2003 BAM S3 - Couple of Questions !

[mikes3]

OK, still having some probs with my car.

1st problem is boost - its erratic and the car seems underpowered. I have replaced the TIP as I had a split in one of the branch nipples - and now I've found another shagged pipe. It comes directly off the top of the throttle body (rubber, 90deg bend - into a metal pipe which goes over the engine toward the back somewhere). What is this pipe for ? I tried to describe it to Audi parts desk and I might as well have been talking to a giraffe. No sense at all. Does anyone have any ideas /and/or part numbers ? Or any suggestions as to if I could replace it with samco hose all the way across the engine?

2nd problem - Engine management light still on - I have 1 fault code on the ECU which is

16497 intake temp sensor G42 signal too high

I took out the sensor last week and cleaned all the black crud off it, and took it back to my mate at the garage today to try to clear the code. It came straight back on. I've ordered a new sensor from Audi (£36 !!!) which will be here tomorrow. Im asking you guys what could be causing the intake air temperature to be too high ? If the air comes from the turbo, through the intercoolers and straight into the inlet manifold then could it just be the intercoolers blocked ? I'm startin to get very annoyed with this car.

Thanks very much in advance.

 

[finesse]

You could take it to Awesome GTi in Manchester so a health check/service, better than Chester Audi.

 

[Welly]

If the intercooler was blocked, I would expect to see worse problems than that to be honest. Also, there shouldn't be anything getting in there to block it. The standard pipes are 63mm so to block one of the cores, the blockage would need to be sizeable.

Is the car remapped? If so, the extra boost can produce extra heat, although I'd say that's unlikely to produce the amount of heat that would be required to flick the IAT warning.

The best thing to do will be to change that sensor and then see what you've got. The engine management is most likely putting more fuel in than it should be to help disperse the extra heat it 'thinks' is coming in. This will result in poor performance and high fuel consumption.

If you've changed the sensor over and are still getting that fault code, I would investigate furthur at that point. But up until then, you don't really know whats going on.

The hose which is split won't be helping power wise - can't remember where it goes, but if there is a split you will lose vac at idle and boost when going. This again won't help performance and usually results in the car hunting at idle. Swap the whole thing out for some silicone hose - it's only a metal pipe so that it can be bolted to the engine IIRC. The standard DV vac hose is metal like that one on the A3, and most people bin that for some silicone. It will be fine.

 

[mikes3]

Just been for a visit to Audi Cheshire Oaks. He gave me 2 part numbers for the pipe which comes off the throttle body.

O6A 133 352 C - £50.36 !!! (small rubber hose, 90deg bend)
O6A 133 356 R - £80.22 !!! (metal connecting pipe)

If ever you needed reminding of how much they rip you off, here it is. Two small pipes, supposedly for the brake servo breather system ??? for £130.
I think I'll replace this with some silicone as you suggest, might have to route it around the engine block to reduce the heat it will take. My friend at the garage suggested I get hold of some wiring schematics to check out the cable going to the IAT sensor, says I can buy a version from flea bay. Anyone ever managed to find wiring schematics for a BAM engine ?
Anyway, new sensor tomorrow, see what happens after that ....

 

[badger5]

AIT is a thermocouple so a resistance device.. crudded connections fooling it into thinking its hot?

 

[mikes3]

Maybe yeah - as you say, its a thermocouple with a resistor on one of the legs I think. Both wires were covered in a hard dark black material - it didn't look good so it came off with some carb cleaner and a little TLC. A job for next week will be to clean the throttle body too - I noticed a bit of oil residue in there when I took off the intake hose to inspect. Do I need to take the throttle body off completely, or just spray some carb cleaner up from the open end at the butterfly valve. ?

 

[mikes3]

Just another quick question - what size silicone pipe will I need for the majority of the PCV system under the inlet manifold ? Found some 5mm ID on ebay, will this do ?

 

[badger5]

4mm and 5mm vac piping will do most jobs yes.
brake cleaner or carb cleaner should clean it yes.. and a wipe

PT100 thermocouple I believe is the thing used for AIT

 

[mikes3]

Quick update.

