Clutch delay switch defeated = joy!

Greetings folks - my wife and I just purchased our '07 Boxster S 2 weeks ago and I've been educating myself on everything I can get my hands on with this particular forum being most useful. My issue is simple - during low loads (feathering the clutch up a slight incline or away slowly from say a drive through) I have a distinct metallic rattle/tink coming from the rear of the car. Initially it sounded like a loose exhaust clamp to me, but I finally narrowed it down to the clutch last night. It is very noticeable when backing up out of the garage, or where sound will be echoed back (parking garage, alongside a wall, etc). I can replicate the sound 100% of the time by doing this : - car started and idling - transmission in neutral - clutch in, slight revs (800 to 1200 rpm), so just above idle By contrast, if I rev gently in neutral from idle without touching the clutch, all is buttery smooth. But if I depress the clutch, disengaging it, just 100 revs up from idle and through 1200, there is a very distinct metallic rattle sound that actually sounds much more like exhaust noise than flywheel chatter. If I hold revs at say 1,000 and remove my foot from the clutch, the sound slowly goes away. Clutch back in while holding revs at 1,000 and voila, sound is back. It doesn't happen any other time during driving and shifts are wonderful direct and smooth, so I've attributed it to just being a quirk of the car and not a real problem. But in the past few days it seems to have gotten louder and I'm uncertain that it's not a symptom of something else. The car has 3,800 miles on it - 2,800 of them put on by a previous owner (we purchased the car from a dealer out of state). My first gut check is that the previous owner was a "clutch rider" and the throw out bearing is in less than fantastic shape. Usually however, a bad throw out bearing will squeal a bit and vibrate when clutched in, neither of which happen in my case. I guess I'm looking to see if anyone else also has this sound with their car before dragging her up to the dealership. I've lightly lubricated the connecting rod on the transmission (shifter linkage) as that was rather "klinky" with the amount of play it had. I've read up on the clutch slave failures and pressure plate bolts and while I haven't ruled those out, I don't think that's the case (I intend to bleed the clutch this weekend which will give me a chance to inspect the slave mounting and snugness). My car was built in January of '07 so it looks to be a mid-year build. If I'm honest, it almost sounds like an engine control version of BMWs much hated CDV (clutch delay valve). Various new Mazdas employ ignition retardation when the clutch is depressed to smooth out shifts (and preserve clutch life). I wonder if perhaps Porsche does something similar? The next time anyone is backing up out of their garage, roll down the windows and give this a shot. Maybe they all do it, or maybe I need to meet my Porsche service advisor for the first time... Cheers!

Do you have the PSE ? Could be the valves in the exhaust system which open/close to produce a louder exhaust ? Just a guess.

Nope, no PSE on the car. I did wonder if perhaps the vacuum hook up point for the car had come loose, as I imagine the 2007+ cars have a connection point capped if you don't have PSE , but I'm unsure of where to look for that.

I explored some more tonight and I'm even more uncertain now about what it is, or what's causing it. It's the exhaust note changing for certain - nothing mechanical is rattling or loose. The same criteria applies in testing...clutch in, slight revs (or slip the clutch as you would when climbing a slight incline) and it's there and impossible to miss. Not the sort of note you want your new instrument to blare. The best way I can describe it is....flat flatulence. The exhaust note on these boxers is fairly unique as it is, and some have referred to them as flatulent to begin with. But to my ears, when it's idling or in neutral (or of course at full song), it's a symphony and harmonious. The flat tone while slipping the clutch is certainly not normal. Also, it's a narrow window. Idle = fine. 2,000 revs = fine. Anything in-between results in our new little gal cutting the cheese... So, I'll keep looking. I noticed tonight that relative to the other cars in the stable, she was quite drippy when cold...a bit of exhaust vapor condensation when cold (rich) is normal, but I had a small puddle pouring out the back of the exhaust tips tonight when looking once again. The other cars may bead a bit on the tips, but nothing even close to what the Boxster is producing. Curious...tank of bad gas perhaps, but we're on our 4th tank now and the sound has been there more or less since we brought her home. No codes either (code reader handy) - so if it's a cat on the way out, or perhaps something with the air injection pump, it hasn't gotten bad enough for the car to throw a flag. I'll post what it is when we discover it for posterity.

