ABY engine don't start after a water hose blown.

[Piu]

Last weekend I went to a dragstrip to make some passes with my original 94 S2 ABY sedan.

After 3-4 passes, I got some steam under the bonnet and drove to box to see what happened. So I turn the engine off by key and after open the bonnet, I saw a small plastic pipe with a temp sensor that goes from head to internal heater cracked and leave the hot water all over the engine bay and over the wiring loom at back of engine.

After a small repair, I tried to start the engine, but without success... The engine cranks but not starts. No sparks and no injection.

After a small checkup in the timing and speed sensors it's looks OK. I traced the signal with a scope and got a clean 5Vpp pattern from both sensors at cranking.

With scope I traced the signal at camshaft hall sensor and got a perfect 5V square signal in the signal terminal of the sensor connector next to camshaft pulley when cranking, so I think the problem are not the 3 main sensors who if it fails, the engine wouldn't start.

With VagCom, I got the "mechanical malfunction camshaft sensor" message after each trying to start the engine. If I pull the camshaft sensor connector off, the message in VagCom changes to "open or short to +B camshaft sensor", what tell the wiring from the sensor to ECU looks OK. I also get a oil pressure warning message in the dash, but the oil pressure meter at dash show 1 bar pressure at cranking.
VagCom show about 80 RPM while cranking, and I thinks it's the confirmation the ECU is recognizing the speed and timing sensors at flywheel.


Things I've observed:
Few months ago, I leave the car in the car wash service and they washed the engine bay with a high pressure water-wash machine. After that, the tachometer in panel stopped to work and I got the same oil warning in the onboard computer. After few days, the tacho back to work and the oil warning goes away.

I guess the not starting engine have to do with the water blown after the plastic pipe fails and pouring hot water over the engine, because I got almost the same simptoms after the engine wash few months ago.

What would cause these simptoms? The wiring loom are in excellent conditions despict the age of the car. If the ECU is recognizing the sensors, what would make the ECU not firing the coils and injectors?

Where can I get the electrical diagram to trace the signals from ECU to dash to look for the tach and oil signal lost?

[A80Avant]

oh no.....
everyone is going to be saying to you now: never wash this engine...NEVER....it acts like a cat.cats dont like to get washed..they hate it actually...cremlin...better get a headdryer,dry everything up,let sit for a few days...then it me be OK again.

[kwlw]

What would cause these simptoms? The wiring loom are in excellent conditions despict the age of the car. If the ECU is recognizing the sensors, what would make the ECU not firing the coils and injectors?

Check/clean the ground connections on intake manifold and the point wherever they go on S2.

Sau

[dest]

Remove all electrical connectors one by one and make sure they are dry

[anton]

sounds like a short to me, was driving in bham once and there was a huge puddle, almost a ford across the road, cars broken down all over the shop after, my 7a's dashboard just lit up like a christmas tree giving me a heart attack then all the warnings went away over about 10-15 mins. differance being you have a decent ecu! having said that, 2 weeks seems like a very long time for water to be trapped anywhere......

Ant

[newsh]

Have a look inside the wiring connectors on the bulkhead where the loom joins.

[Piu]

Last sunday I spendt some time to search the problem, since I dind't support to see the car parked waiting for help.
I got the scope and dissassembled the ECU connector to get access to pins when it's coupled in the ECU connector.
Once I've got sure that all input signals from sensors was in good shape, I opened the case of ECU and started to trace the crank signals trough the board (i'm electronic technical, so it's easy job to me) With the scope probe in a certain capacitor in the camshaft signal path, I tried to start the engine and it's miraculously started! I did wait some time to get sure the engine was OK and so I turned off the key to stop the engine and then it's not started again. I did the same thing, touched the capacitor lead with the scope and voilá, the engine started again.

At this time I assumed an ECU problem, but before I replace the capacitor, I did figure out the scope probe was distorting the camshaft signal and lenghtened it a bit. So I got a blast tought the signal from camshaft sensor could be retarded or advanced a bit by a teeth jumped in the pulley. With the distortion and lenghtened pulse by the scope probe, the ECU recognizes the correct position of the signal and started the engine.

In the next morning, I disassembled the front of the car, cover and pulley assembling and found the timing belt pulley in the crank damaged at the keypin (I dont now the name in english). Only a small bit of the keypin was holding the timing belt pulley from a false spin and knock-off my valves and God knows what more would happen if the pulley got loose. The small bits loosen from pulley keypin also damaged the front of the oil pump and the crank seal, but I think it's repairable.
Now Í'm in the search of a pulley to replace the damaged one, but unfortunattely, this engine is very rare in Brazil, and I think is difficult to find one.

Any other audi engine share same pulley or it's unique from 5 cyl. engine? Here we have tons of 4 cyl. A3, golf, Jetta and few other engines in the junkyards. Any of these share same 26 teeth crank belt pulley?

Sorry my english, but I would like to say that any help or suggestion in how to get a pulley will be very appreciated.

[kwlw]

Any other audi engine share same pulley or it's unique from 5 cyl. engine? Here we have tons of 4 cyl. A3, golf, Jetta and few other engines in the junkyards. Any of these share same 26 teeth crank belt pulley?

Sorry my english, but I would like to say that any help or suggestion in how to get a pulley will be very appreciated.

One of forum members sell pulley machined from steel which will not break (use search). I think you can ship it to Brasil, because it is quite small.

Sau

[UrS4boy]

Any other audi engine share same pulley or it's unique from 5 cyl. engine? Here we have tons of 4 cyl. A3, golf, Jetta and few other engines in the junkyards. Any of these share same 26 teeth crank belt pulley?

Sorry my english, but I would like to say that any help or suggestion in how to get a pulley will be very appreciated.

Piu: The pulley in question has a PN of 034 105 263A. It almost universally common across Audi 80s, 100s and 200s as well as the UrS-cars. You should be able to find a new one at a dealer or, at worst, a good used one at wrecking yard. HOWEVER, do not use an AIR IMPACT WRENCH to remove it. This is what helps to break the cast key away from the pulley itself. Good luck.

Dave F.

[Piu]

Thanks for the advice. In fact, I used an air tool to remove the bolt, but as the oil pump was damaged by the key pin, I think that wasn't the air tool that broke the pulley. Today I came to few car yards and didn't been succeful to find a pulley. I then leave the old pulley to a machinist and he said is easy to make a channel in the pulley and put in a new key pin. The pulley slides freely in the font of the crank and the way this pulley is made, the key pin is jus a orientation reference for assembling. Is the 4 small bolts that drives this pulley and not the key pin. If I could machine the key channel and put a new key, I'll be able to reuse this pulley. Just to you have an idea of the rarity of this car in Brazil, I heard from a Audi dealer just 20-30 S2 where sold here and I think the sum of all 5 cyl. audi cars doesn't pass 200 cars in whole country.