Blue44

In 2nd, 3rd, and 4th gear I get a check engine light when I'm boosting at 1.6 bar on the factory cluster gauge. I'm usually able to go to 1.9bar. This of course means I'm not getting nearly the gusto out of my engine at the moment.

Pulled faults. I get only one. # 2142

•2142 (Blink Fault Code), VAG1551/2 Fault Code Number 00524

Knock sensor #1

Open or short circuit, Defective sensor

Check sensor and wiring

Symptom: Timing retarded, High fuel consumption, power loss, Boost pressure not attained

This is what I have in the car.
MC-1 10valve 2,226cc motor

Chipped ECU

Wastegate Spring 1.9bar

turbo bypass valve (N75)

(some other goodies but nothing directly related to the engine.)

I'm guessing it's PRE-IGNITION due to some white hot carbon deposits and kicking the knock sensor fault (and limiting boost)

Question: What do you recommend?! I'm thinking I should pull the head and clean all the carbon off of the pistons and valves. Does anyone know of any other way I can clean 203k miles of carbon off of the cylinder chamber?

Thanks in advance,

Alex

Katman

What makes you think " white hot carbon deposits" ? ANy basis for that?
Often we go and look for the easy/quick answer, when the true answer is something we don't want to hear. Human nature.. :-)

I'd think that with the age of these cars, it IS more likely to be what the fault codes suggest: An electrical problem between the sensor and the ECU.

The only way to eliminate an electical problem is to test. (I'd think you may get the same codes if you just unplug the knock sensor?)

I'm curious if there is another (different) code fo the ECU actually backing off timing because of knock sensor output, rather than this code that implies that the sensor isn't connected. Perhaps the light comes on when retarding, but no codes are kept?)


If not, then codes don't help too much. Maybe also make sure you are really runing premium fuel (perhaps a bad tankful of fuel from somewhere?)

yodasfro

Are you using 93 octane? Got the correct spark plugs? Perhaps you need a new knock sensor or yours needs re-torquing

Blue44

Thanks for the input.

I have been using 93 octane for at least a month now that I've moved to Chicago. Before I was in the mountains where 91 was the top fuel available.

Why I think it's carbon. The knock sensor fault only comes on under high boost. The car feels like it is retarding the timing when this happens to compensate. If I remember correctly I'm using an NGK 5 spark plug rating. Single electrode. This is a bit on the hot side. Any recommendations on the plug temp? The plugs are only about 2 months old.

Maybe I should simply replace the knock sensor. The engine light came on a while back but I was going 125mph when it happened(middle of "no where" at 4:30am). Now it happens all the time under full throttle.

I have an Air/Fuel mixture gauge which I will install before I look any further. I want to see how rich/lean I'm running under boost.

I'll keep you updated.

Again, thanks for the input

yodasfro

Use the stock plugs ngk BP6ET try changing the knock sensor too.

audi_marv

Although I agree that when your CEL comes on at 3000 rpms...you need to check your knock sensor wiring, retorque or replace the knock sensor.


Got this off the site http://tech.bentleypublishers.com...

Re: Sea foam ?
Posted: Apr 3, 2007 8:55 PM Reply


Oh Seafoam is rough all right, stuff will eat the paint off battle ships. On the + side it also eats all the carbon off the tops of valves and pistons and washes intakes clean in a jiffy!

I Prefer to go in this order when cleaning a _badly carboned engine.._

1 - Heat engine up to full op temp.

2 - Run car @ 2000 RPM while sucking in 1/2 the can of Sea-Foam or Top Engine Cleaner into the intake VIA the intake vacuum ports.

3 - Let the car return to idle and stall (flood)

4 - Have car sit for an hour...or overnite

5 - Restart car, and suck in rest of can, go drive car, beat pants off it.

6 - Return home, suck 1/2 a quart of water into the intake the same way as you did the 1st time. Don't let the car stall. Run engine until the RPMs clear up/

7 - Let car cool down, change oil (important).

8 - Enjoy near Zero HC readings at inspection.

I did this last summer on my 5kT...and agree with the results !
You must be careful doing this, as if done incorrectly can cause cylinder damage( the official term is hydro_? something).

What I would add to this is:

a.)Put Seafoam in a glass jar so you can see how much is going in. --- i actually used a spray bottle to send thru a mist.

b.) Add the seafoam in 1 second intervals...not all at once.

c.) Use a vacuum line closest to the throttle plate to clean out as much carbon thru the system as possible.

d.) I used a wrench to hold the pushrod in place at 2000 rpms while i added the seafoam. if the car started to stall, i held off a sec or two on the spray. When down to the last ounce or so, i sprayed more in to cause the car to stall, and let it sit. This gives the cylinders a good soaking, but not enough to cause the hydro_? compression thing.

e.) replace the vacuum hose you used to suck Seafoam thru.

f.) when adding water, you'll get a TON of white smoke out the exhaust, which is normal. Don't try this in the apt. complex parking lot or someone may freak out and call the fire dept.

g.) i actually read somewhere to do the water first, to loosen up the carbon a bit, so the seafoam cleaned better.

Some feel the Seafoam is too harsh on soft metals. You could probably dilute it with a bit of water, or use Techron instead.

If you've never done anything like this, I would check for other tips/procedures on the net also before going ahead, but i must say i was completely impressed by how my car ran afterwards.

Blue44

Oh my gosh.. thank you marv for the tips. I'm going to do this right away! I've have years of experience working on cars.. and Audis too; at the dealer. We never did anything like this but it makes perfect sense. I've never used Seafoam but I recall someone saying it works wonders. Thanks a million!!!

(by the way, the word is 'hydrolock' - when you have enough liquid in the cylinder it causes the engine to instantly lock up - this usually causes instant engine damage to hard parts.. because of course liquid doesn't compress)


And thank you ORFSADOY for the plug rating. I'll swap them out right away If the Seafoam doesn't do it I'll get a knock sensor. I'd like to do the Seafoam regardless.

I'll let you know if I get this baby back to 13.5 PSI (1.9bar on gauge)It's so much more fun that way!

audi_marv

Hydrolock !!! That's the name. Boy, I was having "Brain Lock" trying to remember that. Thanks !

SteveAngry

I would just replace the knock sensor since that is what the fault codes are calling for.

Not much will trigger the check engine light under boost...usually when it happens it's the intake temp sensor/wiring which is a different fault code completely.

As for cleaning carbon deposits etc, I always use Techron gas additives myself.

Steve

Blue44

progress update



hmm.. I did the Seafoam and I can feel a difference - not big, but some. My boost gauge goes to 1.7bar now instead of 1.6.

check engine light still remains.

When I did the Seafoam I noticed billows of smoke coming from the exhaust manifold or wastegate. I believe I have at least one gasket failure and I'm for sure losing exhaust pressure to the turbo some place down there. I feel this has to be addressed regardless so I will be changing out the gasket(s) first. (then knock sensor if needed)

I installed an Air/Fuel ratio gauge and it shows I'm running all the way rich under full throttle. To be expected somewhat but as I have read it's best to be running slightly under stoichometric center with full boost - meaning a little on the lean side (0.3-0.4volts)

I'll change the gasket first.