I think you need to go back to basics
Check all fuses, there will be some by the dde (ECU) passenger side back corner of engine bay in a big plastic box also check main fuse board.

I had loads of lights come on on my e90 turned out that water had ran down the loom for God knows how long and the fuse board behind the glovebox was rotten in the back at the connectors, just a thought from the bad weather

Also recheck all the wiring you have disturbed while carrying out your service

Sent from my SM-G960F using Tapatalk

 

Thanks for that. I was thinking it could be a fuse but didn't really know where to start as the manual just has symbols rather than descriptions of what the fuses are for (useful...). Completely forgot about the fuse box under the bonnet, if I remember it's under the bracket where the cabin filter goes.

I'll try that first, then work through the one in the glovebox. I don't think it would be the weather as where I am it's been blazing sun the last few weeks and the front of the car is protected pretty well from rain where it gets parked. I'll post an update if anything comes of it.

Feel free to continue suggestions if anyone knows any forbidden BMW knowledge.

 

You could try disconnecting the battery for 30 minutes again to let everything reset.
Also is the battery fully charged.

 

Sounds to me like it's got quite a general bus comms problem.
Might you have caught some wires under the manifold when you put it back on?

 

Ok so bit of an update. I had the same thought as Alan G about disconnecting the battery for a while to see if it resets everything and we have progress. Disconnected the battery and went through all fuses in both glovebox and engine bay. Only fuse that was busted was a 10amp one listed as for the seats (Which explains why the electric lumbar adjustment doesn't work), however when I plugged the battery back in and cleared codes I can now connect to all the modules fine so looks like it's fixed that.

Having a little drive around I still get an engine warning light but now all the codes are to do with Mass Air Flow. When I took the manifold off I cleaned out the EGR pipe (Think thats what it is, metal pipe on bottom of intake manifold) and the throttle body as both were absolutely full of soot. The little sensor inside the manifold was completely covered in soot so I'm guessing it was never giving a proper reading.

Main question now is would that sensor now reading correctly cause a MAF sensor issue near the air box? Perhaps it's been faulty for a while and now the other sensor reads correctly it's flagged it up?

Only other useful piece of info I can give is that if I disconnect the MAF sensor by the air box, clear codes, and drive around the engine light does not come back on. Just want to get opinions before I get a new MAF sensor as it feels like maybe I'm treating a symptom rather than the cause.

Thoughts?

 

Might have a damaged MAF sensor now.
Perhaps a second hand one as a test before spending a load of hard earned on a new one.
Have a look for the part number on realoem then on the bay.
https://www.realoem.com/

 

Right, so been a couple of weeks delay. Took a while to locate a known working 2nd hand MAF sensor that wasn't been sold for extortionate prices. Replaced the current one, cleared the codes, and 2 minutes up the road it throws a check engine light again. The only codes I seem to get now are ones about mass air flow and throttle actuation. I know it can't be the MAF sensor as I've tried a known good replacement. Also I've run the throttle body actuation tests on ISTA with the feeder pipe off and it opens and closes just fine, no issues. Banging my head against a wall trying to work this one out.

Only symptoms I can confirm since driving it around a few times to see if anything jumps out is that the car feels like it's got no pull. It's fine low down and drives around side roads as normal, but if I try and put my foot down at all it's got nothing, just really sluggish where it used to just pull and pull. Other than that the car is really lumpy turning off. When you shut the engine off there is a sudden jerk side to side just as it dies that it never had before the error codes.

Anyone got any idea's on what to look at next?

 

Does the throttle body momentarily close and re-open when you press the engine stop? If not this could be the cause of the engine shake. You’ve had the manifold off, did the vacuum pipes go back as intended. The vacuum pipes are serving the engine mounts and also the egr valve which in turn has an effect on maf readings.

 

I'm pretty sure everything went back as it came off. I made sure to take photos of everything as I went. I'll give it the once over again at the weekend just to make sure everything seated properly and theres no boost leak anywhere.

 

Thought I'd post this here for anyone interested. Luckily I've found the cause of the issue. It looks like one of the gaskets for the intake tore as it came off first time. The inlets were pretty coked up so I'm guessing it stuck more than it should have and pulled it apart. Has a split across the gasket so it looks fine until you pull at it. My guess is that this is where the boost leak was coming from causing the sluggishness. Secondary to this, possibly because of the leaking gasses, the hose that runs from the vacuum pipe in the little holder behind the intake to the EGR valve had gone all crusty and split.

Now replaced both of them and the car ran fine.... for about 5 minutes. I already know what's wrong with it and it's my own stupid fault. I put everything in the boot of the car after disassembling as I didn't want to put it all back just to take it off again a week later when parts came off. Now seeing as it's hit the mid 30's lately that boot has got preeeeetty hot. It's dried out the gasket on the boost hose to the throttle body on the intercooler end. As you can imagine, as soon as I put my foot down a bit and gave it some load "BANG!" boost pipe comes off. Luckily everything else seems undamaged so just a new gasket to put on and it should be right as rain.

Thanks for all the suggestions.