Ticking 2002 Disco II - Unplug SAI Solenoid, ticking stops
#11
11-04-2011, 11:27 AM
Super Moderator
The SAI pump is wanting to come on for those few seconds you describe. But it is only supposed to run for maybe 90 seconds, and only on cold engine start. It makes fuel combust outside the normal engine cycle (like when exhaust valves open, so that would translate to some rough running). Rover does this to warm up the cats as fast as possible. (in the 50's guys hooked up an extra spark plug at the rear to make flames come out of their exhaust from this un-burned fuel - nothing new under the sun, paying for music "downloads" was invented by gramp's Rockola jukebox, etc...).
With respect to the cited article, using a resistor to "fool" the wire harness integrity test would work, however you would still get codes from the passive test failure where the ECM must cycle the pump to check for operation. There is a foam air filter that has to be changed from time to time (an like all things ever owned by a previous owner, it will lack frequent service), and the pump will be noisy, need replacement.
attached are RAVE pages and Bosch info on the SAI, for those that plan to pickup the wrench and soldering iron, might want to read through these first.
With respect to the cited article, using a resistor to "fool" the wire harness integrity test would work, however you would still get codes from the passive test failure where the ECM must cycle the pump to check for operation. There is a foam air filter that has to be changed from time to time (an like all things ever owned by a previous owner, it will lack frequent service), and the pump will be noisy, need replacement.
attached are RAVE pages and Bosch info on the SAI, for those that plan to pickup the wrench and soldering iron, might want to read through these first.
#12
11-04-2011, 02:06 PM
yeah, Im going to open mine up monday with a load of other things... tiling kitchen, changing coolant to the green stuff.. hopefully oil to rotella 15-40 and changing clutch on A/C compressor from my spare good one! 
this time aftermarket is coming in handy! lol Do you think I might need to change that SAI solenoid since the 1412 code ir just change out that filter? looks easy enough... on my engine the hairdryer is not bad just can hear it but it does stumble on warmup and occasionally when driving and idles funny when plugged in .. but when unplugged only happens in the initial 90 seconds... even when I turned off Disco at bank and went to ATM and back to Disco ( not music) , it stumbled again initially when driving at about the 1 minute time and then smoothed out :-) wow! when it runs quiet, you can really hear all the other parts doin their thing! lol NICE! Thanks!
this time aftermarket is coming in handy! lol Do you think I might need to change that SAI solenoid since the 1412 code ir just change out that filter? looks easy enough... on my engine the hairdryer is not bad just can hear it but it does stumble on warmup and occasionally when driving and idles funny when plugged in .. but when unplugged only happens in the initial 90 seconds... even when I turned off Disco at bank and went to ATM and back to Disco ( not music) , it stumbled again initially when driving at about the 1 minute time and then smoothed out :-) wow! when it runs quiet, you can really hear all the other parts doin their thing! lol NICE! Thanks!
#13
11-13-2011, 11:46 AM
#14
11-13-2011, 07:44 PM
Super Moderator
Hers some info from the RAVE engine management section:
high altitude
The vac storage bottle has two vac lines going to it. It also has that check valve inside. If you pulled off both lines, and left them unplugged, it would be a vacuum leak and engine would not be smoother. Since you pulled off one, it is probably the one between the vac storage bottle and the SAI solenoid valve. Removing that shut off the vacuum supply, just like turning off the valves. So you have disabled the valves, and they may have been stuck on electrically or the solenoid valve could be defective. You did not fix anything, but you may have proved that the solenoid valve or other vac lines in that part of the circuit are in question. Keep in mind that the SAI system only works for two minutes or less, under certain conditions. So having it not run might make a code, and might make emissions test fail, and Al Gore will come to your house with a warrant.
Air from the SAI pump is supplied to the SAI control valves via pipework and an intermediate T-piece which splits the
air flow evenly to each bank.
At the same time the secondary air pump is started, the ECM operates a SAI vacuum solenoid valve, which opens to
allow vacuum from the reservoir to be applied to the vacuum operated SAI control valves on each side of the engine.
When the vacuum is applied to the SAI control valves, they open simultaneously to allow the air from the SAI pump
through to the exhaust ports. Secondary air is injected into the inner most exhaust ports on each bank.
When the ECM breaks the ground circuit to de-energise the SAI vacuum solenoid valve, the vacuum supply to the
SAI control valves is cut off and the valves close to prevent further air being injected into the exhaust manifold. At the
same time as the SAI vacuum solenoid valve is closed, the ECM opens the ground circuit to the SAI pump relay, to
stop the SAI pump.
