Audi Repair Questions? Ask a Mechanic for Answers ASAP
Ok, let's go down the detailed code list again:
Sec.Air Inj.Sys.,Bank1 Flow too Low
P0455 16839 - EVAP system large leak detected
Now, from these and your pictures, it still sounds like you have a major vacuum problem, however without seeing the big picture, meaning a good detailed picture of your engine compartment with all covers off, it's still somewhat difficult to see if anything is out of place, and obviously it is, since all of the vacuum lines need a source and a component it works upon. There should be some vacuum solenoid valves that have an electrical connector and vacuum lines connected to them as well as a series of vacuum tees and check valves all over the rear part of the engine above the intake manifold. I would want to see these as well. Again, not trying to be a pain, but the 4.2 ART engine code is a fairly rare one, so memory doesn't serve very well in this case.
What exactly do you mean the vacuum doesn't hold at the LDP vacuum supply line.
Meaning, if you remove the vacuum hose that goes to the intake, and put a vac gauge on it, what happens?
Let me do a bit of thinking again, and I'll get back with you when I get into the shop
Still going to need more drive time before:
1) the monitor sets
2) and when it attempts to set, if there is a fault, determine if the sensor is on the same bank as the cat problem.
Usually O2 monitors are done on steady-state 60 mph/2300 rpm drives without a lot of throttle movement.
If you had a factory scan tool or vag-com, the test can be done within 5 minutes without the car moving anywhere.
Ok, first, the code list and descriptions
Evaporative Emission System Incorrect Purge Flow
Wow...this seems to be a cyclic problem, and it seems as though it's related to one.....*possibly* two problems. First thing to take care of the the 1141 and 441 codes. They may be related. Have you checked your EVAP purge valve? This valve lives on top of your airbox, and has a two wire harness connector with a rubber hose on each side of the valve. Remove this valve and see if a vacuum pump holds vacuum on either side of it.
Olle, you're absolutely right. I've got to admit, there's a lot of information that has gone back and forth here, and I overlooked my previous response.
I can't say for sure that this is the problem. This is especially true, since the purge valves can be finicky, meaning they can sometimes stick in the open position, but not always. This can be ambient temperature dependent as well. Still, it shouldn't pass any air either way if it's not energized.
I'm thinking that I'm starting to reach the end of my long-distance, through-the-computer screen diagnostic ability on this one. A problem like you're experiencing would be tough enough to tackle with the car right in front of me, and it's starting to get darn near impossible online.
I do appreciate the two accepts and the bonus you've previously authorized. Would you like me to see if I can opt out and possibly get another expert involved who may have a different strategy?
Thank You for choosing Just Answer for your query. Yes, I can help you.
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I previously owned an 02 A6 4.2 and work on MANY. First off I can see the intake manifold assembly has failed and requires replacement. In your photo I can see the two vacuum motors are stuck in the "activated" position. These control the intake runner lengths within the manifold. They should be deactivated when the vehicle is shut off and activated when you start the vehicle and idle. You can check and you will find both levers that go into the manifold are seized. This is very COMMON on the 2000 year model 4.2s only. I have replaced about 8, and only on the 2000s. They retail for about $1,800 and about 3 hours to replace.
The P0441 EVAP code is typically the purge control valve, I would just go ahead and change it as they often work intermittently.
I need to see the Measuring block #32 values. This needs to be scanned after running the vehicle for some time and BEFORE you clear any stored Diagnostic Trouble Codes (DTCs). When you clear the codes, it resets the fields to 0%.
P0432 - The catalyst has likely failed. I suggest you clear the code, correct the other conditions and see if it comes back, as other conditions can effect it, but typically not. Also, be sure to run premium grade fuels as required. Mid grade is OK once in awhile, but not regularly.
In your images I can not see the vacuum hose you have plugged. I see the two running from the left front of the head to the side of the vehicle, but I do not see the plugged one. There should be NO FREE vacuum hoses, so I must see which one is now "plugged". Can you send a image of the plugged hose, or at least of where the other end goes?
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Not sure I can afford a new manifold. What happens if I just lubricate and try to get the shafts and activators moving again?
Won't work, I've tried. You would have to take the manifold apart and clean and lubricate or replace the bushings. The bushings and seal are not avilable seperatly you would have to come up with your own solutions. I have taken them appart and looked into it, but it would be too time consuming for me to do so. If you had lots of time...
Does the manifold affect DTC?
Not typically, just performance and possibly MPG.
I ordered a purge valve as you recommended.
That usually takes care of it.
What is measuring block 32?
