Engine Squeal and P1124 P1126

[JustOneMoreLap]

Hi Everyone!

This is my first post here. I have been reading the forums since I got my 99' tiptronic C2 but have never posted. It's my daily driver and I have put on about 30k miles since I picked it up with 90k on the odometer. Thanks to all for some great DIY advice in the past. I've had the following symptoms for about a month but have not been able to pinpoint the cause. I've searched and searched but no one seems to have the same set of symptoms.

SYMPTOMS:

• Mild engine squeal while idling and low RPM in drive (sounds like pulsing belt squeal). No squeal in park, or while accelerating. Squeal comes and goes without any consistancy and is loudest right around the rear license plate.
• Check engine light just went on and threw codes P1124 (Oxygen Sensing Adaptation Area 1 (Cylinders 1 - 3) - Rich Threshold) , P1126 (Oxygen Sensing Adaptation Area 1 (Cylinders 4 - 6) - Rich Threshold), and P0740 (Torque Converter Clutch Circuit Malfunction).
• Slight loss in throttle power
• Slight loss in fuel economy
• Transmission has misbehaved on rare occasions in the past but seems to be absolutely fine in recent months.

From other posts I have seen anything from MAF, O2 sensors, AOS, fuel pump/filter, vaccum leak, power steering fluid low, malfunctioning oil cap, serpantine belt, pulleys, loose spark plug, transmission. I have already checked the power steering fluid level and the belt, and both appear to be in good shape. I am just trying to narrow the list of possible culprits.

Thank you - any help or guidence is GREATLY appreciated!

[JFP in PA]

From the codes and the noise, it sounds like you have a vacuum leak; usual suspects are the AOS, oil filler line, etc. I would start with the AOS unit as they are known culprits.

The P0740 is a Tiptronic issue and should not be related to the other codes

[RFM]

Given the DME rich threshold stands for both cylinder banks, this means that the engine is running too lean and not richer can be put, an air leak is likely the cause. The squeal noise is also an indication of, among other air leaks, a comming AOS failure. A decent check with a smoke machine is a must for the fast detection of air leaks.

[RFM]

Looks like JFP is too fast for me.

[fpb111]

Try this quick test. Start the engine let it run for a minute take the oil cap off. If it is hard to take the cap off very likely the AOS. If not doesn't mean it isn't but probably leak somewhere else. Maybe the oil filler tube is cracked?

Edited March 28, 2013 by fpb111

[JFP in PA]

Looks like JFP is too fast for me.

"Faster than a speeding bullet"............well, at least some of the time anyway :eek:

[fpb111]

I slept in. :notworthy:

[JustOneMoreLap]

Thanks JFP, RFM, fpb111 for your fast replies!

An air leak or failing AOS makes sense. I will try the oil cap test and see what happens. If the cap comes off with ease I might have to take it to my indy for a smoke test. If not, I will probably replace the AOS and see if that cures it. I heard its a tough job but can be DIY - at least its a relatively inexpensive part.

[JFP in PA]

It is not really that tough, but it is located in very tight confines, particularly with a Tiptronic gearbox.

[JustOneMoreLap]

Oh man....

I did the oil cap test and yes, the cap was tough to pull off and when I got it off there was a big hissing suction.

I got a new AOS (part) and found a DIY. Got the airbox out and the drive belt off very easily. I tried to remove the alternator and (after lots of penetrating oil and tapping the screw as the DIY says), I could not pull it out. Looking at the alternator with both fastening screws removed, I could pry the alternator to the left, but there was not enough room to lift the left fastening screw and pull the alternator out. So, I tried to remove the lower alternator bracket that sits just below the alternator. Bad idea.

PROBLEMS:

1.) From jiggling the alternator around too much, I snapped the really stiff, thin rubber tube that runs over the alternator and parallel to the oil dip stick.

2.) From breifly loosening the lower alternator bracket, I lost a maybe 15-30oz of fluid.

QUESTIONS:

1.) Does anyone know what that thin rubber tube is? Can it be patched/taped, easily replaced? DIY?

2.) The fluid that was lost seemed to be pure water (clear and no odor). I did some seaching online and found it might actually be coolant (the alternator bracket covers part of the crankcase where coolant suppossedly flows). Assuming the fluid was coolant, can I just top-off the coolant or should go get a coolant flush?

Any help or advice is much appreciated.

[logray]

You can use a crow bar and piece of wood (against the alternator & case) to gently coax the alternator out.

The thin hard plastic tubing you broke is probably for the SAI changeover valve that controls the resonance flap. You can buy new tubing and a rubber splice/joiner from most auto parts stores. Or Porsche sells new stuff. Don't leave that open because it will be an intake air leak and your resonance flap will not work.

P

1. That is a coolant line that runs to the AOS.

2. That is coolant.

Q

1. You can patch it using a hose repair kit from home depot and some high quality stainless worm clamps, but I recommend replacing the hose, these are all inexpensive items. I'm not sure which items you broke (breaking the plastic joiner is common), so here are the three parts. Use high quality stainless worm style clamps.

996 106 224 51 long hose996 106 226 52 plastic joiner996 106 223 52 short hose

2. Yes it is coolant. You can top it off using distilled water, only top off when engine is cool. Be sure the cap goes on securely. Raise the bleeder valve on top of the coolant tank and drive around like that for a few days. Then move it back to the normal position.

Edited March 30, 2013 by logray

[JFP in PA]

To get the alternator out, the long lower mounting bolt needs a good smack to force the rear threaded insert back so it releases. This has been covered before in alternator threads.

From your description, you may have disturbed one of the lines running to the coolant surge tank or AOS (difficult to discern without photos). If you have snapped a coolant line, it needs to be replaced as the system runs under nearly 20 PSIG of pressure when the car is hot; taping or patching is not going to hold.

[logray]

I've used the brass barbed hose repair kits very temporarily and they don't leak when coupled with quality worm clamps, but JFP is right, just replace the hose.

http://www.renntech.org/forums/topic/40226-little-water-pipe-near-throttle-body/

Very cheap and no reason not to just replace the hose though. The hose repair kit should be a "out in the desert stranded local garage only has a hose repair kit" to get you home option.

If you damaged the small hose I wouldn't consider patching that since it's so small.

Edited March 30, 2013 by logray

[JustOneMoreLap]

Thank you everyone for your help - I really appreciate it.

Went to the dealer to get a replacement tube and some coolant and was able to talk to one of the mechanics - he said the tube that broke is a small vaccum tube. He gave me an extra replacement he had lying aound. Was also able to finally get the alternator out. Looking at the rest of the job though, I think I am going to have a REALLY tough time getting to all the stuff in the back. I think I would be able to dissassemlbe everything, but my concern is that I won't have enough room/leverage to get all the bolts tight again when re-assembling. Also, there's VERY little visability to make sure everything is reassembled correctly when finished.

I decided to call it quits - think I will give my indy a call Monday and see if he can drop the engine. That way he can also make sure everything is on tight and make sure I didn't knock anything else loose while I was fumbling around in there (there's a good chance of that).

Bummer, but at least I tried. Certainly wont be my last DIY attempt, this one just happened to be a strech.

Thanks again for your help - I'm already looking forward to posting again.

BTW - I saw a bunch of 991's when I was at the dealer - WOW they are beatiful cars... cant wait to see the new Turbo in person!!