Silver_TT

With respect to your comment "But N to 1st often needs a throttle blip to allow the teeth to engage at all" and general issues regarding shifting, especially in 1st and 2nd gears, you might want to read up on the following link. It's not only for pop-outs (that's the extreme case) and you should not be having any trouble with 1st or 2nd. They should be just as smooth as 3, 4, 5, and 6.

http://www.gboxweb.com/detent.html

Also, disagree that these transmissions are not good. They are good transmissions but you have to be careful with them and only use the OEM spec fluids, etc. They are not forgiving when you don't.

Silver TT, these transmissions are not bad they are just not as good as the G50 made by Getrag. I have just finished a 1 and 1/2 year experiment using 5 different transmission oils in my car through all the weather conditions we have up here in New England and I will be posting a DIY on transmission oil changing including all of the results of this experiment. It took so long because I had to use all the oils in winter conditions and it took two winters to get them all in. In most circumstances but not all, Millers is the best and my personal favorite. But, you are welcome to chug along with PTX. That is why Howard Johnson's made 28 flavors.

A34735, when someone tells you something that is wrong they are full of it. I myself have been full of it on occasion. I am with you on the voltmeter but the water temp gauge is important. As you have noticed there is a lag between oil temp and water temp. This is because the oil is down in the sump where the water is hopefully not. Going the other way, if your car starts to over heat, under some circumstances you will see it sooner in the water temp

Wouldn't ever think of putting anything but the OEM PTX in the gearbox. I have first-hand experience with the damage this will cause. $6K for a gearbox rebuild, or you can buy a reman from Porsche for $10K (before labor). The OEM PTX is an oil which is unique in that it literally has properties that no other oil has. Using the non-OEM will cause wear inside the gearbox over time (some people notice right away, in other cases this can take many thousands of miles). A lot of things people do with their cars I think are obsessing more than anything else, but with this topic I know first hand that if you use anything but the OEM gear fluid, you're asking for trouble.

How are you sure there was no problem ever before you got the car? I don't see how it's possible to know this for sure unless you know the previous owner personally and trust them. The problem should have nothing to do with the lower temperatures where you are, etc, which means if this really only first happened right after you took possession of the car, it's a pure coincidence. As a matter of fact if this is an electrical problem, which we already mentioned to look at closely, these usually get worse as temperature gets higher (aka increased resistance) -- NOT as temp gets lower.

Get a new loaner DME if you want. The memory on these cars can be flashed and reflashed over a thousand times and it would take a lot less work than swapping out the DME, but you can do it either way. I don't see how if a new loaner DME solves the problem though you think this points to a hardware fault in the current DME you have. The odds of you having a hardware fault are pretty low (unless your car has specifically been flooded or had moisture in it, etc). The odds of behavior like this due to a flash, regardless of the tuner's reputation, is much more probable. Not saying the flash is for sure your problem, but I've been down this road. I personally would never run a flash because of the issues it can create.

With respect to your comment "But N to 1st often needs a throttle blip to allow the teeth to engage at all" and general issues regarding shifting, especially in 1st and 2nd gears, you might want to read up on the following link. It's not only for pop-outs (that's the extreme case) and you should not be having any trouble with 1st or 2nd. They should be just as smooth as 3, 4, 5, and 6.

http://www.gboxweb.com/detent.html

Also, disagree that these transmissions are not good. They are good transmissions but you have to be careful with them and only use the OEM spec fluids, etc. They are not forgiving when you don't.

This subject is an area which I've learned more about than I wish I ever had to. You're not going to want to hear it, but JFP is right. Trust me on this, if you're sure your wiring is all in good shape as Loren alluded to (each cable in the series to needs to be tested so check and double check the work on this, there have been some good write-ups how to do it), and you're still having these "random" issues and it's telling you it can't communicate with the DME, for example, I would definitely go back to the stock flash immediately to see if your problems go away. It should be very easy to re-flash to stock to test this. Takes 5 mins with a PIWIS. Literally. Or if you live close to your tuner, most tuners keep stock flashes on hand and some tuners even allow for switching between stock and custom tunes with a device (Revo SPS comes to mind--biggest piece of !@$% ever by the way, I hate that company with a passion).

