Revs Drop Slow

[nuklearmaniac86]

I was referencing my B5 S4, different vehicle though. But I just drove my buddies B6 s4. I see what you mean, revs drop quickly any where above 4k but start to hang at around 2500rpm some kind of bad and drops super slow from there, very aggravating/annoying really. Maybe it is an ECU and DBW issue, bummer.

[loucura]

Definitely something going on here....went for a spin yesterday and shifting from 1st to 2sd, had the issue almost every time. So, step on clutch to shift to 2sd RPM you stay "stuck" at 2k RPM for a second and sometimes I had a feeling it went a bit higher too and then drop like it would usually.

Never had this issue before...started last week. I will try the throttle body alignment, unhooking the battery for a couple minutes, then hook it back up. Then turn the key to the run position without starting the car and let it sit for one minute. Then start her up.

[jrhaze]

You really should be giving it some throttle input when you engage the 2nd gear, otherwise you'll have wear issues over time. And it doesn't have to do with my shifting style, I can get the revs to stick in neutral just giving it a small amount of gas. I originally just thought my throttle valves were dirty, but I was wrong, haha.

I had this problem with the revs hanging even in neutral . . . it turns out it was a leak in my intake tubing after my MAF. How this caused that issue I have no idea, but after fixing the clamp the problem is cleared up.

But, I also have the problem of the revs hanging for a short period when I shift below ~3000 rpms. Very annoying, I'll follow this closely with hopes of finding a solution.

[Sunny4]

I man i totally forgot about this thread till earnhard brought it up. I was suppose to go to the dealer to fix this but a lot of shit happened after getting my car back and well its like 5 months later and i guess i phased it out...mainly by shifting at 3 rpms so this issue dosen't happen. I still think its the ECU thats the culprit but the MAF is a probable cause. Again if a dealer had ruled a solution on this issue and has fixed it, it would be great to find out about it. I can relay this to my dealer and have him fix this issue. If not when i get around to going to the dealer which idk when cause i live like 50 miles away from them and its been a busy couple of months I will post up any solution the try that works or dosen't. Good luck guys!!

[4ever s]

Has anybody found a solution to this problem. My problem is my rpms will hold even after letting off the throttle and engaging the clutch sometimes.

[jrhaze]

Has anybody found a solution to this problem. My problem is my rpms will hold even after letting off the throttle and engaging the clutch sometimes.

Check my reply above as one easy thing to check . . . I had the same issue and that's all is was for me.

[outlaw77]

I just had this problem fixed in my car, its the clutch sensor switch. The dealership just changed mine out for free.

[loucura]

Has anybody found a solution to this problem? I'm gonna have to bring the car in for service because I have to wait until the revs drop to shift and it's very annoying.

outlaw77 had this problem fixed by replacing the clutch sensor switch, others said it could be the throttle body going bad. How could the clutch sensor switch be related to this issue? can someone shed some light....

Also, I don't have this issue when the engine is cold but as soon as it warns up, it never fails..revs hold steady at around 2K rpm when I press the clutch.

[Justincredible]

Im not sure who it was the E mailed me and asked for me to post on this but here you go..


OK

Ive seen this in the past and it can be several issues. I don't see it on a day to day as I have a automatic but my car still does kick up the throttle with out me requesting it.

Here is what I saw in the past when someone brought this up to me at a meet.

First cause can be a MAF that is bad or clogged this will slow the fuel adjustment rate, also you can and will see this with people that have a bad or failing 02

It is normal to have the revs below 3k on non aggressive shifts to hold when the clutch is depressed. Next time you see it happen put the car in Neutral and take your foot quickly off the clutch, then watch the RPM's drop like a rock. The clutch switch pressed in under 3000 seems to effect the throttle position drop off reaction. It looked like the injectors would hold on longer and the throttle would never get below 5% in a 2-5 sec window

With your clutch pressed in, or really its having the clutch switch activated. Rev the car, free rev it. The revs will drop quick till they get to 3000 and then they will slow down, the car has to be warm. All this is in the ECU you can see the throttle open a little and the injectors kick on again for a sec in VAG-com.

Now here is the kicker. You will see the REVs drop slower at 3000 but the amount of time seems to be effected by your speed. Speed MPH not speed RPM. If your rolling it tens to do it more or act longer. Low speeds it will do it more then at a stop and at a point at higher speeds it seems to not do it at all.

If your clutch switch is going bad then this is going to make the car think you still have the clutch in and trying to find the next gear. Even if you don't..thus by extension the car will hold the RPM's for what fixed amount of time I don't know thinking its keeping the RPM's up to help you with a smooth shift.

You can make it better. Putting Dp's on will help but you need to remove the Pre cats, this time not for just performance but it helps stop the back pressure that can make this worse.

Its tough because some people notice this more then others. So how much this or any other fix will help is going to be relative to how observant that person is. The flywheel is also going to keep the inertia going slowing down the free revs as well.

Ok so what does all this mean. Well the ECU does slow down the RPM drop. Not everyone will notice it as much. Also I don't know if its temp dependent. Both on the temp of the motor and the temp of the out side. I can't get it to repeat on ever car the same way.

