Sound of the Cold Air Start system

I just got my 03 456M GT. Finally have made it through all the registration, state inspection, insurance cert, etc., etc., processes and now actually have a car.

I noticed today (note: absolute all time record setting warm temps in New England....everybodies toys are coming out to play this weekend) that on start, there was a somewhat high pitched whine that went away as soon as there was any appreciable engine temp. Having had much joy with other auxiliary air pump systems both on BMW M3 and Porsche Cayman, I wonder if I am hearing the cold start air pump.

Any feedback greatly appreciated. I am also assuming that the system would be similar if not identical on 550 & 575s.

Thanks in advance....this place is a fabulous resource.

 

It had all the characteristics in sound and duration. Thanks for the confirmation.

 

I wouldn't recommend disabling the aux air pump system. When the pumped failed on my older 97 E36 M3, cold start was really painful. The engine really wanted that extra air. She'd spin, catch, and fire. But then she stuttered, coughed, *****ed, and moaned until there was enough heat that the air system would have kicked out. New pump resulted in all symptoms disappearing immediately.

Perhaps others here with more experience on this family of V-12's can inform if the difference would be equally dramatic, but the S-52 single vanos was seriously unhappy without it.

 

Stefano, I agree on the purpose of the cold start air pump in terms of emissions, however, I cut and pasted these diagnostic symptoms of an air pump failure from a mechanic site. The failure of the pump does have influence on the engine performance, particularly the rough running, stumbling, and stalling. I have experienced all of these with the pump failure on my M3.

1. Engine is running rough

One of the first symptoms of a bad or failing smog pump is a rough running engine. When a smog pump fails the finely tuned air-fuel ratios can be upset, and it will negatively affect the performance of the engine. The engine may have trouble idling, and may drop in engine speed, or stall when the pedal is pressed. Temp sensors plus the flow rate of the air pump are data inputs to the fuel injection ECU.

2. Reduced horsepower

Another common symptom of a bad air pump is a reduction in power output from the engine. Again, a failed smog pump can upset the tune of the vehicle, which will negatively impact overall engine performance. A failed air pump may cause the engine to hesitate or stumble on acceleration, and in more serious cases, cause a noticeable reduction in total power output.

 

Hmm, I cheerfully bow to the more knowledgeable than I.

As a new owner of one of these V-12s, I am becoming more familiar with the car, the engine, and all of its sub-systems. Generally, one extrapolates from existing knowledge and thus my experiences with other air pump systems.

So, the assertion is that the Motronic 5.2 ECU does not "see" this pump as an input to the air/fuel map? I would be quite happy with that as the operating mode since the other experiences make that system actually rather critical to cold start and if it fails, a supreme PITA in New England winter.

Thanks for pitching in, Rifledriver.

 

Comparison of the Motronic 5.2 ECU input parameters

http://www.bosch-motorsport.com/media/catalog_resources/ECU_MS_52pdf.pdf

to those of the Bosch DME ECU for the M3 makes much of this clearer.

The measured input value set are substantially similar but the DME unit also expects a number of other parameters (MAF, Exhaust backpressure, and others) that indicate how the use of the air pump would modify the fuel/air map.

The Motronic is actually a bit simpler on the engine side, and quite more complex on the stability control side.

 

Curious. I never intended nor do I think I indicated that I would make any changes. Merely wished to understand if that was the sound of the air pump system on these cars.

It's my intent to keep this beast as close to OEM as possible. A few thoughtful fixes to well identified issues and/or weak spots, but I have other cars if I want to play tuner games.

I like this one just the way she is.