Secondary Air Injection System P0491 and P0492

[nerdtalker]

A week ago I had an issue with my secondary air injection system on bank 1, got P0491 and rough / weird idle after coming to a stop after freeway driving. I checked the secondary air pump and sure enough it didn't make any sounds or vibration on cold startup on the passenger side bank. I replaced that pump, then had an unrelated water pump maintenance event (smelled coolant, saw play in the pulley, and replaced the pump and pulley).

 

I blew down the passenger side SAI hose and it was fairly difficult (I thought I'd give myself an aneurysm), and sucking didn't pass any air. I believe that's the correct operation. 

 

A day passed, and now after coming to a stop after freeway driving again I look down and see CEL illuminated, and after scan P0491 and P0492. It seems unlikely that both the new pump and the old pump are dead. I had a bunch of other codes from turning the car on to accessory status while the MAP and N75 solenoid and a few other things were unplugged while replacing the water pump. I'm hoping that the DME was just confused or something.

 

Any ideas why suddenly both SAI pumps would show as failing?

[JFP in PA]

You seem to have multiple senor faults that are electrical in nature.  Time to start checking the harness for damage or a loose connector.

[lewisweller]

2 hours ago, nerdtalker said:

A week ago I had an issue with my secondary air injection system on bank 1, got P0491 and rough / weird idle after coming to a stop after freeway driving. I checked the secondary air pump and sure enough it didn't make any sounds or vibration on cold startup on the passenger side bank. I replaced that pump, then had an unrelated water pump maintenance event (smelled coolant, saw play in the pulley, and replaced the pump and pulley).

 

I blew down the passenger side SAI hose and it was fairly difficult (I thought I'd give myself an aneurysm), and sucking didn't pass any air. I believe that's the correct operation. 

 

A day passed, and now after coming to a stop after freeway driving again I look down and see CEL illuminated, and after scan P0491 and P0492. It seems unlikely that both the new pump and the old pump are dead. I had a bunch of other codes from turning the car on to accessory status while the MAP and N75 solenoid and a few other things were unplugged while replacing the water pump. I'm hoping that the DME was just confused or something.

 

Any ideas why suddenly both SAI pumps would show as failing?

The first 5 codes are exactly what you see if you switch on the ignition with the map sensor and throttle body disconnected electrically. Ask me how I know. Clear codes and do the throttle body calibration either with the software or just ignition in and don't touch throttle pedal and don't start engine, after 1 minute switch off ignition and then back on and start engine, idle for a few min and go for a normal drive. 

 

The SAI codes I also have them on the very rare occasions it will need a cold start. These SAI are prone to failure due to age but also the check valve leaks and let's hot exhaust gases and carbon fry up and coke up the SAI internals plus the fan blades like to snap off and get lodged in the check valve. 

 

You don't really need SAI, (emissions blah blah and quicker cat warm up to get into closed loop) you can plug the pipe with a 3/4" GI threaded plug and jubilee clip and ignore the code. Cold starts might be a little lumpy as the cats take a few seconds longer to heat up but who cares. 

This is what I did because the check valve is a real b * tch to get to at the deep back of the engine. 

Saves money and it cant break cos it already broken .......

[JFP in PA]

1 minute ago, lewisweller said:

The first 5 codes are exactly what you see if you switch on the ignition with the map sensor and throttle body disconnected electrically. Ask me how I know. Clear codes and do the throttle body calibration either with the software or just ignition in and don't touch throttle pedal and don't start engine, after 1 minute switch off ignition and then back on and start engine, idle for a few min and go for a normal drive. 

 

The SAI codes I also have them on the very rare occasions it will need a cold start. These SAI are prone to failure due to age but also the check valve leaks and let's hot exhaust gases and carbon fry up and coke up the SAI internals plus the fan blades like to snap off and get lodged in the check valve. 

 

You don't really need SAI, (emissions blah blah and quicker cat warm up to get into closed loop) you can plug the pipe with a 3/4" GI threaded plug and jubilee clip and ignore the code. Cold starts might be a little lumpy as the cats take a few seconds longer to heat up but who cares. 

This is what I did because the check valve is a real b * tch to get to at the deep back of the engine. 

Saves money and it cant break cos it already broken .......

 

He does that in California, he will run afoul of the state emission police   They not only check for system function, they also look for "non factory" modifications, like plugged lines or capped off ports.

[nerdtalker]

1 hour ago, lewisweller said:

The first 5 codes are exactly what you see if you switch on the ignition with the map sensor and throttle body disconnected electrically. Ask me how I know. Clear codes and do the throttle body calibration either with the software or just ignition in and don't touch throttle pedal and don't start engine, after 1 minute switch off ignition and then back on and start engine, idle for a few min and go for a normal drive. 

 

The SAI codes I also have them on the very rare occasions it will need a cold start. These SAI are prone to failure due to age but also the check valve leaks and let's hot exhaust gases and carbon fry up and coke up the SAI internals plus the fan blades like to snap off and get lodged in the check valve. 

 

You don't really need SAI, (emissions blah blah and quicker cat warm up to get into closed loop) you can plug the pipe with a 3/4" GI threaded plug and jubilee clip and ignore the code. Cold starts might be a little lumpy as the cats take a few seconds longer to heat up but who cares. 

