[doomfinch]

Hello

Hoping I can get some advice. I've had my Australian 2007 e91 323i for about a year now and I haven't been able to resolve a low rpm hesitation issue. It mostly runs well, but occasionally the engine will bounce around in gear with no throttle, sometimes hesitate when trying to accelerate from standstill, and fuel economy seems to be higher than expected (14-15 L/100k). Always seems to be a bit "surgey" when starting off from a standstill, and seems underpowered at low rpm, but great when the rpm is higher. Car has had this issue since purchasing.

Car has about 135,000km on it. In the last 10,000km I have:
- replaced valve cover (to solve PCV diaphragm squeal)
- replaced VANOS solenoids
- inspected and cleaned (though they were quite clean) VANOS filters
- replaced coils and spark plugs
- installed 3 stage intake manifold (not to fix anything, but just an upgrade while changing valve cover)
- cleaned MAF with MAF cleaner, and connector with switch cleaner lubricant
- run some "heavy duty" injector cleaner in a tank of petrol

Any suggestions on what to check next?

Thanks.

[E92William]

Have you scanned the car? Have any codes? If you can get a kdcan cable and inpa from the bimmergeeeks website and scan it it would be great to diagnose it.

[F31B48]

Originally Posted by doomfinch

Hello

Hoping I can get some advice. I've had my Australian 2007 e91 323i for about a year now and I haven't been able to resolve a low rpm hesitation issue. It mostly runs well, but occasionally the engine will bounce around in gear with no throttle, sometimes hesitate when trying to accelerate from standstill, and fuel economy seems to be higher than expected (14-15 L/100k). Always seems to be a bit "surgey" when starting off from a standstill, and seems underpowered at low rpm, but great when the rpm is higher. Car has had this issue since purchasing.

Car has about 135,000km on it. In the last 10,000km I have:
- replaced valve cover (to solve PCV diaphragm squeal)
- replaced VANOS solenoids
- inspected and cleaned (though they were quite clean) VANOS filters
- replaced coils and spark plugs
- installed 3 stage intake manifold (not to fix anything, but just an upgrade while changing valve cover)
- cleaned MAF with MAF cleaner, and connector with switch cleaner lubricant
- run some "heavy duty" injector cleaner in a tank of petrol

Any suggestions on what to check next?

Thanks.

Did you test the DISAs before installing the manifold? They are prone to failing. If they aren't working, a 323i will be extremely gutless at low rpm. Had the same issue with my 323i when i bought it. As E92William said, it would be best to scan the car for fault codes

[doomfinch]

I have cable and INPA and no relevant codes (although I haven't checked lately).

I didn't test the DISA flaps, good suggestion.

[F31B48]

Originally Posted by doomfinch

I have cable and INPA and no relevant codes (although I haven't checked lately).

I didn't test the DISA flaps, good suggestion.

A faulty DISA will rarely throw any codes. The only real way to test them properly is to remove them from the manifold and activate with INPA and watch to see if they fully open and close.

[E92William]

Usually you can test them in the manifold if you know what they're supposed to sound like when they close and open. Should be a solid quick plastic clack sound. But they surely don't throw codes at all unless the board itself is bad. I've plugged in ones that have had a motor that's dead and they don't even give a code lol.

[doomfinch]

No ECU codes. Testing with INPA the 1st/2nd stage DISA sounded sluggish compared to the 2nd/3rd stage. Pulled it out and it wasn't completely opening or closing. Split it open and it was full of oil. Cleaned with degreaser and switch cleaner lubricant and it operates properly now. Glued it back together and waiting to dry. Thank you very much for the help!

I read a youtube comment that someone had build a thing to flush out disa valves that are full of oil. I imagine a couple of strategically drilled holes to flush oil out and then lubricate gears could make a quick repair and also a serviceable DISA.

Is an oil filled DISA a PCV issue? I did replace the valve cover due it squealing.

[E92William]

I have my own rig built to flush oil out of the motors in disa valves since I rebuild them very often. What you did is fine and should last okay. Mine basically runs the motor with a set of propeller blades with a reduction gear set that forces cleaner through the motor itself as it runs. Good thing you didn't have any board issues. Make sure while you're there, well it's a bit late now, that there isn't any play between the shaft and the flap.

I actually inquired in a thread a long time ago regarding venting the N52 engine's pcv to atmosphere because that pcv oil is what destroys these valves. The only thing keeping the valves internals sealed from the intake manifold is a small o ring seal and the way the flap is designed as soon as any oil gets at the bottom it'll just run down into the seal and gear set.

N52 PCV Venting to atmosphere https://www.e90post.com/forums/showthread.php?t=1706320

[doomfinch]

Thanks again for the help. Glue dried and disa now works great. Installed in car and has made it a lot better to drive.

[E92William]

That's great news. What glue did you use? Fully sorted now?

[doomfinch]

Cheapest 2 part epoxy I could find at hardware store. I have a spare DISA valve with the same issue that came with the 3 stage manifold if I need to fix again. Should see me through until I do a 335i conversion. In before "sell car and buy 335i" comments, no chance of getting N54 E91 in AU.