[kkowalsk]

Hi Guys, really need some help.

Thanks in advance!!!!

I need some help and thoughts.

I have a 07' E92 328i - N52 engine.

Between 1500 - 3500 RMP's while accelerating the engine has significant hesitation like a misfire.

No codes.

Only happens when vehicle is started from cold after sitting overnight or longer.

Doesn't happen on initial start-up. Begins after 5-10 minutes and continues thereafter.

This is where it gets odd. If the car is shutoff and restarted the problem is eliminated.

I monitored the engine temp from the hidden menu, from cold the temp only reached 86 C - 87 C max. When quickly restarted the temp jumped to 95 C and reached up to 103 C and fluctuated by driving condition and correctly ran.

I tried the following with no change:

Fuel System Cleaner
(2) New Coils moved to different cylinders to determine if failing coil.
Cleaned MAF - Did not appear dirty.
Air Filter clean.
Unplugged the MAF and it ran poorly.
Replaced upper temp sensor located near oil filter housing.

My feeling is the issue is related somehow to coolant temperature causing the ECU to run a rich fuel map.

Water pump?
Thermostat?
Other coolant temp sensor?

[F31Bimmerman]

Did you clean/check vanos?

[kkowalsk]

No. I was thinking about pulling and cleaning them. They were replaced with the new cylinder head about 2 1/2 yrs ago. I keep the oil changed very regularly between 6000 - 7000 miles so I figure they "should" be ok.

[medusacomp]

Dis you ever changed your coils?? I was having the same problem, i got new coils, put them on start the car same.. I got mad!! I started unplugging coils pulling them in and out.. Oh surprise one of them was locked but not all the way in.. Engine was still running i clicked it all the way engine revved and quiet down.. Problem solved. I guess the tab can click down even if the harness is not all the way in.. Problem was 1 coil that did this.. No codes came up.. Till i got mad and started pulling stuff.. Cleared codes good to go car runs like new at 134k

[kkowalsk]

So far it looks like a dirty VANOS solenoid was the culprit!!

I pulled both VANOS solenoids tonight. They looked very clean, however I soaked the ends in some gas oil mix for my trimmer, blew them out with air and let air dry. The gas was barely discolored and no debris in it after cleaning them.

Wiped everything off, oiled the orings and reinstalled in the same locations.

Took it out for a ride and the issue seems to be eliminated. Will see tomorrow on the way to work. Keeping my fingers crossed.

Thanks for all the suggestions. Hopefully I can cancel my service appointment when I get to work tomorrow!!

[kkowalsk]

Unfortunately it started acting up on the way into work today.

Ran perfectly last night and for 60 miles on the freeway today.

Then it started to run poorly on acceleration again.

Fuel economy dropped and oil temp dropped.

Possibly one of the VANOS solenoids I cleaned are actually failing.

It goes in tonight to my indy to try to figure it out.

[MrQuickR1]

Where is this hidden menu for engine temp? Where would I find that, I hate not having an indicator.
EDIT: Never mind, I found it through google

I think I know what you are talking about, I have some weird sputtering when I throttle at times and mostly after the car is started.
Almost like it chokes and spits a little before going.

I haven't dug in yet but have replaced in the past year and a half, the coils, plugs, cleaned vanos a couple of times, eccentric shaft sensor, valve cover gasket, oil filter housing gasket, changed out fluids; coolant, brakes, differential, steering, MAF sensor, Air filter.... runs a tad better but still no solution.
Wondering if an injector might be acting up. Even on cold starts the motor turns over harsh, like a jump.

How is your idle? Steady sitting at a light in gear?

[kkowalsk]

My idle is good...so far. I have a manual so no load except accessories at idle.

Starts good.

Just intermittently it runs poorly under load around 2000 - 3000 RPM's. Feels like I have half engine power. After 3500 RPM's it's fine.

When this happens the fuel economy is poor, water and oil temp drop.

[kkowalsk]

Car spent (2) days at the service shop and they couldn't recreate the issue or find anything wrong. Arrrrrgggg

[Surly73]

Originally Posted by kkowalsk

Car spent (2) days at the service shop and they couldn't recreate the issue or find anything wrong. Arrrrrgggg

Your description of RPM based issues leads me to think the issue is VANOS or possibly DISA related (though I don't think that DISA problems would cause something as dramatic as feeling half power.

There should definitely be codes, if you aren't reading with INPA or a similar BMW specific tool then you aren't going to see everything. My DME was logging VANOS shadow codes for thousands of miles saying "stuck" or "implausible" and I have no CEL or drivability issues at all. Something as serious as your issues should be leaving a novel worth of codes.

[kkowalsk]

I've had my car back for a couple weeks without issue since my shop looked it over and couldn't find anything. They have BMW scan tool and an aftermarket one.

It has been running fine without any issues....until today it started acting up on the way home.

Poor acceleration, fuel economy dropped and my oil temp was lower than normal at 210F.

I pulled over, restarted it and the problem stopped. The fuel economy resumed to normal and the oil temp rose up to 230 - 240F after running for a couple minutes.

I somehow keep thinking this is related to coolant temp, engine temp, intake air temp or even an ambient temp sensor if the ECU reads that.

Please help.

[ccraig13]

Hey any updates on this? My car sucks until I hit 3500 RPMs as well

[clarkbar]

Just recently, I've run into the same exact problem. When I turn off the car and turn it back on again, the problem goes away, until a week later when I'm driving it and the issue comes back. Has anyone found the culprit or a fix for this?? I'm worried that if I take it to the dealership they won't be able to diagnose the problem since it happens intermittently.

[StereoSteve]

rough acceleration AND idle?

I've heard problems with your symptoms if the coils aren't pushed in all the way. The first time I took mine out, I thought i pushed it in until i compared it to the next one, which was way deeper.
Also, spark plugs? My 07 E92 had rough acceleration in the lower rpm's and would sometimes start to sputter until i restarted the car. drove fine most of the time. 1 spark plug was failing but the rest were good.
Hope you get it fixed!

[e90ben]

I've had issues with this before: Turned out to be the Throttle Position Sensor.

Quick way to test, when you are getting the hesitation set your cruise or floor your car

No hesitation=TPS
Hesitation= Coil, Vacuum leak, etc...