I had a nice little "Eureka!" moment this evening and thought I'd share my findings. First though, a quick history lesson. My wife owned (briefly) one of the new MX5 PRHTs. Fun little car, but not our cup of tea. One of the first irks we discovered with it was that there was a rather peculiar amount of throttle lag post shift. This was very noticeable on brisk shifts from first into second under WOT. It felt like the car was holding back a bit for say a 2 count, then giving you what your right foot had originally requested. When really stomping the loud pedal from a dead stop, you felt it on the fist 3 shifts and it drove you MAD! It felt this way, as it turns out, because it WAS this way. In an effort to extend the life of the clutch (and by association the entire drivetrain in general), Mazda engineered a software version of BMW 's infamous CDV - clutch delay valve. The clutch in the MX5 triggered two switches. One switch, at the bottom of full travel, to indicate that the clutch was fully depressed to allow the car to start. A normal feature on all manual cars. But the second switch was the culprit - it resided at the top of the clutch arm and was always "IN" when the clutch wasn't depressed. So, when you pushed the clutch in, this switch would release "OUT" and the ECU would slightly retard timing for just under 2 seconds. This made for smoother (though laggy) throttle response from a dead stop in 1st gear, smoothed out the throttle uptake post shift for most drivers, and in, theory added life/miles to the clutch. So WTF does this have to do with our 987?? I'm getting there...let me put this whiteboard away... Our 987 has exactly the same arrangement as the MX5. I searched here and abroad (googleahem) and found nothing relating to this topic, so I'm bringing it up here in as much detail as I can muster at 4am. It took me 30 seconds to verify that this is what I was hearing (as described in my first post) once I had the switch removed. Press the switch pin in while holding RPMs at 1,000 and the engine sounds (and is) normal. This is the state that the clutch is normally in (foot off the clutch, pushing this second switch pin IN) If you release the pin however while holding 1,000rpm and "Braaaaaappppp" - note change. Timing change. It lasts just at or under 2 seconds. In the MX5, disconnecting this switch (or taping it shut to be always IN) resulted in a CEL after 50~80 miles. Nothing major, just the modern cars way of telling you that something was amiss. My scan tool resulted in, yup, "CLUTCH SWITCH ERROR" on the MX5 which was easily erased and reset. In that car, where HP and response was much more dear, it made a world of difference and was worth the slight inconvenience of having to hook up the scan tool every so often. In fact, I'd say that the acceleration times that magazines posted for that car were nigh impossible without having defeated the clutch delay switch. It was THAT intrusive in those first 3 upshifts under full giddy up. In the 987, I'm guessing it will do the same (throw a CEL over time) but if we're lucky it will throw a soft code, store it, realize that it's not the end of the world and not trigger a CEL. I drove 25 miles tonight with the switch taped IN (to replicate what position it is in during normal driving). As expected, the difference is dramatic. The flat engine note "Braaapp" when leaving a light in 1st gear with the top down (obviously a Boxster here but windows down in a Cayman would be very similar) is gone. Throttle response is very quick from a dead stop, which takes all of 4 stoplights to readjust to (to compare, think of non-sport to sport mode throttle response and it's similar). Before the switch defeat, I had subtle but noticeable delays on moderate (low speed) low RPM shifts that are now gone. In my case, this always happened right around 3,000rpm under normal driving conditions (not too slow, and not having fun either) and because it was rather consistent in this regard, it felt like a brief surge or hiccup when it happened. What I was feeling was the clutch delay (just under 2 seconds). So, to illustrate, you'd pull away from a stop in 1st gear, accelerate up through say 3,500rpm, shift into second, revs falling to 2,300 or so, and as you accelerated through 3,000, right