2001 S idle issues / hesitation when warm

[bg305]

Hi all,

This is my first real post, I just bought a 2001 Seal Gray Boxster S and after about 150 miles have run into my first issue.

The short story:
Have driven it about 150 or so miles in the just over a week I have had it. Everything was going great until today when in passing a garbage truck ~5500rpm in second gear I noticed a sudden drop in power. I gingerly drove on and noticed the motor seemed to be hesitating. Went about a mile to the next stop light and it stalled when I put the clutch in as I rolled to a stop. I waited 10 seconds or so, and started it. It started without much fuss but continued to drive ruff. No lights on the dash. I was not far from home and got it back taking it slow, the hesitation stayed the rest of the journey (2-3 miles). I would definitely say the car was 'limping' but there were no violent shakes of the engine or anything like that. The top was down, I did not see or smell anything out of place. I have a OBDII scanner which I attached and it reported no codes or freeze frame data. (it only reads the generic codes on the Porsche)

So I did some searching and found lots of threads talking about the MAF, oil filter, and ground points. I had to replace the reverse light switch to pass inspection, so I tried pulling the battery while doing it. I cleaned the terminals with a bit of sand paper and cleaned up a ground above the engine I found a reference to in another thread. When I was done with the reverse light switch I reconnected the battery and turned the key to run and left it there for a couple of minutes, then I turned it back to off and let it there for more then 10 seconds (I believe I read this was the procedure to get the computer to relearn?). I started it and everything seemed great. It started up no hesitation and kicked down to a nice even idle after a bit. I decided to take it out for a quick drive to see how it was doing. I did not push it hard, most of the time staying below 4k rpm. I did a couple of light pulls ~4500 / 5k shifts later in the drive and started to notice that the engine would "almost" stall if i pushed the clutch in. The rpms would fall to about 400-500 then pop back up to 1k or so and then find an idle ~600rpm. After about 3-4 miles I did notice that it felt like it had less power in low rpms (<3k or so). There was no stalls while driving and the power loss was not nearly as bad as the earlier drive.

When I got back in the garage I shut it off for a minute or so and then tried restarting it. The idle became very erratic and it eventually stalled. I did it again (this time taking a video see link) and it hunted less, and did not stall.

Link: https://youtu.be/vLHhLmebIWo

Note: the last rev around 25 seconds in is me moving the car up in the garage. Everything before that, my foot is not touching the gas and the engine is warm.

Plan:
I ordered an oil filter, replacement air filter, and MAF cleaner. going to change these items / clean them when i get them over the next week.
I was reading you can disconnect the MAF and see if the problem goes away to test it?

I am thinking it might be the MAF??? thoughts? I was also reading about a relay for the computer possibly being a culprit.

Thank you in advance!
-Brian

[blue62]

If your MAF sensor is faulty and causing your problems unplugging it will force the computer to go to a default fuel program. The car will usually run reasonably well with the MAF unpluged You can try unplugging it and see if things improve.
Most things involved with OBDII that are going to turn on the CEL and throw a code, take two back to back events over two back to back drive cycles. On the first event the computer stores the code as a pending code with no CEL. On the second event the computer triggers the CEL and throws the permanent code.
If your OBDII scanner can do it, look for pending codes. That may be a help to you. Good luck keep us posted.

[itsnotanova]

I'd check for a vacuum leak too

[bg305]

Thank you for the replies... I know my obdii scanner can show pending codes. When I was looking at boxsters to purchase one of the ones I looked had a pending code for an o2 sensor. So far no codes at all, pending or otherwise. I also just had the car inspected in NY state yesterday and they hooked it up to the shop computer (not porsche shop) and said nothing. (i have had them tell me there were pending codes before on other cars when getting inspected and that they would clear it and I had to drive to see if they resurfaced.

I will try the MAF disconnect and will look for leaks. It seems to have been getting better, I drove it yesterday 20 miles and while it still felt weaker then usual below 3k rpm, the idle was much improved (honestly if i was not looking for problems I would not notice the amount it moves around now). Since I have only had the car a week and am a bit scared to lay into the throttle now, I am honestly thinking the car could be normal and just seems under powered because of the way I am driving it.

I am going to do an oil change and inspect the oil and filter, I also got a fuel filter, air filter (stock paper one). So I will report back after i change the maintenance items and inspect the oil (might be a bit have a busy week coming up).

If there was an issue with the VarioCam solenoid/actuator is it likely that i would likely have codes or pending ones?

[blue62]

Originally Posted by bg305

Thank you for the replies... I know my obdii scanner can show pending codes. When I was looking at boxsters to purchase one of the ones I looked had a pending code for an o2 sensor. So far no codes at all, pending or otherwise. I also just had the car inspected in NY state yesterday and they hooked it up to the shop computer (not porsche shop) and said nothing. (i have had them tell me there were pending codes before on other cars when getting inspected and that they would clear it and I had to drive to see if they resurfaced.

