someone school me on measuring block 032 / p1557

[erykv1]

Heyya Azine,

I've been chasing a P1557 positive deviation code to no success and its driving me nuts... so hopefully I can summon the power of azine to get this sorted...

Been closely monitoring measuring block 032, currently as it stands these are the following values (the part idle values have been as high as low 20s), and yes I have reset the codes every time before I checked these values:

Adaptation Idle B1S1 6.3%
Adaptation Part B1S1 -16.5%

Adaptation Idle B2S1 6.8%
Adaptation Part B2S1 -15.6%

These idle adaptation values lead me to think that I have a boost leak somewhere, but a recent smoke test and a pressure test (up to 15psi) has yielded no leaks. Car doesn't idle weird, vaccum levels are in the proper ranges.

Here's what I've tried thus far:
-early pressure test revealed a leak by the intercooler, which has been fixed. problem still exists.
-swapped MAF with 2 known good MAF's, no improvement
-tested the new n75 with a mityvac (holds vaccum on wastegate actuator side), no problem
-tested the newly rebuilt wastegate lines with mityvac, holds vac with no leaks
-wastegates crack at proper pressure
-smoke test shows no smoke leaking anywhere
-I have an APR bi-pipe so not the common torn TBB for the source of this code
-spider hose recently rebuilt so should be no leaks there


Here are my questions (please dont let this sway your opinion/input):
-what are the proper ranges for Idle Adaptation? (as close to 0?)
-what are the proper ranges for Part Adaptation? (+/- 10% normal?)
-when pressure testing, does any air leak through the throttle plate?
-since there are no external leaks, I am thinking it could possibly be internal?
-I have ordered two replacement green check valves (the green buggers) and they are on the way

If there is anything you guys think I have missed let me know.

Thanks in advance for any input!

[vavJETTAw36]

Out of spec part is indicative of bad MAF.

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info


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[erykv1]

Out of spec part is indicative of bad MAF.

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info


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I know you're trying to help, but please read through the post.
"-swapped MAF with 2 known good MAF's, no improvement"

I've been through the depths of the internet / google searches on this issue. lol.

[airjawed]

MAF backwards? Or more likely an internal leak.... I would check the diverter valves. Are they facing the right way? I'm assuming you pressure tested from the Y pipe. What is the back story on this car?

[Monty23]

First off, if your going to check your long term fuel trims, you need to give the ecu time to adapt to the proper values. If you clear the fuel trims and then read them right away, you are going to get bogus reading since the ecu is still making adjustments until fueling is close to what the ecu says it should be.

So have the "part throttle" long term fuel trims always been near -15% or is this a recent issue? are the idle fuel trims usually near 20% as you stated before clearing codes?

[Corradovolksb]

Mvb 32 Will not help you find a boost leak. It will give you short and long term fuel trims. Short term spec is +-5% and long term is +-10%. Mvb 115 will show you requested and actual boost value in Mbar and they should be close to each other all of the time. There can be 100-200 difference while boost is building at Lower rpm but should equal out at higher rpm. That fault can be tricky and could indicate a boost leak or an overboost situation. Log mvb 115 and see what your boost profile looks like and that will give you a better Idea of what's going on.

[vavJETTAw36]

I know you're trying to help, but please read through the post.
"-swapped MAF with 2 known good MAF's, no improvement"

I've been through the depths of the internet / google searches on this issue. lol.

Sorry about that I posted when I was still laying in bed and I admit I didn't read it...

So deviation is from boost pressure either being too high or too low. This is going to be key in finding your issue. You need to know is it too high or is it too low. What's your boost gauge telling you? Log your boost with vcds. You'll log requested boost, specified boost, and engine speed. Can't remember the block but you will just find them with advanced measuring blocks.

Too much boost is going to pointing to something wastegate, wg line, n75, or compressor line (opens wastegate) related. Too little doesn't rule out the above, but it also points to charge hoses, intake, etc.

How did you pressure test?

[erykv1]

MAF backwards? Or more likely an internal leak.... I would check the diverter valves. Are they facing the right way? I'm assuming you pressure tested from the Y pipe. What is the back story on this car?

checked DV's as outlined here: http://www.vaglinks.com/Docs/Misc/VA...rter_Valve.pdf no problems.

I don't think its possible to install the MAF backwards on my car due to the mounting hole location.