at that point you would get what felt like a slight hiccup or surge. This didn't happen all the time, but was quite noticeable when it did happen. As with the MX5, that brief hiccup or delay is gone making for very linear, smooth throttle take-up and response, post shift. I have a rather sensitive backside and if you're like me, you'll appreciate this change. Anyone who owns (or has owned) modern BMWs and has performed the CDV-ectomy will know what this feels like, pre and post. The advantages for me are simple - the embarrassing and annoying "braaaaap" is gone, making for much more enjoyable 1st gear starts (as well as driving up any inclines, parking the car, backing up, and so on). And, of course, linear and smoother shifts. The disadvantages for someone doing this are perhaps a slightly lower life expectancy of the clutch, the possibility of a CEL (check engine light) and/or stored "CLUTCH SWITCH" error and, quite probably, the lose of clutch triggered cruise control deactivation. If these things bother you, this probably isn't something you want to try. But if you want to try a 30 second experiment to see how your car feels with this "feature" disabled, it's a piece of cake, and just as easy to restore if you don't like it. To have your own little Eureka! moment, poke your head down in the footwell and peer up at your clutch pedal. Operate the pedal and observe the two switches - one beneath the clutch arm, and one at the top of the clutch arm. The one beneath the clutch arm will be pushed down (IN) as you push the clutch in. This switch is the "Have you pushed the clutch in yet, you sod?" switch before the ECU will allow you to start the engine. Ignore this switch. The reddish switch at the top of the clutch pedal is the one you want. By pushing the clutch in, you will observe the pin releasing OUT as the clutch pushes in. When the clutch is up, the pin is pushed IN. The switch module is a sort of terracotta/red color. If you grasp it and turn it gently anticlockwise, you can remove it from the bracket holding it in place. You will see the pin is now out. All you have to do is tape that pin in (I wrapped mine end over end several times with black electrical tape) - you can use a zip tie or rubber band as well. Once you've taped it down, you can simply snug the whole bit behind the carpeted fuse panel surround trim (if you've done the Mods4Cars module, you know which panel I'm referring to). You can also probably push it back into the bracket, but this will weaken the tape in the fashion it was wrapped around end to end. Alternatively you could probably just disconnect the harness wired to this switch, but in the hopes that the switch being plugged in, just simply not used any longer, will not result in a CEL. Unplugging it may result in a CEL straight away. Anyhow, if you're bored or curious to see how your car drives with this "feature" switched off, have a go and report back on what you find. I quite like it and intend to keep it this way, CEL or no. I'll simply keep my pocket scan tool in the door cubby and clear the code as needed. But here's to hoping that it simply stores a soft code and won't light up the dash after 100 miles (25 miles so far and no CEL). What would be grand, if I may dream for a moment, is for someone like Scott at Softronic to see if it's perhaps possible to // this particular switch activity altogether, or perhaps ignore the error message (if generated) by having it disabled. Keep in mind that this will make the throttle snappier off the line, so if you're clutch uptake challenged, this may frustrate you more than tickle you. On the other hand, if you enjoy full control over the tactile and feedback heavy controls of your car, you will quite enjoy this tweak. For me, it's a 50/50 affair...50% of my joy comes from no longer having the flatulent flat "braaaap" when parking/backing up or leaving a stoplight. It's not the most pleasing tone in the world and now I'm left with that glorious flat six arrangement, sans drunk trombone player. The other 50% of course comes from having linear throttle response post shift(s). Apologies for the lengthy post here, but I figured I'd better explain myself if I was going to offer up a solution to my own question and go over the "why". Cheers!

