:02 AM
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Don't know much about engines, but this is a quote from Peter Morgans 'Original 911':
"For the 1986 model year, the engine was heavily revised again (930/68) to bring it in line with worlwide emissions legislation. This was made possible by the new mapped Digital Motor Electronics (DME, or Motronic as it became known) developed by Bosch. Equipped with this new motor, the turbo went on sale again in the US."
Is he talking about some equipment being used to develop the -86 engine, or is it actually part of the engine?
cheers
/christian
"For the 1986 model year, the engine was heavily revised again (930/68) to bring it in line with worlwide emissions legislation. This was made possible by the new mapped Digital Motor Electronics (DME, or Motronic as it became known) developed by Bosch. Equipped with this new motor, the turbo went on sale again in the US."
Is he talking about some equipment being used to develop the -86 engine, or is it actually part of the engine?
cheers
/christian
11-07-2002, 07:04 PM
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i did a little more diggin' and found that the motronic unit in the 86+ 930s also control a fuel enrichment function. There is another black module beside the motronic unit (under the driver's seat) that has intelegence in it. It looks like a large relay but it actually has electronics in it and is wired to the motronic unit. I am curious if this controls fuel enrichment via the bypass regulator or via the cold start valve or???
Anyone know more about this?
Anyone know more about this?
