Acceleration stumble at highway speed SOLVED!
I started this post back in April and finally found the correct solution this past weekend, pre-cat O2 sensors. I have posted my solution below and if you scan through the entire thread (only 6 pages) you can see what I tried, replaced, checked, tested, and what didn't work and what did. My eventual conclusion is that If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.
Post#56 with solution.
It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.
Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.
1st Post from April.
Hi Everyone,
I am hoping that someone on here can point me in the right direction for the issue that I seem to be having. 2004 zhp auto with 105,000. About 2 weeks ago I started to notice a high speed acceleration stumble when I am trying to accelerate from a cruising speed of around 70. The car has near perfect smooth power throughout the whole range up till this point but if I ask a little more of it there is a noticeable stumble like it is being starved for fuel or has a bad misfire. It will eventually get to where I am asking it to go but not without a stumbling jerking feeling throughout the whole car. Verified by cruising at about 70 then opening up the throttle to accelerate up to 90, it will get there but it doesn’t seem to like it. It is fine around town and will only give me this problem on the highway. Since this probably has more to do with cruising rpm than speed, at these speeds in 5th rpm is around the 3,000 range or a little over. My wife says that I should just slow down but there is obviously a bigger issue here.
Maintenance in the last 20,000 miles includes: fuel pump, fuel filter, spark plugs, silicone intake boot, rebuilt DISA with GAS kit, rebuilt VANOS with Beisan Systems seals. Valve cover gasket, and probably a few other things I am forgetting. I am thinking possible causes could be O2 Sensor, camshaft position sensor, VANOS solenoid, coil pack, vacuum leak? I have no codes and no issues in the lower power range.
Any more solid ideas would be greatly appreciated?
Last edited by daytona90t; 08-21-2017 at 04:23 PM.
Reason: Found solution
Steve,
2004 330i zhp
2009 X3
2013 X1 35i M-Sport