I posted a complaint/question regarding the flat "braaaap" I was getting with my 987 Boxster S . I discovered the cause of it and posted here - I figured I'd create a new thread with a title that actually captures the crux of what it was, versus my original post "Odd clutch rattle" Link to original post... http://www.planet-9.com/cayman-complaints/25405-odd-clutch-rattle.html#post285624

Pictures? Do you have sport mode and did you try it in sport mode vs non-sport, I am wondering if in sport mode the ECU ignores the switch because I don't seem to get the effect you are talking about in sport mode but I'm curious if that's just in my head and it would be even more responsive with this modification.

I merged these two threads - no sense having both floating around on the same exact subject. People who posted to the thread will be looking for the same title. brad

Nope, sport mode doesn't ignore the switch functionality - I have the Softronic flash with sport mode on all the time and the switch continued to function in spite of it. I'll snap some pictures and perhaps whip up a 5 minute article on this - currently, the thread title "Odd clutch rattle" may not draw in folks interested in learning about the clutch switch and how it functions and I don't think I can rename the thread title....

Changed title... brad

omg I'm going to try this immediately. I absolutely hate the lag/delay/sound whatever it is in the Cayman when you try to go up ramps and inclines in first gear. I have to go up and around 2 levels of underground ramps on my way out from my garage everyday, and it is hugely annoying. When feathering the clutch up the ramp (sometimes I have to stop for other traffic) the engine feels like it has about 45hp or something!

Give it a shot and post what you think. The difference is immediate and very noticeable to me. For what it's worth, I'm up to 60 miles without a CEL or stored soft code. So far so good.

Excellent! Thanks Brad! :cheers:

I find this thread very interesting but I thought of a quick question. Since you mentioned this could shorten the life of the clutch, do you think that there would be any issues with trying to cover warranty repairs? I think the clutch should be a covered item should it have major issues in a low mileage vehicle.

The clutch is considered a wear item and is not covered under warranty anyway unless it's due to a covered failure ( e.g. clutch slave cylinder) or Porsche is covering it as a "good will" replacement.

Done mine and have covered 100 miles with no faults showing. The car seems better and the only downside was stalling twice at traffic lights.

Nice research. I previously thought the "braap" was the oil scavenger.

Cleared 200 miles today - no CEL and no stored codes so far. Throttle in sport mode with AC on full (105 Dallas heat) = touchy. You get used to it, but from a dead stop the throttle is now linear and sensitive meaning your immediate instinct is to back off when revs rise too rapidly (happened to me, too).

Very intrersting... do you think this has a noticable difference on acceleration? 0-60 times would be improved? Thanks for posting this!

Thanks again Nexus-6, I agree you need to adjust a bit from a dead stop but the end result is all good. J Cay asked if 0-60 time might be better and I would say yes what do you think ?

Nexus-6 BTW I made a plastic cap that is .430 long with a .417 bore and it will slip over the pin and slightly press on to the switch body below and holds the switch in the depressed position and then there is no needed to tape or even take the switch out and with this cap you can do this mod in 20 seconds or less and reverse it the the same amount of time. The cap fits in a position so the part of clutch pedal that makes contact with the switch pin does not touch the cap so repeated clutch pedal operation will not effect the cap and it's funtion. To show thanks to you for your post on this mod you may if you so choose send me a PM for one free cap .

Elmo, That sounds like a fantastic and elegant solution! I'd be tickled to take one of those caps - PM on the way.

Two points : 1. With the mod, cruise still deactivates if you dip the clutch 2. I noticed that there is a red plug which fits into the back of the switch. Instead of capping of taping the switch, if we disconnected the plug would that mean the car would think the clutch was always up or always floored?

So...is this the REAL reason why the car is so stall happy? I have always felt that it was odd that it took so many revs to pull away from a stop. Without exception, parking attendants stall the car. Read this: http://www.zeckhausen.com/CDV.htm How is the switch under the clutch involved with this? (I know this is a BMW...but how is ours different?)

Excellent news on the cruise feature still working. Hadn't gotten around to trying that. I'm guessing that unplugging the switch, versus tricking it via tape (or caps) will throw a code for certain. With the circuit completed, even if it's not functioning correctly, it seems not to care. I'm guessing, though of course not 100% certain, that unplugging the switch = incomplete circuit = CEL or code.