I will try the MAF disconnect and will look for leaks. It seems to have been getting better, I drove it yesterday 20 miles and while it still felt weaker then usual below 3k rpm, the idle was much improved (honestly if i was not looking for problems I would not notice the amount it moves around now). Since I have only had the car a week and am a bit scared to lay into the throttle now, I am honestly thinking the car could be normal and just seems under powered because of the way I am driving it.

I am going to do an oil change and inspect the oil and filter, I also got a fuel filter, air filter (stock paper one). So I will report back after i change the maintenance items and inspect the oil (might be a bit have a busy week coming up).

If there was an issue with the VarioCam solenoid/actuator is it likely that i would likely have codes or pending ones?

Itsnotanova is correct a vacuum test with a proper vacuum gauge is an important test to do.
You are looking for 18-22 in/gh with a steady needle at idle.

The Variocam solenid/actuator works as an on off / or in out actuator that ingauges around 1500 RPM (I think) and then deactivates around 5000-6000 I think, not positive on the RPM's Anyway like most things it will have acceptable wear limits. If they fail I think they can throw a code but not positive.
There are also chain tension pads that wear and cause camshaft deviation.
If you have a OBDII scanner that can read camshaft deviation the acceptable limit is +or- 6 degrees.
With all that said I would stick with simplest most basic things first like the vacuum test. and work my way up step by step.
Something you do not mention is how many miles on the car?????

[blue62]

Just looked at your video and see that you have 50000 miles on her. That is about what I have on the 2000S I bought a year ago. I am thinking with the low miles your problem should be something simple.

[bg305]

Originally Posted by blue62

Just looked at your video and see that you have 50000 miles on her. That is about what I have on the 2000S I bought a year ago. I am thinking with the low miles your problem should be something simple.

Fingers crossed!

I will look into testing the vacuum system. That is a really good idea.

[bg305]

So in looking into the vacuum leak i encounter more questions:

First, a quick update...

I have ordered a Foxwell****NT520 loaded up with Porsche software.**** I don't yet know when it is coming, but my old scantool is absolutely useless other then reading none existent codes.**** On my other cars it gives me live data and all sorts of data, but on the porsche it can't even read the vin correctly. I want to use the Foxwell to better diagnose if my current efforts fail.

I cleaned the throttle body (more on this late)

I had to get bits to get the MAF out and got them today, so I will be taking it out to clean it, doing the oil change and****fuel filter change.

One way to check the vacuum is to open the oil cap with the engine running, which brought me to the following new discovery / question:

Does a oil - air separator fail suddenly?**** When I cleaned the throttle body I noticed a decent amount of oil in the intake plenum (see pics).**** Now I am (all of the sudden) noticing a large amount of white smoke on startup and when I took the oil cap off a pretty loud whistling noise which I read is caused by the extra negative vacuum experienced during the failure of the separator. Prior there may have been small amounts of smoke on super cold starts, but nothing like what i have seen in the last couple of days.**** I really had not noticed anything before my issues started and it seems like a rather sudden failure.**** I instincts tell me something like an oil-air separator would fail gradually, with more smoke appearing at startup, etc.**** Either way, could it be the oil in the intake that is causing my 'sudden' loss of power in the low revs and idle issues?**** I would think oil being sucked in to the combustion chamber would have a negative effect and possibly be fouling my plugs too.

Here is the oil i found when I cleaned the throttle body:


and here are before and after pics of the throttle body

[itsnotanova]

Yes the AOS can fail suddenly and sometimes catastrophically. I'd say it's time to change yours. Most vacuum leaks I've found by just listening for them and poking around. The oil filler tube is the most common cause of a vacuum leak that I've experienced, but any of the many tubes on these motors can cause a leak.

[Pdwight]

Originally Posted by itsnotanova

Yes the AOS can fail suddenly and sometimes catastrophically. I'd say it's time to change yours. Most vacuum leaks I've found by just listening for them and poking around. The oil filler tube is the most common cause of a vacuum leak that I've experienced, but any of the many tubes on these motors can cause a leak.

This was my problem as well

[Stl-986]

Your AOS has failed. Replace it. With that much oil you should be seeing smoke on startup and most likely while it's running.

[bg305]

Thank you!

I ordered one from Pelican yesterday, should arrive tomorrow. I have the car up on stands already and dumped the oil and cleaned the MAF.

Do you think the failing separator could have caused the loss of power though? I have not seen much discussion on that. I am worried i will get it all back together and still have an issue... Will know soon enough.

[blue62]

Originally Posted by bg305

Thank you!

I ordered one from Pelican yesterday, should arrive tomorrow. I have the car up on stands already and dumped the oil and cleaned the MAF.

Do you think the failing separator could have caused the loss of power though? I have not seen much discussion on that. I am worried i will get it all back together and still have an issue... Will know soon enough.

