View Full Version : RPM bounce?????
So I've worked nearly all the bugs out of my recently purchased, then painted 2002 S6. The only issue I have left is a slight murmur in the RPMs while I'm cruising at different speeds in the low RPM range. It occurs while my foot is just barely on the gas and RPMs just above 1,000. It will bounce around 1,000 to 1,200. I have zero hesitation if I jump on the gas, and it doesn't occur at idle. I just did the timing belt, tensioners, water pump, thermostat, serpentine belt, spark plugs, oil and filter, coolant, and some vacuum hoses. Those weren't done to try and correct the issue, but I was hoping maybe it would fix it. The car has 140k on the ticker, and since I just bought it I wanted to make sure all that maintenance stuff was done.
Any ideas what the RPM bounce is?
sline22
12-07-2012, 07:24 AM
I have the same thing going on. 124k on the clock. I put new plugs fuel filter and coil packs no change. I notice it mostly on decel. Thinking of cleaning the TB next.. I'm at a loss
Scotty@Advanced
12-07-2012, 08:01 AM
Mine does the same.
Audi_Tech
12-07-2012, 10:23 AM
Mine is the same as well
awdjunkies
12-07-2012, 10:33 AM
Type/quality of Gas?
sline22
12-07-2012, 12:15 PM
I use chevron or shell always 91 Car didn't always do it.
awdjunkies
12-07-2012, 01:09 PM
I use chevron or shell always 91 Car didn't always do it.
Even if it's the best gas station out there, sometimes you get a bad batch of gas and the car runs crappy ... Not saying this is your culprit or the OP's, but it is known to happen.
I've been through more than one tank in the car while it does it. Good to know other's cars do it, but I would still like a fix. haha
sline22
12-14-2012, 10:23 AM
Anyone have any ideas of what it could be ? Im pulling my intake manifold next week to do a coolant pump so I'll clean the manifold and TB. I'll give an update on how it turns out
juve021
12-14-2012, 10:27 AM
dirty injectors? fuel pump needs replacing?
sline22
12-14-2012, 10:20 PM
dirty injectors? fuel pump needs replacing?
I've been running an injector cleaner the last 1/4 tank the last 2 times I have filled up. No change yet.
dubthis
12-15-2012, 01:13 PM
Mine does the same. From my research I think it's a torque converter issue. Pressure regulator in this transmission is a poor design resulting in extra strain on the torque converter lock up clutch. Basically what you feel is the torque locking and unlocking which is extremely annoying.
Just a theory but it is documented on the x5 forums as a pretty common issue. The x5 shares the zf 5hp24a trans with the s6 and s8.
khalimadeath
12-15-2012, 01:33 PM
Mine does the same. From my research I think it's a torque converter issue. Pressure regulator in this transmission is a poor design resulting in extra strain on the torque converter lock up clutch. Basically what you feel is the torque locking and unlocking which is extremely annoying.
Just a theory but it is documented on the x5 forums as a pretty common issue. The x5 shares the zf 5hp24a trans with the s6 and s8.
I was gonna say this. I would imagine with a 6 speed it would eliminate this.
Audi_Tech
12-15-2012, 02:09 PM
^^ [up]
Mine does the same. From my research I think it's a torque converter issue. Pressure regulator in this transmission is a poor design resulting in extra strain on the torque converter lock up clutch. Basically what you feel is the torque locking and unlocking which is extremely annoying.
Just a theory but it is documented on the x5 forums as a pretty common issue. The x5 shares the zf 5hp24a trans with the s6 and s8.
