I need the correct : P0171 Engine Diagnostic Parameters for my 2003 Audi A4 1.8T

[DanTexas]

I need the correct : P0171 Engine Diagnostic Parameters (PIDs) for my 2003 Audi A4 1.8T. If you can also tell me a good Website for finding PID Parameters for different cars it would also be great.

Thanks!!!

Dan

[walky_talky20]

Not sure what, exactly, you are looking for, but this is what I can tell you:

P0171 / 16555 = Fuel Trim, Bank1: System too Lean

This is almost always caused by a dirty or faulty Mass AirFlow sensor (MAF), but can sometimes be caused by other faults, like 'false air'. I would start by looking at the Long Term Fuel Trim (LTFT) data in the ECU. This is in measuring block 032. No need to log it, just turn the key on and read that block. The data is lost if you clear the codes, so always check the trims first. You will get 2 values: idle/additive and part throttle/multiplicative. Both are important to identifying where your issue lies. Specifically, the relationship between them will help you narrow down which failure type is most likely (ie: MAF or something else).

Assuming the fuel trims point toward a possible MAF issue, the next step is to data log the MAF value on a 3rd gear, wide open throttle pull from 1500 rpm to red line.

[DanTexas]

My Actron Auto Scanner Plus displays the code and gives you an idea on what to replace. I just installed a new MAF today and also found out my little $125 Scanner displays more data (No Graphs), so I'm trying to learn more about Diagnostic's in this process. (I did attend Auto Repair School but, I just took a couple courses).

The "Freeze Data" shows:

Trouble Code P0171
ENG Speed (RPM) 920
CALC Load 14.1
Coolant(F) 199
ST FTRM1 25.0
LT FTRM1 3.9
VEH Speed(MPH) 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A

Should the new MAF solve this problem or do I possibly have leaking Fuel Injectors? I did do a Boost Test with the PVC connection I found on the Forum and I didn't have any Air Leaks.

Thanks for your help!

-D

[diagnosticator]

PM sent.

[old guy]

The "Freeze Data" shows:

Trouble Code P0171 Fuel Trim Bank 1: System Too Lean

ST FTRM1 25.0 Short term or additive trim
LT FTRM1 3.9 Long term or multiplicative trim

I did do a Boost Test with the PVC connection I found on the Forum and I didn't have any Air Leaks.

The additive trim is the adjustment the ECM makes with the engine at idle or very low load. The multicative trim is the adjustment being made to the base fueling map. Essentially an across the board adjustment. The maximum adjustment for either one is ±25°. Adjustments of ±5% are relatively common.

Your very high STFT (additive trim) indicates that you have a significant amount of "false" or non-metered air entering your intake somewhere after the MAF sensor.

If you performed a boost leak test and didn't find anything I suspect you probably have a leak in your block breathing system. If your PCV valve is functioning correctly it will "check" or stop the boost pressure at that point. Consequently any break in the block breathing hoses between the PCV / PRV and all the way to the TIP won't show up with the boost leak test.

Normally the block purge air is being drawn from the TIP after being metered through the MAF sensor. If one of the block breather hoses are cracked/split/broken it will be a significant source of false air at idle since the air will be entering downstream of the MAF sensor. Once you start driving the % of air compared to the total volume of air is a lot less significant and thus the relatively low LTFT (multiplicative trim).

A really quick check is to simply clamp off the vacuum hose that connects the PCV valve to the intake manifold and watch the STFT at idle. If it immediately drops from +25% to single digits it will confirm that you have false air entering from somewhere in the block breather system. A very common break is at the "L" shaped hose under the intake manifold and above the oil filter housing that connects the PCV to the block breather.

[DanTexas]

After doing another Boost Test , I found the Lip of the "Suction Pump Purge Valve" was just barely leaking. I just ordered the part , along with the Hose Assembly. I hope this fixes my problem.

[old guy]

After doing another Boost Test , I found the Lip of the "Suction Pump Purge Valve" was just barely leaking. I just ordered the part , along with the Hose Assembly. I hope this fixes my problem.

That is definitely something that you want to address before the SJP blows apart. But I really don't think that is causing your P0171. You have a fairly significant leak to cause the STFT to add 25% to the fuel map.

Try clamping the vacuum hose to the PCV valve as I suggested previously and see what happens to the STFT. You can even pinch the hose by hand (if you don't have arthritic fingers like me) and see if the STFT drops.

