idling issues - mixed up error codes

[mik15]

so for the last few weeks i have been experiencing some idling issues, waiting at the traffic light it has moments when the engine almost dies, the rpm goes so low that it almost stalls if in N, if i keep it in D, due to the load i guess, it is better but still lower RPM than cca 760 which is the usual one...

then taking off takes a bit of struggle, feels like it's chocking, once i get rolling it starts running as it should.

All of the above are intermittent, some days can be all good, then the next day it goes back to rough idling..

Errors so far were only the ones Fuel Trim related, on both banks, which were either showing system too lean or system too rich, both ADD and MULT, and all intermittent, except the one on Bank 1 which seemed to be permanent and it was ADD, if i remember well.

Now, another thing i noticed, on one of the scans, the MAF on bank 1 was reading 10mg/s compared to 5mg/s on bank 2, at idling.

This makes me think there is something wrong with that MAF, but today after a similar experience with almost stalling and later all being good, did again a scan and both MAF's were reading 3.6mg/s and no errors were stored.

So, what is this related to? Could only be the MAFs? i have already ordered a set of gaskets....

Could be the chocked fuel filter? or a dying external fuel pump?

[mik15]

the problem didn't go away yet, not by itself anyway, yesterday the car ran good, no issues at all, in the morning it started again having an idling problem with rmp going down....ran the vcds and all errors i have is:

Fuel Trim: Bank 1 (Mult): System too Rich
Fuel Trim: Bank 2 (Mult): System too RIch


again my bank 1 MAF reads close to 10mg/s while bank 2 MAF read the normal 3.64mg/s

does this means we can narrow it down to the MAF's ?

Under load seems to be alright, pulling ok, it is only at idling when it exposes its issues...

L.E. guess i was wrong, now it felt even worse, the engine died a few times at the traffic light and it pulls like a beaten dog...here is a few logs:

log 1

log 2


error codes would be now:

Wednesday,26,November,2014,10:32:16:59543
VCDS Version: Release 14.10.0 (x64)


Address 01: Engine Labels: 077-907-558-BCY.lbl
Control Module Part Number: 4D1 907 558 B
Component and/or Version: 4.2l V8/5VT G 0002
Software Coding: 0005752
Work Shop Code: WSC 74500 745 89414
VCID: 2D5AEBE5B7F9A949F4D-5120
4 Faults Found:


17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich - Intermittent
17535 - Fuel Trim; Bank 1 (Mult)
P1127 - 002 - System too Rich - Intermittent
17545 - Fuel Trim: Bank 1 (Add)
P1137 - 002 - System too Rich
17547 - Fuel Trim: Bank 2 (Add)
P1139 - 002 - System too Rich


Readiness: 0000 0000


maybe some of you more technical guys can have a look and let me know where to start, to me all numbers seem to be off in regards to MAF and Boost...

[RSoverAll]

Based on codes/symptoms, I'd say MAFs.

"Too Rich" codes mean the O2 sensors are detecting too much unburned fuel in the exhaust stream and the ECU is unable to compensate any further to lean the mixture to achieve an ideal "stoic" A/F ratio. A failed fuel pressure regulator can cause the same symptoms as you have described highly unlikely the pump.

Maybe try cleaning the MAF wire element?


Oh also when logging both MAFs at once it is normal to see some variance between the 2. I don't recall the Bentley spec right now as far as how much of a variance is acceptable but I can def pull it up later tonite.

[RSoverAll]

How do I open the logs? I didn't even see them yet.

[mik15]

well finally got time to take out the airbox and check it...initially all seemed fine and MAFs looked as they were sitting properly, but i've remembered something i read here so i have detached the MAF's from the airbox and fitted it in the inlet pipe and boom...that's when it showed up how large was the gap between the seal and the MAF itself. Most likely those seals might still be the original ones, if so they've done well for 10 years and 147k miles so it is time to have them replaced.

The thing is, with MAF's attached to the airbox you can't really tell they'd have play in the inlet pipe, because the size of the airbox will minimize the amplitude of the looseness.

I have ordered the MAF seals kit from Apikol. Meanwhile, i have used some duct-tape to wrap the MAF's and then forced it back into their place , that's how i tested it and the car is now pulling as it should and no more fluctuating idling....pheeewww

I will do some logs again as soon as i have the new seals installed. Will also leave the MAFs detached from the aribox so i don't have to always disconnect the wiring when taking it off, it seems that it holds very well and there shouldn't be any issues, even if it wouldn't be 100% flushed with the MAF's it didn't matter as the air passing by would be metered anyways, the main thing is not to get air passed by after the MAF sensors.