Been working on the motor today - fitted my new IAT sensor - cleared the faults on the ECU - started up the engine - same fault came straight back up.
My question again is - what possible causes are there for just this one fault to come up ? I'm baffled.

I removed the throttle body, cleaned all the black gunk out of it and refitted with a new gasket and paste.
Also, bought some 5mm and 6.3mm samco silicone hose from DT, replaced a couple of vac lines as time allowed.
Still having the boost problems, and my head is getting sore now from hitting against a brick wall.

 

[mikes3]

Arghhh couldn't leave it alone.

OK, so I found a nice little page here which tells me all about the IAT sensor fault P0113. Put my multimeter across the connector terminals and get no voltage at all. Stripped back the wires as far back in the loom as I could, and still no voltage. Next I neeed to get to the ECU plug and check output voltage from there. I have a vague idea the ECU is underneath the trim under the passenger side wiper. I slackened the locking nut, but the wiper wouldnt budge off the pin. Sprayed WD40 in there and tried to prise it off with a big flat had screwdriver, but it wouldn't budge. Am I missing a trick here ? Passenger wiper removal, or easier access to ECU input plugs.

Would appreciate a quick one on this, got the car under the lights and my motivated head on - just don't want to damage anything.

Cheers.

 

[mikes3]

Still can't get the wiper arm off, can't believe how tight it is on the spline. Tried my pullers from work but the legs are too bulky to fit underneath the arm housing.

This fault is really doing my nut in now. I'm convinced my boost problem is down to this fault, but can't get to the ECU to check the source of the wires.

I spoke with a former Audi engineer today who told me that the sensor cables will go directly wired to the ECU (ie, no joint in between) as they are reference voltage signals (0-5v), so I don't even know if its worth all of the aggro to get to the ECU. If the ECU was faulty and not putting out reference voltages, would this be logged or trackable with VAGCOM ?

I'm competent enough with the electrical side of things, but lack the local knowledge of the S3 and have never had to deal with an ECU. Also, I have a holiday in a couple of weeks and money is too tight to mention. I know the right thing to do is to get it into a specialist and have it professionally looked at, but I simply can't part with the cash. Any help from you guys is truly appreciated, even if its pie in the sky, at least it might get me thinking in another direction.

Fault code is P0113 - Intake Air Temperature Sensor - Signal too high

Many thanks in advance

 

[Welly]

Wiper off mate, it is just a pull it job! I normally use a pry bar to help ease it off - do so at your own risk!

Have you checked the condition of the plastic sleeving all the way down the loom for the two mires in question? Splits in the wiring on these motors is not uncommon and it could be shorting out somewhere.

Good shout checking the output from the ECU.

 

[mikes3]

Thanks bud.

I stripped the entire wiring loom back yesterday, all the way to the point where it passes the pollen filter. I snipped the cable and stripped the ends, tested for voltage and got nothing. I now have the wire lenght from the pollen filter back to the ECU to check, must only be 18inches of wire. I'm doubting whether there would be a fault in the loom there, it never sees any action. Beginning to think its a goosed ECU, but surely it would throw a code ?

 

[mikes3]

Final update.

After tracing through the loom and belling out the plug into the ECU, I found that the guy who rebuilt my engine had plugged the IAT sensor connector into the Knock Sensor connector (and vice versa). Cleared all the codes and took it for a drive - all my power is BACK !

I should be annoyed with the guy, but strangely Im not. I learned more about my car over the last few weeks than I ever would have otherwise. Silicone vac/boost lines, new TIP, new IAT sensor, earthing points remade etc .... (and a few body scars) .... I'm glad in a way. Probably more relieved than anything, and excited about driving to Hungary next Friday with all my horsepower back.

Thanks to all who took the time to read, digest and help me. I really appreciate it.

The moral of the story is ... don't trust a mechanic to be any good with wires !

 

[Welly]

Good work mate.

Glad you sorted it!!