[DanTexas]

My Scanner doesn't have live datahttps://actron.com/content/obd-ii-auto-scanner-plus , I have to drive a full drive cycle before I can get information. Today , I got another P0171 code and below is all the all the data I can find on my Actron CP9580A Scanner. Take in mind, this is after I replaced my MAF sensor and glued the small leak on my "Suction Pump Purge Valve"(I did order a new one). I also about two months ago changed many parts including a new head from china. This is the link showing those repairshttp://www.audizine.com/forum/showth...ng-rough/page2

FREEZE DATA
Trouble Code P0171
ENG Speed (RPM) 840
CALC Load 24.3
Coolant(F) 199
ST FTRM1 1.6
LT FTRM1 -0.8
VEH Speed(MPH) 0
FUEL SYS 1 CLSD
FUEL SYS 2 N/A

O2 Monitor Tests
O2 Bank1 Sensor1

Test $81
MOD $10
MAX 255
MEAS 128
MIN 90

Test $82
MOD $10
MAX 255
MEAS 98
MIN 90

Test $83
MOD $10
MAX 205
MEAS 82
MIN 36

Test $84
MOD $10
MAX 180
MEAS 124
MIN 76

O2 Bank1 Sensor2

RICH-LN Thresh
MOD $10
MAX -----(V)
MEAS 0.575(V)
MIN -----(V)

LN-RICH Thresh
MOD $10
MAX -----(V)
MEAS 0.575(V)
MIN -----(V)

MIN V for CYCLE
MOD $10
MAX 0.565(V)
MEAS 0.000(V)
MIN 0.000(V)

MAX V for CYCLE
MOD $10
MAX 1.040(V)
MEAS 0.835(V)
MIN 0.590(V)

TEST $01 / TEST $03 / TEST $09
(Empty other than a $10)

TEST $05

ID 04
MOD $10
MAX ----
MEAS 8FF
MIN 8F6
STS OK

ID 11
MOD $10
MAX ----
MEAS 7D0
MIN 2B7
STS OK

MODULES PRESENT
$10 K@K*


Thanks Everyone for the your help , past and present.

-Dan

[old guy]

It's really hard to beat live data for troubleshooting problems. do you have an Android phone? If so, purchase the TorquePro app for $4.95 and pick up a cheap ELM 327 Bluetooth adaptor. This will allow you to view live data such as the STFT and LTFT. Then you can simply clamp off the various vacuum hoses and see in real time where you have a vacuum leak.

Have you inspected the block breather hoses that connect the PCV to the block for any cracks or splits?

[DanTexas]

It's really hard to beat live data for troubleshooting problems. do you have an Android phone? If so, purchase the TorquePro app for $4.95 and pick up a cheap ELM 327 Bluetooth adaptor. This will allow you to view live data such as the STFT and LTFT. Then you can simply clamp off the various vacuum hoses and see in real time where you have a vacuum leak.

Have you inspected the block breather hoses that connect the PCV to the block for any cracks or splits?

Yes, I have but I will re-check them again tomorrow. I have an IPhone 4 and a Lenovo Laptop with Windows 7, is there a good (Cheap)App/Or Program that displays "Live Data".

Is it possible this Code is from a Bad Fuel Filter or Fuel Injector Seals , I haven't replaced them yet....

[walky_talky20]

Yes. You want a "VAG KKL" usb cable from ebay, like this one:
http://www.ebay.com/itm/VAG-COM-KKL-...766554&vxp=mtr

Then download VCDS Lite from Ross-Tech.com (for free). This would be for the Lenovo unit, not the Apple.

This is the "hot setup" for reading codes and logging live data from VW/Audi vehicles, among many other functions. Capabilities are limited on the free version, but it should be plenty for this small problem you have now. Full unlock of all features is $99.

Old Guy is right on the money (as per usual!) with his suggestion of an a-sploded PCV system causing a large false air entry point that is not detectable during a boost leak test. There is a very high probability of that being the exact problem. There are also some other leak points. Watching live MAF value or STFT (or even listening closely to RPM) while pinching off various hoses coming off the manifold is a good place to start in order to find your leak.

I'm not certain why you've replaced your MAF already. We did not suggest you do that. Rather, we have so far only made suggestions to test and identify the problem first, before buying any parts. Good Luck.

[DanTexas]

Yes. You want a "VAG KKL" usb cable from ebay, like this one:
http://www.ebay.com/itm/VAG-COM-KKL-...766554&vxp=mtr

Then download VCDS Lite from Ross-Tech.com (for free). This would be for the Lenovo unit, not the Apple.