Some fixes are to look into a new maf and clutch switch if its sticking. Aside from that there is a difference when you remove the Pre cat on the Dp's and obviously when you put in a L/W flywheel..

Ill see if I have time over the next few weeks to get a hold of a Manual and go over this again

[loucura]

Justin, I emailed you yesterday asking for your input..and I thank you for taking the time.

Here's a vid that shows the RPM stuck at 2K when shifting from 1st to 2sd then 3rd. REVs hold steady at 2K then drop and I have to wait until the RPM drops to shift.

MAF has been replaced and it didn't do anything, I also did the throttle body alignment by disconnecting the battery for 2 minutes and nothing.

I just uploaded the vid:

http://www.youtube.com/watch?v=IxbcLJYVmhU

[Justincredible]

Justin, I emailed you yesterday asking for your input..and I thank you for taking the time.

Here's a vid that shows the RPM stuck at 2K when shifting from 1st to 2sd then 3rd. REVs hold steady at 2K then drop and I have to wait until the RPM drops to shift.

MAF has been replaced and it didn't do anything, I also did the throttle body alignment by disconnecting the battery for 2 minutes and nothing.

I just uploaded the vid:

http://www.youtube.com/watch?v=IxbcLJYVmhU

Thanks for the link that helped me find it.

Ok so you can tell there is a throttle bump...not to worry about Ive seen that. So lets get you on the road to fixing it.

lets try to duplicate it and then like I said. Push in the clutch and then when its sticking take your foot all the way off the clutch switch..your foot has to be all the way off

Best to make sure we can reduplicate it over and over and over.

There are several reasons the car will do this, we just need to find out what its doing it to you....but we can get it.

Try the above and let me know...we can move forward from there.

[loucura]

OK, got on the road this AM and it was 43°F outside. Shifting is fine when engine is cold, RPM drops as soon as I press the clutch. As the engine started to warm up, RPM gradually started to hold at 1500K and once the engine was warn, RPM was stuck at 2K every time I shifted.

Justin, i followed your recommendation and after pressing the clutch, I shifted to neutral and let off the clutch and no difference...RPM stuck @ 2K then it drops like a rock.

What I don't get is why it doesn't when the engine is cold.

Again..thanks for your help!

[Woodhead2k]

I only experience this the first couple minutes of driving while the engine is still cold. If you look at your instant mpg it doesn't hit --- like it usually does but hangs in the teens, which means the injectors are still firing so not sure if it's directly related to the fw.

[Justincredible]

Man ok so some get it while the motor is cold and some get it while the car is up to running temps...

Ok we can get this.

So lets move on to this. Everyone posting if you can. Respond to your car and its reactions to some of the tests others are performing. In other words test your car with say the clutch peddal out all the way and let me know what happens

Next test. Unplug the MAF and see if it still happens...when you unplug the MAF don't worry the car will run rough for a small second and then be fine. You will get a Code for the MAF signal (when you unplug it) so you might want to make sure you have a VAg to clear the code.

Try that and let me know if its the same or better

[loucura]

Unplugged MAF went for a ride and no luck....same problem.

[S4DTM]

Audi replaced my throttle body and it definitely made a difference, but lag is still there. They told me that it was an emissions thing, as there is still gas present and it must be released. Dunno, sounds kinda bogus to me, but that's what they said. Anybody try this?...CLICKY

[shaddai]

Audi replaced my throttle body and it definitely made a difference, but lag is still there. They told me that it was an emissions thing, as there is still gas present and it must be released. Dunno, sounds kinda bogus to me, but that's what they said. Anybody try this?...CLICKY

I've heard from other sources (on other cars) that this "holds on to revs" issue is in fact emissions related. Lame, really, it seems more like a safety issue to me. For what it's worth, my old 335i did this too, just not as bad.

As for that sprintbooster thing, I doubt it would work. We're trying to get the revs to drop as we're releasing the throttle, not make the throttle more aggressivly applicated. (shoot me for that sentence, please)

I'd like to see if there's a way to log the gas pedal position (0-100) and the actual throttle body (0-100) and graph out it's response. Perhaps the Vag coms already do this, but I'm too cheap to buy one.

[Sunny4]

Justin,

I have same symptoms as Loucura....only happens after the car is warmed up. I can do some testing as well if needed. Also, I have had some cases...rare...sometimes after hard driving (mostly in summer times, when its hot out)..where the rps actually climb after I push the clutch down...but lets not get into that as that might be a complete different issue. Any progress would be great...glad to see this old thread is picking up.

[loucura]

Justin,

I have same symptoms as Loucura....only happens after the car is warmed up. I can do some testing as well if needed. Also, I have had some cases...rare...sometimes after hard driving (mostly in summer times, when its hot out)..where the rps actually climb after I push the clutch down...but lets not get into that as that might be a complete different issue. Any progress would be great...glad to see this old thread is picking up.

Sunny4, same issue here..after I press the clutch, RPM holds steady at 2k and climbs up just a bit then drops. Please test as well, sounds like we are having the same exactly issue because only happens when engine is warn and no issues when it's cold.