I don't think PCNA is going to be much help. They are going to tell you that it's not their flash and you have molested the OEM state of the vehicle and your warranty is void. Running these myriad of aftermarket flashes can cause all sorts of headaches not limited to this. You're taken a known, tested, proved software configuration and modified it. As with any kind of software, just like on a PC, there are millions of things that can go wrong when you make just one little change. This is why it's so key having a configuration that has been tested so heavily, like the OEM stock flash. No tuner can match that. What I have seen first hand in the tuning world frankly scares the daylight out of me. People put faith in these guys like they are Gods and it's really not like that. I have first hand experience with similar types of issues and going back to stock fixed the issue immediately. Also, for what it's worth, I never could tell the difference with the tune off. She still ran like the wind.

Kind of hard for me to see what's going on in that picture you have in the .pdf. I have edited Loren's photo and drawn a black down arrow showing you where the relays are. If you just unscrew this panel (should be held on by just a bolt or two) and flip it over then you will see what's shown in my second picture. I have circled the fuse you are looking for in red.

If you removed the rear panel, you will see the metal plate as shown in Loren's second picture. The relays are bolted to the underside of that metal panel.

Right. Loren does have a very relevant point. Part has been revised multiple times, makes it less surprising. Should be a free replacement under warranty as stated.

To clarify your question about the fuel system, as I mentioned, this very possibly could be related. Should be no hesitation under load with the 996TT-- quite the opposite.

Wouldn't have anything specifically to do with 2nd gear but, yes, if the fuel system isn't properly delivering fuel then you would experience a "break" or interruptions, especially under heavy load (acceleration). The engine needs properly delivery of fuel to run optimally.

Very good points about the larger K24s on the X50.

Just my opinion, but I would not use an ECU tune to try to address this.

Yes, please post updates until you are 100% sure you have solved the problem. Too often there are good threads like this that end with the original poster never following up with a conclusion.

+1 CPS

What specifically do you mean by "turbo lag". My entry into the Porsche world is pretty recent, starting with the 996. But my understanding is that turbo lag was more of a thing of the past. For example, my 996TT never really needed much time to spool the turbos and get power. As soon as you step on the gas, it gets violent extremely quick. Do you have ECU tunes on the car? Or are the only mods you have what you stated? The 996TT (x50 especially) has tons of power and you should not be experiencing much lag compared to other turbo engines.

Very sad story, I'm sorry to hear that.

Jpflip, I was not surprised when I read it was you that was helping someone work through this issue after I first found this thread. Thank you for the contributions of your knowledge you have made over the years on this site (and others). This site is much stronger because of a handful of people specifically, and you are certainly one of them.

A lot of folks gap the Bosch FR6LOC plugs around ~ 0.028, but I would stick with spec in my own car. Certainly sounds like yours were too far out of spec regardless, so hopefully that's what is causing your problem (it often is the plugs and/or packs as the culprit when dealing with misfires). Hopefully you can trust that they put on new coil packs and this debacle with the plugs was just an innocent mistake.

By the way, not sure if you're running stock boost or not, but some gap tighter if running higher boost. I personally don't have any direct experience with that as I always ran stock boost and nothing but stock boost.

They installed different plugs than what they told you they did? Sounds like it's time to get a new mechanic who knows what they are doing.

Sorry to respond to a post from 2009, but if you guys are still around .... I'm dying to know......... how did this end? Terrible to leave your thread in this condition with us hanging like this ^_^

I don't want to be a downer but I don't think anyone can tell you for sure that you don't have a more serious issue (like a valve issue or something else) before we figure out what's going on. It's good your car runs well and that this only happens on cold idle, but is still a pretty serious fundamental issue in my opinion. Even though I don't think the odds are that high in your case, anything that might have the cams out of timing isn't something I would take lightly if it were my car. This is one of the most fundamental and critical aspects of your engine. Yes, you have one of the best Porsche engines ever made....but anything is still possible.

Dump a bottle of techron in before your next full tank of gas. It's cheap and worth a shot, and good to do anyway. Never a bad idea to get your oil changed shortly after this, but I wouldn't fret too much if you're not due for an oil change just yet -- it's just good form if you can.

Get the variocam and bracket looked at closely. Make sure you are 100% sure that everything we have gone over looks ok. If you're sure about all those things I think it is in fact something more serious with the engine.... but if I had to take a shot in the dark, my money is still on an issue with the variocam. Report back once you're able to get these things we discussed looked at by a professional.

Yes, those are good brands on the plugs and coils -- should be fine. I mean, possible they didn't torque and space the plugs correctly, but given that you said you had this problem for years before those were ever touched I'm wondering how likely that is. If that were the case then, yes, it could cause misfires. Just doesn't seem like the most likely cause.

Don't think the ECU needs any more time. The fuel cap was presumably not air-tight before you replaced it and that's why the error went away after you did. My thought was that this leaky cap could have caused unmetered air to enter into the system and make your trims too lean as RPM increases -- therefore causing misfires. I would think that once you fixed that problem with the cap anything related to this issue was over then on the spot.