First off, if your going to check your long term fuel trims, you need to give the ecu time to adapt to the proper values. If you clear the fuel trims and then read them right away, you are going to get bogus reading since the ecu is still making adjustments until fueling is close to what the ecu says it should be.

So have the "part throttle" long term fuel trims always been near -15% or is this a recent issue? are the idle fuel trims usually near 20% as you stated before clearing codes?

I usually reset the codes, drive for about a day ~50 miles, and recheck, these arent immediate values as I understand that the LTFT's only log while the car is in close loop operation. This is a recent issue, the car was apart for a tip to 6 speed swap, and while everything was out I redid all the seals / vac lines. Now I have to fix this code before I can get re-tuned.

Mvb 32 Will not help you find a boost lean. It will give you short and long term fuel trims. Short term spec is +-5% and long term is +-10%. Mvb 115 will show you requested and actual boost value in Mbar and they should be close to each other all of the time. There can be 100-200 difference while boost is building at Lower rpm but should equal out at higher rpm. That fault can be tricky and could indicate a boost leak or an overboost situation. Log mvb 115 and see what your boost profile looks like and that will give you a better Idea of what's going on.

From what I understand, P1557 is actually an underboost code just listed wrong? P1555 is the actual overboost? I will log with ME7 logger if it will help.

Sorry about that I posted when I was still laying in bed and I admit I didn't read it...

So deviation is from boost pressure either being too high or too low. This is going to be key in finding your issue. You need to know is it too high or is it too low. What's your boost gauge telling you? Log your boost with vcds. You'll log requested boost, specified boost, and engine speed. Can't remember the block but you will just find them with advanced measuring blocks.

Too much boost is going to pointing to something wastegate, wg line, n75, or compressor line (opens wastegate) related. Too little doesn't rule out the above, but it also points to charge hoses, intake, etc.

How did you pressure test?

To pressure test, I disconnected the pancake valve on the side of the Y pipe, plugged it. Disconnected intake pipe, and attached the tester directly to the end of the Y pipe. Slowly regulated the pressure up until I heard leaks / heard no leaks. The first time I forgot to remove the oil cap and it pushed the cam seal out but after reinstalling and testing again with the oil cap off, I could no longer hear any leaks.

Thanks for all the input.

[vavJETTAw36]

I thought you didn't have to pull the oil cap if you were capping off the pancake? How would the pressure pass through the TB butterfly?

How much pressure did you use? What's your source for air?


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[phila_dot]

Same guy on the Daz base file?

I'm pretty sure it's your MAF calibration, the ECU is calculating airflow higher than actual which causes you to run rich and it inflates load so boost diagnosis activates when it shouldn't (part throttle/early on while spooling).

[Monty23]

I thought you didn't have to pull the oil cap if you were capping off the pancake? How would the pressure pass through the TB butterfly?

How much pressure did you use? What's your source for air?


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The butterfly is a very good restriction, but its hardly leak tight. Static pressure during a pressure test will leak past the butterfly and begin to pressurize the intake manifold and flow through any open valves in the head and pressurize the crankcase (pressure in the crankcase will be dependent on the pressure drops throughout the system, mainly at the throttle).

[Corradovolksb]

Another thing I just thought about is that if your still on a base tune the LDRXN could be requesting boost sooner than the boost can be built by the K24s causing the p1557. Just a thought. Like phila_dot said your Maf or injector calibration could be off too.

[axnjaksn]

interesting cuz I had/have been chasing these types of numbers myself, with this code still being thrown, I have a brand used (new oem remanufactured audi maf) and also and aftermarket new maf that give me totally completely different values and driveability concerns. I do have srm k24's/rs6, my aftermarket maf the short terms show +- 2% at idle and +- 5-10% on the part throttle. My new reman oem throws the idle a slight difference but the part throttle is banging on the +-20% ceiling. I have had an abundance of leaks, however im certain they are all fixed, buuuuut, this weekend im going to go over it and daaable-check all my connections, attempt to find a used good old hitachi (tuner has also had bad luck with newer oem maf's)

I also have apr bipipe, r1's, samco hoses, awe ic's with shrouds, the works as far as bolt ons go, I also ordered new check valves, made my own brake booster hose with a green check valve, my only real thought is my pancake valve and booster hose, still using the old school slide and click lock may not be sealing as well as a hose with clamp would, that's what im aiming to change this weekend. then after that idk, tuner said the MAF is already scaled waaaay back but I really have nowhere else to look. my car makes and holds 22 psi with out any issues, no fluttering of boost when in full boost. I kinda figured if it had a substantial leak that something like this would be felt.

