Recently bought an Audi A4 Quattro from a dealer with 112,876 miles on it… The car runs absolutely beautiful, it up-shifts and downshifts without any noticeable issue, it changes gears without any issue, however… When I am trying to maintain a stable speed of around 35 - 40mph and my engine hangs around 1700RPM it’ll bounce up and down slightly… The revvs will hop between 1700RPM up to around 1750RPM and then back down, and then up again… It’s hardly noticeable and the only time it causes any issue/delay is when it hops above 2000RPM and then back down… Is the torque converter the issue or what else could be the cause?
EDIT:
Timing belt has been done, spark plugs have been checked, oil has been changed.
Have you checked the transmission fluid level? If it’s OK then I would check the torque converter inhibitor relay or the torque converter lockup system.
Since your vehicle is a fly by wire throttle…i would go thru the Throttle relearn procedure. First I would disconnect the battery…which forces a relearn anyway. Then i would go thru the throttle relearn procedure manually. See if that fixes you up.
It could also be a wonky tach or tach signal issue if the RPM’s arent actually going up and down with the engine itself. You need to decide for us if the engine RPM are actually changing or if its just a bad reading on the tach.
Blackbird
I have not checked the transmission fluid level, however I was planning on doing that since to my knowledge it hasn’t been done in the vehicle’s lifetime… As for the throttle relearn procedure, I’ll run through that.
The vehicle most certainly does experience the increased RPM however, the RPM doesn’t bounce up and down during idling, or when parked… But it most certainly is revving up and down, the only time it is truly noticeable is when running right at around 1980RPM - 2030RPM… Basically… It bounces over 2000 and then back down.
EDIT: I simply do not know if the transmission fluid has been changed or not, however I’m sure it has at some point… Just not sure when.
Does this vehicle have an overdrive On/Off Button on the shifter or anywhere else that could possibly be malfunctioning and switching the Torque Convertor between Lockup and UnLock?
Just a thought. Thats not an uncomplex tranny in that car either.
Blackbird
Haha no… That it certainly is, it’s quite an… interesting tranny…
Uh… It has the Tiptronic which is of course that semi-automatic function, it has the ‘Sport mode’ which is the closest thing to an overdrive… Basically keeps the engine under a certain number of Revs to keep it in it’s ‘power zone’, but according to some that is controlled by the computer to a point when pressing the accelerator down a certain amount.
Now this issue generally occurs at lower speed and lower RPM, the car shifts beautifully… I can press my foot to the floor and there isn’t any real hesitation or issue with the engine shifting… The only sign that there is anything wrong is when I try to hold my speed around 35 - 40MPH and the RPM bounces up and down.
Wow…that is a strange issue. Its a bit daunting since you have such a complex transmission and you also have a “Fly by Wire” throttle…with no mechanical connection between your accelerator pedal and the throttle proper…its all remote controlled and uses an electric stepper motor to open and close the throttle. 50 Rpm’s is pretty specific and you seem rather sure of that number which tells me that you are paying attention. I really cant answer this one except but to postulate on it.
No mention of any Trouble codes to go on either. I would have to suggest you hit up some of the Audi specific forums that deal exclusively with that make of vehicle. The people who attend those forums usually possess a wealth of knowledge on their favorite make of car…and together they hold an enormous amount of knowledge…Yeah…I would hit those places up and post the same question. This could be a known issue or bug and they may have a fix for it.
I would like to also recommend a Throttle body cleaning using a rag and some TB cleaner spray…spray it into the TB…but more importantly saturate a rag with it so that it doesnt evaporate so fast and has time to work and cut thru the carbon around the butterfly valve…you will need to hold the butterfly valve open…I like to use the plastic handle of a screwdriver for this…or something similar and wipe out the TB as well as the butterfly valves edges…
Then spray off the MAF sensor to give her a quick cleaning…then see how she goes…still the same? Hit up the Audi Forums…got nothing to lose.
Blackbird
I guess it’s unlikely that the trans is just plain hunting, at a speed where it can’t quite decide which gear to be in?
Thanks for the advice Honda, I’ll have to check it out… I’ll probably end up bringing it into Audi and just see what they find in an inspection.
Also… I’m not sure Auto-Owner I guess that seems unlikely to me considering the sheer complexity of the transmission.
I briefly thought the same thing but then I caught myself. If it was “hunting” then the variation in RPM’s would be much larger than a fluctuation of only 50. There are no two gears that are next to each other that would yield a discrepancy of 50 Rpm’s only…it would be like 500-750 more or less.
Blackbird
Yeah exactly, this is such a miniscule change… It ONLY happens at right around 1700 - 2100RPM and ONLY happens at 30 - 40MPH… Basically any higher than that and it’ll remain steady, and any lower than those speeds and it’s steady… It’s really odd.
It can be the stepper motor on the throttle body…That motor has to control the butterfly for the air intake/throttle… and guess what position is most often finds itself in? Yup…right at the 1700-2100 range… The stepper motor might be having issues or wearing out and not knowing that it is already in the proper position…but cannot tell because the stepper motor stepper system isnt giving the motor a good reading on its position…
This must be looked into…as this entire problem has this throttle motor as one of the prime candidates… The other candidate is the accelerator remote controller
Welcome to “Fly by Wire” issues… I will take a throttle cable ANY day of the week thank you.
My GTi has the same system and I have been afraid of it almost constantly…Im afraid I am going to “will it into failure” sometimes
I forgot to mention!!! When you own a newer Audi or VW product…you MUST buy the VAG-COM System…this is the software and Hardware that allows you to diagnose and check the Audi/VW vehicle Systems… You can look much more deeply into error codes…you can switch solenoids and relays on and off to test their operation…change Maps and other parameters that you can get into big trouble with…and more
The VAG-Com system is an absolute must if you are going to be a DIY guy in the Audi and VW world…its like flying blind without it. Since there are now 4 Audi/VW’s between me and my friends we all decided that we need to invest the money in the system… Now we will be able to diag and repair those vehicles much much easier. If you are going to work on this vehicle yourself…or just want to have a leg up on any garage or shop…you need the VAG-Com…What do you think the garage will be using?
Check it out http://en.wikipedia.org/wiki/VAG-COM
These are available second hand when owners sell their vehicles. You can find them on Ebay for anywhere from $150-300 DO NOT BUY the cheap knock off versions of this system. Even today I am still confused on all the different flavors of the system… Is it just the cable I need? Or do I need the cable and the software and the license keys etc? All of the above? I do know that you should not buy the “El Cheapo” style of cable that costs 12 bucks or so… Its worth the 150-300 all day long …when you repair your first issue it pays for itself.
Blackbird