[RK_E92]

Hi guys,

Wondering if you can help give me some insight. So to start off car is a Jan 2011 E92 335i N55, currently sitting on 69k miles.

The car has been maintained well, just bits I have done in my ownership that I can remember off the top of my head:

New Valvetronic motor, eccentric shaft, water pump and thermostat, OFHG, new valve cover and gasket, new sump gasket, ACL rod bearings, silicone vacuum lines, new belt, tensioner, and pulleys, crank guard seal, mickey mouse flange, walnut blast, stepped intercooler, decat and of course, your standard coils, plugs, oil changed every 3-5k etc etc. Also tuned stage 2+ with MHD for about 7k miles.

The majority of this work has been in the last 15k miles.

The only things I haven't done that are fairly common to my knowledge would be the fuel pump and maybe injectors?

So now on to my issue...

The car was running sweet, went to drive it home from work, and boom it starts up but immediately dies, tried a few times but the same result. The only way I could keep it going was by disconnecting the MAF. Ran a bit groggy as to be expected with MAF unplugged, but once warmed up it was absolutely fine. Got it home and started to think about why it didn't start. I assumed it would be an air leak, but from what I can see all vacuum lines, intercooler piping, and PCV are good. (Genuine valve cover and gasket less than 2k miles ago)

I can not get any codes from the car through the MHD OBD reader other than MAF faults when unplugged. If I plug the MAF back in the only way it will go is if you're ready to ride off the clutch the second it starts up, again once warm whether the MAF is on or off the car runs okay. Possibly a bit rich as getting a lot of gunshot pops unlike my normal pops (not nice).

Injector values seem to be quite high on a cold start (is this normal?) values ranged from about 3-9 but settled down after about 2 minutes and started to get warmer.

I can not find an air leak so I am about to drop the money on a set of new injectors... can anyone advise me otherwise as I am no mechanic. I have had two different shops look at it and neither can come to a conclusion, one thinks injectors and another thinks HPFP (thought this would give a long crank?), and neither can find an air leak either. The car instantly starts but just as quickly dies.

Any help is greatly appreciated people! Many thanks

[wheela]

When you unplug the maf, I beleive the dme defaults to running via speed density using the tmap sensor. So if it runs fine with the maf unplugged, I think that suggests your injectors aren't the problem. I suspect either an air leak somewhere upstream of your tmap, or a bad maf sensor (they can go bad).

Can you post a log at idle? Your stft and ltft at idle will help shed light on if you have an air leak.

[RK_E92]

Thank you! I didn't think unplugging the MAF should have any effect on injectors... I have just taken a quick log at idle, MAF is still unplugged as it won't idle with it in.

https://datazap.me/u/rke92/car-won%E...og=0&data=3-15

[RK_E92]

Originally Posted by wheela

When you unplug the maf, I beleive the dme defaults to running via speed density using the tmap sensor. So if it runs fine with the maf unplugged, I think that suggests your injectors aren't the problem. I suspect either an air leak somewhere upstream of your tmap, or a bad maf sensor (they can go bad).

Can you post a log at idle? Your stft and ltft at idle will help shed light on if you have an air leak.

Thank you! I didn't think unplugging the MAF should have any effect on injectors... I have just taken a quick log at idle, MAF is still unplugged as it won't idle with it in.

https://datazap.me/u/rke92/car-won%E...og=0&data=3-15

[RK_E92]

Any Help?

[wheela]

How did you check for air leaks? If you just did a visual, I'd do a smoke test, or boost leak test to rule out leaks. Since it happened all of a sudden vs. gradually getting worse over time, I'm guessing it's not a dirty maf. If it were my car, I'd rule out air leaks, and clean the maf connections. If there are no air leaks, and you still have the problem after cleaning the maf connections, I'd probably try a new maf sensor. You could try cleaning your maf before buying a new one, as that's easy and cheap to do. But those are my guesses (air leak opened up, or bad maf/maf connection).

Any other ideas from the peanut gallery?

[wheela]

Oh yeah, thanks for posting the log, but I was thinking that it would be with the maf connected. Since its sans maf, I don't think we can conclude if there are any leaks based on the fuel trims.

[wheela]

Since it started suddenly, you could also give the front of your intercooler a visual, incase a rock kicked up from the road and punched a small hole in it.

An interesting aside - I had installed the burger tuning silcone coupler to replace the factory accordian coupler on the air duct. It was fine for a couple weeks, but one day I started it up and the idle was loopy, and my trim values settled into new values over the next couple days. Then idle was fine again. I finally discovered the culprit by accident - I was under the hood looking at something else, and noticed that the plastic duct under my burger silicone coupler buckled, creating a huge air hole in my duct. It must have been a combination of force from the hose clamp, and heat that softened the plastic duct, as the buckle could not be forced back, it was like it melted and resolidified in the buckled state. I had to buy a new duct. Long story short, look for little things like this that could have just given up all of a sudden.

[RK_E92]

[IMG][/IMG]

Just had it smoke tested, massive air leak however the garage said they couldn't order the part in. Is this the inlet pipe? Where lower air duct pipe meets metal pipe was his explanation.

Any links would be greatly appreciated.

[wheela]

Originally Posted by RK_E92

[IMG][/IMG]

Just had it smoke tested, massive air leak however the garage said they couldn't order the part in. Is this the inlet pipe? Where lower air duct pipe meets metal pipe was his explanation.

Any links would be greatly appreciated.

Hmm, not quite sure what to make of that? All the factory tubes are plastic. Do you have an aftermarket metal charge pipe? If so, he could be referring to the plastic pipe between your intercooler outlet and your charge pipe inlet. I've seen the end of that pipe buckle and leak from over-tightening the hose clamp where it connects to the chargepipe. (#18 on this drawing)

[RK_E92]

I've got a sneaky suspicion this guy thought the connection to the turbo was a metal pipe some how, as he was pointing at the inlet pipe and said where that pipe meets the metal. I'm thinking maybe "15"?

[wheela]

That could be too. No hose clamp on that joint, just a press-fit seal, but it certainly could be leaking there.

[RK_E92]

I had a lot of work done quite recently. Had rod bearings, engine mounts, vac lines, walnut blast and a new valve cover put on the car probably about 700 miles ago. Is it possible they could of completely forgot to put that push fit seal back on? If that pipe needed to be taken off?

[wheela]

Maybe, except if they forgot the seal, then you should have had this issue as soon as you got the car back from them. It sounds like it was driving fine for you for a while, and then all of a sudden started acting up?

Out of curiosity (and unrelated to your current issue) did you do your rod bearings preventatively, or were you having an issue with them?

[RK_E92]

Yea car was fine then it starting turning off on cold start all of a sudden about 700 miles later.

My last oil change I had quite a lot of glitter in the oil and shards on the oil filter, did a report and it came back fine but I wasn't convinced.. couldn't get it out the back of my head lol. Luckily looking at the bearings they weren't too bad but definitely starting to wear, definitely would of lasted longer.