have code 17544 Fuel Trim: bank 1 (add): System too lean, doing boost leak test!

**daverdfw** · 08-11-2012 11:58 AM

As the title displays, i have gotten this code a few weeks ago, cleared it, now its back, I have cleaned the MAF already, now today i do a boost leak test, and i still cant find a leak! I hear air rushing thru the Turbo, but i would assume I would still be able to hear a leak? What else can i look at for this?

**old guy** · 08-11-2012 12:50 PM

You should not hear air rushing through the turbo when performing a boost leak test. You should be able to build pressure and have it bleed down slowly. Sounds like you have a leak somewhere on the turbo side of the motor that needs to be corrected. A split in the TIP would sound like air releasing near the turbo and could be what you are hearing.

**daverdfw** · 08-11-2012 12:54 PM

hmm, i just hear air rushing into like the valve cover, a little air comes out from the oil cap when i remove it, is this normal?

**old guy** · 08-11-2012 12:56 PM

Since you have an '03 your PRV should be mounted on the back of the valve cover. Did you disconnect the line running from the TIP to the PRV and plug it before performing the pressure test?

**daverdfw** · 08-11-2012 12:57 PM

yeah i did, i plugged it with a cork, also there was another small hose in the TIP, i blocked it off as well. Should it be totally silent when injecting air into the system?

**old guy** · 08-11-2012 01:04 PM

Originally Posted by daverdfw

yeah i did, i plugged it with a cork, also there was another small hose in the TIP, i blocked it off as well. Should it be totally silent when injecting air into the system?

You will hear some air entering the block. Usually it will be a gurgling sound. Try the test again with the small hose hooked back up. That one runs to the SJP and provides a fresh air source for the vacuum amplifier portion of the SJP. You need to pressure test that one also. In fact there are two small connections to the TIP that should remain in place. The upper one goes to the SJP and the lower one goes to the Evap system.

**daverdfw** · 08-11-2012 01:05 PM

i did the test the first time with the small one still connected, i have inspected the SJP, when i looked up the carfax on this car, the dealer had repair the SAI system, i also always seem to smell a faint scent of burning oil after i drive the car also.

The 3 way valve next to the SJP was missing hose clamps, i replaced those, and cleared codes, and they still came back. Thanks for the help!

**old guy** · 08-11-2012 01:10 PM

The burning oil smell could be from the valve cover gasket. Unfortunately it is a common failure point. If yours has never been replaced it is probably due. It usually starts leaking on the exhaust manifold side since that is where the cover sees the largest temperature extremes. It's kinda hard to spot the leak because of all the heat shielding on that side.

Are you experiencing any performance issues that go along with the code or are you just getting a CEL?

**daverdfw** · 08-11-2012 01:12 PM

i also noticed the rubber seal on my oil cap is breaking apart as well, well since I just bought this car in May, i am not sure what is "normal" or not, i dont experience and misfires, or anything like i that. I did log vag-com and say 8-10PSI boost, which is guess is normal for a stock 1.8T. I also just looked at block 002 and measured my MAF, and from everything i am seeing, it "looks" normal.

**old guy** · 08-11-2012 01:20 PM

The oil cap needs to seal completely. The block ventilation system is controlled on either end by the PRV on the back of the valve cover and the PCV valve on the lower block just above the oil filter. The PRV regulates the amount of air entering the block when the PCV pulls vacuum on the block. A faulty seal on the oil cap could be letting excessive air through the block breathing system and cause a lean condition when under vacuum.

The code you are experiencing is an additive code. That means the problem is probably occurring at idle and the ECM is having to add fuel. A multiplicative code would mean the ECM is adding fuel across the whole RPM range and indicates a different type of problem. You need to be looking for something that is adding a small amount of air at idle.

Another possibility is a faulty N80 Evap control valve. If it sticks open it will add extra air at idle and can cause an additive code.

**daverdfw** · 08-11-2012 01:23 PM

so I guess the first and easiest thing to do is fix the oil cap, reset codes, then look at the N80 valve as well. Ill head down this path, and report back, thanks for your time and expertise!

**daverdfw** · 08-11-2012 01:35 PM

here is a pic of my oil cap

and the back of my valve cover, i see a small amount of oil, but not sure if its enough to cause my smell. or if its the Oil Cap burning the oil.

**old guy** · 08-11-2012 01:39 PM

Oil cap very well may be what's causing the lean code. Definitely start there. That doesn't look like enough oil on the back side of the valve cover to cause an issue. If the oil cap doesn't cure the smell take a very close look along the turbo side of the valve cover.

Good luck!

**daverdfw** · 08-11-2012 01:41 PM

going to order the oil cap now, thanks again!

**daverdfw** · 08-20-2012 12:08 PM

got the oil cap today, should i reset the check engine light or will it go off if the condition is corrected?

