Well this is repost from MBworld because no one has answered yet and I need help ASAP..
I got my 430 back today from the dealership for a service (oil change, and stuff like that). I also had them look over my check engine light that had been going off and on for the past month or so, the car hasn't been performing at its full potential. They told me that it was a faulty mass air flow sensor, so they replaced it. I just got home from cruising around for a little, and on the highway I decided to gun it to see if she would perform better. She defiantly did, but after gunning it a few times on a long stretch I decide to do it one last time. This last time I had the throttle at WOT, 2 seconds into it the engine just cut off for a brief moment and I let off the gas immediately. My car acts fine at all throttle positions except at WOT with the kick down petal depressed. I tried it a couple more times, it does it again. Has anyone ever had this problem? It seems as though only when the kickdown petal is activated for 2 seconds the engine cuts off and starts back up again. If I hold it at WOT and ignore the engine cut offs it still goes, but there is a problem. Do you think the MAF just needs more time to break in? Any comments?
I recently changed my Maf after having your same symptoms. It choked at wot and started jerking when I hit the kickdown button before I changed it. Immediately after changing it the car ran like new no break in necessary. When you change your Maf it is highly recommended that you change your air filters at the same time. The dealer probably didnt change them. Maybe your filters are clogged. Also no one ever changes their fuel filter either and the dealer usually wont do it unless you ask. You should defininately change your fuel filter. I changed mine at the same time I changed my Maf and it was amazing how different the car felt.
I had a similar situation with the same symptoms involving performance loss on my Bimmer I ignored it and the fuel pump died because of a clogged fuel filter. So if you dont know when the last time it was changed change it asap.
I just found out my fuel filter was never changed so i'm changing it today. Your problem doesnt sound like a MAF to me unless its sluggish throughout the power band, especially at the top end. Do you have access to diagnostic equipment?
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