I have been working to get rid of a P1498 code for a long time now and I have recently been able to cause the code to happen and to keep it from happening.

To make it happen:
I drive the car as normal and it will always happen when the motor is winding down when the car is coming to a stop. When the RPM's go to 800-900 and reaches idle, the light comes on. I have a real time OBD program on my phone and I can see the error come on in the ECU.

To keep it from happening:
I drive the car as normal and when I start to slow down for a stop I can down shift the car as I approach a stop keeping the RPM's around 2000 during each down shift and let the car rev up in first gear for just a second before the car completely stops and the light will never come. I verify with my OBD program on my phone that the error is not being set.

Here is what has been done and replaced:
Smoke test - Found a few vacuum leaks
Vacuum lines replace
Intercooler boots replace
BPV gasket - I found that the BPV is not shutting completely

 

I would check to see if the vacuum line underneath the supercharger horn is disconnected. That was causing my P1498 code in my '06 R53. It's an easy enough job to connect it back up again.

 

Can’t anyone help?

 

Looks like you've already covered the usual suspects, if all of that is good, the only thing I can think of is the possible early stages of the T-MAP sensor starting to go, since that's the sensor that reads the manifold pressure to recognise that un-metered air issue.

 

Did u reset adaptations?

 

Which vacuum line are you talking about under the supercharger horn? The one on the Bypass Valve?

 

I have not reset the adaptions. Can I do that myself or do I need the super duper computer that the dealer has to do it.

 

Looks like he's talking about the Fuel Pressure Regulator vacuum line. And yes, they can dry out and crack after a while. But your smoke test should have caught this.

No, you'll have to go to the dealer or find someone local with the right software.
There is a supposed adaptation reset that you can do with key cycling and gauge reset buttons, but it really only resets the dash, not the actual adaptions in the ECU.

As for my earlier suggestion about the T-MAP sensor.
Quite often the T-MAP can go bad because of burnt oil mist residue, you can attempt to clean it with some brake or carb cleaner, won't really be an actual fix, but sometimes it will work properly for a short time again.

 

I found the fuel regulator line was leaking and replaced it as part of this process. I will look at the TMAP next

 

Yes you can. All details and downloads needed are in my post titled “inpa” here on the forum.