Engine Stalling - 986 Forum - The Community for Porsche Boxster & Cayman Owners

rock88hard · 08-26-2014, 10:34 AM

I drove down the interstate for about an hour and left it in neutral while going down hill to see if I could save fuel.

Beginning when I got off the interstate, it now stalls when I put it in neutral while coming to a stop!

Weird thing is I can be going up hill and throw it in neutral to drop the RPMS to about 300 or 400 and it won't stall doing that. But same thing on flat or downhill terrain and I'm stalled!

Anyone have any ideas on what this could be?

epapp · 08-26-2014, 11:12 AM

are you running out of fuel??

edit: shehadehd had this problem with a different car of his...if he parked nose facing DOWN the driveway, the car would run fine, if he parked nose UP in the driveway, the car would stall, but if he pegged the gas it would chug on around 4k rpm.

It was water in the gas. After trying to suck the gas out of the tank with an old (and our only) vacuum cleaner, it not only didnt work but we were left with a vacuum that would never smell clean again...

Long story short, drain the gas if water is a suspected problem

rock88hard · 08-26-2014, 11:34 AM

Would it rule out water in the gas if I let it run to empty and then completely fill it up?

The top does have some leaks from cracked plastic window and the clamshell not fitting tight. Also, I did have to leave it out in the rain a few days before the problem started.

seningen · 08-26-2014, 11:57 AM

Quote:

Originally Posted by rock88hard

Would it rule out water in the gas if I let it run to empty and then completely fill it up?

The top does have some leaks from cracked plastic window and the clamshell not fitting tight. Also, I did have to leave it out in the rain a few days before the problem started.

Check under your drivers seat to make sure the Immobilizer is not getting corroded.
Not sure how that might cause a stalling issue -- but the immob sits in the lowest
point in the chassis and is a magnet for rain water.

If this get's bad enough -- the car will not start, the repair can get pricey AND
if the Immob needs replacement -- it can only be programmed at the dealership.

In other words -- make sure you are not getting your Immob wet regardless
of your stalling problem.

Mike

rock88hard · 08-26-2014, 12:13 PM

Damn! I did hear a pop 2 or 3 times under or behind me. Usually when I first start it and start driving it. This started only after the stalling problem started.

JayG · 08-26-2014, 02:58 PM

Quote:

Originally Posted by epapp

It was water in the gas. After trying to suck the gas out of the tank with an old (and our only) vacuum cleaner, it not only didnt work but we were left with a vacuum that would never smell clean again...

OMG, you are lucky you didn't blow yourself up
NEVER use a vacuum cleaner to suction gasoline

epapp · 08-26-2014, 03:28 PM

Seemed like a great idea at the time

...who wants to actually put their mouth on the tube and suck gas out of the tank like in the movies??

seningen · 08-26-2014, 03:52 PM

Quote:

Originally Posted by epapp

Seemed like a great idea at the time

...who wants to actually put their mouth on the tube and suck gas out of the tank like in the movies??

The more proper way to drain the fuel tank is to take the fuel line off and
then jumper the fuel pump relay.

Shouldn't take long that way -- and a lot safer.

mike

epapp · 08-27-2014, 07:59 AM

Well certainly that is the correct way, but when you're in college and around a bunch of guys, ideas get out of control quickly.

It was a house of 8 guys, who needs a vacuum anyways???

seningen · 08-27-2014, 08:15 AM

Quote:

Originally Posted by epapp

Well certainly that is the correct way, but when you're in college and around a bunch of guys, ideas get out of control quickly.

It was a house of 8 guys, who needs a vacuum anyways???

I'm surprised you guys didn't figure out how to distill it and make an evening out of it....

But in this case I guess it would have been a good thing the car doesn't start.......

m

rock88hard · 09-04-2014, 05:28 AM

I didn't get a chance to take the seat off and clean the immobilizer or cycle the fuel, but I did take it to Advanced and they got some codes, but they only know what 1 of them means.

P0102 - Mass Airflow Sensor

P1125 - ?

P1123 - ?

Does anyone know what the last 2 are?

Xpit77 · 09-04-2014, 06:02 AM

p1123 o2 sensor 1-3 cyl
p1125 " " 2-6 "

rock88hard · 09-04-2014, 07:06 AM

Thanks Xpit! Do you think a bad mass airflow sensor and 2 bad O2 sensors will cause it stall when coming to a stop?

It's fine once in idle if it doesn't stall. It stalls around 250-300 rpms and seems to stall less when going uphill.

jdraupp · 09-04-2014, 01:48 PM

Hmm...the experts can chime in here but Im betting on the maf before I bet on the o2 sensors. Doubt all would fail at the same time.

jdraupp · 09-04-2014, 01:49 PM

Year engine and mileage is also helpful

rock88hard · 09-05-2014, 05:18 AM

Its a 99 base. She just turned 75K miles. I think it is time for an oil change. I'm also going to change the air and fuel filters, run Seafoam through it, clean the mass air sensor and the throttle body. It seemed to work for the person in this thread http://986forum.com/forums/general-discussions/53915-engine-dieing-throttle-less-responsive.html

Retroman1969 · 09-06-2014, 04:16 PM

I had a 2002 Nissan Frontier once that did this exact same thing. Would die sporadically, and only when either throwing into neutral or coming to a stop.
It was indeed the MAF sensor in this case. Replaced it, and it never did it again for the remaining few years I owned the vehicle.

rock88hard · 09-30-2014, 05:16 AM

I havent had the chance to get the special bit to test the MAF, but this morning she wouldnt start at all. The battery cable was completely broken off. Do yinz think this could be the culprit? If not probably part of it huh?

Going forward, I will be making sure my battery is secured!

CJ_Boxster · 10-02-2014, 03:17 PM

Well more than likely the broken batt cable is the culprit, but that means your missing the little bracket that holds the battery from sliding all over the place. get one.

CJ_Boxster · 10-02-2014, 03:28 PM

if the pop sounded like a gun shot behind you, your issue is a check valve located on top of the engine, mounted underneath the intake plenum on the drivers side of the engine, it has a plastic hard pipe that leads to the front of the engine bay and runs down to the under carriage along side other similar style plastic hoses... if your lucky You can test it but having the engine running, and engine cover off, locate the valve and give it a hard smack with the handle end of a screw driver, sometimes itll unstick and cel will go away but the cel will come back usually once the ecu tries to trigger that valve into another position, causing it to get stuck once again.

had the same thing happen to me (1 gun shot sound) and 986 was really under powered and I kept going back to maf and aos replacements till i did some research and made the proper fix.

Im talking about part 14 in the image below.

Quote:

Originally Posted by rock88hard

Damn! I did hear a pop 2 or 3 times under or behind me. Usually when I first start it and start driving it. This started only after the stalling problem started.