Z4 Coupe 3.0SI power dip

[rocky79]

Hello,

I have been having this issue with the car since I bought it. When I push on the accelerator, the car seems to have a power delay and then it picks up. It's not like the car stumbles or hesitate.

Does anyone knows what is it? Thanks

[3002 tii]

You're not giving much to go off of. Pull codes, what maintenance have you done? Auto or manual?

[rmousir]

I'm guessing this is the auto.. its a lag. I've experienced it with other cars.. its almost as if the computer (I don't believe we have a cable throttle) is double checking when you floor the gas before it kicks the car off into go, correct?

[Incompatible]

Another quick check if you have the Sport Package (button). Is there any noticeable difference with the button on and off? As 3002 suggested, more info would help.

[rocky79]

Thanks for the reply guys.
I have a manual transmission, sport package.
I have close to 130k miles now.

Ever since I got the car @ 122k I have done the following:
Replaced all spark plugs: Bosch FR7NPP332
Oil Change Mobile1 0W40.
Replaced the valve cover gasket+ Eccentric shaft sensor o-ring.
Replaced the air filter (OEM)
Replaced all 4 shocks with Koni-Yellow.
Replaced rear brakes ( Testar) and Rotors ( Zimmerman Coat Z)

[BruceJ]

As for a Z4Si auto-box causing a lag, mine is very freaking quick. Response is commensurate with the amount of right foot I give it. I.E. gentle gas is a very smooth start, stomp it and it provides a lot more torque. Both have "zero" lag. Overall, one of the best autoboxes I have driven without it being a DSG. Yes, I know he has a stick but I get tired of the autoboxes inferior thought process. They are a trade-off like everything else. Seen them last 250k + when maintained and how many of us actually have a car with that kind of mileage. Sorry, lecture ended....

As for the "lag": Its most likely engine vacuum related, With 130k on the clock could be a number of things that are going but not gone enough to throw a CEL (wont be long though). If I had to say one thing I would pick ** "EDIT" VANOS solenoid, BUT, Any of the below will contribute to sluggish start.
I.E.:
Intake air filter
Intake Boot(s)
Valve cover gasket (saw you did it already -great)
vacuum lines
DISA Valve
ignition coils
CCV plumbing
***EDIT -VANOS solenoid dirty see: http://www.e90post.com/forums/showthread.php?t=106696
I would check/replace in the order shown as its sorted easiest/cheapest first. If you have not started looking at these things, you need to. They do wear out/break down with time, heat and miles.

You also need to start thinking about your cooling system and suspension bushings, if not already done.

I did all the above on my 330i (m54) at 120k and it was a huge change for the better. CCV was the biggest PITA, frustrating for the cost, but worth it. It literally fell apart as I removed the old one.
All the above are also inherent to the N52 engine and will most definitely cause your issue; and much worse.
Otherwise, could be more complex/expensive fuel injector/engine issue but usually not....

**EDIT - I originally stated VANOS orings. In the N52 engine apparently the VANOS orings are much better quality, But its solenoid(s) can become dirty. Typically causes rough idle.
Good luck
Bruce

[rocky79]

Originally Posted by BruceJ

As for a Z4Si auto-box causing a lag, mine is very freaking quick. Response is commensurate with the amount of right foot I give it. I.E. gentle gas is a very smooth start, stomp it and it provides a lot more torque. Both have "zero" lag. Overall, one of the best autoboxes I have driven without it being a DSG. Yes, I know he has a stick but I get tired of the autoboxes inferior thought process. They are a trade-off like everything else. Seen them last 250k + when maintained and how many of us actually have a car with that kind of mileage. Sorry, lecture ended....

As for the "lag": Its most likely engine vacuum related, With 130k on the clock could be a number of things that are going but not gone enough to throw a CEL (wont be long though). If I had to say one thing I would pick VANOS o-rings, BUT, Any of the below will contribute to sluggish start.
I.E.:
Intake air filter
Intake Boot(s)
Valve cover gasket (saw you did it already -great)
vacuum lines
DISA Valve
ignition coils
CCV plumbing
VANOS O-rings
I would check/replace in the order shown as its sorted easiest/cheapest first. If you have not started looking at these things, you need to. They do wear out/break down with time, heat and miles.

You also need to start thinking about your cooling system and suspension bushings, if not already done.

I did all the above on my 330i (m54) at 120k and it was a huge change for the better. CCV was the biggest PITA, frustrating for the cost, but worth it. It literally fell apart as I removed the old one.
All the above are also inherent to the N52 engine and will most definitely cause your issue; and much worse.
Otherwise, could be more complex/expensive fuel injector/engine issue but usually not....
Good luck
Bruce

Bruce, thank you. That is very helpful.
I will go through the list and see which one needs work.

[Francisco4]

Have you reset the throttle adaption since you have owned the vehicle? Simply and free option to try. I was surprised as to how much it changed the response to my right foot.

FDR

[rocky79]

Originally Posted by Francisco4

Have you reset the throttle adaption since you have owned the vehicle? Simply and free option to try. I was surprised as to how much it changed the response to my right foot.

FDR

Thanks for the reply. Yes, I did it few times before.
I also noticed that when idle and if I blip the throttle a bit the engine rpm go up then it drops below the average and then goes to normal. Not sure if that's an obvious indication to something.