Having owned 7 BMWs in the past several years, I've become rather familiar with the CDV method they employ (note that familiar and fond are very different things!). Defeating or removing it in each one meant a world of difference. In fact, with more than one it meant the difference between being able to drive without thinking about it (as all of us old fashioned manual lovers like to do) or constantly trying to avoid stalling the car or jerking shifts under normal driving conditions...devoting cycles to a process we would much rather take for granted. Simply put, the BMW method (Clutch Delay Valve) is the mechanical way of doing what Porsche, Mazda and others are doing in software. The CDV is a narrow portion of the clutch fluid line, just before the slave. And by narrow, I mean it's a pin hole - what happens is that fluid is passed through here more slowly than it would in a proper size tube. This means that your input (clutch has been operated - all done!) isn't 1:1 with what's actually taking place. A fraction or two later, the clutch, now delayed by the slowly returning fluid in this narrow portion, engages the flywheel completely, but not at the moment you complete your portion of the equation. I will say that a sloppy driver will find a CDV-less BMW very tricky to drive smoothly, especially if they had previously become accustomed to the "help" the CDV was providing. Smooth and experienced drivers will appreciate that the clutch pedal will actually directly modulate where the clutch disc is at in the operation. Most folks that defeat the CDV so they can actually shift quickly at redline without the slight (but measurable) delay the valve creates. In other words, folks often do it so they can chirp 2nd gear. Others (like myself) do it simply because our brains are wired from past years of driving to expect that the pedal on the left there directly modulates the clutch, and thus the smoothness of our uptakes post shift. To have it modified slightly puts our brains off just a bit. If you're the sort of person who loathes understeer, the CDV is the sort of thing that drives you bonkers. You want immediate, direct and expected results from your actions. Anything that interferes with or lags that, well...it bugs us is some deep ways. I have no idea if Porsche involves more than just a software version of the clutch delay by employing that switch (they may use it for other things...as a feedback loop, it's a pretty solid example...to the switch, the clutch is either out, or in and this data could be used for other things I imagine).

I just tried this mod and I can tell you the difference is night and day....not dusk and dawn but night and day...especially in first...my foot and clutch now work in unison...before I thought - "now I know I haven't driven a manual in quite some time and that I was rusty", taping up this button I now think...hmmm my skills weren't so bad after all. I don't know whether to leave it or try to get used to Porsche 's high revs to move out of first. Really what's the real harm...and why is this there in the first place.

Man I'm getting tempted to try this out... like saucerman, I'd appreciate a discourse on what any harm would be. The sluggish clutch engagements and the brraapp, especially accentuated with the AWE exhaust when in parking garages, really makes me want to do this.

Hey,Nexus-6 Got your PM and cap is on it's way.

Now I know what that sound is. The dreaded "brraapp". I am giving this one a try.

In my opinion, the reason these measures even exists is to lengthen the life expectancy of the the clutch and drivetrain in general. If you can eek out another 15K miles before things need replacing (given that the clutch is a non-warranty item, but transmissions are covered and are quite pricey), well then you pad the bottom line a bit more. In other words, I'm guessing that clutch delay devices in general are, foremost, pushed hard for by bean counters. The marketing is "smoother shifts!" but the reality is "less wear!" which means less $$ spent covering "blowed up" transmissions in the real world. And honestly, for most drivers it's not that noticeable so it makes the case pretty simple for car makers in general. Case in point = my wife. The only difference she detects is that the car is touchier from a stoplight. But she may drive the car, at most, 2/10s at her friskiest. For her, and for many, the difference is almost imperceptible. For me though, it was night and day...and got rid of the flatulence! It's my understanding that you can more or less beat the living !@#!@ out of a BMW with CDV (high rev clutch dumps, power shifting, etc) and within reason, the CDV does a good enough job at protecting the clutch, flywheel, trans from shock that you can't really do much harm. Without it, that safety buffer isn't there to absorb the shock if you're brutal with the car. My point in all of the above is that I don't believe there will be any harm whatsoever in disconnecting the switch (or defeating it) short to medium term for folks who don't abuse their cars. Long term (and by that I mean 75~100K miles) I can imagine more clutch and flywheel wear without the switch operating, but for me, that's of no concern as I doubt that my 987 will ever see more than 40K during my ownership. If it does throw a CEL or store a code at some point, that could be a nuisance to deal with, but it's a simple task to erase it - and, touch wood, she hasn't thrown any codes in 200 miles as of this evening. If anyone is concerned about warranty work, you can always remove the tape (or cap as Elmo has devised) and you'll be back to normal in less time than it took me to type this sentence. Of course it should be stated that I might be talking directly out my rear end here as I'm not an engineer for Porsche , but I'm relatively confident that it's the same line of thinking as BMW and others (extend the life expectancy of certain expensive to replace/fix parts). The comparison to variable rate steering is spot on - I had to fight tooth and nail with my sales guy a few years ago as to why I didn't want it on my 335i, and felt oddly out of place defending my preference for direct and precise interactions, sans assistance. He finally let up when I used the (lame) statement "It's the ultimate driving machine, right? When did they begin selling the ultimate parking machines?"

