986 S problem at idle, engine won't rev and shakes, battery disconnected
 

Hi guys,

I’m writing from Italy, owner of a 2000 986 S, 84.000 km on the clock.

First of all, I have to apologize for my poor English.

Recently I had my cluster bulbs replaced thanks to the good DIY guides found over here, so, thank you so much for helping us all with your knowledge and patience.

In order to do the job, since my car features the optional alarm, I previously disconnected the negative cable of the battery while leaving the ignition key on position 2 as read on the board in order to avoid the siren to scream (is this correct, BTW?).

With the cluster back in place, without touching the key nor the gas pedal, I connected the negative cable and found everything was fine, then I waited for a few minutes with the key still in position 2 thus letting the e-pedal to reset itself, and eventually removed the key and left the place.

Two days later I picked the car up but the engine was really strange at idle. No fault lights on the cluster but no power at all, it hardly reached 1600 – 1900 RPM with the aircon switched off even if I floored the pedal.

The whole car shaked violently but the engine didn’t stall. If I pushed on the gas pedal, it revved a little making a smoother noise and behaving normal, but just up to 1600 – 1900 RPM. It seemed there was something at work avoiding the engine to rev.

Tried several times to do the 1-minute procedure, tried to fire it up and swich it off a million times, then called the local PD but received nothing but a “shame on you for having disconnected the battery”.

Called an indi whose suggestion was to blindly replace the MAF (...even though the problem was showing itself at idling and not over 4000 RPM).

Eventually phoned another indi; this nice chap came, attached a small diagnostic device to my car and told me there were no error codes displayed. After half an hour the engine got warm and everything was perfectly normal, so he invited me to drive the car for some thirty minutes and so I did.

Problem is, though, yesterday the issue came back again and didn’t go away even after a million 1-minute procedures, dozens of key-on-0-to-key-on-2.

I haven’t got access to a Durametric.

When I set the key on position 2 I hear a very low “buzz” which goes on forever, until I fire the engine.

I’ve got a GPS from my Insurance Company on the positive pole which I cannot remove.

What do you suggest? I’m really struggling… Shall I disconnect the negative cable and leave it aside for a few days, as read over here? What must I do when disconnecting the battery in order to avoid the alarm to wake everybody up?

Thank you in advance for your help, I really need it!

Cheers,

G.

P.S. If you reckon it would help, I can record the engine noise and attach a file...

Man that could be a whack of different things.... I'm thinking MAF, Vacuum leak or possibly a bad ignition coil. Disconnecting the battery doesn't normally hurt anything at all and if the PD said "shame on you for having disconnected the battery" he was probably just being a smart ass lol. The throttle body calibration should be done after the battery was disconnected but the car should run fine without doing it and even if you don't do it, after driving a while it will calibrate itself (just takes longer).
I would pull the connectors to each coil one at a time to see what happens. If you pull one and it doesn't have any effect then you either have a bad coil or a bad plug.
I've seen these things fail and cause issues and not set any CEL. Bizarre but it is what it is... It probably had nothing to do with your bulb change, it was most likely just a coincidence.
A failed coil will usually cause shaking to what you described....
I hope you find the gremlin - good luck.
Heiko

At that mileage I would replace the plugs if I was going all the way in to check each coil pack, they are fairly inexpensive and it eliminates one more point of failure. If you have access to a code reader plug it in and post the codes, that might help zero in on it too. Port is under dash driver's side near the fuse panel. Just out of curiosity why the insurance company gps? Do they track your speed in Italy or something to validate whether they want to insure you?

Thank you Heiko, the biggest problem is the car is at -1 level and the power output is not enough to take her out, not to mention I wouldn't be able to reach the indy without getting killed in the process by other cars, it's a 20 km trip...

I'm getting really disappointed... :(

Hi and thanks for your reply!

The sparkplugs were replaced @60.000 km in April 2007.

Last time the guy attached the reader he didn't find any errors.

Thanks to the GPS I can save a lot of money on insurance; since my 986 S isn't a DD (less than 4000km/yr) the GPS allows me to pay just for the kilometers yearly covered. The drawback is they track your trips and your max speed.

You dont need to take it out, just start and let it idle then start disconnecting one pack at a time (if you unplug one and notice it changes the way the car idles, plug it back in and move on to the next one) You dont have to pull the coil packs themselves out to see if they are working... Just unplug the connector that feeds the coil thats it, you can do that without any tools; If you unplug one and there is no noticable effect at all, chances are either plug/coil is bad.
Just because the plugs are new doesnt mean they are good... I've seen brand new plugs come out of a package that are bad.

