Sorry it cannot be vacuum starvation as no vacuum keeps the valve open. (In the resting possition.) Faulty spring perhaps?
Willie from Jo'burg
White Gen 3 SWB Pajero 3.2 DID
White Gen 3 SWB Pajero 3.2 DID
Affiliate Member
The top diaphragm is definitely the idle diaphragm as it has the adjuster screw.
The bottom is definitely the engine kill diaphragm as it has no adjuster and is simply designed to close the throttle plate 100%.
Easy test - disconnect the bottom vacuum pipe and the intake boost pipe so you can see the throttle flap. Switch the engine off and see if the throttle flap closes.
I'm hoping this was the cause of my poor fuel economy. Time will tell as My throttle flap is currently completely disconnected and will stay open at all times.
I'm probably filling up over the weekend so I can have a full tank to test.
The vacuum to drive the diaphragms come from the vacuum pump. the throttle flap is kept open by default by a spring.
The bottom is definitely the engine kill diaphragm as it has no adjuster and is simply designed to close the throttle plate 100%.
Easy test - disconnect the bottom vacuum pipe and the intake boost pipe so you can see the throttle flap. Switch the engine off and see if the throttle flap closes.
I'm hoping this was the cause of my poor fuel economy. Time will tell as My throttle flap is currently completely disconnected and will stay open at all times.
I'm probably filling up over the weekend so I can have a full tank to test.
The vacuum to drive the diaphragms come from the vacuum pump. the throttle flap is kept open by default by a spring.
OK Marius, I did exactly what you suggested as a test.
Findings:
1. With bottom vacuum pipe disconnected the throttle plate stayed open at max. However the engine did cut out with the throttle plate open.
2. The top diaphragm is connected to the throttle plate but by hand it will only shut off to a near full shutoff. There seems to be some interaction between top and bottom to close the thing fully.
3. With all pipes back on again there is no sign of the throttle plate moving as per the video you shot through your windscreen. The plate remained fully open all the time during idling. This Nismo and I do not understand. Why is it there?
Thanks for the lesson, I'm learning.
Findings:
1. With bottom vacuum pipe disconnected the throttle plate stayed open at max. However the engine did cut out with the throttle plate open.
2. The top diaphragm is connected to the throttle plate but by hand it will only shut off to a near full shutoff. There seems to be some interaction between top and bottom to close the thing fully.
3. With all pipes back on again there is no sign of the throttle plate moving as per the video you shot through your windscreen. The plate remained fully open all the time during idling. This Nismo and I do not understand. Why is it there?
Thanks for the lesson, I'm learning.
Willie from Jo'burg
White Gen 3 SWB Pajero 3.2 DID
White Gen 3 SWB Pajero 3.2 DID
Affiliate Member
Top Diaphragm
Only closes the plate about 90% at idle and only if the car is up to operating temp. If it doesn't then the car is either
- not at operating temp
- engine coolant temp sensor that feeds ecu is faulty (dash guage uses separate sensor)
- vacuum solenoid faulty that feeds it
- vacuum leak
- wiring issue to vacuum solenoid or temp sensor
Bottom Diaphragm
It closes for a few seconds when you shut the ignition off, effectively choking the engine for a smoother shut down.
- if it doesn't do this then you have either
- vacuum solenoid faulty that feeds it
- vacuum leak
- wiring issue to vacuum solenoid or temp sensor
The thing I'm not sure of is whether the ecu uses one of these diaphragms to marginally close the flap (with an intermittent signal to regulate angle - google PWM) when it wants to use EGR which
- throttles air
- richens mixture - higher EGT
- robs performance
- kills economy
So mine is open at all times now and my next tank will determine if there is proof in the pudding.
Only closes the plate about 90% at idle and only if the car is up to operating temp. If it doesn't then the car is either
- not at operating temp
- engine coolant temp sensor that feeds ecu is faulty (dash guage uses separate sensor)
- vacuum solenoid faulty that feeds it
- vacuum leak
- wiring issue to vacuum solenoid or temp sensor
Bottom Diaphragm
It closes for a few seconds when you shut the ignition off, effectively choking the engine for a smoother shut down.