With the failure of your AOS and the resulting oil in your intake my guess (and it is only a guess) is that oil mist has had an ill affect on your MAF sensor. Cleaning them with a good MAF cleaner will "sometimes" fix the problem. They are actually very sensitive to very fine dirt and oil particles. so it may need replaced even if fairly new.
The MAF can be tested with a multimeter but I don't know the values that you need to see.

[Starter986]

Originally Posted by blue62

With the failure of your AOS and the resulting oil in your intake my guess (and it is only a guess) is that oil mist has had an ill affect on your MAF sensor. Cleaning them with a good MAF cleaner will "sometimes" fix the problem. They are actually very sensitive to very fine dirt and oil particles. so it may need replaced even if fairly new.
The MAF can be tested with a multimeter but I don't know the values that you need to see.

How is that mist getting upstream?

[bg305]

I doubt it is.. my maf looked new honestly, I think it has likely been replaced in recent history. The wire was shiny and clean

But I can't imagine that a fair amount of oil being sucked into the combustion chamber wouldn't cause issues with spark / ignition of gas. My guess (hope) is that once I replace the AOS and burn off any residual oil that everything will return to normal.

Looking back at my symptoms it makes sense. The car ran well enough if i stayed off the throttle. In staying off the throttle I was likely keeping pressure lower so less oil was making it through the broken diaphragm in the AOS. I was also not pulling nearly as much air and with much less force through the intake which would take the oil with it.

[blue62]

Originally Posted by Starter986

How is that mist getting upstream?

Well as I stated it was only a guess. But look at the condition of the throttle body butterfly. Does it look like oil dirt residue??????? or just dirt???? Not sure myself. But I believe it is upstream of the oil in the intake. So like I said I am only guessing.

[blue62]

Originally Posted by bg305

I doubt it is.. my maf looked new honestly, I think it has likely been replaced in recent history. The wire was shiny and clean

But I can't imagine that a fair amount of oil being sucked into the combustion chamber wouldn't cause issues with spark / ignition of gas. My guess (hope) is that once I replace the AOS and burn off any residual oil that everything will return to normal.

Looking back at my symptoms it makes sense. The car ran well enough if i stayed off the throttle. In staying off the throttle I was likely keeping pressure lower so less oil was making it through the broken diaphragm in the AOS. I was also not pulling nearly as much air and with much less force through the intake which would take the oil with it.

Good points. I still think with your low mileage that the issue is relatively simple.
yes I consider AOS failure relatively simple

There were a few simple issues with my 2000S with 47000 miles when I Bought it last year.
Coolant tank leaking, Motor mount shot, real sloppy shifter, leaking CV boots.
I fixed all of them, the car has been golden every since
Hopefully when yours is sorted it will be golden as well.

[Starter986]

Originally Posted by blue62

Well as I stated it was only a guess. But look at the condition of the throttle body butterfly. Does it look like oil dirt residue??????? or just dirt???? Not sure myself. But I believe it is upstream of the oil in the intake. So like I said I am only guessing.

I don't know when last your oil was changed, or your air filter (didn't again read this entire thread) but I'd suggest it's just oil. When I purchased my car a couple years ago I chose to remove the air intake... and what I saw mirrored your "dirty" pic and with more oil. I pulled the throttle body and the asociated tubes... and they had a fair amount of oil. I, too, pulled the MAF... cleaned it up.

Cleaned it all up... put it back together and, not long thereafter... installed the OEM AOS.

Pulled off the TB about a month later (and after the new AOS install) just to double check... and all was good.

Your TB looks clean now... you'll be all good. You'll find that as more you read upon these pages you'll begin to "know" better your car. Ask questions for those answers you can't find and you'll be a Porsche mechanic in no time. Maybe not on the same level as the "Masters" who serve as outstanding resources... they Rock.

Cheers!

[bg305]

Huzzah!!! It is fixed!

I just took it for a 10+ mile drive and it was awesome!

Thanks everyone all for your help!

It was relatively straightforward getting the AOS out and in. The hardest part was getting the old ones bottom hoes off. Had to use a really long 90 degree needlenose and hook it just right and squeeze so i could pull up on the AOS and wiggle it out. I found it easiest to have the car up because i used bottom and top access. There was a nice spot on the bottom if you moved a wiring harness out of the way.

Celebratory pics of the car (from last week).

[blue62]

Originally Posted by bg305

Huzzah!!! It is fixed!

I just took it for a 10+ mile drive and it was awesome!

Thanks everyone all for your help!

It was relatively straightforward getting the AOS out and in. The hardest part was getting the old ones bottom hoes off. Had to use a really long 90 degree needlenose and hook it just right and squeeze so i could pull up on the AOS and wiggle it out. I found it easiest to have the car up because i used bottom and top access. There was a nice spot on the bottom if you moved a wiring harness out of the way.

Celebratory pics of the car (from last week).

Always great when thing come together.
Nice looking car