SAI pump noise
 

I pull into my driveway, and hear what sounds like an exhaust leak. Pop the hood, listen, sounds like it was coming from the sai pump area. I'm thinking- ok, it has to be reverberating off something and projecting up there. As I'm looking/feeling around, I hear a click(like a relay)and no more noise???

Is it possible for exhaust to backfeed through the sai pump?

SAI pump preparing to die.

do you know how to play TAPS... from my understanding the SAI should not operate after warm up... let alone when you have been running and the engine is up to temp.

Could be exhaust leak / controlled by SAI system valves / something cracked in SAI system. Pump when failing is usually called a hair dryer.

Sensor in radiator could be faulty causing the pump to run.. it seems to have been going around with the 03-04s lately. Also as you described could be faulty relay (it's #6 and if I recall it's actually listed as glow plug relay).

For there to be the slightest possibility of the exhaust flowing back the vacuum solenoid would have to be stuck open so you could try pulling the SAI vac line from the right side of the canister and see if it stops. That's not to say the actual valve(s) couldn't be stuck open as well. I hate SAI.

Edit: but if it's the relay it "should" have thrown a code.

Check the Solenoid in the SAI system, on the drivers side, The Solenoid turns the valves on and off as needed. When the Solenoid fails the valves stick open, low frquency burbling sound comes from SAI pump. This is exhaust backflow through the open valves.

Let this continue and you will cost yourself a new pump for $300 and possibly new valves at $250 each.

Solenoid: $28.

Hmm, I will have to look through rave and familirize myself with the system and how it works. I know what it sounds like when it runs, on a cold start I can hear a faint whirring noise(sounds like a hairdryer, just a really quiet one) for maybe 45sec to a min.

If it does it again, I think I will try pulling the vacuum line or the selonoid(whichever I have to do) to close the valves and see if that helps and/or was the problem. When it did do it, I unpluged the electrical connector from the pump itself and that caused no change.

Thanx for the ideas on where to start. And just when I thought all was right in the world....

pages attached for those who have yet to get their own hi def copy of the RAVE, starts on page 259 of the shop manual. This is fuzzy because I can only post small files (says 4 GB for PDF, but upload max is 2 MB).

Maybe it is the control solenoid. After reading through rave, I see the sai is only supposed to operate when ambient air temp is higher than 46 deg farenheight. I can clearly remember it coming on on cold starts when it was in the 20's.

At $20, what I got to lose?

Yeah, on the 46 ambient thing I think the technical writers either got it wrong or it was a planned update that never materialized. That bit only showed up in the last of the tech docs and even with the latest ECM firmware it still comes on well below 46F.