Engine speed sensor change from the top

[beerad]

Anyone changed the engine speed / crank sensor from the top? Found some information on the a4 guys managing it but we probably have less space. Removing the oil filter / coolant tank any help? Car is stopped on the street, I think this is the problem and would rather not be laying on the road. Car is auto as well so probably less space again.

[alcatranz518]

You can definitely change it from the top. I just did this about 2 weeks ago, grab yourself a nice thick blanket to cover it, take off the belt, and get ready to hump that fender.

Move the coolant tank out of the way (no need to take off the lines), remove and unplug the harness located on the firewall in the little block with the o2 harnesses. Make sure the harness is free from all places first, it is wrapped through what seems to be the the fuel or EGR/SAI hard line. ..that step actually took longest out of everything. My forearms are like Popeye's, so if I can fit my arm down in there I think most people can...it will be tight though.

Reach down and in by following the wire to locate the sensor and use a regular old 5mm allen wrench (if I remember the size correctly) to unbolt. Don't be surprised if you drop the wrench a couple times until you get a feel for the position, hopefully your rear belly pan isn't on there or it will fall onto it....Once you unbolt the allen, just lightly twist while pulling and the sensor should come out. Logic dictates there should be an o-ring on it to help keep debris, oil leaks, and moisture from entering in there, and if so it will be a little more difficult to remove. However, my old one didn't have one nor did my OEM replacement I bought (077 905 381F), so I'm not too sure if one should be there either way. You should at least make sure the hole is clean and lightly wipe it before you put the new one in.

Hope this helps.

[beerad]

Cheers mate, just what I wanted to hear, ill give it a go when the parts come in, thanks for the reply.

[badger.]

I just did this job a couple weeks ago, had to go in from the bottom and take a bunch of shit off.

I tried from the top but couldn't get enough stuff out of the way. Guess my arms are too fat or something, idk. Apparently some people have had success from the top. Not me though :)

[0396]

Good luck with this venture, it sounds easy but it's not as you need a small 5mm allen.
That simple task took me 5 attempts and about 4 hours. One suggestion is to tape a string to the 5mm wrench. If it falls, simply pull it back up.
I even tried getting it off from under the car...I had no luck with that. These S4 with that big V8 makes it difficult to work on them. Good luck

[badger.]

here was my thread FWIW

http://www.audizine.com/forum/showth...will-not-start

[alcatranz518]

I'm at a loss, however reading through your thread I see someone else had the same experience as I did, whereas others did not including yourself. I can tell you mine is also a tip, but I don't recall cooler lines being in my way. The only inconvenient part was "un-threading" the harness through the Smaller hard lines (I think they were the EGR or SAI but not sure), which was like an hour itself. The actual rest of the work I'd say was 1/2 hour total (coolant tank, allen screw, removal, replace, put all back together) I'm curious if by some strange chance the B6 has a slight difference in there from the B7, such as cooler routing. (I'm definitely not sure, just guessing on why such a different experience but from more searching it seems a 50/ 50 split on misery rating of this).

I do admit the space was limited and my arms definitely aren't small, I did have quite the battles wounds from the experience but nothing to the point where I felt it couldn't be done. Admittedly I did try going in from the bottom at first, but after I got the skid shields off and attempted to go up in and then saw all what had to be removed so I figured I'd give a try from the top before I took heat shield and everything else off. To be fair I have long tubes w/ several layer of heat wrap, and heat shield removal isn't quite as easy as with down pipes, so that was a contributing factor.

I have to say I wish I would have thought of the tying a string to the wrench, I dropped that damn tiny wrench quite a bit from the arthritis in my hands. That's a helluva a great idea, although in contrast what a cardio workout chasing it every time lmao. (...So I rewarded myself with some In-N-Out afterwards )

[beerad]

Thanks for the info guys, sensor came today but heavy rain expected tomorrow we will see how keen I am. Picked up a ross tech cable today atleast so I can check the codes.
Thankfully I removed the plastic under trays last week chasing an oil leak, but the string idea is good. I've got a half decent tool collection hopefully I can get something onto it.

