forum.audiv8.com Foren English Audi V8 Forum Problems - water got under the hood!

Hello!

I ran into some very puzzling problems after the engine room got wet. (Not with pressure, just water falling over the engine)

First problem is with the throttle - i press the pedal like 5%, so the engine should keep RPM at around 1,200 or so - then it starts to rise and fall rapidly, it goes between 1000 and 2000 like i would be smashign the throttle on and off even im not.

When i press a bit more, RPM rises normally to maximum with no problems - unless i press the pedal so far the kickdown would step in - then the engine "thinks" for 1-2 seconds, and then continues accelerating.

Idle RPM is fine, and the engine "runs" fine, fuel/air mixture seems just fine and it gets good spark so the problem has something to do with the electronic throttle or something?

And the next problem comes up when i hit around 100kmh or so, when the transmission should "lock"... when it SHOULD happen, it will instead put 3rd gear on, and it wont shift up nor down no matter what i do, only thing i have from that on is P,R,N,3 - nothing else. 1, 2 and 4 just wont go on even id put the stick on that number, use the M mode or slow down.

And kickdown wont work, ever, at all. It will always think for a second or too keeping the RPM stable, like waiting for it to shift down, nothing happens and then it just keeps accelerating like nothing happened..

Very puzzling, any help would be very welcome, as it sure aint cheap to take this kind of problem to the shop...

HI,

that one is easy: You have the "throttle valve sensor" in Front of the engine, just beyond the idle valve. The connector has - I guess - 6 pins and it became wet. It also happens when people clean the engine and is really common (it happened already to me also). Just disconnect, dry the pins and the inside of the connector, put some contact spray on it and reconnect. Et voila, runs

If it works, I'm going to tell you why you also have the problem with the 3rd gear. It's one problem with several symptoms, therefor.

Many regards

Bastian

Thanks alot, glad to know its not a big issue!

Im not sure what connector it is that i need to clean, this far ive cleaned both of those connectors in front of the engine that you can see in the picture, cleaning those didnt help so im assuming the connector i need is somewhere else?

The lower one in the picture had 6 pins and lots of water and erosion, cleaned it and put some contact spray in but had no affect to the throttle or transmission problem :(

I already lost a metallic "pin" that keeps these connectors in place, im never getting a job as a car mechanic ;)

Hi,

the connector is on the picture, it's the one below the throttle valve. The error you describe, in comparison with the water problem, is definetely a result of problems with the throttle vavle sensor.

Regards

Bastian

Hmm.. Maybe its possible some water got inside the box? So cleaning just the connector is maybe not enough, i could try to disassemble this thing and check if everything is fine inside.

There doesnt seem to be any difference if this connector is connected at all, makes no difference to how the car runs - could as well drive it without plugging it in.

Hi,

can't be! I think you head for the wrong one - have attached a picture.

Regards

Bastian

Yes, thats what im after - its clean and dry, and doesnt make any difference if i plug it in or not..

This is quite puzzling... is there a second connector somewhere for this same wire, if that has some water in it as well? Or any other possibilites?

Hi,

once again: You disconnect the throttle valve sensor and say you can drive around without problems? That's amazing, as the engine has no idea about the position of the throttle valve then, and this affects everything (fuel injection, ...). Or can you just start the engine and haven't tried anything else?

Regards

Bastian

Yes, exactly.

Actually there is a slight difference, when driving it unplugged, the transmission problem comes up right away, but when its plugged in, seems like the transmission problem is gone, atleast for a while.

However, the throttle problem excists in both cases!

Im going to try if the transmission problem is gone for good after cleaning it and plugging it in, or if it still comes up at certain speed.

Hi,

okay, wow, then I have some other suggestions:

- Intake air temperature sensor
- Intake air flow sensor

Or with other words: Grab all connectors you can find, disconnect them, dry and clean them and reconnect them. Same for the spark plugs and the distributors. Sure, it's possible that one of you sensors also got broken by the water or just by bad luck. If you want to be more deterministic, you can readout the fault memory of your ECU!

A really weird fault!

Bastian

its giving me more symptoms now!

I went for a ride with everything connected, after a while 3rd gear locked on.. as usual.. usually it is fixed by turning the car off and back on...

