Fault Codes - Help Required !

[mikes3]

Hey guys.

2003 S3 BAM

Had a few problems this week with my car with boost. The car seems to have less power and the boost isn't smooth, coming in and out fairly randomly. Anyway, I had an inspection under the bonnet and found a split in the intake hose where it branches off up to the pressure relief valve. The joining pipe has also gone lame (rubber been getting too warm).

Anyway, over the weekend I had removed the whole intake pipe assembly, and attempted a repair on the split. I cleaned out the relief valve and renewed the adjoining pipe. Before I order the replacement parts from Audi, I wanted to tap into your knowledge base for some help/suggestions.

I have the engine management light on the dash, and took it to a friend with VAGCOM to see if we could clear it. I got three faults.

16497 - Intake Temp sensor G42 signal too high
17864 - Exhaust gas temp control bank 1 limit attained P1456 intermittent
16716 - Knock sensor 2-G66 signal too low P0332

So ok, I had a look at the intake pipe again, and I think Im right in guessing the intake temp sensor is on a small T piece, branching off from the top of the intake pipe. Also, my logic is saying that if the air is being read as too hot, then the car will run lean and thus affect the exhaust gas signal ?? Also, with these in mind, could the knock sensor be due to the engine not running smoothly as a result ?

Anyway, hopefully someone will know what Im rambling on about. Id appreciate any info or suggestions as to what I can do as the next step or just any help in general.

Thanks in advance.

 

[<tuffty/>]

Intake temp sensor is in the inlet manifold just after the throttle body facing the front of the car, EGT sensors box of tricks is under the inlet manifold and the knock sensor is gearbox side front of the block under the inlet manifold... as all of this lot sits off more or less the same loom I would imagine the first place to start is to look for a wiring fault maybe an earth or damaged wiring?

<tuffty/>

 

[mikes3]

Thanks tuffty.

Maybe Im looking at the wrong sensor then for the inlet air temp. From the air box, the first sensor is the MAF sensor right ? So working to the left of that, the sensor Im looking at is facing the back of the engine, just off a branch of the main air intake pipe. Do you happen to know which general direction the loom runs for these sensors ?

Also, do the fault codes themselves make any sense together for the original fault I had ? Basically, air being allowed in or out throught the split in the pipe ? Sorry to sound like a noob, I really really want to learn more about my engine, but its hard to find the hours to get under the bonnet these days.

Thanks again.

 

[mikes3]

I just removed the sensor I believe to be the intake temp sensor. Here it is.
http://img189.imageshack.us/img189/8929/dsc00355k.jpg
Is this correct ? Anyone have any idea how to test it ?

** EDIT ** NOOB ALERT **

OK, so I just googled "EATON 058906283F" which is printed on the side, and I find out this is my N75 valve. Well now that it is off, is there a way to test it ? I have the 3 tubes, two are passing air in each direction, the other is air tight, nothing comes through it. Is this correct ? I measured the coil resistance as 28.8 ohms. Help needed !!!

 

[<tuffty/>]

I just removed the sensor I believe to be the intake temp sensor. Here it is.
http://img189.imageshack.us/img189/8929/dsc00355k.jpg
Is this correct ? Anyone have any idea how to test it ?

Thats the N75 valve mate... that controls your boost.... Make sure you put it back the right way around else you could end up with uncontrolled boost and a blown engine... Boost in the bottom (small hose from metal charge pipe) long outlet into the TIP and actuator pipe in the opposite end...

The MAF sensor is the one in the tube coming out of the air filter box... The inlet manifold is the alloy thing at the front of the engine.... Has the fuel injectors in it etc...

No offence but TBH if you are unsure of what it is you are doing at this point I would advise you to take the car to a specialist for advice as removing key components (such as the N75 valve) without knowing what they are or what they do could actually do more harm than good...

The split in the pipe you mention should only be repaired but a replacement part as you cannot repair a pipe that is under pressure (boost)...

I still think the faults you have are wiring related, common problem is earths and typically to get a bunch of anomolous elettrical faults in sensors that are in the same part of the loom as each other (as these are) then it smacks or wiring to me...

Assuming you have cleared the faults, have they come back?

If a knock sensor is showing as faulty this would indeed send the ECU into apoplexy and the engine will not run very well at all...

I would recheck for fault codes, replace any split pipes/hoses then check the wiring loom at the front side of the engine.. the earths are under the battery tray so that would need removing to get at them and see what state they are in...

The loom may have been damaged somehow so check everything for damage, use a light (torch or something) as just staring into the engine bay won't reveal all...

<tuffty/>

 

[mikes3]

Thanks again.

I just put the N75 back on, took photos of the way it was mounted before I did anything anyway, its all back together fine.

I took your advice and looked at the wiring loom and removed the battery tray to check the earthing points. I removed the two I could see, cleaned up the contact faces and screwed them back. Having had the battery disconnected, the engine management light had gone out once I turned the ignition back on, and so I took it for a drive. Still the same lack of boost (or intermittent) and Ive noticed that at idle, the engine is knocking slightly intermittently. I came back on here and looked through some threads, and found the MAF sensor could be causing the poor idle. Anyhow, I unplugged the MAF and ran at idle again - MUCH SMOOTHER, and no knocking. Replaced the sensor and started again, crap idle was back. Also, after 10 minutes of driving afterwards, the EM light came back on.

So, I think I'll get a new MAF sensor as a starter, and order the new intake pipe and relief valve. I know it will narrow down the faults eventually, but I want to keep the costs down if I can.

Forgot to add - just wondered if there is anyone in the Northwest / Chester area on here who has some knowledge and some spare time ... would be nice to get a second opinion on the way things are running.

 

[mikes3]

Update.

Took car back to garage to clear the codes on the ECU. The engine managemt light stayed off all day, and decided to come back on when I was putting the car back in the garage for the night. Took it back to get plugged in the next morning, and it was logging just one fault.

16497 Intake temp sensor G42 signal too high

I still have the problem with the boost and the new parts are on order, but the ECU isn't logging any faults for the boost side of things at all. Im a bit confused. What can I do with this sensor, and what might it be indicating as the problem ?

Any help greatly appreciated.

 

[jonny87]

have you removed the sensor and cleaned it?

unsure if this will help but takes 2 mins and is worth a shot, just one bolt securing it to the inlet mani pull out and gently clean with a clean rag, i wouldnt use any chemicals on it as it could totally ****** it

 

[mikes3]

Yeah, I took the sensor out and it was all blacked up, so I cleaned it with some solvent spray and a little scouring pad. Got the two wires shining nicely with minimal effort really. Anyway, I have put the sensor back in and I disconnected the battery for 10 minutes. The engine management light stayed off again for half an hour or so while driving. I stopped the engine and restarted, and hey presto the light is back on.....

.... the question is, does disconnecting the battery actually clear the ECU codes or does it need doing manually with VAGCOM ? IS it the only way to actually know if what you have done to try to remedy the problem has actually worked ?

Thanks again .....

 

[jonny87]

not entirely sure mate, i would use vagcom to be sure, disconnecting the battery may clear the cel but i think the ecu will remember any faults it detected and put the light back on, vagcom will clear the memory of the fault, could be wrong though mate, i dont really have a clue when it comes to ecu's etc this is only what i have gleaned off various other threads

 

[wilcog33]

hi mate, i have the exact same boost problem on my 02 plate car but its not putting the management light on. Just wondering if u got to the bottom of the problem, before i put my car i to the garage?