ive been getting weird surging too under part throttle cruising (aka 0 psi on boost gauge) or right around 3k rpms (under light acceleration), another forum member on here suggested I log and post it on nefmoto and see what the community thinks. this is of course my next step if all looks good, again, leak-wise and IF I get my hands on another MAF and have the same issues.

ps the part that keeps getting me, my car drove fine, no codes and then I upgraded my turbos, and drove around for a couple weeks with stock MAF housing, stock injectors, giac x chipped ecu, had no issues or concerns other than the right rear o2 code I was getting since my wideband was wired in through the factory plugs, no charge pressure codes, no weird driveability concerns, all seemed fine I didn't dip my foot into it too much seeing as how the stock fueling and tuning was in place, but all seemed good.

sorry for the long post, your not alone....im subscribed to this so I can follow and hopefully we both can figure this out!!!

[erykv1]

I thought you didn't have to pull the oil cap if you were capping off the pancake? How would the pressure pass through the TB butterfly?

How much pressure did you use? What's your source for air?
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Home made pressure tester with a shut off valve as well as an in-line regulator that allows me to slowly increase / decrease flow as needed. Tested to 15psi.

Same guy on the Daz base file?

I'm pretty sure it's your MAF calibration, the ECU is calculating airflow higher than actual which causes you to run rich and it inflates load so boost diagnosis activates when it shouldn't (part throttle/early on while spooling).

Yep! lol. I agree with everything you've said. After I rule out the green check valves I will know if its 100% tune related or not.

Another thing I just thought about is that if your still on a base tune the LDRXN could be requesting boost sooner than the boost can be built by the K24s causing the p1557. Just a thought. Like phila_dot said your Maf or injector calibration could be off too.

I had this exact same thought with regards to the LDRXN, this would occur if if the ramp map is set to a k03/k04 map as it would be expecting more boost at certain RPMs than what the k24's can deliver.

interesting cuz I had/have been chasing these types of numbers myself, with this code still being thrown, I have a brand used (new oem remanufactured audi maf) and also and aftermarket new maf that give me totally completely different values and driveability concerns. I do have srm k24's/rs6, my aftermarket maf the short terms show +- 2% at idle and +- 5-10% on the part throttle. My new reman oem throws the idle a slight difference but the part throttle is banging on the +-20% ceiling. I have had an abundance of leaks, however im certain they are all fixed, buuuuut, this weekend im going to go over it and daaable-check all my connections, attempt to find a used good old hitachi (tuner has also had bad luck with newer oem maf's)

I also have apr bipipe, r1's, samco hoses, awe ic's with shrouds, the works as far as bolt ons go, I also ordered new check valves, made my own brake booster hose with a green check valve, my only real thought is my pancake valve and booster hose, still using the old school slide and click lock may not be sealing as well as a hose with clamp would, that's what im aiming to change this weekend. then after that idk, tuner said the MAF is already scaled waaaay back but I really have nowhere else to look. my car makes and holds 22 psi with out any issues, no fluttering of boost when in full boost. I kinda figured if it had a substantial leak that something like this would be felt.

ive been getting weird surging too under part throttle cruising (aka 0 psi on boost gauge) or right around 3k rpms (under light acceleration), another forum member on here suggested I log and post it on nefmoto and see what the community thinks. this is of course my next step if all looks good, again, leak-wise and IF I get my hands on another MAF and have the same issues.

ps the part that keeps getting me, my car drove fine, no codes and then I upgraded my turbos, and drove around for a couple weeks with stock MAF housing, stock injectors, giac x chipped ecu, had no issues or concerns other than the right rear o2 code I was getting since my wideband was wired in through the factory plugs, no charge pressure codes, no weird driveability concerns, all seemed fine I didn't dip my foot into it too much seeing as how the stock fueling and tuning was in place, but all seemed good.

sorry for the long post, your not alone....im subscribed to this so I can follow and hopefully we both can figure this out!!!

I've done everything you've mentioned. I was also told new MAF's were not the preferred method to go (even if OEM). I have tested out 2 other known good used MAF's from other stage 3 daily driven S4's to no avail. Our cars don't seem too far off mod wise.

Did those green check valves help at all? I have also thought that there could possibly be a leak POST throttle body (ie intake manifold gaskets or something)

As for your part throttle crusing. I am experiencing this as well. It feels like its hitting a fuel cut to me, but I think its due to my injector pulse widths being off / still need to be dialed in. I am on 630cc injectors and a bosch 044 pump.