[Sunny4]

When i ment climbed...i ment like 100-400 rpms...almost like its rev-matching but without me touching the gas...that was scary...

[madmax]

I have the same symptoms when the engine's at operating temp. Anyone got a solid fix yet?

[jpo]

I have the same symptoms when the engine's at operating temp. Anyone got a solid fix yet?

x2

[Sunny4]

This I am almost certain is due to the current flash you have. Go to the dealer and ask them for a reflash...it should be one of the TSB's they have. There is a few threads...go to my profile then look for a similar thread with more info on this issue.

[Sunny4]

By flash i mean your ECU

[jhmotard]

i figured this was an issue and i'm not the only one...

my car does not hang the idle when engine temp is cold but rather when at operating temp, it does it in 1st-4th gears. i've tried as much as cleaning the throttle plate. i'll be cleaning my MAF sensor and checking for air leaks.

[SleeperAvant]

Any of you guys get this CEL? http://wiki.ross-tech.com/wiki/index...#Special_Notes

[SquiddyB6S4]

Listen up because I have the answer for this problem, once and for all

Not to be a deusche with the large font, but this is a common question, and you the Audi community need the answer.

This is a feature of the ECM. It can and has been corrected by Audi with an updated flash for the ECM. That update has a few other things attached to it, so that would NOT be my preferred method for fixing it. JHM's ECM tune DOES fix the ENTIRE problem, plus a whole crapload of other benefits. If you have a different tune, stop wasting your time and get the JHM. You won't be sorry.

[Sunny4]

Listen up because I have the answer for this problem, once and for all

Not to be a deusche with the large font, but this is a common question, and you the Audi community need the answer.

This is a feature of the ECM. It can and has been corrected by Audi with an updated flash for the ECM. That update has a few other things attached to it, so that would NOT be my preferred method for fixing it. JHM's ECM tune DOES fix the ENTIRE problem, plus a whole crapload of other benefits. If you have a different tune, stop wasting your time and get the JHM. You won't be sorry.

I agree...but if your under warranty then get the flash from AUDI, other wise JHM is another option...but 550 for a flash...vs free at the dealer...id go dealer and start enjoying the car again.

[SquiddyB6S4]

You don't need to be under warranty. It'll probably cost you ~$125 for an hour's labor plus shop fees, but yes, it's still cheaper. But if you've ever driven a JHM-tuned car vs. one without the tune, you'll know what I mean. The JHM tune IS "go start enjoying the car again" because it feels like a whole different car.

[quattroism25]

I wouldn't say the jhm tune completely resolves this issue. Does it help, definitely yes.

[Sunny4]

From the fan fair on the site, I'm sure its a good product, a bit pricey but small shop, gotta recoup the R&D. But I believe it more a part of an equation involving cat-less/pre-cat downs and x-pipe catback. None the less....i had the crap tune before and I was new at driving stick when I first got the car; after a few months and learning the ins and outs I realized the issues with the drive by wire and the ecu. After multiple visits to the dealer regarding this issues and others they flashed my car on a random visit and it noticed the difference right away. But its up to you.

Squiddy

What did you find out that was attached to the tune? The only think I remember from reading about it was that the flaps on the rear of the exhaust doesn't open...I have an 04 and I think thats the only model that had the flaps on the exhaust.

[SquiddyB6S4]

Squiddy

What did you find out that was attached to the tune? The only think I remember from reading about it was that the flaps on the rear of the exhaust doesn't open...I have an 04 and I think thats the only model that had the flaps on the exhaust.

Attached to their tune is the latest update from Audi, which is probably why the revs don't hang under certain circumstances like before the tune. You could just get the update from Audi, but they'll charge you for it (since I doubt any warranty would cover an ECM update). My '04 does not have exhaust flaps, FWIW. The JHM tune might disable exhaust flaps, but that would only be because you're supposed to have an aftermarket exhaust and downpipes before getting the tune.

[jhmotard]

any update?

was also wondering if an exhaust leak after the main cat connector would cause this?

[dmaxben]

My car did this, only at low rpm, low throttle "around town" shifting.

The JHM tune 99% fixed it. Every once in a rare blue moon it will still do it (even with the JHM tune), like if im putting around in a parking lot and doing a lazy low rpm low throttle % 1-2 shift...it will hang for a second. I just ignore it, since, as I said above, the JHM tune fixed it 99% of the time...

[jhmotard]

My car did this, only at low rpm, low throttle "around town" shifting.

The JHM tune 99% fixed it. Every once in a rare blue moon it will still do it (even with the JHM tune), like if im putting around in a parking lot and doing a lazy low rpm low throttle % 1-2 shift...it will hang for a second. I just ignore it, since, as I said above, the JHM tune fixed it 99% of the time...

thats reassuring, thanks
and just to make sure....did you do anything else to your car at the same time you did the tune? j/w

[dmaxben]

thats reassuring, thanks
and just to make sure....did you do anything else to your car at the same time you did the tune? j/w

no, just the tune.