Now, however, when i start it and put it on D, it goes on the "Limb home mode" all the transmission lights come on, but only when putting D on, not with N or P or R...

Ill try cleaning all the connectors i can find and see whats going on, do you know if theres any wiring for the gearbox in the engine room that couldve taken some water?

Hi,

I could only think of water which flew down to the gearbox itself, but I'm not too familiar with the wirings of the automatic transmission. There is no possibility that water came to the ECUs and they became wet? Usually engine sensor problems don't cause all lights to went on but it's definetely a fact that problems with the throttle valve sensor cause the transmission ECU to lock the 3rd gear for safety reasons, so that misleading values derived from the throttle valve sensor don't cause harm to the transmission.

Having the transmission in safety fallback mode with all lights on usually points to problems with sensors of the transmission or even worse mechanical problems (but that seems to be unlikely in your case). But it also tells you that something is seriously wrong at the moment and that you should avoid driving around unnecessarily - in the end some things happened at the same time and you have e.g. too less tranmissions fluid, who knows?

Please readout the errorcodes stored in the ECUs fault memory so that we can border the problem.

Many regards

Bastian

Reading the codes costs around 200 euros on the shop, and they refuse to sell the cable needed to connect the car to my laptop.

Seems this isnt one of those 1-cent repairs

Hi,

I guess it IS one of these 1-cent-repairs. Fortunately Audi had an eye on guys like us when engineering the ECUs in late 80s, as they also provided a raw and simple "blink-out" errorcode reading for their fault memories. You just have to connect a 12V lamp to two specific pins at the error readout plug console, and it "morses" the error codes just straight forward towards you

Now the only problem is that I don't know precisely how to blinkout the ECU, but I'm sure others will reply here and tell you how to do that (and save 200.- bucks). In the meanwhile consult this one:

http://www.sjmautotechnik.com/trouble_shooting/ecufv8.html#blinkblink

... and return with the codes you retrieved.

But for heaven's sake keep the 200 bucks and be patient!

Bastian

Aha, this seems great. My last car had a brilliant feature of just pressing a button and it bliked it right in to the dash.

Ill try to blink them out, so its a 12 volt lamp or some kind of led as the site says, leds usually are much less than 12v?

Hi,

the lower voltage the bulb is intended to be faced with, the lighter it will be. So if you use a 12V lamb, it's probably to dark, I can't tell you. Take whatever they suppose

Regards

Bastian

Tried to run the car after it was unused for 3 hours - all problems gone even i didnt do anything to it....

Well all works now, wonder how long itll last!

Hi,

hehe, it went dry, I tell you
Take care the next few days if everything is fine and if, be happy.

By the way, where do you come from?

Regards

Bastian

Finland

Worked well for the rest of the day, only 1 problem - transmission went to the limb home mode after i carelessly changed from N to D while there still was some RPM in the engine after reversing - tho it went back to normal after i restarted the car and no problems.

I ordered the stick to measure the ail level in transmission, better be safe than sorry!

Tip of the day:

Removing the upper part of the plastic engine cover (Yeah, its made of 2 pieces!) so the air filter shows up gives nice little grunting sound @ high rpm from the air intake

Now if i just had a replacement pipes to remove the last muffler i could really bring the V8 out on this beast!

Hi,

well, having a look on you name would have discovered that you're from Finland. Lazy me

Removing the cover can lead to hot air intake and can cause he engine to have less power and a more rough idle op. Be aware.

Regards

Bastian

Good point there, ill think of something

But how did the throttle control affect the transmission? Doesnt make any sense!

Hi,

makes sense: The transmission control utilizes the throttle position for gear-shift decisions. You have probably notified that not only a kickdown causes a gearshift, but also and mainly in S-mode accelarating can cause the transmission to shift down one gear, even when not making a kickdown. So the transmission control has to know the throttle position to decide whether or not shifting down (an up again!). If the signal is weird, misleading or just impossible for any reason the transmission control makes a fall back to failsafe mode (3rd gear) and stays there to not cause harm to the transmission.

Regards

Bastian

Problem solved.

Strange throttle behaviour was solved by drying the connector, and the transmission problem was because the transmission control switch next to the transmission was pretty much corroded, propably got wet inside!

So anyone else with same problem.. <img src="/forum/images/graemlins/tongue.gif" alt="" />