986 S problem at idle, engine won't rev and shakes, battery disconnected - Page 2 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

tony_fury · 11-13-2012, 07:28 AM

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

Gorthaur · 11-13-2012, 07:45 AM

Quote:

Originally Posted by tony_fury

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.

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

Quote:

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?)

GPS installed in April 2012 after battery replacement.

Quote:

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?)

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

Quote:

Also reading you stated that after the Indy checked for codes, the car warmed up for half an hour and ran fine.

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

Quote:

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.

Overnight the battery is always connected to the smart charger.

Quote:

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

Thank you again, I will surely try.

Homeboy981 · 11-13-2012, 08:02 AM

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!

Gorthaur · 11-13-2012, 08:15 AM

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.

Gorthaur · 11-13-2012, 08:59 AM

Quote:

Originally Posted by Homeboy981

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.

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!

Heiko · 11-13-2012, 06:49 AM

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

Heiko · 11-13-2012, 06:52 AM

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

Gorthaur · 11-13-2012, 07:21 AM

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?

Heiko · 11-13-2012, 07:45 AM

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...

Heiko · 11-13-2012, 07:55 AM

"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.

tony_fury · 11-13-2012, 08:14 AM

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

Gorthaur · 11-13-2012, 09:06 AM

Quote:

Originally Posted by tony_fury

I'll shut up now.

Gorthaur:
Good luck with your diagnoses

T

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!

Heiko · 11-13-2012, 09:19 AM

Quote:

Originally Posted by Gorthaur

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

Homeboy981 · 11-13-2012, 09:25 AM

Quote:

Originally Posted by Heiko

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

@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!

tony_fury · 11-13-2012, 09:20 AM

Quote:

Originally Posted by Gorthaur

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!

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

Eric G · 11-13-2012, 08:54 AM

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?

Gorthaur · 11-13-2012, 09:04 AM

Quote:

Originally Posted by Eric G

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?

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!

Heiko · 11-13-2012, 09:28 AM

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 :-)

Homeboy981 · 11-13-2012, 09:32 AM

You crack me up! Funny sense of humor!

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

Heiko · 11-14-2012, 04:51 AM

I say it still could be anything... E-Gas system/MAF... potential key/ignition issue...
I think we're all assuming he changed the bulb and put everything back the way it was....
If something on the fly-by-wire wiring was jerked loose behind the dash that could also do
it... but without troubleshooting hands on, I think the chances are slim to pinpoint.
Hey Gorthour, put some floats on the bottom and drive it accross the pond and drop by with the car

I'm sure we could get it running.