Chokes at 4,000 Rpm’s

[Bryan330i]

I am having a problem with my car cutting out at around 4,000 Rpm’s in any gear. I would call it more of a flat spot, it takes a second or two and recovers, continuing with normal performance after its little tantrum. Is this a normal thing? There is a definite flat spot on acceleration at the same Rpm’s. Is anyone experiencing this?

 

[MyHarley]

You're car seems to be a little bugger at times......mine only has a pause between 6000 and 6500 RPM's, what its doing then I dont know other than telling me I shouldnt be doing that.

 

[MrElussive]

The engine should be linear throughout the rev band, no hesitations anywhere. MyHarley, there's nothing wrong with taking the engine to redline. Bryan, perhaps you should tell your dealership about your problem that seems like a really bad thing to happen.

 

[PuShAkOv]

My engine is perfect.

 

[MrElussive]

Post whore.

 

[Bryan330i]

Post whore.

I just sent an email to BMW Owners Circle and copied the dealer. I gave them a list and asked them to please schedule the car for sevice and plan to keep it until ALL problems are resolved. Today I still cannot get the A/C unit off auto, it just does what it wants. I am hoping that BMW USA can give some pointers to the dealer.

 

[jrt67ss350]

Might that have something to do with the VANOS?? I'm just guessing, but doesn't VANOS change the valve timing somewhere around 4000 RPM? This high-tech variable valve timing stuff is new to me.

There is definitely something wrong, though - my '87 eta engine with 230k on it has no flat spots or hesitation whatsoever, so I certainly wouldn't expect a brand new, higher tech engine to have a flat spot like that.

 

[Kirby]

My engine has been fine - took it up to redline several times to day. Never had any flat spots. I have always put Premium fuel in it as recommended. What rating of fuel are you using?

 

[Bryan330i]

I have only been using premium and from newer stations. I have got gas from Chevron about 5 times and Texaco/Shell about 3 times.

 

[Wadula]

take it to the dealer. there is no good reason for that then a failure. i assume you might still have warranty, so just get there and have it done.

push, nice to hear your engine is perfect.

 

[Akakubi]

Yep, take her in. It could be the VANOS unit, Drive-by-Wire or software bug. They will fix it under warranty. And if they offer loaners, you get to drive another Bimmer.

 

[QuickCivicGuy]

There are a number of things that an cause hesitation

The first and simple check is spark plugs/ injectors/fuel pump

The second could be a software glitch in the ecu....highly unlikely since there would be multiple owners complaining of the same flat spot

Also something to consider is oil pressure....ecus with variable valve timing use load, oil pressure and rpm to sense timing change activations....if oil pressure above 6000 rpm si slugish for some reason the ecu could pull the VANOS timing changes

I am not too familiar with VANOS but I know my VTEC is very oil pressure sensitive due to the secondary lobes being linked with oil pressure activation