Fuel trim data. Here is an article I copied off of the Ross-tech site the leading aftermarket VW/Audi scanner company. Andy doe s a very good job of explaining trims and ch #32.
Fuel Trim Info
From Ross-Tech Wiki
Understanding Fuel Trim Some of the most common Fault Codes (DTC's) pertain to fuel trim (rich mixture, lean mixture, etc.) Here is an explanation of fuel trim and what it does for us. The ECU controls Air/Fuel mixture in order to maintain power, efficiency, and emissions. A/F is expressed as either a ratio (14.7:1 for example) or as a Lambda value. With iso-octane ("ideal" gasoline), Lambda of 1.0 is equal to 14.7:1 A/F. This is known as "Stoichiometric", a condition where there is a perfect balance between oxygen molecules and the various hydrogen and carbon based molecules in petroleum. With the oxygenated gasoline that most of us use, actual A/F ratio of 15:1 is closer to stoichiometric.If Lambda is greater than 1.0, then there is a surplus of air and the engine is running lean. If Lambda is less than 1.0, then there is a surplus of fuel and the engine is running rich. It should be noted that the ratios are mass-based, not volume-based. So, why don't we always run at 1.0 all the time? Well, we do MOST of the time. At cruise and idle, mixture is held tightly to 1.0 to keep the catalytic convertor at optimal efficiency, so the emissions are minimized. However, when we need acceleration, the mixture gets richer. Why? Maximum power is made between 0.85 to 0.95 Lambda (12.5 to 14.0 A/F with iso-octane). So, under acceleration, mixtures get richer. Sometimes you want to get even richer under acceleration to keep detonation (pre-ignition of the mixture from excess cylinder temperatures) away. The 1.8T has a relatively high compression ratio for a turbocharged engine, which especially under lots of boost, is very succeptible to detonation). So, now that we know that the ECU wants to be able to control the A/F ratio. It has a prescribed set of values (maps) for a given RPM, Load, etc. So, the ECU tells the injectors to pulse for exactly XX.X milliseconds and that SHOULD get us the proper A/F ratio that we want. Well, if you tell an employee to go do something, you want to make sure they actually did it, right? The ECU has some snitches (the front O2 sensor and the MAF, for the most part) that will report back whether or not the desired mixture has been attained. The rear O2 sensor is used mostly to monitor the condition of the catalytic convertor, although in some applications it also contributes to trim information. Based on feedback from the snitches, the ECU learns to apply a correction factor to its commands to the fuel injectors. If you know that your employees take longer than the standard allotted time to do a specified job, you will need to adjust for that in your planning (injectors are in a union, so it is tough to fire them ). The learned values go between the maps in the ECU's Flash ROM (the "chip") and the signal to the fuel injectors. These learned compensations are known as "trim". So, when you see "trim", it means "compensation". "Add" means additive trim, which is addressing an imbalance at idle. When the ECU is using additive trim, it is telling the injectors to stay open a fixed amount longer or shorter. The malfunction (e.g. vacuum leak) becomes less significant as RPM increase. For additive adaptation values, the injection timing is changed by a fixed amount. This value is not dependent on the basic injection timing. "Mult" mean multiplicative trim, which is addressing an imbalance at all engine speeds. The malfunction (e.g. clogged injector) becomes more severe at increased RPM. For multiplicative adaptation values, there is a percentage change in injection timing. This change is dependent on the basic injection timing. You can check your current state of trim by using VAG-COM or equivalent to look in Group 032 (in many modern ECU's, consult your Factory Repair Manual for the specific group for your particular vehicle) in your engine measuring blocks. The first two fields will have percentages. The first field tells the fuel trim at idle (Additive). The second field tells the fuel trim at elevated engine speeds (Multiplicative). Negative values indicate that the engine is running too rich and oxygen sensor control is therefore making it more lean by reducing the amount of time that the injectors are open. Positive values indicate that the engine is running too lean and oxygen sensor control is therefore making it richer by increasing the amount of time that the injectors are open. It is totally normal for both the first and second fields to be something other than zero. In fact, zeros IN BOTH FIELDS indicates that either you just cleared codes (which will reset fuel trim values) or something isn't working properly. If values get too far away from zero, it will cause a DTC (fault code) and can set off the MIL (commonly referred to as the Check Engine Light, or CEL). Specifications for normal operation are usually somewhere near +/- 10%. In general, an out-of-spec value in the first field (Additive) indicates a vacuum leak since it is mostly present at idle, when vacuum is highest. An out-of-spec value in the second field (Multiplicative) indicates a fault at higher RPM, and may point to a faulty MAF. Here's a good sanity check for the status of your MAF. Do a full-throttle run all the way to redline in a single gear (second works fine). Group 002 usually shows air mass in g/s (in many modern ECU's, consult your Factory Repair Manual for the specific group for your particular vehicle). Your peak airflow should be roughly 0.80 times your horsepower. So, if you have a stock 150 hp 1.8T, expect around 120 g/s. If you see significantly less than that, you MAF may be on the way out. This still works if you are chipped, but "race" programs may make more power through timing, rather than airflow. Therefore, take all readings with a grain of salt.