This is what I did because the check valve is a real b * tch to get to at the deep back of the engine. 

Saves money and it cant break cos it already broken .......

 

Yeah I'm less concerned with the first 5, I had to change ride height while working on the water pump to get comfortable so I had to turn the vehicle on. I just didn't bother clearing afterwards, but I did let the throttle re-adapt and heard the normal clicking sound associated with it feeling out the range of travel of the throttle plate. 

 

My passenger side SAI pump was seized and seemed to have truly just died, that's why I replaced it with a brand new one a week ago. Seeing both showing some error is pretty alarming. At startup everything seems fine, it's after I come to a stop after the freeway when SAI pumps kick in again for emissions that I get the CEL. It was pretty lumpy and clearly stuttered when the passenger side pump was dead, and returned to smooth after I replaced it. I have no idea why both showed up today as I felt and saw no change in revs.

 

I found Loren's P0492 troubleshooting document in another thread and will work through that. 

[nerdtalker]

1 hour ago, JFP in PA said:

 

He does that in California, he will run afoul of the state emission police   They not only check for system function, they also look for "non factory" modifications, like plugged lines or capped off ports.

 

Yeah I have no love for CARB and the combination of visual inspections and the gestapo feeling. 

 

Funnily enough if you have a Boxster or Cayman though I've found almost no mom and pop smog shop will actually bother visually checking the engine compartment since it's buried inside. They just wave their hands at it.

[JFP in PA]

1 hour ago, nerdtalker said:

 

Yeah I have no love for CARB and the combination of visual inspections and the gestapo feeling. 

 

Funnily enough if you have a Boxster or Cayman though I've found almost no mom and pop smog shop will actually bother visually checking the engine compartment since it's buried inside. They just wave their hands at it.

 

But every once in a while, you will find the exception that has to look at absolutely everything, and the problems start.

[lewisweller]

4 hours ago, JFP in PA said:

 

But every once in a while, you will find the exception that has to look at absolutely everything, and the problems start.

Yeah that's a pita, in uae they test in 3 mins no joke, brake test rollers, beep horn, look at lights on front and back, roll forward and shove Gas analysis probe in exhaust so quick it doesn't even settle, roll on to ramp lift and wave their touch around looking for road kill left overs maybe and the DOT for the tyres less than 3 yrs ago and that's it! Rubber Stamp and pay 150 dollars see you next year suckers. 

 

Funny when they did the Audi ......The Inspector revved the engine and intake sound of the supercharger made his colleague who had his head in the engine bay doing a "torch inspection" Sh*t his pants. Lol hehe hehe 

"Whats that?" he said trying to play it cool after he left his skin for a brief moment. An air filter I replied, why it makes strange noise? It's because of the carbon fibre cover I said.... Hehehe

 

 

[lewisweller]

6 hours ago, nerdtalker said:

 

Yeah I'm less concerned with the first 5, I had to change ride height while working on the water pump to get comfortable so I had to turn the vehicle on. I just didn't bother clearing afterwards, but I did let the throttle re-adapt and heard the normal clicking sound associated with it feeling out the range of travel of the throttle plate. 

 

My passenger side SAI pump was seized and seemed to have truly just died, that's why I replaced it with a brand new one a week ago. Seeing both showing some error is pretty alarming. At startup everything seems fine, it's after I come to a stop after the freeway when SAI pumps kick in again for emissions that I get the CEL. It was pretty lumpy and clearly stuttered when the passenger side pump was dead, and returned to smooth after I replaced it. I have no idea why both showed up today as I felt and saw no change in revs.

 

I found Loren's P0492 troubleshooting document in another thread and will work through that. 

I don't get how the engine runs lumpy?

The SAI pumps air into the exhaust and doesn't affect combustion directly. Indirectly the feedback from the lambda sensor will have some effect on fueling but to run lumpy as a result doesn't sound correct to me.

My idle is fine and both SAI don't work. 

You sure the pulsing isnt the exhaust Gas pumping up passed the check valve? Mine did that on bank 1 until I blocked the pipe off, no sound now. 

Unless the US models are different? 

 

[nerdtalker]

Well I fixed it. Turns out when the SAI Pump died it also blew the fuse. I thought I visually checked it but accidentally checked the wrong one. Replaced the fuse, and everything is great, no more CEL or issues. 

[nerdtalker]

On 5/5/2017 at 9:08 PM, lewisweller said:

I don't get how the engine runs lumpy?

The SAI pumps air into the exhaust and doesn't affect combustion directly. Indirectly the feedback from the lambda sensor will have some effect on fueling but to run lumpy as a result doesn't sound correct to me.

My idle is fine and both SAI don't work. 

You sure the pulsing isnt the exhaust Gas pumping up passed the check valve? Mine did that on bank 1 until I blocked the pipe off, no sound now. 

Unless the US models are different? 

 

I'm not sure either, except that maybe because one bank was very different than the other it caused some issue? 

 

When bank 1 SAI pump was not working, after coming to a stop I'd see idle go up and down and had the sensation that the vehicle was going to stall. If I let it continue doing its dance, it'd stabilize after a moment and then illuminate CEL.