This is the "hot setup" for reading codes and logging live data from VW/Audi vehicles, among many other functions. Capabilities are limited on the free version, but it should be plenty for this small problem you have now. Full unlock of all features is $99.

Old Guy is right on the money (as per usual!) with his suggestion of an a-sploded PCV system causing a large false air entry point that is not detectable during a boost leak test. There is a very high probability of that being the exact problem. There are also some other leak points. Watching live MAF value or STFT (or even listening closely to RPM) while pinching off various hoses coming off the manifold is a good place to start in order to find your leak.

I'm not certain why you've replaced your MAF already. We did not suggest you do that. Rather, we have so far only made suggestions to test and identify the problem first, before buying any parts. Good Luck.

I just ordered the USB Interface Cable .I replaced the MAF because my Scanner showed that as the Top Reported Fix for P0171. Today I'm going to go through the whole PCY system, pinching off hoses and listening to the RPM's (That's a great idea).

Thanks!!

[DanTexas]

Today,

I found that I had installed the Check Valve to the right of the Purge Valve backwards and it was blocking Air Flow, I fixed that . I also found my Fuel Injectors hissing along with the engine bogging down when I poured a little water over the Seal areas , so I replaced all 8 Fuel Injector Seals. I also replaced the Suction Pump Purge Valve that I had ordered already. I hope these are the issues causing my P0171 code. I will give an update to see if the Code comes back after I drive a drive Cycle.

[DanTexas]

The additive trim is the adjustment the ECM makes with the engine at idle or very low load. The multicative trim is the adjustment being made to the base fueling map. Essentially an across the board adjustment. The maximum adjustment for either one is ±25°. Adjustments of ±5% are relatively common.

Your very high STFT (additive trim) indicates that you have a significant amount of "false" or non-metered air entering your intake somewhere after the MAF sensor.

If you performed a boost leak test and didn't find anything I suspect you probably have a leak in your block breathing system. If your PCV valve is functioning correctly it will "check" or stop the boost pressure at that point. Consequently any break in the block breathing hoses between the PCV / PRV and all the way to the TIP won't show up with the boost leak test.

Normally the block purge air is being drawn from the TIP after being metered through the MAF sensor. If one of the block breather hoses are cracked/split/broken it will be a significant source of false air at idle since the air will be entering downstream of the MAF sensor. Once you start driving the % of air compared to the total volume of air is a lot less significant and thus the relatively low LTFT (multiplicative trim).

A really quick check is to simply clamp off the vacuum hose that connects the PCV valve to the intake manifold and watch the STFT at idle. If it immediately drops from +25% to single digits it will confirm that you have false air entering from somewhere in the block breather system. A very common break is at the "L" shaped hose under the intake manifold and above the oil filter housing that connects the PCV to the block breather.

I just paid for VCDS-Lite and I'm working on getting more data. This is what I have so far.

VCDS-Lite Version: Release 1.2
Wednesday, 17 February 2016, 19:08:15:29734


Chassis Type: 8E - Audi A4 B6
Scan: 01,02,03,08,09,0F,11,15,16,17,18,36,37,45,46,55,56 ,57,65,67,69,75,76,77

-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Controller: 8E0 909 518 AF
Component: 1.8L R4/5VT G 0001
Coding: 0016581
Shop #: WSC 63351
VCID: 749B2BF557A3
4 Faults Found:
17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 001 - Upper Limit Exceeded
17536 - Fuel Trim; Bank 1 (Mult): System too Lean
P1128 - 001 - Upper Limit Exceeded - Intermittent
17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 001 - Upper Limit Exceeded
17887 - Brake Boost Vacuum System: Mechanical Failure
P1479 - 008 - Implausible Signal - Intermittent
Readiness: 0000 1101

-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: 8E0-951-177.LBL
Controller: 8E0 951 177
Component: Innenraumueberw. 0604
Coding: 00001
Shop #: WSC 00000
VCID: EBA9B0898A9D
1 Fault Found:
01463 - Alarm triggered by Sensor for anti-theft alarm System
43-00 - Closed

End --------------------------------------------------------------------------------------------------

[old guy]

Have you perform the boost pressure leak test yet? All of your codes indicate a fairly large leak somewhere.

[DanTexas]

Have you perform the boost pressure leak test yet? All of your codes indicate a fairly large leak somewhere.

