When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My car is a 2002 WS6 A4 21K miles. I recently noticed that when I lightly accelerate and reach around 40 & 50 MPH the rpm drops & you can feel it lose power and there’s a minor shaking or vibration that lasts for a split second then it’s back to normal, It doesn’t happen all the time but when it does you’ll notice it. I recently had the car serviced (engine oil and filter changed, added a TA performance diff cover and 75W90 gear oil designed for cars with LSD). I drove the car for a few days and it was fine.
I’m sure that it’s something simple but I don’t know where to start.
Its normal that tranny uses a pwm controlled TCC and you are feeling the TCC apply. With that few of miles and depending on how old the tranny fluid is change the trans fluid and filter and then go drive the **** out of it and put a few hundred miles on it. It's had someone who hasn't driven it much and the fluid is aged out and it flat needs to be driven.
Its normal that tranny uses a pwm controlled TCC and you are feeling the TCC apply. With that few of miles and depending on how old the tranny fluid is change the trans fluid and filter and then go drive the **** out of it and put a few hundred miles on it. It's had someone who hasn't driven it much and the fluid is aged out and it flat needs to be driven.
thank you for the above reply brother 👍
I live overseas in UAE 🇦🇪. I’ve had the car for 3 years now, it had 15500 miles back then, To be honest I don’t really drive it that much (1-2 times a week).
I checked the transmission fluid when it first arrived and it was good. I’m afraid to change the transmission fluid due to the car’s age as I’ve heard it might damage the transmission. I’m pretty sure no one changed it from factory.
Is there a specific way to safely change it without damaging the tranny or any other components?
It will be fine changing oil on it that tranny it hardly has any miles on it and the additive package has wore out this is why you feel the TCC shudder when it applies.
Drop pan pop filter out dump pan let it drain 30-45 minutes reverse procedure. Fill it with 4-4.5 qts of whatever flavor you can get over there thats close to dex 6 spec. Start it make sure its at the add mark cold then drop it down and go drive it. Put 20-30 miles on it and then do it again so you will come closer to a full fluid change.
Then drive it a few hundred miles and it will probably be Aok.
It will be fine changing oil on it that tranny it hardly has any miles on it and the additive package has wore out this is why you feel the TCC shudder when it applies.
Drop pan pop filter out dump pan let it drain 30-45 minutes reverse procedure. Fill it with 4-4.5 qts of whatever flavor you can get over there thats close to dex 6 spec. Start it make sure its at the add mark cold then drop it down and go drive it. Put 20-30 miles on it and then do it again so you will come closer to a full fluid change.
Then drive it a few hundred miles and it will probably be Aok.
much appreciated brother 👍 thank you for explaining the process.
Anytime please update with results when completed if you don't mind. It always stinks when guys ask for help then disappear to leave us wondering if the repair or diagnostic etc was successful.
Anytime please update with results when completed if you don't mind. It always stinks when guys ask for help then disappear to leave us wondering if the repair or diagnostic etc was successful.
Got it brother 👍 it’s gonna take a while and I’ll have to put it on hold for now because supposedly there’s a storm ⛈️ coming after tomorrow. And summers are just way too hot to do anything.
luckily, I updated all my old threads, even the ones that were months old.
In order to get rid of the transmission shudder,
I ordered the Transmission filter kit from Rockauto as I wasn’t able to find it where I live. The kit comes with the gasket and small seal as well. Luckily I found the ACdelco ATF Dexron 6 at a Chevy dealer.
I recently noticed that when I lightly accelerate and reach around 40 & 50 MPH the rpm drops & you can feel it lose power and there’s a minor shaking or vibration that lasts for a split second then it’s back to normal, It doesn’t happen all the time but when it does you’ll notice it.
Sounds perfectly normal to me. 40 to 50 MPH and light acceleration is about where the torque convertors' direct drive lockup clutch wants to kick in. Your 'split second' description is when the lockup clutch is engaging. When that is occurring, you lose the convertors' fluid coupling and go into direct drive ( like a manual tranny) with a sense of power loss.
