04 ZHP Surging but not the "Classic" ZHP flash issue.

[95m3ltw]

6 months ago, the car started developing a surging after 2600rpm. Smooth as butter at any throttle input up to 2600, once past that point it starts to surge. Full throttle it is not noticeable but if you are at 40% or more throttle, a very noticeable surging starts and continues up to near redline. It feels like the throttle is going from 40%-70%-40% every 1/4second.

No codes.

New fuel pump, fuel filter with reg. Rebuilt Vanos. Car had latest flash in the DME but we reflashed it anyway, no change. Unplugging vanos seems to change the frequency and make it less noticeable. At that point I rebuilt the vanos thinking that was the smoking gun. Well it improved but is still noticeable. Car has 120k miles on it and auto trans. Torque converter seems to lock up normally so I don't think it is the transmission.

Replaced the injectors, DISA, Throttle Body, Smoke Test, New o2 Sensors, Guibo, Driveshaft support bearing, even updated the trans software.

Any ideas or suggestions would be awesome. It's my wife's car and we are ready to sell it but I'm not passing the problem on to someone else.

[slater]

vacuum leak?

i have a similar issue, mostly from 2500-3000rpm, doesn't matter what percentage of throttle is applied, although it is a lot less prominent now with the colder weather.

peter

[SoarinZHP]

I would check the intake boots for leaks
the DISA valve to make sure it moves freely
the fuel filter to make sure it's not clogged

[LivesNearCostco]

Yeah but he has a new fuel filter and DISA. Could be CCV failed internally, or maybe one of the crankshaft position sensors. If you go to the Beisan web site, he lists other possible causes of drivability issues including the CPSes, stuck VANOS solenoid, etc. Here's one of his forum replies explaining how to unstick the intake VANOS solenoid:
http://www.bimmerboard.com/forums/posts/1241760

[BADCLOWN]

i had a seemingly similar issue to what you are describing and i ended up having a bad coil pack (didn't throw a code surprisingly)

[OtterEffect]

My car does this as well. Seems like some days I barely notice it, other days the hole car continuously lurches.

[95m3ltw]

Thanks for the responses guys.

I have access to another 330 so I swapped coils, disa and throttle body with no change and tested them in the other car, no issues.

I'm not ruling out anything at this point but in my experience, Vanos issues usually set a code when it affects engine performance and same goes for vacuum leaks. Anytime in the past when I had even the slightest leak, it set a check engine light for the banks affected by the leak.

Over the next week I will be spending more time testing and documenting everything to date, anything else one might think of checking please let me know.

[Dave1027]

I assume you also tried swapping the MAF? Have you pulled fuel trims?

You could try clearing the throttle adaptations. Do the sequence below:

1. Turn ignition ON (position 2) for 10 seconds. DO NOT ATTEMPT TO CRANK / START THE ENGINE.
2. Turn the ignition OFF for 10 seconds.
3. Start the engine.

[llll1l1ll]

I also have the same issue as the OP. I thought that getting the DME updated would fix it, but I guess the OP already found that out and it doesn't help.

It's really a peculiar issue and for me it's most noticeable at around 40-60% throttle.

My fuel filter is stock, so I guess I have some work to do...

[BADCLOWN]

any updates from OP?