New guy...same old problem... *Updated with Codes!

[gilsmak]

Hello, I just purchased a 2001 S4 with about 138,XXX miles. It was immaculately cared for and I do have the full service history on it. It appears that the EGTs were replaced recently, but I am having an issue...

I have not had it vag-com'd yet, so I am not sure on codes. I do have a CEL, always on, never flashing. I am boosting to 6 and holding 5 in 1st and 2nd. I get about 8 and hold 6 in 3rd on. Now, without checking the vag com (as I dont know anyone locally who has one at this time) is there any incling as to what this may be. The DVs are stock but the TBB looks to have been replaced as it has a newer screw style clamp.

I know that this is semi-vague, but it is the best I can do right at this moment. And yes, I have scoured the site looking for similar problem. It seems that none of the similar issues were ever met with a straight answer. So I am asking with the most complete information I have.

Thank you in advance,
-Joshua

[JDM EJ1 95]

at least go to autozone and have the code pulled with a standard code scanner.. thatll give you SOME idea of what the code is

[gilsmak]

I'll try that at lunch (2nd shifter) and see what I can find out.

[gilsmak]

Ok...codes...

P0113 IAT (intake air temp) Circuit
P1131 Inner Resistance Too Large... Something about the H02S. I don't know what or where that is.

Any help is appreciated, thanks guys.

[gilsmak]

Ok, I have since figured out that the H02S is my passenger side O2 sensor. The front one. So I am guessing that I need to replace that?

I have also unhooked my MAF to see if there was any residual effect. Seems peppier, but that could be all placebo or the cool night air. But still spiking at 7 and settling at 5. Vaccuum is better though, now idling at between 16 and 18Hg. But I am guessing that the IAT sensor is not built to the MAF at this point. I may be wrong.

Any input would be appreciated. Thanks.

[gmann]

Ok, I have since figured out that the H02S is my passenger side O2 sensor. The front one. So I am guessing that I need to replace that?

I have also unhooked my MAF to see if there was any residual effect. Seems peppier, but that could be all placebo or the cool night air. But still spiking at 7 and settling at 5. Vaccuum is better though, now idling at between 16 and 18Hg. But I am guessing that the IAT sensor is not built to the MAF at this point. I may be wrong.

Any input would be appreciated. Thanks.

If you replace one, you should replace both... And be prepared to pay some $ for them.

And by both I meant both pass and drivers side o2's before the cat. And you'll need a LONG extension for the pass side one.

[gilsmak]

Anyone else? Info on the IAT? Would the O2s be causing my issues?

[highPSI-S4]

I'll ask some questions and then you can answer so that it makes it easier to see what the problem is.

Do you have any software on the car? It seems like your vaccum maybe alittle low.
Do you know how to pressure test for boost leaks? You seem pretty decent about searching so i would look at testing for boost leaks. and i wouls also change That O2
CAUSE IT WILL GIVE YOU TROUBLE.

[gilsmak]

No software on the car. Whole car is bone stock except for maintenance replacements. But totally OEM. I did replace the FPR hose with a vacuum hose. I couldn't find 3mm so it is 2.8mm. Not sure if that would make a difference or not. Also, today, while MAF was still d/c, I was back to 18Hg.

I have not pressure tested yet. I know how it's done, I just dont know anyone here in Grand Rapids yet that would have access to a regulated air line. I am planning (Tuesday morning) to go through and visually check all the connections (hoses and clamps) for possible trouble. After seeing the condition of the hose between my DVs, it is a must.

I am now pretty sure that unhooking the MAF did absolutely nothing for my boost levels or accelleration. But I am still puzzled by this IAT circuit/sensor code.

Thanks for the help!
-Josh

P.S. What is the correct O2 sensor for the job? There are a few options for the one I need. And should I actually do both at once? Even if service records indicate drivers side replaced 15,000 miles ago?

[u7401087]

well

unless you are pretty sure that the driver side O2 is good....i would replace both at the same time....

Vast performance have them in stock for most of time.......you can check it out...