I'll be helping someone diagnose an s4 auto tomorrow and need some heads up advice as I havent dealt with any auto FCs before but every other issue I can tackle.

This is all I know based on a very short phone conversation:
-starts up fine, idles decent
-when put into drive car shakes very violently and takes a moment to settle down

Not sure if it even drives fine or not, conversation got cut short but just want to know if this is most likely a transmission issue or not. I'm assuming the car drives fine other than maybe delayed gear changing. Obviously this is asking alot based on limited info.

I just dont want to waste my time chasing a ghost problem if all it is is a crappy auto tranny problem.

 

Shakes....like vibrating shake or bucking?

 

I dont know I havent seen the car yet. Oh well I'll see how it goes tomorrow. I'll update if I figure out what the problem is for people who search.

 

My car had an auto tranny for a while before I finally swapped it for a 5 spd. Its not too difficult to do and there are some decent write ups on here and on www.rotaryresurrection.com

That said, with most automatic transmission problems, the first thing you want to check is the fluid level. If its too low, wierd things will start happening and it will eventually cause damage to the internal parts of the trans.

 

Thanks for the advice, I'll check the fluid level. I'm not looking to a 5 speed swap unless they are paying me big bucks, to much of a damn hassle

 

Just be happy that it's a tranny problem. Hell, I just got done putting in a starter, and it'll crank like a bitch, yet, it on't even fire. 4 defloods, 4 jumpers, and still no coke and smile.

 

sorry to bump it but the guy finally brought the car over

Here's the symptoms:
-idles fine in neutral (1200rpm but I couldnt get it down with the limited time I had)
-will stall when put into any gear
-have to stay on throttle to keep it from stalling
-no power starting from a stop and you have to modulate the throttle to get it going
-once it picks up some speed it drives nicely and has good power

What I know is wrong:
-speedo cable is frayed to hell
-TPS was way off (solved)
-idle is still high (couldnt find any vac leaks but he told me he turned every screw he could find [screw on AFM, TPS, throttle stop, lean/rich screw, etc.])
-lock key on the auto shifter is broken (can get into gear with holding the button)
-gear selecter had ALOT of lateral play (solved most of the place with a spacer)
-he adjusted the parking gear tension (?) way off allowing him to start it random gears (adjusted and fixed)

So I didnt have time to check everything and needed some info for people who know about autos. Didnt have time to make an s4 code checker since I mostly work on s5s. Will the fact the speedo cable is destroyed have any effect on it? (not sure if they are speed dependent and interact with transmission). I'm thinking it may be a transmission issue still. Could it be that the gear selecter is slipping in and out of gear at low loads? Seems like the load put on the engine when in gear stalls it. Electrical issue or mechanical? I dont feel the idle has a very large part in the car stalling in gear at idle but could be wrong.

Any help is appreciated.

 

With the previous owner saying he turned every screw, that may what induced some of the engine problems. The speedo cable is driven from a gear in the tailshaft housing. If the cable is damaged, it still shouldn't slow down the tranny to cause the engine to stall. Jack the rear wheels up off the ground and support the car with jack stands. Start the engine and put it in gear and see if the engine stalls then. If it does, something in the tranny is siezed or binding and its stalling the engine. Check the fluid level by the book (engine running, cycle through each gear then back to park) to see if its low. If it is, the tranny pump and torque convertor will not operate properly and it will result in severe damage to the internal parts. I don't have the pics any more but I took apart my auto tranny after it ran low on fluid (speedo cable gear came out of tranny while driving, causing fluid to leak out). Shafts and bearings were damaged and it didn't take long for it to happen. I eventually put in a manual transmission.

 

Sounds like a plan. thanks.