Sluggish performance when hot
 

When i drive the x 4.4 2001 100 k miles on it in the morning it is fast and responsive . When the car gets warm (20 30 min of driving) it becomes slow and not responsive ( during little acceleration ( 1/4 of gaz pedal) i press the gaz pedal down further but the acceleration doesnt increase and the car requires more throttle than normal when i move off. No COde!!!! Any idea? Spark plugs , heat soak , maf or o2 sensor ( no code!!!) a lot of bmw owner suffer from this problem : http://blog.bavauto.com/1666/bmw-slu...ance-when-hot/. Also: Sluggish acceleration HELP!
Okay my 1992 bmw 325i has a tendency to get really sluggish off the line after you drive it for about 10 min or so. Its odd, right when I start it up its very responsive, but after driving for 10 15 min. the off the line acceleration becomes very low. Its like the rpm's shoot up normally but but the car doesn't agressively accelerate. I changed my O2 sensors, and spark plugs and still the same thing. Any ideas?

http://forums.bimmerforums.com/forum...php?p=22661725

I don’t think it is the spark plugs, I do thing that you may need to replace your air filter. When you first start out your air pump may be still on and the throttle plate may still be opened up still. As the care gets warmer the air pump gets turned off and the throttle plate closes a little.
I would also flush out your radiator and also add some red line water wetter. It will help keep your truck cooler. I would also check your cats out to see if they are plugged. You can kick them to hear if they rattle. If so you me need to replace them.
For your air filter I would recommend a K&N air filter.

THX for the advice! i will change the air filter next week. i forgot to mention that im getting a horrible gaz mileage 6-7 mpg.

as for the cats i cant hear any rattle while driving the car

and i will replace the spark plugs for the first time

You have to kick the cats themself to hear them if they rattle

When you first start out your air pump may be still on and the throttle plate may still be opened up still. As the care gets warmer the air pump gets turned off and the throttle plate closes a little.

Sorry . it is normal \ good thing???



i didnt understand how replacing the air filter would solve my problem: the air filter is ALWAYS dirty ( when the car is hot or cool )

could it be also a dirty fuel filter?

air filter may be dirty anyway, but throttle is opened up to full and + pump is on so it's using more force to get the air in!

More information: i havent changed anything yet but i can hear a little whistle sound when revving the engine . I think it s a clogged catalytic converter (as you said) but i dont get cel light!!!!! Is that possible ?? Nb sluggish performance when hot and the x goes a little faster when smaching the gas pedal ( the x is not very responsive )

Why not lift your car, and kick the Cats. then change the filter, it wont hurt. it is a cheap fix and will be good anyway. then if it presists, go to GT1 indy and get the codes read.

but im not getting any code on the dashboard !!!!

Ok, Listen. On the dashboard you will not get any messages that are engine related. On the cluster text may appear saying you have low coolant, engine oil level, suspenton, tranny, ect... Other, Engine related (for example missfires, ect...) will appear as SES (Service Engine Soon) light, But however, there are priority items, some will trigger SES, some will not. For example when my Thermostat went bad and got stuck in open possition I didn't get SES Unless it realy goes bad. Anyway, sometimes I do a check on the codes and found out it needed to be replaced. So go and get your Codes read, there might be something hiding over there!

haha ok thx will do it this weekend

No rattle !!! But i found this article on ehow : im sure now it s a plugged cat!! http://www.ehow.com/how_6513500_can-...-plugged_.html

My mechanic told me that it could be a failing fuel pump !!! But i dony get cel light . Is that true

Any idea

Can you or your mechanic attatch a fuel pressure gauge to the feed line of the injector rail, and tape the gauge on the windshield and go for a ride. If the pressure gets lower when you loose power, it may be a bad fuel pump or clogged fuel filter.
I don't know if the gaz tank is steel on a X5, but if it is, it may be some rust getting aspirated by the fuel pump, then block the strainer. I had that happened on a 4Runner.

Thx for the tips will do the test this weekend . I called the dealer today and he said :" Some pumps will only fail after warming up, so they appear to work fine after they have "rested" for a while. This is the sign of a dying fuel pump motor" and i have that problem . When the engine becomes cold again it runs fine for 10 min then becomes sluggish and unresponsive and reluctant to downshift

You can attach a pressure gauge to the fuel rail and leave it there long enough to get the motor hot to find out if the pressure is dropping after the system "warms up".

My list of things to check on my own would be: Condition of the air filter, fuel filter, spark, fuel pressure

ECS Tuning

Man, you keep saying you will check this weekend or tomorrow, buy jumping to all theese, you will never solve that problem and car will screw up more. get over with it and check for thsoe problems.

Lol yes you are right!!! Im a medical student and im very busy these days !!! Yesterday i went to my mechanic and i did a tune up: spark plugs air filter fuel filter testing the fuel pump and the cat ( the cat is clean ) changing coolant hoses and overflow reservoir and a new maf sensor !!! And i felt that the x is now a lot more powerful and responsive ! I think the problem was the 11 yrs old maf . ( but i didnt have a cel light ??!!!!!) thx for your tips

I forgot to mention that i paid 700 $ ( including labor ) ??? Whatdo u think?

I did a test drive today and i noticed that everything good( acceleration from a stop, 0 60 ).........but i m still facing the same problem: when i put it in m mode in 2 gear and go slowly to 2500 -3000 rpm and then smach the gaz pedal the acceleration is huge and the rpm climb quikly.( when the x is cold) but when it is warm the same acceleration isnt as fast as the first one ( like i lost some torque). Could it be bad ignition coil or fuel injector??

Good to hear your'e moving on ) very nice. Actually, depends on how cold truck is when you are accelerating. To tell you the truth, on cold engine, it pulls better. not too much difference, but some say so. It also wrecks the engine as the oil is still cold. Good thing, Check computer, if bad igno coil, usually a missfire occurs. Not sure on this one.

I spoke to my mechanic and he said it s a failing fuel pump. But i wont replace it until it fails and throw a code

Today i noticed that the problem exists only in m mode . In sport my x is a different beast.