A vacuum reservoir is included in the vacuum line between the intake manifold and the SAI vacuum solenoid valve.
This prevents changes in vacuum pressure from the intake manifold being passed on to cause fluctuations of the
secondary air injection solenoid valve. The vacuum reservoir contains a one way valve and ensures a constant
vacuum is available for the SAI vacuum solenoid valve operation. This is particularly important when the vehicle is at
air flow evenly to each bank.
At the same time the secondary air pump is started, the ECM operates a SAI vacuum solenoid valve, which opens to
allow vacuum from the reservoir to be applied to the vacuum operated SAI control valves on each side of the engine.
When the vacuum is applied to the SAI control valves, they open simultaneously to allow the air from the SAI pump
through to the exhaust ports. Secondary air is injected into the inner most exhaust ports on each bank.
When the ECM breaks the ground circuit to de-energise the SAI vacuum solenoid valve, the vacuum supply to the
SAI control valves is cut off and the valves close to prevent further air being injected into the exhaust manifold. At the
same time as the SAI vacuum solenoid valve is closed, the ECM opens the ground circuit to the SAI pump relay, to
stop the SAI pump.
A vacuum reservoir is included in the vacuum line between the intake manifold and the SAI vacuum solenoid valve.
This prevents changes in vacuum pressure from the intake manifold being passed on to cause fluctuations of the
secondary air injection solenoid valve. The vacuum reservoir contains a one way valve and ensures a constant
vacuum is available for the SAI vacuum solenoid valve operation. This is particularly important when the vehicle is at
high altitude
The vac storage bottle has two vac lines going to it. It also has that check valve inside. If you pulled off both lines, and left them unplugged, it would be a vacuum leak and engine would not be smoother. Since you pulled off one, it is probably the one between the vac storage bottle and the SAI solenoid valve. Removing that shut off the vacuum supply, just like turning off the valves. So you have disabled the valves, and they may have been stuck on electrically or the solenoid valve could be defective. You did not fix anything, but you may have proved that the solenoid valve or other vac lines in that part of the circuit are in question. Keep in mind that the SAI system only works for two minutes or less, under certain conditions. So having it not run might make a code, and might make emissions test fail, and Al Gore will come to your house with a warrant.
#15
11-14-2011, 07:06 AM
Well I have a protective shield around my house to prevent Al Gore from getting in! lol With that said, I actually used logic and thus REAL change not just hope ! lol With that said, that vacuum reservoir with the 2 vacuum lines on it were drawing a vacuum.. what I did is unplug the one facing the engine and put finger over that vacuum line and then could feel motor having a slight unevenness at idle, removed and it leveled out allot.. then plugged it back in and then unplugged the passenger fender side and felt for suction on the reservoir and I did still feel it drawing in and when plugging with finger that side it would become uneven idle, next just left that same side off and it was allot smoother and drove it to work and it seemed much smoother... so then I can see possibly if reservoir is working correctly then it must be somewhere on the drivers side of the motor where that vacuum line terminates? into that solenoid? ironically it does run better even on way to work... also the SAI comes on and whines ( when all plugged up normal ) for first 60 seconds.. but my temps here are year around in south florida basically 75 deg... isn't there a temperature sensor to prevent that SAI from coming on unless it senses temps around 55deg or less?
#16
11-14-2011, 10:52 AM
Super Moderator
From the RAVE:
engine was last started. The engine coolant temperature must be below 55
Layout attached.
The ECM checks the engine coolant temperature when the engine is started in addition to the elapsed time since the
engine was last started. The engine coolant temperature must be below 55
°C (131°F) for the SAI pump to run.
NOTE: The ambient air temperature must also be above 8
NOTE: The ambient air temperature must also be above 8
°C (46°F) for the SAI pump to run.
Also, depending on the long term 'modelled' ambient temperature determined by the ECM, the minimum elapsed time
required since the last engine start can be up to 8.25 hours. The period of time that the SAI pump runs for depends
on the starting temperature of the engine and varies from approximately 96 seconds at 8
on the starting temperature of the engine and varies from approximately 96 seconds at 8
°C (46°F) to 30 seconds at
55°C (131°F).
55°C (131°F).
Layout attached.
Last edited by Savannah Buzz; 11-14-2011 at 10:56 AM.
#18
11-14-2011, 09:05 PM
Super Moderator
#20
10-10-2013, 05:00 PM
Hate to jump on this thread but I'm having the same issue the original OP had. Just noticed the clicking noise yesterday and when the Gray connector is unplugged it goes away. I plugged in my scan tool and I have an fault code P0415 ( Secondary Air Injection System Switching Valve B Circuit Malfunction) Thanks in advance
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