When you wire in your wideband, you just need to tap the 0-5V signal wire into pin #69 of the ecu box. I don't have any rear O2's hooked up and it doesnt throw any codes.

[axnjaksn]

I actually wired it in a way I was instructed too, lear70 had a good write up that was given to me to follow, I don't get the check engine light with the stage 3 setup, just any other ecu that doesn't have the rears coded out. I also have walbro 450 pump and ev14 60#'s. I cant tell if its a cut of some kind or what, but it definitely feels like someone yanking the ebrake and letting off, very weird. however I hammer the gas pedal and she rips really nasty to redline.

check valves will probably be this weekend, unless they arrive sooner than later. I will let you know.

[Corradovolksb]

Have you talked with Daz about your symptoms? If your on a base file you have a lot more revisions to do

[erykv1]

I actually wired it in a way I was instructed too, lear70 had a good write up that was given to me to follow, I don't get the check engine light with the stage 3 setup, just any other ecu that doesn't have the rears coded out. I also have walbro 450 pump and ev14 60#'s. I cant tell if its a cut of some kind or what, but it definitely feels like someone yanking the ebrake and letting off, very weird. however I hammer the gas pedal and she rips really nasty to redline.

check valves will probably be this weekend, unless they arrive sooner than later. I will let you know.

Gotcha. I read your initial post about the wideband hookup wrong. There are a few different ways to hook it up. Directly tapping into the ECU is cleanest. Hooking it up from the o2 harness yields the same end result.

My green check valves come this weekend as well! I just hope I can find the right clamps for it. I believe one side is larger than the other. From the factory they use oetiker clamps.

Have you talked with Daz about your symptoms? If your on a base file you have a lot more revisions to do

I have been in contact with him, he was pretty sure there was a leak somewhere. My next check in will be after I replace the check valves to see if there are any improvements. Just wanted to see if anyone else had input on maybe something simple we could have missed. I just dont know if those check valves would cause such a large deviation in my trims.

[Corradovolksb]

Ok cool just checking. The check valves can cause some strange things sometimes. Make sure to drive at least 10miles at highway speeds after you replace them to make sure your fuel trims have enough time to stabilize.

[erykv1]

Ok cool just checking. The check valves can cause some strange things sometimes. Make sure to drive at least 10miles at highway speeds after you replace them to make sure your fuel trims have enough time to stabilize.

thanks for your time & input. I will check back in after this weekend.

[Corradovolksb]

Any time.

[axnjaksn]

lemme ask this question pertaining to these oddball driveability concerns and values going way out, back before stage 3, when my car was just all the bolts ons and GIAC x chip.... I had leaks in hoses and boost lines before, they never caused the issues im feeling now.......how come they never made the car feel like it does now?? is the stage 3 software and hacks for 3 bar maps much more sensitive?? or is the leak much larger than I think?? I hold wastegate pressure till redline with no flutter or break in boost once its there, nor does my car show any lack of confidence in building boost. when the k03's were on the car, the way I found out I had a boost leak is my max boost was less and would not hold constant.......

just looking for more info to help me better understand.... thanks in advance

[axnjaksn]

ok, so i drove my car to SD for the weekend, have yet to change the green check valves, car doing the funny dragging/surging while im cruising, on and off of course, the whole way down. I read somewhere that our cars use the n249 and vacuum reservoirs and THE FORCE to actuate the dv's, so as to simulate an N/A engine at lower rpms and help with turbo lag....is this true??if so i have bypassed the valve before , just literally run a hose to bypass and cap off the other one, made no difference. do those green check valves play a part in any of this??

ok im losing my brain, supposed to be taking my wife out for her birthday and while she is getting ready im on the laptop and looking for answers hahaha

[airjawed]

At idle the diverter valves are supposed to be open so that air going into engine is not running through the turbos and getting restricted at low rpm. The diverters also relieve pressure when the car goes from boost to closed throttle plate in order to prevent damage to turbos. There are some one way valves so that vacuum is always available for the n249... either from the manifold or from the vacuum reservoir in the driver fender.

[julex]

answer was already given by phila_dot. In the instance when everything is stock, you should chase mechanical issues only (leak, bad maf, etc) but when tune is involved, then mechanical and then yell at your tuner to get his maf flow maps straight as well as injector flow and dead times right.