**daverdfw** · 08-20-2012 07:16 PM

well the oil cap didnt help with the check engine light, it came right back. I have a small check valve nearest the firewall that looks like its breaking apart, but when i did my boost leak test, it didnt seem to leak , but i am thinking of just replacing them all anyway. This texas heat does a # on these cars in the summer.

**daverdfw** · 08-20-2012 08:04 PM

so i did the n80 070 test, and i heard it clicking, could it possibly still be bad? would i test by taking it off and blowing air thru it and seeing if it leaks?

**daverdfw** · 08-20-2012 08:23 PM

so strange, before the test i had the engine idle for like 5 minutes, never heard or felt the N80 click, then i ran the 070 test, it clicked, let the car idle, and heard it clicking on its own. Could the 070 maybe have given it the kick in pants it needed? or is it faulty?

**old guy** · 08-21-2012 02:41 AM

Typically you will hear the N80 clicking continually after the car has been started and running for a minute or two. Yours sounds normal. If you are hearing air "rushing" into the valve cover you probably have a back check valve somewhere. The reason you don't hear an external leak is because the leak is internal to the valve. In other words it's leaking back into the block.

Here's how you check: Get a Lisle hose clamp or similar:Clicky click. Perform your boost leak test with the oil cap off. Use the clamp to methodically clamp off the vacuum lines connected to the intake manifold one at a time until you find the one that is leaking internally. Trace the hose from the manifold to its source. When you get to a check valve clamp on the other side of the valve. If the internal leak stops replace the valve.

**daverdfw** · 08-21-2012 07:51 AM

looks like that will be my next test, i am kinda interested in why the N80 wasnt clicking before i did the 070 test, and now it is. Maybe i got lucky and kinda "kick started it" working? I will see if the check engine light comes back, but i probably need to replace the check valve that comes off of the 3 way check valve behind the jet suction pump, its kinda broken along the spine, although i didnt hear air coming from you.

one last thing, when doing the boost leak test, on a working system, it should be almost silent? thanks again!

**old guy** · 08-21-2012 10:24 AM

The N80 duty cycle has a delay when you first cold start the car. Was that the case for you?

The three way check valve could be your problem. The side port of the 3-way valve is on the “checked” side of the check valve. In other words if the check valve is still working you will not hear a leak. The check valve will do its job. But once you start pulling vacuum through the valve the split will allow air into the line instead of pulling a vacuum on the vacuum canister and will allow excess air into the manifold at idle.

**daverdfw** · 08-21-2012 11:20 AM

the N80 never clicked after letting the car idle for like 5-10 minutes, until i did the 070 test, then when i start it again, i heard it. As for the valve, there is a pic in a thread on here, its the 2 way check valve that is attached to the 3 way that comes off of the suction jet pump. its kinda hard to get to. When i feel the back of the 2 way vavle, the spine around the middle is broken off, like the heat got to it, but i couldnt find a hole or leak in it. But wondering if its damaged internally. All of the other check valves "look" ok. Not sure if that valve being broke would lead to the air sound i hear when i do the test. But i am planning on getting those hose pinchers and trying that route as well.

**old guy** · 08-21-2012 12:47 PM

Sounds like your N80 was stuck and you freed it up.

Not sure which valve you are referring to. Mayvbe you can point it out in this thread: Clicky click. The two way valves have a stud on the side where the mold is blocked off from producing the three way valve. Is that what you are feeling?

**daverdfw** · 08-21-2012 12:55 PM

its #50 and when looking at it, its like the ridged part in the middle was burnt or breaking off, that spine that runs along the entire diamater of it.

**old guy** · 08-21-2012 01:35 PM

That check valve provides vacuum for the vacuum canister and operates the N112 and N249 valves underneath the intake manifold. If the valve body is cracked on the vacuum canister side and the internal check valve is working you will not hear anything during a pressure test since the check valve will do its job and stop the pressure from going past it. However, once vacuum is applied from the intake manifold the check valve will open and extra air will enter through the cracked valve body.

Start the car and let it idle. Feel the valve body to see if the cracked portion is sucking in air. You can also check it by clamping the hose in front of the valve body and see if it makes a difference in the idle speed.

**daverdfw** · 08-21-2012 01:42 PM

what side of the valve is the vacuum canister? i know these valves only are suppposed to work in 1 direction correct?

**old guy** · 08-21-2012 01:56 PM

Originally Posted by daverdfw

what side of the valve is the vacuum canister? i know these valves only are suppposed to work in 1 direction correct?

Correct. All check valves will flow air toward the vacuum source (manifold) only. The vacuum canister is located underneath the drivers side front fender. If you trace the hoses on either side of the valve you will find that one way leads to the intake manifold and the other way leads to the N249/N112 and vacuum canister.