I'll be the naysayer here, I don't think the problem is related to the transmission fluid age. My '98 Z28 has the same mileage as yours (20k) and the only trans fluid change I did was back in 2005 I dropped the pan and changed the filter (it had about 10k miles then). That resulted in only about 4-5 quarts of fluid being changed, which is less than half of total capacity. No other fluid changes since then, as the car is a garage queen that never sees the track. I don't get any sort of shudder or vibration or loss of engine power at all when the TCC (Torque Converter Clutch) engages or any other time in that 40-50mph range.
There's certainly nothing wrong with doing a trans service, in fact I'll be doing another one on mine soon too now that another 10k miles have passed. It won't hurt anything, but I don't think it will solve your problem.
My first thought would be to do some proper diagnostics. I would hook up a comprehensive scanner and watch the misfire counts when the condition occurs, and I would also track fuel trim data before and after. I'm thinking that you might be dealing with a minor misfire that's only noticeable when the engine is lugging at very low rpm right after initial TCC engagement - but I don't think the trans is the source of the problem. If anything is amiss with fueling or spark, it will be more noticeable under the dual condition of low engine rpm and high load (due to TCC being active). Could be anything from a bad tank of gas to lightly fouled injectors to lightly fouled spark plugs or even a plug wire or two that is marginal. Also wouldn't be a bad idea to hook up a fuel pressure gauge and test pressure under load.
I'll be the naysayer here, I don't think the problem is related to the transmission fluid age. My '98 Z28 has the same mileage as yours (20k) and the only trans fluid change I did was back in 2005 I dropped the pan and changed the filter (it had about 10k miles then). That resulted in only about 4-5 quarts of fluid being changed, which is less than half of total capacity. No other fluid changes since then, as the car is a garage queen that never sees the track. I don't get any sort of shudder or vibration or loss of engine power at all when the TCC (Torque Converter Clutch) engages or any other time in that 40-50mph range.
There's certainly nothing wrong with doing a trans service, in fact I'll be doing another one on mine soon too now that another 10k miles have passed. It won't hurt anything, but I don't think it will solve your problem.
My first thought would be to do some proper diagnostics. I would hook up a comprehensive scanner and watch the misfire counts when the condition occurs, and I would also track fuel trim data before and after. I'm thinking that you might be dealing with a minor misfire that's only noticeable when the engine is lugging at very low rpm right after initial TCC engagement - but I don't think the trans is the source of the problem. If anything is amiss with fueling or spark, it will be more noticeable under the dual condition of low engine rpm and high load (due to TCC being active). Could be anything from a bad tank of gas to lightly fouled injectors to lightly fouled spark plugs or even a plug wire or two that is marginal. Also wouldn't be a bad idea to hook up a fuel pressure gauge and test pressure under load.
I appreciate your feedback brother, I do have a faulty fuel gauge which doesn’t read the fuel level accurately & I was told to change the fuel pump to resolve the issue but I never bothered to do so, I just fill the tank every 200 miles or so as I don’t really use the car often.
I’ve never changed the transmission fluid on the car and I highly doubt the previous owner changed it, it currently has 21K miles. at first, I was hesitant to change the transmission fluid but after doing some research I don’t believe it’ll damage the transmission.
after reading your reply you might be right regarding the minor misfire, I’ll talk to a shop I know and inform the tuner to check spark plugs, wires and perhaps mimic the shudder.
Yes, you will be fine changing the trans fluid, it won't hurt, it's a very low mileage unit, but I doubt it'll do anything to solve the current problem.
Originally Posted by d-mob
after reading your reply you might be right regarding the minor misfire, I’ll talk to a shop I know and inform the tuner to check spark plugs, wires and perhaps mimic the shudder.
You could also try running a fuel system cleaner to remove any light deposits that might be present on the injector tips. Red Line SI-1 would be my personal choice, but lots of folks also have great results with Seafoam or Techron.
Yes, you will be fine changing the trans fluid, it won't hurt, it's a very low mileage unit, but I doubt it'll do anything to solve the current problem.
You could also try running a fuel system cleaner to remove any light deposits that might be present on the injector tips. Red Line SI-1 would be my personal choice, but lots of folks also have great results with Seafoam or Techron.
much appreciated 👍 I’ll contact the shop and see what they’ll be able to do. I’ll keep you guys posted.
RPM drop & split second vibration 