You can click on the links and you should be able to see the logs.

[RSoverAll]

So loose/worn MAF seals... Glad to hear you found the problem.

Will have to see about getting a set of the Apikol seals myself.

Maybe you could post up a DIY with pics when you install your set...

[mik15]

will do that, it should be an easy one i guess(i hope)....anyway, with the airbox out of the equation fitting the MAF's even with some pretty tight seals shouldn't be a problem...

on the way to work this morning the car felt really alive, i think i've been having issues with my MAF's for quite a while now as today it was like i was driving a different car, true though that it was also the summer here until about 1.5 month ago and it was very f05k14g hot and the car feels anyway as a dead dog during 120F so i didn't push it, but i started to feel there is something wrong with it once the weather cooled down a bit so i couldn't blame the high T outside for the low power...before, the power band was released on 2 bands, before 4k rpm and after, the first part was kind of slower and then after 4k rpm it would unleash the power, you could feel the bump, and that is not the way it should be, now it pulls linear throughout the whole rpm range...

hopefully the only problem was only down to the MAF seals...both MAFs read now the same at idle, 3.64 vs 3.56, so it looks good

[RSoverAll]

Oh wow, very close MAF readings. Very good

[hahnmgh63]

I replace my MAF seals a couple of years ago when I had the engine/tranny out (OEM Parts). This was before the Apikol parts, which I haven't seen in person. I do use a little 3M Silicone grease on the seals to keep them from shrinking and helps sealing as well as helps the MAF's being inserted or removed.

[s8prtotype]

Well, I'm really hoping this might be my issue at the moment....

FINALLY had some decent weather today so I jumped right in...

Spotted that my airbox wasn't installed correctly by the last guy...



I also had to go buy security bit tools because they decided to use one of these...



And finally, the electrical tape on the maf plug.... although i'm not throwing any maf codes, yet.



Maf's aren't bolted to the plenum, which I can understand... I see it make things easier for removal...

Here is a video of my problem....

http://vid886.photobucket.com/albums...pselffnkfd.mp4

Car is throwing random misfire codes on BOTH banks when it's super cold in the morning, I assume once the seals heat up is the reason why it smooths out after driving it for a few.

Vagcom cable shows up tuesday and i'll get to log everything then. Definitely wanna wire/solder/wrap that plug the correct way though....

[RSoverAll]

Wow, is the maf seal even in place in that video?

When I pulled my airbox to do plugs and renew the boost/vac lines I found the inside of my connecter broken and causing running/idling issues but no codes. The pinkish color lock in the middle of the connector had just crumbled from all the heat over the years.

Also the rubber grommet for the connector can be a b!tch to replace, so I can see why someone thought the electrical tape would be a quicker fix but obviously it looks like.... yea. I left mine with a small tear and just installed some heatshrink overlapping the torn area. To get just the right size you may wanna pull off the connector to slide on the heatshrink. Pulling the connector might not be a necessity though, just how I did it.

Oh and the Apikol maf seals are the only way to go as far as I can see.

[s8prtotype]

Yea they're actually down in there haha.

Can't believe I'm saying this but I'm going to try wrapping some self-fusing silicone tape (that can handle 500+ deg) around the mafs first and see if that helps. Should keep it airtight until I get the seals...

[mik15]

that's what i did initially so i could get some proper readings, but will definitely make a huge difference in your case, by the looks of it your MAF seals don't even exist anymore

however, you shouldn't get misfiring codes, do the tape thing and then see how it goes from there.

[s8prtotype]

The misfire codes happened because I let the car idle horribly without touching the pedal to keep it up, but we will see. Next on the list is a cam chain tensioner if this isn't it, Or a big boost leak. I have acess to a smoke machine just never used one on a TT car.

[mik15]

the tensioners can be easily checked via vagcom, that's your starting point for checking them up, but if you don't have any rattles from it when starting the car you should be alright.

When was the last time you did the spark plugs?

[s8prtotype]

I just got the car I'll have the vagcom cable tuesday. She definitely needs some maintenance love.

[hahnmgh63]

kind of sounds like a leak downstream of the MAF's. Air leaking out that was already metered so more fuel and less air...Rich?