I was going to point towards trans, but you beat me to it. Autos are stupid.
sline22
12-16-2012, 12:52 PM
So what are my options if it is the TC? will doing a tranny filter flush help at all? I can't image a torque converter being cheap for that car
awdjunkies
12-16-2012, 10:08 PM
So what are my options if it is the TC? will doing a tranny filter flush help at all? I can't image a torque converter being cheap for that car
Not flush but rather a drain.. In terms of a new filter and new oil? It may help, but if it's on it's last leg then it was bound to die no matter what.. Also people who want to stay with a Tip and want to upgrade their TC/Seal, go through Sam @ 517
( 517trans.com ) or Scotty at Advanced ( advancedautomotion.com )
julex
12-17-2012, 06:19 AM
six speed cures that [:)]
Since engine should be power locked to tranny, the only thing, as mentioned, that would cause changes in how engine is loaded could be faulty TC...or really worn axles/driveshaft that has tons of play and causes output flanges to "bounce" back and forth when the supplied torque from tranny to wheel is about what car encounters as rolling resistance. This would change what engine sees even with locked TC. On poorly tuned 6 speed people are having the same problem resulting in slight jerking of the car which is probably dampened by auto tranny on S6.
Scotty@Advanced
12-17-2012, 07:12 AM
I was getting this behavior with a replacement torque converter.. I recently replaced my MAF and noticed it that no rpm bouncing at low throttle/speeds.
Yeah... I'm going to hope it's not the trans. I'll try cleaning the MAF sensor and see what happens.
*off topic... Scotty, were you able to find those under hood parts for me?
G Men 08
12-19-2012, 05:37 AM
ohh the days.. I had a similar problem in my v8 a6. Drove me nuts. After pulling nearly all my hair out I came to peace with the thought that it was not engine related, as others have said.
desmo
12-19-2012, 07:00 AM
ohh the days.. I had a similar problem in my v8 a6. Drove me nuts. After pulling nearly all my hair out I came to peace with the thought that it was not engine related, as others have said.
What does that mean? you eventually found the problem or you're bald?
julex
12-19-2012, 07:54 AM
What does that mean? you eventually found the problem or you're bald?
"no" and "yes" to these questions [:)]
dubthis
12-19-2012, 05:01 PM
I was getting this behavior with a replacement torque converter.. I recently replaced my MAF and noticed it that no rpm bouncing at low throttle/speeds.
Did you replace/rebuild your valve body? After all its the pressure regulator that caused the issue to begin with.....
I personally don't think this issue is engine related at all. I'll let you know as soon as I am done with my 6spd swap. If its gone its obviously a auto trans issue. Should be complete in a couple weeks.
Scotty@Advanced
12-19-2012, 05:56 PM
Nope in my case it was the MAF.
Trans was new from ZF, converter was my street sauce 2800 rpm stall converter. Replaced the MAF and the problem is fixed, thanks for your input however.
Odd thing was with the cruise control the rpm didn't fluctuate prior to MAF replacement.
sline22
12-29-2012, 03:04 PM
What about a bad o2 sensor or EGT sensor? Anyone had issues with those. I do have a k&n filter with oil that could be missing with the MAF.
G Men 08
12-31-2012, 03:39 AM
What does that mean? you eventually found the problem or you're bald?
lol, I ran out of hair on my head to pick from, so I just dealt with the fact that it was something within the automatic tranny.
ColinGruenfeld
09-16-2015, 12:53 AM
Mine does the same. From my research I think it's a torque converter issue. Pressure regulator in this transmission is a poor design resulting in extra strain on the torque converter lock up clutch. Basically what you feel is the torque locking and unlocking which is extremely annoying.
Just a theory but it is documented on the x5 forums as a pretty common issue. The x5 shares the zf 5hp24a trans with the s6 and s8.
I have verified this with live vag-com logging. I have a 2800RPM stall converter and the vehicle has performed this way since day one. With 55k miles on the transmission, I have had zero additional issues or failures. I believe this to just be a symptom of a higher RPM stall converter in our transmissions (5HP19FLA for the B5 S4, in my case). I just drive in tip mode and wrap the RPMs out to no less than 2000RPM. Instant take-off and no cycling of the TC lock.
I will be purchasing a street sauce torque converter from Scotty / Advanced Automation this week and will see if it happens to cure this RPM/power bouncing/creeping symptom between 800-2000K RPM.. I will be sure to follow up.