Andy 10:45, 26 January 2006 (Eastern Standard Time)
The plugged hose in the picture is the one of the two parallel ones in front of the engine left side. One goes to the reservoir and the other is plugged. They come from the T connections between manifold actuators solenoids and the hose going backwards towards the secondary air vacuum solenoid.
I do not have another 4.2 to look at right now. I need a better discription of exactly where the plugged hose comes from, or a picture of the hose (the end that is hooked up) to further assist you. If I get one in in the mean time I will let you know where it should go.
I have a 4.2 A6 scheduled in for the middle of the week and will check the vacuum line routing. If you can get back to me with that MVB #32 data it could be quite helpful on the #17549 DTC.
note: be sure NOT to take your MVB #32 readings after erasing the fault memory as this resets all fields to 0%.
Those are all within normal operating tolerance (+4.0% to -4.0%). I will look into the 17549 and the vacuum routing when the other 4.2 comes in and get back to you. If you monitor the ch# XXXXX reading periodically (without erasing the codes) and it goes out of tolerance range let me know.
Yes I received the picture, but it is unclear to me. I will check the "live" vehicle so I can be sure.
I looked at the 4.2 and the vacuum lines should be routed as follows;
The two lines coming from the left fender both run parallel to the front of the left cylinder head. They both pass behind the timing belt cover through the space between the cylinder head, block, and timing cover. They both "T" into the same vacuum line at the left front of the intake manifold. They are side by side( T T) into the same line. They T into the line that runs from the solenoid valve mounted on the fuel rail on the left rear of the motor. This valve when opened supplies vacuum to the combi valves for the secondary air injection. It is VERY common for this line to shrink and become disconnected causing a secondary air flow insufficient Diagnostic Trouble Code (DTC). The other end of the line (on the other side of both Ts) goes to the intake manifold, it's source vacuum. This is also the source for both solenoid valves that activate the "manifold plane" vacuum motors.
Let me know how this compares.
I did not understand by your previous posts that the line going to the fender was the one disconnected and plugged going towards the fender. I thought you were describing at the engine end of the line. I will look into it further, but in the mean time this should NOT effect any check engine light or storing of any codes so long as the source of vacuum (engine side) is plugged. It is likely a vacuum supply to the climate control or something? I am not sure. Only the 4.2 has the two lines here. Other models have only the one going to the reservoir. Have you removed the inner fender and inspected it?
I will also check into the #17549 your main point of contention I assume. This is not a common DTC, it will take a bit of "looking" into. Sorry if i can;t get to it ASAP, I will do what I can.
Sorry I typed out a response yesterday to the first reply and "lost" it and didn't get back to it.
I do not think the previous "O2 sensors not ready" would have anything to do with it. What?where was that message?
The 17549 is typically associated with the MAF, throttle body or vacuum leak. The thing is the MVB #32 values do not indicate any problem with any of those components. It would be a good idea to try a MAF if you ordered one. Be sure and check the #32 values periodically and definitely any time before clearing any DTCs.
I did run across something (not personnaly) on a 4.2 A8 where the tech disconnected the kick down switch on the throttle cable and the 17549 did not return. This being a 2000 year model (1st year) does it have a throttle cable? Or is it "Fly by wire" like the 2001<?
The 17549 is likely NOT associated with the plugged vacuum line as the vacuum (engine) side is plugged.
What type os VAG-COM do you have? You may be able to clear the DTCs, force the system to set readiness codes (all monitors pass), then get your certification ASAP.
There is ALLWAYS the possibility that the intake manifold is the cause of the 17549 as it is related to the load signal. Though I could not give you a factual specification link. It would be best if the manifold could be replaced and see if that cleared it. Possibly you could try moving the flaps all the way to one position or the other and seeing if either setting changes the DTC status.
Let me know how it goes.
Good deal! It was likely the MAF sensor.
Did you ever try moving the manifold flap positions?
Did you order a factory catalyst? I suggest you only use Original Equipment Manufacturer (OEM). If you use an aftermarket catalyst they tend to fail in short order. Sometimes less than on year.