**daverdfw** · 08-21-2012 03:12 PM

ok, so i got that clamp tool, waiting for the check engine light to come back on first, i have checked 2 time now after starting the car and i can hear/feel the N80 working, It definitely was not working before, the car even feels like it doesnt lag like it used to when driving, on the bottom end when you get on the gas, maybe its a placebo effect, or maybe the N80 affects that?

**old guy** · 08-21-2012 03:19 PM

Originally Posted by daverdfw

ok, so i got that clamp tool, waiting for the check engine light to come back on first, i have checked 2 time now after starting the car and i can hear/feel the N80 working, It definitely was not working before, the car even feels like it doesnt lag like it used to when driving, on the bottom end when you get on the gas, maybe its a placebo effect, or maybe the N80 affects that?

I would be surprised if the N80 would make a noticeable difference in the performance while driving. It can screw up the idle air for sure but once you get moving the amount of air that it controls becomes pretty insignificant as compared to the total volume of air being consumed.

**daverdfw** · 08-21-2012 03:20 PM

ok, maybe placebo effect :) thats ok, thanks for your help, i really appreciate it. Ill update if i get the MIL light so hopefully it can help someone else.

**daverdfw** · 08-22-2012 06:38 AM

Well the light came back on today. Getting frustrated with this. Guess I will try clamping things off.

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**daverdfw** · 08-22-2012 08:34 AM

well the fun continues, just got this code to go along with the orig one

17519 - Oxygen (Lambda) Sensor Regulation: Bank 1: System too Lean
P1111 - 002 - Lower Limit Exceeded - Intermittent

So could both codes be related to a flaky pre-cat O2 sensor?

**boy412** · 08-24-2012 06:41 AM

Strangely enough I am getting this lean code today as well. I am suspecting the pre-cat O2 sensor as well, since I am getting an intermittent P0130 code in addition to the P1136. I'm a bit annoyed since the pre-cat sensor is still relatively new. I'm going to order up a replacement regardless.

As always, props to OG for the thorough troubleshooting advice!

**Gordon804** · 08-24-2012 07:47 AM

Originally Posted by daverdfw

As the title displays, i have gotten this code a few weeks ago, cleared it, now its back, I have cleaned the MAF already, now today i do a boost leak test, and i still cant find a leak! I hear air rushing thru the Turbo, but i would assume I would still be able to hear a leak? What else can i look at for this?

Hi, I've just resolved my issues with this code along with high rpm at idle and pressure leak between throttle body and turbo. These codes came on one by one over a period of a few weeks. In my case I changed the crankcase breather and regulating valve. Quite a common error. I didn't have any visible cracks etc. Do you idle high?

**daverdfw** · 08-24-2012 12:27 PM

Originally Posted by Gordon804

Hi, I've just resolved my issues with this code along with high rpm at idle and pressure leak between throttle body and turbo. These codes came on one by one over a period of a few weeks. In my case I changed the crankcase breather and regulating valve. Quite a common error. I didn't have any visible cracks etc. Do you idle high?

what is considered a high idle? and do you have a pic or part # of the pieces you replaced?

**old guy** · 08-24-2012 02:19 PM

Originally Posted by daverdfw

what is considered a high idle? and do you have a pic or part # of the pieces you replaced?

Damn this has been one long week....Sorry for the delayed response. Gordon replace his PCV and PRV valve. Some of the crankcase breather parts Gordon replaced are different than what is on your car. His is a 2004. The 2003 model made a change mid-year and another change occurred in the 2004 model. Here is an excellent reference for the different parts. Clicky click If you have a breather problem clamping off the hose that supplies the vacuum source to the lower block breather will probably make a noticeable difference ion the idle speed.

Have you tried that exercise yet? Another indicator of a defective PCV valve is when you get a strong vacuum pull when you remove the oil filler cap with the car at idle. You may find this thread helpful when you are attempting to diagnose a vacuum related problem. Clicky click

**daverdfw** · 08-24-2012 04:10 PM

i tried pulling the oil cap while engine is running and there wasn't any suction, but i see this valve goes bad often? http://www.ecstuning.com/ES279955/

I will see if i can take a look at it.

**old guy** · 08-24-2012 04:41 PM

Originally Posted by daverdfw

i tried pulling the oil cap while engine is running and there wasn't any suction, but i see this valve goes bad often? http://www.ecstuning.com/ES279955/

I will see if i can take a look at it.

If you have a late 2003 you have that PCV valve. Do you have a small vent line coming off the back of the valve cover just to the drivers side of the PRV? If so, you have that valve. The small vent line attaches to the side port of that PCV. If you do not have the small vent on the valve cover you have an early 2003 and use the PCV without the side vent. Clicky click Try clamping the vacuum that connects that component to the intake manifold and see if it smooths out your idle.