SAI pump issue????
Thread Starter
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Mudding
Joined: Oct 2009
Posts: 192
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From: Windsor, Ontario
SAI pump issue????
I noticed my SAI pump kick in every now and then when the truck is warm and I am stopped on the red light for example. It seems that it is somehow related to me having my brake pedal pressed. As soon as I let go of the pedal.....the SAI pump shuts off. This only started happening this year. It doesn't happen all the time (at every red light) but at least twice on my way to work and back home (I got 5-6 lights).
Truck runs great and everything else is OK. I don't know???
Then also the sound has changed as well. It is more higher pitch when it turns it ON when it's cold first thing in the morning.
Anybody else had experience with the random SAI pump turning ON?
Also anybody else had their pump change the noise to a higher pitch? Is it on it's way to "go" (kaput????) and therefore the change to higher pitch??
Any advice is appreciated.
Thanks,
Boris
Truck runs great and everything else is OK. I don't know???
Then also the sound has changed as well. It is more higher pitch when it turns it ON when it's cold first thing in the morning.
Anybody else had experience with the random SAI pump turning ON?
Also anybody else had their pump change the noise to a higher pitch? Is it on it's way to "go" (kaput????) and therefore the change to higher pitch??
Any advice is appreciated.
Thanks,
Boris
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
Well, from the RAVE, a little background on when it should pop on..
engine was last started. The engine coolant temperature must be below 55
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
°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
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
°C (46°F) to 30 seconds at
55
°C (131°F).
So if air is under 46 F it should not come on. And coolant must be below 131 F to run. In your area that seems unlikely this time of year, unless thermostat stuck open, or bypassed somehow.
Noise change could be SAI filter needs renewal, or just pump getting ready to die (sounds like a hair dryer at some point).
The trouble codes include ones for failure of a passive test, and failure of an active test; so at some time the ECU must "test" the system, which could account for "random" running. Of course, there is a pump relay in the underhood fuse box, operated by the ECU; could have a relay that is shorting out, etc.
If fan was not so noisy, you might not notice it cycling at times.
So if air is under 46 F it should not come on. And coolant must be below 131 F to run. In your area that seems unlikely this time of year, unless thermostat stuck open, or bypassed somehow.
Noise change could be SAI filter needs renewal, or just pump getting ready to die (sounds like a hair dryer at some point).
The trouble codes include ones for failure of a passive test, and failure of an active test; so at some time the ECU must "test" the system, which could account for "random" running. Of course, there is a pump relay in the underhood fuse box, operated by the ECU; could have a relay that is shorting out, etc.
If fan was not so noisy, you might not notice it cycling at times.
Thread Starter
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Mudding
Joined: Oct 2009
Posts: 192
Likes: 0
From: Windsor, Ontario
Thanks Buzz,
I drive 20 minutes tops (1 way) to work and back. Thermostat was changed a few months ago and it works good for sure. I had to bleed the system a month ago when I did my water pump, gaskets, oil pump, etc. I know that it closes and opens correctly 100%.
I will check that filter you mentioned. It does seem to sound like hair dryer at times. But like I said lately (in the last 2 weeks) every day at least twice on the way to work and back home, SAI pump turns on for 4-5 seconds and then it goes out. If I wait on the red light for a 2 minutes or so, it will turn on 2-3 times and go out. But only on idle while I have the brake pressed. Never while I drive.
Ohhhh.....I just remembered. Sometimes (in the last 2 weeks) the pump does not turn ON at all!!!!! I noticed this 3 times so far. It was cold outside, truck was sitting over night (or all day at work) and when I sat in it and started it, the pump did not turn ON at all!!!!!
I don't know, like I said, the truck runs great, no check engine lights, nothing. Just this random turning on. I'll check the filter and hopefully that will solve that higher pitch noise.....I just hope I do not have to buy new pump cause I heard they are a frickin fortune $$$$$.
Let me know if you think of anything else buddy and thanks again for your help.
I drive 20 minutes tops (1 way) to work and back. Thermostat was changed a few months ago and it works good for sure. I had to bleed the system a month ago when I did my water pump, gaskets, oil pump, etc. I know that it closes and opens correctly 100%.
I will check that filter you mentioned. It does seem to sound like hair dryer at times. But like I said lately (in the last 2 weeks) every day at least twice on the way to work and back home, SAI pump turns on for 4-5 seconds and then it goes out. If I wait on the red light for a 2 minutes or so, it will turn on 2-3 times and go out. But only on idle while I have the brake pressed. Never while I drive.
Ohhhh.....I just remembered. Sometimes (in the last 2 weeks) the pump does not turn ON at all!!!!! I noticed this 3 times so far. It was cold outside, truck was sitting over night (or all day at work) and when I sat in it and started it, the pump did not turn ON at all
!!!!!I don't know
, like I said, the truck runs great, no check engine lights, nothing. Just this random turning on. I'll check the filter and hopefully that will solve that higher pitch noise.....I just hope I do not have to buy new pump cause I heard they are a frickin fortune $$$$$.Let me know if you think of anything else buddy and thanks again for your help.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
For rebuilding DIY see How To Rebuild Pierburg Air Pump (P0410 Code) - Bimmerfest - BMW Forums, it has been mentioned in our forum in the past. Like I mentioned, if it was running silky smooth and quiet, you might not notice these little bursts.
Don't know if a boneyard one would be worth the effort.
Don't know if a boneyard one would be worth the effort.
Thread Starter
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Mudding
Joined: Oct 2009
Posts: 192
Likes: 0
From: Windsor, Ontario
Thanks Buzz!
Here in Windsor there are 3 Discos. No "boneyards" have any parts at all!!!! There might be some around Toronto area which is 3.5 hours away from here. I learned to do all my service and thanks to this forum and you guys, so far it has been working out great. I am gonna look at that link for the BMW forum and maybe rebuild it if it is required.
Thanks again!
Let me know if you think of anything else please.
Boris
Here in Windsor there are 3 Discos. No "boneyards" have any parts at all!!!! There might be some around Toronto area which is 3.5 hours away from here. I learned to do all my service and thanks to this forum and you guys, so far it has been working out great. I am gonna look at that link for the BMW forum and maybe rebuild it if it is required.
Thanks again!
Let me know if you think of anything else please.
Boris
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