[erykv1]

Update from this weekend. New green check valves arrived and installed.

Reset codes and drove about 50 miles. Idle fuel trims right back at 6%.

Checked the spider hose as well and the check valves on it. All in good working order.

About to remove these 034 DVs and replace with some 710s even though they tested fine. Perhaps the spring has weakened over time.

I may also try a 4th maf sensor... But the chances of 3 in a row seems very slim to me.

Really not sure what it could be anymore unless it's tune related which Daz has said it isn't.

[jaychen]

I'd listen to phila_dot.

[erykv1]

I'd listen to phila_dot.

He knows his stuff for sure, I'm not discounting anything he said.
I just wanted to make sure that all possibilities of a hardware related issue is eliminated.

[axnjaksn]

having the exact same issue, im sure philadot is right as well as julex, FRUSTRATING!!!!

[axnjaksn]

im wouldnt mind posting my logs or file and getting a second opinion

[S4lifeXx]

Have you looked into your maf wiring, any pinched lines or sitting to upright and hitting hood. Surging definitely sounds maf related!

[erykv1]

Here are my latest readings on block 032... Daz is pretty sure I still have a leak somewhere due to the idle trims.

I'm at a loss as to what it can be. I've pressure tested more times than I can count.

Maybe I need to purchase a 4th maf? Lol.

[Corradovolksb]

A good way to make sure it's not a leak in your Pcv system or your Evap system is to remove all of the vacuum lines to the intake manifold except for the brake booster line and disconnect the pancake valve to the ypipe and cap that off at the ypipe and let it vent to atmosphere. Then go for a drive without clearing the fault memory and drive it for 5miles or so at a constant cruise. If your values don't change you eather have a leak in your charge system from Maf to the throttle body or its tuning related. That will eliminate all vacuum and Pcv sources. I have yet to see a brake booster cause an issue like this but there is always a first time for everything.

[frankwizzle]

Have you tried simply unplugging the maf? That way it will adapt to the map sensor and o2s.
Though it sounds like you have a leak or possibly an issue with the n75.
http://wiki.ross-tech.com/wiki/index...5/P1557/005463

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[erykv1]

A good way to make sure it's not a leak in your Pcv system or your Evap system is to remove all of the vacuum lines to the intake manifold except for the brake booster line and disconnect the pancake valve to the ypipe and cap that off at the ypipe and let it vent to atmosphere. Then go for a drive without clearing the fault memory and drive it for 5miles or so at a constant cruise. If your values don't change you eather have a leak in your charge system from Maf to the throttle body or its tuning related. That will eliminate all vacuum and Pcv sources. I have yet to see a brake booster cause an issue like this but there is always a first time for everything.

I will try this this weekend. Thanks for the suggestion.
Is it possible for it to leak thru the dipstick? Lol. I replaced the oil cap a few months ago (so thats ruled out) for good measure along with resealing the whole engine.

Have you tried simply unplugging the maf? That way it will adapt to the map sensor and o2s.
Though it sounds like you have a leak or possibly an issue with the n75.
http://wiki.ross-tech.com/wiki/index...5/P1557/005463

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I may be mistaken, but when the MAF is unplugged... doesnt the car run on a speed density map? Either way, a bad N75 shouldnt cause idle trims this high correct?

I know I have a leak (as per what the idle trims are saying) I just can't seem to find it. All the common points have yielded dead ends :(

[Corradovolksb]

Trims won't adjust with Maf unplugged.

[frankwizzle]

Trims won't adjust with Maf unplugged.

Not true. I was mistakenly running a waaay too large maf and my trims were lean as hell. I kept it unplugged while waiting for my 85mm maf to come in and trims settled down. I did have to reset the trims first though.

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[Corradovolksb]

They settled down because they where not adjusting. your injectors are scaled correctly and the ECM was using the limp mode maps for fueling.

[frankwizzle]

It really depends on the tune. Since OP is running a daz tune he could run with the maf unplugged indefinitely. I was just suggesting he unplug it to try to rule out the possibility of a bad maf.

[erykv1]

Can a leaky DV be causing these idle trims? What are the proper ranges for the idle trims? Im hearing +/-2, or +/-4, what is the allowable variation?

[Corradovolksb]

Yes it can if its leaking vacuum but it prob wouldn't cause your long term trims to be subtracting fuel. Short term trims should be +- 5% and long term +-10% are factory specs.