Yes, I did that a couple weeks ago and fixed everything(I cleared the Codes after, and did a full drive cycle),I also sprayed Carb cleaner on all of my Vacuum lines the other day an I didn't have any idle changes. I just did the Throttle Body Alignment (TBA) through VCDS. Are there any other adjustments I should perform on VCDS?

(Thanks old guy)

[old guy]

In post #3 you mentioned that you had a really high STFT. Is it still really high? If so have you clamped off your vacuum hoses one at a time at idle to see if you can read a change in the STFT?

[DanTexas]

In post #3 you mentioned that you had a really high STFT. Is it still really high? If so have you clamped off your vacuum hoses one at a time at idle to see if you can read a change in the STFT?

Is that Engine measuring Block 032 ?

[old guy]

Correct. Block 32 should show idle LTFT and partial LTFT. Block 33 will show the instantaneous STFT adjustment values.

Have to sign off now. Will check back in the morning.

[DanTexas]

[QUOTE=old guy;11410624]Correct. Block 32 should show STFT and LTFT.


The first block is 9.0% and the second is 3.9%

I just did a whole bunch of repairs including changing my Cylinder head. This link has a lot of that information. http://www.audizine.com/forum/showth...ng-rough/page2

[old guy]

I suspect you still have a vacuum leak somewhere. All of your DTC’s can be caused by vacuum issues. Possibly a leak in the PCV system. You mentioned a backward check valve. All of your check valves should permit air in one direction only. They should all flow toward the intake manifold with the exception of the one above the airbox. That one flows toward the TIP. Make sure they are all installed correctly.

Your LTFT at 3.9% is OK. Your STFT at +9% may not be OK. You need to monitor the STFT (additive trim) with the engine at idle. If everything is working properly the STFT should be bouncing above and below 0% add. A typical range would be ± 5%. If the STFT stays as an add and never goes below 0% that indicates that for some reason you’re ECM is constantly having to increase the fueling amount. It could be a vacuum leak. It could also be a faulty MAF sensor. I believe you already replaced yours. It could be low fuel pressure. Fuel pressure is controlled by the fuel filter. When was the last time yours was replaced?

P1297: This code occurs when your actual boost fails to meet the requested boost. Typically this is caused by either a defective DV or a faulty boost signal to the DV. Disconnect the vacuum/boost line that connects to the front of the intake manifold. This line runs from the intake manifold to the N249 valve located underneath the intake manifold and then to the DV. Use an air nozzle and apply about 20 psi to the vacuum/boost line. You should not be able to blow ANY air through the line. If you can blow through the line either the line is split or the DV needs to be replaced. It can also be caused by a boost hose leak anywhere between the turbo and the throttle valve.

P1128: This (multiplicative) code indicates that your ECM has to add fuel across the board. This can be caused by low fuel pressure (dirty or defective fuel filter). It can also be caused by a defective MAF sensor. Since you replaced yours it should be OK. It can be caused by unmetered air getting into the intake system. Again, check for leaks, especially in the TIP and PCV system. Another possibility is a defective wideband O2 sensor.

P1136: This (additive) code indicates that the ECM is has to add fuel at idle. We touched on this above in the discussion about STFT’s.

P1479: Since you have an automatic transmission you also have a vacuum pump to supplement the vacuum needed for the brake vacuum booster. This code can be caused by a defective pump or a vacuum leak that causes the pump to run excessively. A defective check valve or one installed incorrectly can be an issue. I suspect your issue is from vacuum loss rather than a defective pump.

[DanTexas]

Hello, Sorry for the late reply I have been out of town.

I just replaced my Fuel Filter about a month ago. I removed the DV and the N249 today and both are working correctly as well as no cracks in the hoses. I also sprayed Carb Spray at every single possible Vac line ,nothing changed the idle on the car. I'm going to try shooting 20 psi into the boost line as you suggested later today.

Which 02 Sensor is the "Wideband 02 Sensor" , the upstream or the downstream?

Thanks Again.

Dan

[old guy]

Upstream

[ZipMeUpJ]

Now I'm confused as to what a high LTFT means. I have the same code and my STFT bounces around depending on load but my LTFT remains above 20

[old guy]

Now I'm confused as to what a high LTFT means. I have the same code and my STFT bounces around depending on load but my LTFT remains above 20

A very high LTFT indicates that the ECM is constantly having to add fuel. It is typically caused by one of two things. Either a lot of false (un-metered) air is entering somewhere after the MAF sensor or the sensor itself isn't reading correctly.

