[pmcmtnbkr]

Hi everyone I have been chasing a implausible air reading since replacing the fractured turbo inlet pipe with a larger cts silicone intake and installing a dinan carbon fiber intake. I think the mass airflow sensor has gotten lazy and is out of spec esp since it is reporting an intake temp 90deg higher than the ambient temp of 61deg and anywhere from 7.2 to 8.9 kl/h at warm idle 660 rpms. I have a new sensor coming after cleaning and resetting adaptations did not clear up the issue. I am seeing ltft readings of 1.24 at idle returning to around 1 above 1000k rpm. I have done a smoke test sprayed all conections to see if idle changes i cant find any leaks and the car idles smooth with no stumbling or surging that typically accompany a leak. A new valve cover was installed due to the original had just started to leak at 78k miles. If the new sensor doesn't resolve the problem it is looking like a tune might be in order to compensate for the increased airflow. Is there a member here that would be willing to help figure this out possibly remote programming or know a work around? I almost fell over when I priced out bootmod 3 . I am completely new to this type of tuning and could use some serious guidance. Thanks you in advance for any help forgot to mention this is on a 2015 m235i

[SlowN22]

is the code pending? I would continue driving and see if it clears on its own. Did you smoke test at the oil fill on the valve cover?

[MarcoZandrini]

I don't think you can "code" the MAF. I basically sends raw data to the engine computer.

[pmcmtnbkr]

Everything has been smoke tested couldn't find any leaks. Egine runs smooth even at idle. New mass airflow sensor did fix the temp reading and improved things some still get implosibility air readings from time to time. My understanding is the larger diameter dinen or any larger tan stock intake pipe causes air turbulence at idle making the mass airflow sensor readings lower. With a stage one tune specifically bootmod 3 you can acount for the larger intake diameter and in essence tell the computer this is a normal reading. 2 other options I found programing the idle speed up a few 100rpm can basically keep the reading from the mass airflow dropping to low the second is a mechanical fix adding in a laminar air low grid pre mass airflow to straighten out the airflow and reduce air turbulence. I think i will try that first its less than $20 from a turbo supply shop then ill try bumping idle up a few 100 rpms if that doesn't fix it and see what happens

[pmcmtnbkr]

Ok I think i got this thing licked finally. After a ton of diagnostic work. I took the dinan intake out and went back to the drop in filter and and intake tube it was the only part I could convert back to stock. I put the original MAS back in and reset adaptations. After multiple drives. I was still getting LTFT of anywhere from 20 to 25%. Took out the old MAS and installed the new one reset adaptations again and bam LTFT went to -.88 at idle to 0.00.under any load/rpm.once warmed up however LTFT returned to 10 to 12% but only at idle as soon as any throttle is applied LTFT goes right to 0 00 no lag or bouncing around. Engine runs smooth an pulls strong throughout all of this. I have monitored this now for several days. It's remained 100% the same when engine is in open loop and cold and not running on MSA ltft - .88 to 0.01 at idle and 0.00 under load. Once warm and car enters closed loop and runs off the MAS ltft increase to 10 to 12% only at idle. Point to a small vaccum leak somewhere. I couldnt pin point it until yesterday morning whent out to start the car. Put my foot on the brake pedal and it was rock hard zero give. As soon as the car started brake pedal returned to normal. The leak is somewhere in th vacuum lines to the brake booster. This morning brake pedal was normal. Popped the brake booster check valve out of the booster and placed finger tightly over the end of the check valve ltft dropped to under 2% so either the check valve or rubber grommet are leaking slightly most likely and cheapest fix under $60 or the booster diaphram has a small leak least likely since the vacuum leaks down intermittently over night.since I fixed all the other vacuum leaks bad valve cover gasket for god knows how long and the broken intake pipe. My guess is it finally is building more vacuum at idle and the check valve has startdd to fail. Parts are on order should hve them by end of week and see if i am correct. Once I have all this sorted I'll put the dinan back on and see if the computer can handle the larger volume of air.

[pmcmtnbkr]

Parts installed so we will see what tomorrow morning brings

[pmcmtnbkr]

Well the good news this fixed the rock hard brake pedal after sitting over night. Not sure if it was the grommet or the check valve since I replace both but its a solid result. It also seemed to fix the implausible air for a couple of drive cycles then it returned. Was checking wiring on the mass airflow sensor, tmap, and map sensors. Noticed a very small gap on the tmap on the boost charge pipe and could push the sensor in and out a few mm on the bottom bolt. I was able to tighten the bolt a turn or 2 and the play went away. So the bolt had rattled loose. Took both out and added a drop of blue lock tight to the threads and tightened them down. So far no code have come back fingers crossed. I am holding my breath until I have driven the car a few hundred miles and the codes stay away. I found so many post regarding theses symptoms and people ended up throwing the parts cannon at the problem only to have the codes return. We shall see

[jzeiler4]

This reminds me of the time I drove my MGB home to Alabama after it was stored at my FIL house in AZ for two years while we was on Guam. It kept leaning out at hiway speeds and I could smooth it out with the manual choke. So at each gas stop I would richen the carbs up a bit (dual SU) but soon the car was way too rich at idle. Tried everything rebuilt the carbs and set the mixture at idle, replaced the cylinder head (had a small crack in the leaking coolant). I was at my wits end then I tried to pull the hose off the brake booster and felt a rough spot. Sure enough is was a cracked vacuum hose. It is always the last thing you try so strive for doing that thing first!

[pmcmtnbkr]

Finally got it fix 100% open loop idle ltft 0 to 3% above 2500 rpms ltft 3% so this is open loop and not using the mass airflow to calculate fuel trims. At operating temp both idle and above 2500 rpm mass airflow is adding an additional 2 % to ltft so only seeing about a 5% ltft on either end of the rpm range. The final peice i figured out was the turbo inlet cts pipe when I put it on and tightened the clamp it was about 40 deg as the engine warmed up I was getting a small vacuum leak. Once the intake pipe was warm I was able to tighten the clamp a few more turns and this brought the fuel trims down another 5%. What a PITA finding this little leak. I chased this thing for so long every time I thought i had it solved the problem would come back in a few days.