Seems curious that it documents no codes, it couldn't hurt to toss some Techron injector cleaner and some dry gas too, again cheap elimination of another factor. A careful clean of the MAF couldn't hurt either but you will need anti tamper torx to properly remove it. Don't be frustrated, the problem will reveal itself. I think a bad oxygen sensor could make it run rough as well.

Thank you Heiko. Is there any DIY guide on ho to do what you've just described? Maybe here on the board... I'm going to check it out right now.

Get it up on stands with the rear wheels off. Check for "openings, like a little door" in the inner fender well that facilitate access to the coils and plugs, if they aren't there simply go in from underneath. Each set of three plugs on each bank has it's own discreet coil. What Heiko is saying is to locate the connector on each coil and one by one disconnect them. You are looking for the disconnection that makes no difference at all as each other time you disconnect a working coil you are creating a miss which should make the engine stumble more. Hope that helps.

Thanks again. Unfortunately I have no stands and there's not enough room to remove the wheels either. She sits in a small box inside an underground garage which is 70 cm wider then the car itself... I'm going tu bury her down there... Really pissed off! :(

Exactly Ghostrider - or do one side at a time by removing one rear wheel at a time (that gets you easy access to each sides coils... you will just have to pull the little rubber boot back on each coil electrical connector then squeese the ends and pull the connector out.

Sorry Dude without doing a couple of the basic first troubleshooting suggestions, the only thing i got left to recommend is to get a bunch of friends to help you push her out of the garage and get it towed to a shop :-( It shouldn't be anything serious, but you have to get it checked out.

I love my Boxster more than any other car I've ever owned but if you can't lay under one and have no rack you simply have to have access to an affordable mechanic and some reserve $ for repairs. If it's any consolation, it doesn't sound like something deeply serious.

Hey guys don't get me wrong, I really appreciate your help and I'll certainly push her out and try to follow your suggestions. I just made the long story short but now it's worth telling you I haven't taken the car to the PD because of their behaviour in this circumstance as well as in others. Their first suggestion was to come to my garage and install a new MAF without even running a diagnosis for more then 1000 €... And two weeks earlier they wanted to charge me with a 1000+ € bill for a cluster replacement while it was just a poor 7 € bulb...

Maybe another BB member is near you, changing a MAF is really easy from the top of the car in service mode with simple tools and patience.

It's hard for me to believe it's the MAF. The problem shows itself at idle, not over 4000 RPM.

After that last lucky start I drove it for more than 30 minutes and she was really perfect, just like she had always been in the past years. She seems to lay in some sort of "recovery state" I just have to wake her up from. Ok it can be the plugs but... in five years not a problem. Then I disconnect the battery and the problem shows itself on the first start. Then suddenly, after a dozen times of switch the engine off - fire it on, she is just perfect... but the day after she's strange again. Strange coincidence, huh!?

From that description it does sound like the MAF, I'm not inclined to think an intermittent problem would be a plug or coil, I would expect that to be more chronic, no thirty minutes of bliss. As I said, the part isn't crazy expensive, Johnny Danger has a source for good deals on MAF units. If someone lives near you that has the right tools they could hook you right up, you could even do it yourself outside if space permits. Whatever the disconnect with the repair center was aside, they see a lot of cars they seem to think a MAF would help and a new one certainly won't kill the wallet if it's not the MAF. IMO, a MAF not performing could effect the car at any RPM.

Yup MAF is worth changing and as Ghostrider said its pretty easy...
You will definitely notice a coil in idle but the motor usually gets very rough and jerky if a coil begins to misfire at higher RPM's...
The MAF shouldnt cost more than 200-250 Euro's... Here's a DIY article from Pelican :)

Pelican Technical Article: Troubleshooting and Replacing the Boxster Mass Air Flow Sensor (MAF) - 986 / 987

I sure hope this helps... and i will see if i can find an article on the Coils as well :)
Heiko

Ok in regards to the coil connectors - in the little pictures down the bottom left side 'figure 1' the green arrow shows the connector i was talking about pulling...
Heiko

Pelican Technical Article: Replacing Boxster Spark Plugs and Coils - 986 / 987

Well, guys... great! Thanks a lot! I'm really going to read those guides this evening (and in the meanwhile I've ordered Wayne Dempsy's 101 projects book from Amazon).