Run a boost pressure test. Pay really close to the TIP when running the test. A split or crack in the TIP can cause an additive fuel trim without causing a boost leak so typically you won't feel any loss in performance but you will see high LTFT's. If nothing shows up then it's probably the MAF sensor is either dirty or defective. Check your MAF readings at idle, steady state driving at 60 mph as well as the maximum reading obtained around 6,000 rpm.

[DanTexas]

I just paid for VCDS-Lite and I'm working on getting more data. This is what I have so far.

VCDS-Lite Version: Release 1.2
Wednesday, 17 February 2016, 19:08:15:29734


Chassis Type: 8E - Audi A4 B6
Scan: 01,02,03,08,09,0F,11,15,16,17,18,36,37,45,46,55,56 ,57,65,67,69,75,76,77

-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Controller: 8E0 909 518 AF
Component: 1.8L R4/5VT G 0001
Coding: 0016581
Shop #: WSC 63351
VCID: 749B2BF557A3
4 Faults Found:
17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 001 - Upper Limit Exceeded
17536 - Fuel Trim; Bank 1 (Mult): System too Lean
P1128 - 001 - Upper Limit Exceeded - Intermittent
17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 001 - Upper Limit Exceeded
17887 - Brake Boost Vacuum System: Mechanical Failure
P1479 - 008 - Implausible Signal - Intermittent
Readiness: 0000 1101

-------------------------------------------------------------------------------
Address 45: Inter. Monitor Labels: 8E0-951-177.LBL
Controller: 8E0 951 177
Component: Innenraumueberw. 0604
Coding: 00001
Shop #: WSC 00000
VCID: EBA9B0898A9D
1 Fault Found:
01463 - Alarm triggered by Sensor for anti-theft alarm System
43-00 - Closed

End --------------------------------------------------------------------------------------------------

I took my car to a German Auto Repair place in Baton Rouge Louisiana and after two weeks of Master Techs and Techs looking at my Audi , they couldn't find anything wrong.But the car is stilling showing error codes. The Auto shop uses the Autologic Diagnostic System , is there a better system that can be used?

How much does Audi dealers charge for a Diagnostic?
Does the Computer need Tuned or something?

Any help would be super...

[old guy]

Those were the codes that you had back in February. If your engine is running reasonably well (no active misfires or blinking CEL) don't spend any more money having someone else look at your codes. Reset all codes with VCDS and drive it for a day or two and see which ones come back. Post them back up here and we can work through them. VCDS will give you the same basic information that you will get from the dealer or anyone else with diagnostic software. A good starting point.

[DanTexas]

I'm sorry for the late reply, I ended up taking my Audi to a repair place that Baton Rouge Audi recommended. The new shop says that the MAF (Air Flow Meter) is reading at 7 Grams and that the range is supposed to be 4-5 Grams. They think this should fix my problem. I hope it does...

[ZipMeUpJ]

So I took mt car to a local audi tech and had them run a boost leak test and a smoke test to check for vac leaks. The only thing they came up with was that my n80 was stuck open and the reason for my Evap leak. Ok.

I purchase a branch new n80 form the dealer (b7 version), install and car runs full boost for 20 minutes. P0171 is back (lean on bank 1).


I ran a couple tests myself again to narrow this down:

At idle
Vac 29.9Hg
Maf 2-2.5g
STFT - 7 to 6
LTFT still high at 22.0


Redline in 2nd gear reaching 60mph
Boost 5lbs
MAF read 60gs on several attempts
A few times I reached the 100s.
Several weeks ago I ran the same redline test and saw 120gs


Steady at 60mph
MAF reads 20gs.



It definitely has to be my Maf correct?

[ZipMeUpJ]

Also, not sure if this is of any indication, but unplugging my maf and driving around the block the LTFT was quickly correcting itself. I know when unplugged the ecu should go off the predefined mapping instead of the MAF readings.

I want to take it back to that shop and have them redo the boost/vac tests but I want to go back with hard data that they may have messed up or didn't do a thorough enough check, if that's the case here.

[ZipMeUpJ]

Bump

[old guy]

It's probably worth starting a whole new thread and define your symptoms. So far what you have described seems to indicate a defective mass air flow sensor. But if you are only seeing 5 pounds of boost you really aren't going to see much air flow. And I think your idle reading of 29.9 inHg probably isn't correct. I assume you meant 19.9.