Would it be possible for you to post a picture or a how-to for the group?

Hello, Nexus-6. You rule, man. The CDV mod was the first functional change I had done to my ordered E90, done in my first week of owning it. I still have the E90 and I can't imagine driving it with the CDV. No regrets! Now in my third 987 car, I am anxious to feel the equivalent improvement in it. I will consider the implications of doing this mod (warranty, really) before doing it. But I foresee trying it soon. Finally, I understand why I can almost never do the little K turn (required to park in my carport) without goosing my neighbors. The Tubi exhaust accentuates this, of course, so I thought it was at least partly to blame. The poor, innocent Tubi, maligned and misunderstood. Thank you! :cheers: Snaxster

Thanks- did it. I always wondered why no amount of throttle could affect the bogging situation. I always figured I was slipping the clutch way too much and all that time it was awol!

I took some pictures of my switch for those interested: This this looking straight up from the footwell directly above the clutch pedal (i.e. the pedal is directly below the bottom of this image.) The switch is roughly terracotta in color, which matches my interior nicely! To remove it, simply turn the whole switch counter clockwise, and back it out through the bracket its mounted on (back towards the driver's seat). It comes out with very little effort. This is what the removed switch looks like: There is a connector on the back that attaches to the switch with two small plastic clips. You can spread the clips with your fingernails and then simply pull the connector off the switch. The connector removed looks like this: Since I don't care for sticky tape much, I opted for the electrical bypass. A small piece of wire with the ends stripped, stuffed into the two sockets on the connector will do the trick. Looks like this: When the clutch is disengaged (your foot off the pedal), the switch is closed (completely closed; I measured it). When engaged, the switch is completely open. The wire you've shoved in the connector will keep the circuit closed all the time. There won't be an CELs with the switch removed. Just tuck the jumpered connector up under the dash and either take the switch out of the car completely or put it back in the bracket (with the connector disconnected and jumpered). -- Sam

Suneet.... go ahead and try this....I just used a piece of duct tape at first...didn't even bother with taking the switch out of place...took me all of 30 seconds and was out the the driveway...as soon as I put her in first I noticed a difference right away...I was pretty much in awe that a simple mod such as this dramatically makes a difference.

Looking in one of the parts catalog the switch may be represented by figure 16 in the Section on Hand Controls and Pedals the PN is 997 613 109 00. Two comments: First, the picture of switch does not look like switch in photo (just an observation). Second, the application is for model I480 (I480 = 6 speed) does anyone with a 5 speed have this same switch or is it a 6 speed only application? Being a 997 PN seems to imply that 911 model also uses this switch. Question: Since this is an electric switch, how does it delay clutch? or effect engine RPM? In BMW it is a hydraulic restriction (metering orifice) thus limiting release rate of slave cylinder - therfore clutch engagement rate.

I think it accomplishes the goal of a CDV by retarding the engine. So you can let clutch go as quickly as you want, but the engine won't be developing any power...so it does nothing to delay the clutch...it softens the blow to the drive line components by reining in the engine. But I am speculating.

I hadn't driven a manual for many years before picking up my CS and although its always been very drivable, I've consistently felt a disconnect between myself and the clutch. I really want to give this a shot to see the difference, and even though I don't do many mods myself this one seems completely within my realm of difficulty. For those of us who are less mechanically inclined (as in myself ), the pictures showing your electrical bypass there are 4 copper connectors, how can you determine which 2 to short out to disable to clutch delay?