I have a 2000 bmw328i and when I first start it up in the morning... it has a loud screeching sound on the outside, and in the inside it has a suction sound. But then after about 2min the sound goes away and the car drive fine.... there are no check lights on. when I apply pressure on the secondary air pump the frequency (high pitch noise) changes.... I also have a small exhaust leak... does anyone know if this could be where the noise is coming from if so... is it hard to fix...or could I just bypass it....and it is not a belt problem
I read that the SAP is for supplement air feed when the engine is cold, typically winter conditions starting the car after it sat over night chilling. The SAP comes on after several seconds and runs for about 1/2 min to 2 minutes. It's job is done. This is why can make noise on cold start up for only a couple of minutes.
The SAP is a black flat disc shape. With older BMWs, it isn't uncommon for 2-3 of the 6 rivets that hold the housing together to get loose or fall out. The fix is to remove the other rivets, take the SAP apart and clean it. Then reassemble with good fasteners.
If diagnostics indicate a problem with the SAP system and it isn't the SAP, it could be a faulty/dirty check valve. You've probabaly already fixed your problem from 5 years ago, but this is still an on-going gremlin for many even today.
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Re: bmw air injection pump problem...HELP!
Sounds like the secondary air pump has water contamination. If you unplug the connector for the air pump, and check it on cold start, did the noise go away? If the pump is bad, you need to replace the secondary air valve. Sounds like maybe it is contaminated and not seating fully.
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Your AC pump is starting to faiL. It's starting to bind and putting heavy back pressure on the belt causing it slip and screech. After the car cools off inside, the load on the AC compressor is lower and the sound will die down. Also when the belt gets hot it gets a little more flexible and grippy which also lowers sound.
Take it to an auto AC repair place and have it checked.
well it may help if you open the hood, then start the car and see if that helps you locate the item which is whistling. many cars have a power steering pump which likes to whistle until it gets warm. generally this is less than 5 minutes, and that is more like a screeching sound. something is either blowing out or sucking in through a small orifice to make the whistle, you need to physically locate the source of the sound. many bearings are in there spinning and any of them can be doing a cold screech.
myself I have been know to use a BFS, which is a big long screwdriver, i touch the pointy end to each of the spinning components and put the handle end to an ear. yes this process is not suggested for people with long hair or just no damn sense. but as i move the pointy end from component to component i know immediately when i touch it to the screechy one.
1997 BMW 328I 2.8L
MIL is on with trouble codes P1421 and P1423, for incorrect secondary airflow on both cylinder banks.
1. Perform a functional test of the Air Injection Reaction (AIR) system. Tee a vacuum gauge into the vacuum hose attached to the diverter valve, located on the cylinder head towards the front of the engine.
2. Allow the vehicle to sit over night. Start the engine (cold) while monitoring the amount of vacuum on the gauge at startup. At temperatures from -10 to 40 degrees Celsius, there should be at least 17 inches of vacuum. At the same time, the AIR pump should run and pump a large volume of air into the exhaust.
A.I.R. Pump Air Pump Relay Restricted Cylinder Head Diverter Valve Tech Tips:
These codes are related to a problem detected in the Secondary Air Injection system. Scan tools with BMW software include a feature to command the AIR pump on and off. The pattern failures for these codes are the AIR pumps due to leaks in the diverter valve and moisture or condensation in the AIR pump.
Possible fix but not all items. Just areas to look at:
A.I.R. Pump, Air Injection Reaction Diverter (AIRD) Valve
Air Injection Reaction Diverter (AIRD) Valve
Check Valve, Secondary Air Pump
Diverter Valve Vacuum Lines
its your secondary air pump. it turns on in the cold morning to inject more air into your exhaust, something about emission. its normal to be high pitched. once on my car it was way loud, i looked and the hose had disconnected. either way its normal if its not super loud. but if its everyone is looking at me loud then check for loose hoses!
The clear line will be your fuel line.The pump would normally keep pressure on your injectors and consequently has no air. There is a non return(check) valve in the pump to keep fuel at you injectors. Sounds like this has failed. New or 2nd hand fuel pump required