Don't think it's the O2s because a problem here should show-up in your fuel trims. If you want to make sure your O2s are working, these values can be logged in Durametric.

I'm not a practitioner so I'm not sure how often a batch of plugs can be bad (in your case it's not just a single plug). I would think this is very rare for Bosch, which are good plugs. But anything is possible.

As you are, I wouldn't sit on this if it were a variocam issue. In theory if your timing is off it leaves open the possibility that there could be valve/piston contact. Someone can double check me and look in the manual, but if memory serves the 996TT variocam is activated when the engine oil is cold at idle speeds. Please verify this, but this is one of the things making me wonder if you could have an actuator that's not 100%. I really think you need to look at that bracket. Anyway, I'm not sure but I think only the intercooler needs to come off....so it's not like you're dropping the engine. Can't really think of anything I would do while the intercooler is off unless you're interested in welding a few of the coolant lines.

To be honest, I think you need to get JFP in PA to chime in here if you can get his attention.

We have been over the "usual suspects": You fixed the gas tank leak issue and there are no other codes except these misfires. You already replaced the plugs and packs. You said you are comfortable with the cam/timings, and have checked any issues possibly related to the variocam. You said the fuel trims are good. I would just check and double check your work on these to be sure you are comfortable that they have really been eliminated. If I'm not mistaken, if it's not something above you could have a more serious problem. Like I said, the Mezger isn't invincible but it's a **** good engine.

Given some of the stuff you are saying, it's really hard to say for sure without actually being able to see it, but it sounds possibly related to variocam to me (eg. actuator).

Yes, you also definitely want to check those cam deviations closely to make sure they are within spec. Could also be related, I believe, to a variocam solenoid as I believe variocam is activated at idle speeds and you said this is only on idle. Definitely check the bracket that holds the actuator. Checking these and the fuel trims should tell you a lot.

Ok, so you're still getting misfires. And how do the fuel trims look against spec?

It's always good to give background on recent service, such as you said you just had the plugs and coil packs done. You use premium gas, and that's fine, but I was referring to moisture and just making sure the fuel is fresh. For folks that keep the car in a more humid climate this can be an issue, especially if the car isn't driven every day.

Even if the cap fixed your gas tank issue, you still need to make sure the fuel trims look ok. If you have done all this and are comfortable with what you are seeing then, like Ahsai said, it may be time for a leak down compression test. Anything is possible, however, this wouldn't be my first guess as your engine is widely known as one of the best engines Porsche ever made. Things happen, but if maintained properly these engines are not often as prone to fundamental failures.

Yes, the CEL is only triggered by the DME similar to what I described above when a certain threshold of criteria is met (eg. so many misfires within a certain period of time). However, that said you really should not be getting misfires, so I would start by addressing the issue above and then starting to think about things like when the last time was that you changed your coil packs and plugs.... and making sure you have good, fresh fuel with no moisture. Like I said above though, if you have a vacuum leak in the fuel tank, it can cause unmetered air to enter and cause you to run too lean, which could potentially result in a misfire.

Link does not work for me. I don't have it in front of me but it should be pretty easy to find if you look through all the variables. You can also simply call Durametric and ask them where they are in the software interface. They are friendly and generally answer the phone with a person without going through a lot of prompts. I'm sure they would be happy to answer a question like this for one of their new users.

A lot of these "readiness states" are not set instantaneously and are rather set as the DME takes measurements over a period of time. It's possible this issue has manifested itself since you had the test done, but this should have shown up if it was the kind of test where they simply plug in their reader through he OBD2 port and you did have this issue at the time. As a matter of fact, most states now don't even actually test these "states" directly -- they simply query these "ready states" from your DME and ask if everything is ok. If you're car says "PASS" to all of them, they give you a pass and you go on your way for the next year or two until the next test.

If this is the gas cap, which it often can be, this is the cheap-to-replace low-hanging fruit so to speak. You need to be sure you're getting a nice tight seal. I would address this first, as it could be the cause of your misfires..... have you looked at your fuel trims? A vacuum leak could cause your fuel trims to go out of spec and therefore cause misfire(s). You should be able to monitor the fuel trims in the Durametric in realtime, and I would test as the RPM increases. If your fuel trim keeps getting leaner as RPM increases, this indicates a fuel delivery issue -- aka unmetered air entering into the system from that leak. To this point, you may be able to hear the air leak at the gas cap as you rev the engine a little.