Brief update: just got back from the car, I went to the garage just to try and disconnect again the battery for a day or two. Key inserted, turned it and... nothing, no cluster light, nothing at all. Tried a few more times, then eventually everything was fine. Please note the battery is always under a smart charger so I really doubt it was not full (it's almost new, by the way). Taken it away then inserted again, nothing. Left the key inserted and operated the headlamps and BANG! Cluster lights on. Never had I notice before that the key, while inserted and put in position 2, has a huge play (even though it doesn't fall off at all).

Any clues? Does this evidence point towards any different direction?

While not as experienced as the guy's providing you suggestions.
From reading all the different problems members have encountered on this forum, the number one item that resolves a lot of issues is the MAF.
While also noticing a very low battery will cause some very erratic behavior. If voltage levels are low, sensors can do some strange things.

Reading your post:
The problem started after you disconnected the battery to replaced the dash bulb. I can only assume that the battery was disconnected quite a long time while removing and reinstalling the dash.
My guess is the ECU is having to re-learn all the sensor readings all over again.
You also had the GPS installed for your insurance. (Was this installed after the bulb replacement) (Battery disconnect again?)
You state the GPS was installed on the positive side of your battery, is it drawing from the battery all the time.
(How old is your battery?)

Also reading you stated that after the Indy checked for codes, the car warmed up for half an hour and ran fine.
You have no codes.
I would stop with the 1 minute procedures. Let the car reach operating temperature and re-learn the air/ fuel mixture readings.
Possibly get a volt meter and check the battery voltage after it sits overnight.

My suggestion is to let the car run and warm up, let it re-learn.
Once warm, if it's running fine, take it for a a drive close by and don't baby it.

My 2 cents..
T

Hi Tony and thank you for joining. The battery has been disconnected for 20 hours.

GPS installed in April 2012 after battery replacement.

My battery is 6 months old and yes, the GPS is always transmitting.

Yes. But the same didn't happen on the next day.

Overnight the battery is always connected to the smart charger.

Thank you again, I will surely try.

Just had a similiar forum discussion on this the other day... the switch at the back of the ignition is a common failing item (although I cant see that keeping your car from reving up or shaking)... The switch is a cheap item you can find at Volkswagen/Audi dealer and also easy to change (VW Part number 4A0905849B) :-) If this little unit fails, it seems to cause all sorts of strange issues including being able to spin the key 360 degrees, steering wheel not unlocking etc....
Regarding the battery... once your car is running the alternator should supply all the power required for the engine...

"My suggestion is to let the car run and warm up, let it re-learn.
Once warm, if it's running fine, take it for a a drive close by and don't baby it.
My 2 cents..
T"

Sorry Tony I have to disagree - If in fact he has a bad ign coil and something is misfiring I would highly advise not to rev the engine high as it could do potential damage. So even if its warm i would baby it and not push it... if he even gets it that far.

May be a bad ground somewhere…possibly that "GPS device" that is not connected to the rest of the car's grounding system, huh? With the ground pulled, you should NOT STILL BE PULLING AMPS from your battery.

My factory stereo experienced similar problems when I replaced the HU and tried to use factory wiring, and original wiring was taken out in favor of wiring I KNEW WAS GROUNDED PROPERLY.

A dead battery or corroded battery posts, faulty ground circuitry, or a MAF about to croak ALL would be producing similar "spotty" problems. Your problem seems intermittent - it does NOT happen ALL the time. The guys have provided AWESOME and CORRECT troubleshooting information, given the responses you have provided.

It may be a job for an experienced mechanic to trace back some of your wires, replace the MAF, replace a faulty battery, clean posts or check the wiring. Batteries DO fail, even new ones. Insurance companies GPSs are made for the masses…how long has that thing been on there?

Your problems, as described, DO NOT seem to 'go by the book' of troubleshooting….unless some bit of information eludes us!

LOOK HARDER you will find a bad ground, visually check the MAF - clean it with MAF cleaner, clean the battery terminals (even IF you have a new battery there can still be crud on the posts-check it).

Your answer lies within. If not, there is no shame in going to the Indy (would not trust the dealer) and have him try 'specific' items, as described.

Good Luck!

Heiko:
You know more about these car's than I do.
I am by no means an expert.

