Welcome to Tech Talk, where our resident BMW tech Nick Owen answers all your pressing BMW technical questions, frustrations, and issues. Have a question for Nick? Email him at techtalk@roundel.org. Let’s get into it.
E90 N52 Misfire
My 2007 325i, Steptronic, w/331,440 miles has a misfire. I’m the original owner (no iDrive, I’m never getting rid of this car!) and it has been meticulously maintained. The most recent ignition coils and spark plug replacement was in September 2025 at approximately 325,700 miles.
Several weeks ago, when it first happened, I put my Foxwell NT530 code reader on it and it showed an error for Engine Electronics DME Fault | 1. Expanding that error code, the error was 2E98 BSD, message; Alternator missing.
I had the (probably original?) alternator replaced and drove it for two days (approximately 250 miles, mostly 65 mph, mostly using the cruise control) and it misfired again. This time my Foxwell didn’t show any error codes.
Can you provide me a checklist/flowchart of how to troubleshoot this, from most likely things to check to least likely, now that it doesn’t show an error code? Does the BMW dealership have any diagnostic equipment that would be helpful given the fact that there is no error code this time?
Robert
I have to say congratulations on the mileage! Impressive.
Do you feel the misfire while driving or at idle?
Sometimes, in order to store a misfire fault, you have to go beat on the car. Also, if you have a long steep hill to drive up, you can use that to put extra load on the engine to get the misfire to store. Basically, you want to accelerate from a low speed in a high gear. I can instruct you further based on how you feel the misfire.
BMW has plenty of diagnostic capability but the diagnostic path is the same. We need to get the fault to set before we can pursue the next course of action. Let me know what you find.
I feel the misfire while driving. I will take it out tonight after work and put some miles on it. I parked it in my driveway after I felt it misfire (after having the alternator replaced). But that misfire did not produce an error code.
I’ll let you know tomorrow if I get an error code tonight.
I tried beating on it this weekend. There is a six-mile-long hill on the east side of town that has a 700-foot elevation change. I did four bursts up the hill from 65 mph with no misfire. Then I tried one run up the hill holding it at a steady 60 mph in the truck lane. Still no misfire.
Before the alternator was replaced, when it would misfire, I would get four misfires in about one minute. Since the alternator was replaced, it has only misfired twice, but only one misfire each time, instead of four.
So, given the age of the car there could be several other components that are on the edge of failing. At this point we don’t know if it is spark or fuel. If/when I get an error code, I’ll let you know.
It sounds like you got a misfire that won’t show. Here is what I would do next:
Pull out all the coils and switch them to different cylinders. Even though they’re new, it’s possible they are not fully touching the plug and causing a poor connection, resulting in a misfire you feel. Make sure you push them all the way down.
Go drive the car and go back to that long road with the hill. Shift into manual mode and go to the highest gear and slowest mph possible without it shifting down. I think 20mph should do it. Slowly roll into the throttle so that the engine has low RPM and a tall gear, which forces the engine to work hard and can make a failing coil/plug show. We used to do this at the dealership a lot with N51/N54/N55/N63 issues.
M2 Break-In Procedure
My son and I received calls from our BMW sales associate today that we received factory allocations for our cars. We have been waiting since last December, so we are very excited. Both of us are going to have our M2’s delivered to the Greenville, S.C. BMW Experience Center, hopefully on the same day.
I will be driving my car back to PA and want to do the best possible job of “breaking in” the fantastic M engine.
I know that I should drive gently, not exceed certain revs, no full throttle accelerations, and never maintain the same speed for long periods (vary mph and revs). I wondered if there were any other tips that you would recommend? I thought that I read somewhere that it was good to go up and down mountain roads (not lugging the engine) which encourages me to take some back roads in North Carolina on the way back to Pennsylvania. Is there a link for the recommended procedure for M engine break in at BMW or a BMW Club Site? I know also to strictly follow the one year or 1200-mile engine and differential oil change by the dealer.
Russ DeJulio
Pittsburgh PA
Congratulations on the allocations. The wait will seem long but it will all be worth it. As someone who ordered an E90 M3 and took delivery in S.C. and then drove it back to San Diego, I think I can help you out. Traditionally, the main thing here is don’t go full throttle or hit redline until the 1200-mile service is done. Doing it on accident won’t hurt anything but the way to break the car in is to drive the car “normally.”
I’m not aware of any guide on break in because street cars are not built to the same tolerance as a race engine. Therefore as long as they have a wear pattern (break-in mileage) then they’re good to be used in whatever manner the owner uses them for. I personally believe low RPM break-in is not ideal, however when driving a car across the country, there isn’t much you can do. Ironically, I never ever had an issue in the 36k miles I put on mine and never had a customer bring their car in for a complaint that resulted in the break-in mileage being done incorrectly. (Except when they don’t bring it in at 1200 miles) I think driving the car back to PA with some highway and back roads would be ideal to enjoy the car and get acquainted, which is mostly what the first 1200 miles is all about.
2007 Z4M Roadster Recommendations
My Z4M is doing fine and I drive it a lot. It has 110,000 miles with no issues, but with this amount of use, I am concerned about potential challenges that might come along. Unlike my previous S54, this one has always had a VANOS rattle. It is not getting worse and runs great. It does have a bit of suspension wear. Other than these two things, it’s great.
Henry Johnson
Sounds like your Z4 is just getting broken in! If you’re at 110,000 miles, then it would be wise to take a look at the rubber bushings. Both suspension and motor/transmission mounts. Some might be ok, I’m sure some are showing signs of wear. Something to keep an eye on as the car ages.
In regards to the engine, an oil analysis might give you an idea of how the internal wear is going. This would be a good indicator of whether or not you should replace the connecting rod bearings. It seems this is a wear item for this engine and if they have never been done before, would be good to see if they should be done soon.
For the VANOS assembly, I would take a look at the exhaust camshaft sprocket at the next valve adjustment interval. Which I believe is around 120,000 miles. If the sprocket has signs of damage, then the unit should be serviced as needed. Might be a pricey repair, so be sure the car is with someone who knows what they’re doing.
