I recently bought an A6 quattro, problem with it is that it does not seem to shift 99% of the time. I have even tried manual shifting 1st, 2nd etc and that did not work either. It will only go about 20 mph at most and gets pretty high in the rev range, at that point it will begin to miss...i am guessing it is hitting rev limiters.
scanned for codes with a VAD PRO had a couple of misfire codes, a left front wheel speed sensor code and a brake switch signal implausible code....no trans faults. cleared the misfire codes and drove without hitting the rev limits and misfire codes did not return. I tried disconnecting the MAF sensor..no change. disconected the trans control module...no change. 2 things I did notice 1. whenever I am going in a down hill direction seems like it wants to shift 2. when i let it sit and first take off it feels like it is going to work ok and get up to almost 30 mph, but still high revs. I am wondering if it may not have a fluid level/filter issue? Looking for suggestions.

 

Hi VJ,

I am copying and pasting my post that I've put in three other threads.

Sad to say, but that slamming, lurching, and high reving have nothing do your engine. You tranny is pretty much on the dead door step.

If you want to take the first steps to trying to get the tranny operational, try a flush by yourself, change the filter. That will be the cheapest option, but I have a feeling a clutch pack or a valve is the issue and that translates into a full tranny rebuild or replacement.

If you see that the colour of the tranny fluid is black = bad. You can pretty much count the fact that the tranny is done for.

Sorry to be the bearer of bad news., but there is a small chance the flush might make it happy enough to last another 6-12 months.

 

Thanks, I think I will try a filter and flush, but I figured I would hear this, guess I just wanted to be sure I hadn't overlooked anything

 

Hi. Before you dump a ton of money into the car hoping to fix existing drivability issues, why not address the issues you already know exist and see if they are the cause of your shifting problems. I can tell you from past experience that a faulty brake light switch and or a faulty wheel speed sensor or ABS sensor can cause shifting issues.
The vehicle stability program and ABS system will cut power and delay shifting if the ECM thinks that the car is skidding or if it feels that a wheel is not getting traction...which is in effect what the ABS system and vehicle stability system reads because of a faulty wheel speed or ABS sensor. The same being true with the brake light switch. As you accelerate, your ECM may be sensing that the brakes are still applied because of the faulty switch and hence begin cutting back power and delaying transmission shifts. In my opinion you should corrrect the known mechanical issues first. These small things are many times simple fixes for cars with such complex and elaborate safety systems.

 

Your idea isn't a bad one, but considering the age of the Audi, it would be more practical, both financially and physiologically to deal with the tranny fluid first. You know how pissed I would be if if I ended up fixing all this other stuff, then find that the tranny is still fizzled.

Start at the core of the most basic issue. Transmission. I do agree with TwinTurboC5 that there parts that should be factored in to the fix, but looking at the tranny fluid and pan will give you a CLEAR indication if it is even worth proceeding.

If the fluid is black and burnt smelling, this will tell you fast that the transmission is at the failed or near failing point. When the fluid gets that dark and burnt smell, all the internal parts of the transmission (clutch pack, etc) are very much on deaths door step. And if the pan has a decent amount of metal fragments on the magnet - that speaks for itself.

Now if it isn't, this changes the game plan, and the scope of how much work and money will be needed. If the fluid is brownish and there aren't many metal bits on the magnet, the transmission is probably ok. Finish the tranny fluid change, and start working on the rest of the issues.

Dealing with the state of the tranny fluid, will set you expectations VERY fast to know what you are up against for the rest of the car.

 

The brake light switch and ABS speed sensor are relatively cheap and inexpensive fixes(especially if the OP is a DIY'er) compared to dicking around with the transmission.

Start with the faulty brake light switch and wheel speed sensor. If neither resolves the problem, then you can turn all your attention towards the transmission and decide what you want to do with the car at that point.

 

Thank you both. Trans is a ZF4HP18. I dropped the pan Sunday afternoon, found the fluid still smelled good, like the new fluid I have. No burnt smell, very little stuff in the bottom of the pan...I have seen more in the pan of chevrolets with 1/3 the miles this car has. Found:the filter has a 'column" of sorts that descends down into the fluid, this plastic 'column" is broken in the forward part, enough so that trans may not have been sucking up enough fluid. Break looks to be from deterioration of plastic due to age. I had noticed that on a downhill slope it almost seemed to upshift a little. I will get a new filter and reinstall and refill. I will post the results. I still plan on addressing the abs sensor and the brake pedal signal.

 

I stand corrected, last I looked - I looked up the wrong part = higher cost. my bad.


Sounds good about the tranny fluid - that is a great headache to avoid

 

Well here is the update so far. I changed the filter ( the pickup section was broken, i think it was sucking air) and fluid....it shifts. Now on to other things. Found plugs that look like they were original no center electrode left at all....replaced those....found the air filter in the same shape....very dirty.....tested fuel pressure and it is in specs but seeing how the maintenance was kept up (NOT) on this car I am going to change the fuel filter also.. Did a back pressure test on passenger side cat and it is clogged, I will test the other one tomorrow but guessing it is in the same shape.

 

Driver's side cat is clear, but i am changing both. with both upstream o2 sensors i was able to take a short drive, no overheat, shifting fine and running good....considering I had the mass airflow sensor disconnected ( turns out it is bad, too). Well not bad considering I only paid $450 for the car.