- if it doesn't do this then you have either
- vacuum solenoid faulty that feeds it
- vacuum leak
- wiring issue to vacuum solenoid or temp sensor
The thing I'm not sure of is whether the ecu uses one of these diaphragms to marginally close the flap (with an intermittent signal to regulate angle - google PWM) when it wants to use EGR which
- throttles air
- richens mixture - higher EGT
- robs performance
- kills economy
So mine is open at all times now and my next tank will determine if there is proof in the pudding.
One more theory is that engines with a moderate fuel supply at idling maintains idling speed by means of the amount of fuel it receives. When the fuel supply becomes to liberal the throttle flap has to control the idling speed. It would really be nice to also understand the logic the EGR system is designed to follow. All very interesting.
Willie from Jo'burg
White Gen 3 SWB Pajero 3.2 DID
White Gen 3 SWB Pajero 3.2 DID
Affiliate Member
diesel engine's idle is purely controlled by means of injection amount.Bigwill wrote:One more theory is that engines with a moderate fuel supply at idling maintains idling speed by means of the amount of fuel it receives. When the fuel supply becomes to liberal the throttle flap has to control the idling speed. It would really be nice to also understand the logic the EGR system is designed to follow. All very interesting.
The throttle flap is only there to smoothen the idle, kill the engine faster at shutdown and to help draw in exhaust gasses when EGR conditions are met.
EGR is only used at part throttle and light load. Full throttle and idle does not see EGR usage at all!
That could explain why EGR Delete seems to have reduced my turbo lag from standstill a little when starting slowly.
Willie from Jo'burg
White Gen 3 SWB Pajero 3.2 DID
White Gen 3 SWB Pajero 3.2 DID
Affiliate Member
jip. general consensus is that EGR delete improves turbo spooling.
Affiliate Member
Current performance (about 13 seconds)
[BBvideo 425,350]http://www.youtube.com/watch?v=I-uPUjBoXOk[/BBvideo]
Compared to a gen4 3.8 Mivec petrol (about 10 seconds)
[BBvideo 425,350]http://www.youtube.com/watch?v=7_h1jHTLaYA[/BBvideo]
compared to a gen4 3.2 Di-D with a chip (about 10 seconds)
[BBvideo 425,350]http://www.youtube.com/watch?v=Aqt-zpJIMuY[/BBvideo]
It looks slow but man it feels alive at cruising speeds now. I'm not too stressed about the performance. It has more than enough pulling power, but just from the last quarter tank I did I think it has been more economical.
[BBvideo 425,350]http://www.youtube.com/watch?v=I-uPUjBoXOk[/BBvideo]
Compared to a gen4 3.8 Mivec petrol (about 10 seconds)
[BBvideo 425,350]http://www.youtube.com/watch?v=7_h1jHTLaYA[/BBvideo]
compared to a gen4 3.2 Di-D with a chip (about 10 seconds)
[BBvideo 425,350]http://www.youtube.com/watch?v=Aqt-zpJIMuY[/BBvideo]
It looks slow but man it feels alive at cruising speeds now. I'm not too stressed about the performance. It has more than enough pulling power, but just from the last quarter tank I did I think it has been more economical.
Hi
The more I read the more I worry about the EGR removal.In the first few posts it seemed simple, just remove and blank out. The latest is becoming more technical in regards to vacuum and blanking off.
I need some piece of mind, please. Can I follow the steps in removing the EGR and not worry about putting T pieces ect. in.
The more I read the more I worry about the EGR removal.In the first few posts it seemed simple, just remove and blank out. The latest is becoming more technical in regards to vacuum and blanking off.
I need some piece of mind, please. Can I follow the steps in removing the EGR and not worry about putting T pieces ect. in.