ohioboxster

Yea, MAF always gets accused when anything goes wrong. You probably just need to put some miles on it.

Macster

Give the car time. Even if the MAF (or injector) was bad often just shutting off the engine will have the problem absent and the symptoms absent for awhile.

Also, reads like you have a good place to help you take care of your car. That goes a long way to upping the enjoyment level.

Sincerely,

Macster.

sbefar01

Yes ill give the car a little time, it was "sitting" for 1.5 months before i actually got it registered and driven. Could be that paired with a bad tank of gas. Finally just ran the first tank of gas down to Empty and refilled it, no problems yet, fingers crossed

Lance 4c

Really think you should go with UMW (Kevin) software tune!

sbefar01

OK, ill look at UMW too. So yeah car still smoked a bit with the fresh tank, perhaps ill get an oil analysis, or the Wideband O2's, plugs and coilpack might be the fix . . . . even though im not sure exactly what both the wideband O2's and coilpacks do.


Good news: Got fresh rubber on, the Sumitomo's HTR Z replaced the Perelli Rosso's. Wow the ride comfort is so much better and handling seems identical if not more true (not even broken in yet). Very happy about this. i love everything about this car except maybe the large steering wheel, not accustomed to it yet. I'll do a quick post inquiry on some options. Thx guys.

SSST

Plugs, coil packs, and o2 sensors, are basically the major tuneup items on these cars. Depending on miles, they may be contributing to your problem. I thought my car was running good until I had them replaced at the 60k mile service interval.

Huge difference. If the car doesn't smooth out soon you might consider having this done.

JG 996T

^ Time for a UMW tune-up.

Macster

One and a half months sitting could have the gas stale. Premium gas goes off pretty quick relatively speaking. And you do not know the age/condition/quality of the gas that was in there to begin with. It might have been crummy gas. Time will tell.

Wideband O2 sensors measure the oxygen content in the exhaust gas compared to outside air and signals this via a voltage to the engine controller which uses this data along with the data from other sensors to properly fuel the engine.

(Narrow band sensors measure the oxygen content too but have a much narrower range of fuel/air ratios to which they respond.)

Both the #1 wideband sensors (those ahead of the converters) and the #2 narrow band sensors (those after that are used to monitor the performance of the converters) are wear items, but Porsche does not have a replacement schedule.

These sensors are tested/checked once and my info for the Turbo twice every trip to make sure they are working properly.

If the DME finds any problem the CEL (check engine light) is turned on and one or more O2 sensor related error codes are logged.

There is a good argument to be made to leave these alone unless there are clear signs they are bad. One such sign, obviously, is a CEL and one or more error codes that point to the sensors.

Some believe I guess that Porsche is too lax on the monitoring of these sensors and their performance can deteriorate and affect the engine's performance without any CEL/error codes.

Generally automakers are too strict for I have encountered (at least in a few other car brands though not in Porsche) the check engine light comes on too readily.

But one can choose to believe what he wants and act upon it as he sees fit.

It is apparently an unpopular position around here but I have decided to rely upon Porsche and its DME expertise to inform me when something like the sensors need attention.

Of course were I to detect a change in fuel mileage or some other abnormal engine behavior even if no CEL came on nor no error codes were present, I'd diagnose the possible causes. But so far my car's engine has continued to run just fine and I see no need to replace/fix something that is not broken.

The coil packs, 6, one per spark plug, are used to produce the very large voltage spike that generates a spark at the spark plug.

Coils can deteriorate over time. As with sensors they are monitored, but not in a direct way. The DME constantly measures the speed of the flywheel to verify the output of each cylinder at its combustion/power stroke is within tolerance.

If this output falls too low (or goes too high) one or more misfire error codes are logged and the CEL is turned on. In some cases if the misfires are those that can result in raw gas being fed to the converters the CEL flashes. The converters can be quickly ruined if they receive raw gasoline. Porsche (as is true of all automakers) are required by federal/state rules/regulations to warranty these items for 80K miles and 7 years (IIRC).

In this case the automaker is going to err on the side of caution because converters are very expensive and if they have to be replaced under warranty... well, better to flag a possible problem and signal the driver stop driving the car or at least get it to the work shop pronto before it becomes fatal to the converter.

As for converter prices: I've never priced those for my Turbo but a few years ago I priced one for my Boxster and it is over $1000 with a total replacement cost of around $1200 to $1300. I would not be surprised to learn the Turbo converters are even more expensive to buy and replace.

So the coils are (indirectly) monitored for proper operation.

But as with the sensors, same with the coils. Some believe the coil performance can drop off and even though there are no misfires these are often replaced on not much more than a hunch or a feeling.

This is not necessarily wrong. It is up to the owner of his car to determine what he wants to do and if he is comfortable making this call then that's all that matters.

But as with sensors same with coils, for me. I will continue to rely upon the DME to keep tabs on the performance of the engine and directly or indirectly the performance is its critical sensors/subsytems -- including the coils -- and only if the DME flags a problem then take action.

Of course the above is always subject to immediate modification if I ever detect any abnormal engine behavior regardless of if the CEL is on or off.

Sincerely,

Macster.

Kevin

To back up my statements we have to go to the actual component manufacture. Have fun with these documents. One can select the wideband and post CAT O2's. Like I have stated, ONE does not have to wait till you receive a CEL. These sensors degrade over time.

http://www.boschautoparts.com/Oxygen...O2ConBro08.pdf

http://www.boschautoparts.com/BAP_Te..._Intervals.pdf

sbefar01

well, im getting schooled here, i carefully read the last two posts, since im still stalling now again frequently on startup only and never a CEL, im not sure what my best guess is. What i will do is change back to the paper filter and see if my car has better consistant startups, unless you educated gentleman have a better idea

ohioboxster

Strange it's not throwing any codes, wonder if you have a fuel problem. Failing fuel pump or something along those lines. I've had a few issues with prior P-cars , not my current car. The first one was a vacuum leak and my Targa would run rough when wet. Actually, I was changing the coolant tank and coolant leaked onto the coils. Of course they were cracked and the car ran like crap until they dried out. Not sure if I said it on this board or even this thread. My friends and I have noticed coils seem to be cracked after about 30k miles. This has been true on only 5 cars, nothing scientific, just our observations. I have the updated coils sitting on a shelf if you end up needing them in a pinch. I bought them for my turbo, but haven't had a chance to crawl under it yet. If there's anything I can do to help, fire away. Again, keep us posted, we can all learn from each others experiences.

sbefar01

Ohioboxster thanks. I might actually need them bc . . . . . . the car is starting up well all of a sudden, seems to be getting much better, BUT now my fuel gauge is quite a bit OFF. I just filled up my tank completely and it only registers 78% full or 178mi remaining. So the symptomology seems to shift from one electrical/fuel system to the next! Not a huge issue but I think the issues are connected, What do you guys think? Coils?
Pic attached of after just filling Tank up.

neanicu

Are you sure you've filled the tank all the way up? The reason I'm asking is because I've noticed in these cars that when you fill up,the pump will stop before it's full. Don't know why...I'm suspecting the lower position than the other cars or something because the pump will most of the times stop before full.

ohioboxster

Yea, I don't know why either but sometimes you have to put the pump nozzle parallel to the ground to get it to fill all of the way up. Funny you posted that because it happen to me last fill up.

SSST

Another guy on this board who PMd me was having these same problems. He went with Kevin's reccs of plugs, coil packs, and O2 sensors and the problem went away.

I'll let him chime in if he wishes, but if they can't find anything wrong, and you are still having the problem, it is probably a tune up issue. You are almost at the 30k interval, so go ahead and have it done. You need to do it anyway.