P0492 Advice
08-03-2017, 03:08 PM
#1
Instructor
Thread Starter
P0492 Advice
Hi All,
I've searched high and low and tired some things to nail this down, but am running out of options. My car has been intermittently throwing a P0492 for the last year or so and I'm having trouble nailing it down. About 10 months ago, I dropped the engine/trans for coolant line pinning, clutch and a bunch of other stuff - the code was present BEFORE I did this stuff. While I had it out, I replaced all the vacuum lines, vacuum canister, valves and smoke and vacuum tested the whole system. I took the hard metal secondary air line off and cleaned it thoroughly. After getting the car all back together, to my despair, the code has not quit coming back.
The pump tests out fine (I removed it and checked airflow). The valves work as they should and have been tested. The air regulator valve holds vacuum. Both diverter valves have been replaced and all hoses tested for leaks. The pump comes on when the engine is cold and turns off after 60 seconds or so and sounds as it should.
After driving the car for an extended period of time is where it gets interesting. If I'm coming off of the highway and come to a full stop with engine idling, the SAI pump comes on (I know this is normal) but it has a whining/vibration sound. This only occurs after driving - when the pump comes on with a cold engine it sounds fine. On the occasions when the pump does come on and I can hear it, the car will throw the CEL almost immediately after the pump turns off. I can clear the light and drive for days (code will be pending) but will only turn the light on after the pump comes on, makes it noise, and turns off.
I am getting ready to put my car up for sale and want it in perfect running condition before doing so, so I need to get this figured out. Again, the code was coming up before any mods and before I had the engine out. Any help appreciated!
2003 996TT, speed yellow
66k miles
Cobb AccessPort Stage 2 OTC tune
Fabspeed Gen 1 exhaust w/ 100 cell cats
Drop in high flow air filter
I've searched high and low and tired some things to nail this down, but am running out of options. My car has been intermittently throwing a P0492 for the last year or so and I'm having trouble nailing it down. About 10 months ago, I dropped the engine/trans for coolant line pinning, clutch and a bunch of other stuff - the code was present BEFORE I did this stuff. While I had it out, I replaced all the vacuum lines, vacuum canister, valves and smoke and vacuum tested the whole system. I took the hard metal secondary air line off and cleaned it thoroughly. After getting the car all back together, to my despair, the code has not quit coming back.
The pump tests out fine (I removed it and checked airflow). The valves work as they should and have been tested. The air regulator valve holds vacuum. Both diverter valves have been replaced and all hoses tested for leaks. The pump comes on when the engine is cold and turns off after 60 seconds or so and sounds as it should.
After driving the car for an extended period of time is where it gets interesting. If I'm coming off of the highway and come to a full stop with engine idling, the SAI pump comes on (I know this is normal) but it has a whining/vibration sound. This only occurs after driving - when the pump comes on with a cold engine it sounds fine. On the occasions when the pump does come on and I can hear it, the car will throw the CEL almost immediately after the pump turns off. I can clear the light and drive for days (code will be pending) but will only turn the light on after the pump comes on, makes it noise, and turns off.
I am getting ready to put my car up for sale and want it in perfect running condition before doing so, so I need to get this figured out. Again, the code was coming up before any mods and before I had the engine out. Any help appreciated!
2003 996TT, speed yellow
66k miles
Cobb AccessPort Stage 2 OTC tune
Fabspeed Gen 1 exhaust w/ 100 cell cats
Drop in high flow air filter
Last edited by centexsi; 08-03-2017 at 06:36 PM.
08-04-2017, 08:56 AM
#3
From what you describe above here's my educated guess....
SAI pump bearings are failing.
When the engine is cold and the pump kicks on the bearing/shaft tolerance is tight enough to run ok. As you drive and things heat up the bearing/shaft tolerance grows, when the pump kicks on it vibrates and runs erratically and the ECU sees that and throws the code.
SAI pump bearings are failing.
When the engine is cold and the pump kicks on the bearing/shaft tolerance is tight enough to run ok. As you drive and things heat up the bearing/shaft tolerance grows, when the pump kicks on it vibrates and runs erratically and the ECU sees that and throws the code.