[beerad]

OK so ive done this from the top today, wasnt too bad at all. Mine wasn't even routed in the hard line was instead wrapped in a heatproof sock with a clip top and bottom to remove.
Just removed covers, unbolted coolant tank and moved forwards (lines left connected). Then follow the cable down from the connector to the sensor location, I found I could bend the exhaust heat shield towards the exhaust to gain alittle more room (remember to move back). I had a small ratchet with an 5mm allen key attachment that got in easy enough (smaller then my 1/4" ratchet) to undo the sensor and pull out. Hardest part is getting the bolt back in the new sensor without dropping it which took some nimble hand work but managed it.

Where you stuff your arm (was a pretty tight fit):

Ratchet used compared to car key. Also the heat sock:


unfortunately this wasn't my problem, still wont start.

[Kambesama]

OK so ive done this from the top today, wasnt too bad at all. Mine wasn't even routed in the hard line was instead wrapped in a heatproof sock with a clip top and bottom to remove.
Just removed covers, unbolted coolant tank and moved forwards (lines left connected). Then follow the cable down from the connector to the sensor location, I found I could bend the exhaust heat shield towards the exhaust to gain alittle more room (remember to move back). I had a small ratchet with an 5mm allen key attachment that got in easy enough (smaller then my 1/4" ratchet) to undo the sensor and pull out. Hardest part is getting the bolt back in the new sensor without dropping it which took some nimble hand work but managed it.

Where you stuff your arm (was a pretty tight fit):

Ratchet used compared to car key. Also the heat sock:


unfortunately this wasn't my problem, still wont start.

Is it cranking or anything? Fuel pressures and spark present? Go through the basics and let us know what you find if you haven't already.

[beerad]

Car cranks and cranks. Cleared codes and tried to start afew times and no codes came up.
I was having start issues 2 weeks ago changed the fuel pump relay under the dash and it started straight away.
Drove down to the snow and back (1000km) with no issues then it stalled while driving home from work one turn from my house.
Tank was low at the time but still said 50km until empty maybe I have a bad level sender i'll try and get some fuel in it and see if i get lucky.
Otherwise yes ill be checking for ignition / fuel, checking fuel pump.
Didn't want to start another "my car wont start" thread and get hammered for not searching haha.

[alcatranz518]

Sorry to hear the problem wasn't fixed. When you turn the key and the engine cranks, does the tach read 200-400 RPM? This way you know the sensor wasn't bad out of the box. Being electronics, you never now. OEM parts run very little risk of it but still can happen.

If the tach does indicate engine movement, then next to check your fuel pressure (or you can check for spark first which ever is easiest, if no spark then I think your only choice is a ECU but I could be wrong). It should hold pressure I believe if memory serves 36-40 psi, if not then (if not already changed) replace your fuel filter first, it is MUCH less expensive then the pump and I have seen many instances it was clogged. Be sure to replace with a genuine Audi filter as even the German aftermarket ones are not optimal, and also be sure if yours is early model (4 line) or late model (3 line) version for the filter. They are separated by VIN, but to just peak under and look at the filter is easiest. Apologies if this is already info you know, just want to be sure and double check.

[beerad]

Thanks for the help, its looking like the pump. Checked for rpm as the engine cranks, yep.
Took the fuel line off the fuel rail and tried to start, no fuel. Checked for 12v at the pump relay under the dash, yep.
Checked for relay clicking on start up, yep. Checked for 12v at the pump when the key is turned, yep.
Cant hear any noise from the pump, I will likely change both pump and fuel filter.

[alcatranz518]

I'm glad to see you figured it out, although it sucks its likely the pump because they are so freakin expensive. It is good on one aspect that you get a complete all new OEM sending unit and its simple to replace.

FWIW, there are options to replace just the pump/ strainer like Autotech, HFP, and Walbro if you don't mind going the universal "custom" route. (which I'm sure you are aware of, but as with me I didn't know I could get one that would work for our platform). Anyhow, they can be much less expensive and don't necessarily need to be a high volume version. The "universal" pumps don't require much modification to install into the OEM VDO sending unit assy and are just as reliable as OEM in my experience (as long as you get a known quality brand). Granted you ONLY get the pump and and a "universal" harness to adapt in (Walbro will also give you a new strainer too), but at least you can save a decent amount of $$$ in the end.

[beerad]

Finally got the pump and fuel filter. Bit of a pain to get the old one out but it did the trick, cars going again. Now on to the oil leaks.