I just look at the symptoms then try to analyze cause and effect.
In this case the cause was when the battery was disconnected for a long period of time.
The Indy check the codes and no codes were found.
Just trying to use some deductive reasoning for the side effects described.

You may be on to something with the ignition switch given his comment about the 0 to 1 to 2 procedure many times as well.

I just find it hard to believe the car was fine until the battery was disconnected for an extended time and now all these components may be at fault.

When I saw his comment about letting the car reach operating temperature it seem to run fine. It sounded to me like the ECU had time to learn the settings after being disconnected so long.

I'll shut up now.

Gorthaur:
Good luck with your diagnoses

T

Homeboy... thank you!

Maybe there's something more. When I was about to reconnect the negative cable, I incidentally dropped the hexagonal nut which allows the end of the cable to embrace the battery pole. I tried to find it but I didn't make it, so I used another hexagonal nut which seemed to fit perfectly even though it had a different outer size. Perhaps the problem lies there, and since I went to the dep to buy the nut of the right size, this evening I'll be able to throw it in while reconnecting the battery. I will record a video as well and hopefully I'll show it to you.

Will be interested in seeing if this helps. I know Porsche has a "safe drive mode" where the engine will drop cylinders when the CPU detects an engine problem and gives you just enough engine to return home. The symptoms you are describing are identical to the conditions my 928 S4 would go through. No codes were thrown, but if I remember correctly it ended up being a coil related issue. On the 928 you would go from 8 cylinders to 6... I have not found if the Boxster has the same function going from 6 cylinders to 4?

The GPS device is not connected to the rest of the car's grounding system, as far as I know. Later I will post some pics.

Thanks!

At 1500 RPM I'm not so sure I would be able to go anywhere, even a small ramp would be too much for the poor power available. :( There's clearly something wrong!

Hey T, I'm sure Heiko didn't mean to sound rude (otherwise he would not have been as nice and helpful as he has) so please stay with us, any suggestion will be highly appreciated!

Tony... If I did sound rude my appologies...did not mean to come out that way. There are too many unknown variables here to properly diagnose this one quickly... My gutt reaction was 'protect the motor' so I wouldnt run it hard until this is found. Anyhow sorry if that came out wrong...

Heiko

It's all good, I didn't take it that way.
I respect Heiko. I hope you can figure out your problem.

@Heiko,
Looks like you need to lend @Gorthaur your mechanic in a trunk! Was that you in there?

The guy looked too happy to be a mechanic! The picture would have been different AFTER the repairs were complete I'm sure. Just ribbin ya! It was a good post!

LMAO - Yes that was me in the trunk :) that was the happy smile after getting that oil leakin beast outta there. We got it all torn appart, just waiting for some parts and then she's going back together. Dont worry you'll see some finished photo's when done :-)

You crack me up! Funny sense of humor! :D

That pic should be your Moniker….it was hilarious! A Mechanic in the Frunk is what these cars should come with!

this tread is becoming very interesting.
i have one question.
did the problem started right away after messing with the cluster? or couple of days later? (just want to be sure)

On the very next restart, after many hours without battery.

On sunday 3 PM I disconnected the battery and did the job, on monday 10 AM I reconnected it and on tuesday 13 AM, I started it for the first time.

OK. this is my 2 cents.
after 20 years of installing every available aftermarket electronic equipment in cars (4 years of them as the official installation shop of Porsche Israel), i can tell you one thing.
if you worked on something (in your case the cluster) that where the problem is.
problems usually don't happen by themselves. the chance that a MAF/coil will blow at the same time you were working on something ells, is close to zero.
car was working fine before taking the cluster out. right?
remove the cluster, check the connectors and wires. these connectors are very sensitive and tend to break or loos a pin (ask me how i know).
also take Homeboy advice, and check the ground points behind the cluster. make sure they are tight and none of the wires is broken. some of them are very thin, and can break easily when working in that area.
http://986forum.com/forums/uploads01...1352866175.jpg
http://986forum.com/forums/uploads01...1352866196.jpg

whit that said, it can also be that you are very very unlucky, to have somethig ells go bad when working on unrelated part of the car.
i truly daubed it.

taking the cluster connector apart, is described hear in figure 6:

Pelican Technical Article: Boxster On Board Computer (OBC) Upgrade / Boxster Turn Signal Switch Replacement - 986 Boxster (1997-04) -

good luck.