Today my 986 died on the Bay Bridge

[schoir]

Originally Posted by Oaktown 986

Ok.. tested the gas while starting: no difference. Air filter and oil are all good. I guess everything else begins mañana.

"Tested the gas", may not do it.

Try keeping the gas pedal completely floored while you try to start it. That has started many a Boxster that would not start.

Search the archives here and on RennTech and you will find some examples of that exact scenario.

Regards, Maurice.

[Tranlm]

Did you check the tubing on the AOS? A common problem in boxsters are air leaks, though I don't know if it'd be severe enough to cause your car not to start.

Please keep us updated. I'd like to know the outcome.

[Oaktown 986]

Originally Posted by schoir

"Tested the gas", may not do it.

Try keeping the gas pedal completely floored while you try to start it. That has started many a Boxster that would not start.

Search the archives here and on RennTech and you will find some examples of that exact scenario.

Regards, Maurice.

UPDATE: Today, got home from work, and I held the gas down fully. Car started for a split second, then sputtered out, like it didn't really have gas or spark. Any thoughts? Keep in mind I got the three cylinders that misfired right before it went kaput.

Jon

PS, Tranlm, I did not yet check the AOS, but when I get 'er jacked again this weekend, I shall.

[tonycarreon]

i don't want to presuppose your mechanical skills or troubleshooting prowess. however at some point ( if it were me ) i would stop trying all the "do this, do that" and get a professional opinion.

that said, have you checked the oil level?

http://986forum.com/forums/showthread.php?t=24415
http://986forum.com/forums/showthread.php?t=24564
http://sites.google.com/site/mikefocke2/checkenginelightcausedbymassairflowsensor

[23109VC]

I agree - at this point, if you haven't found some simple solution - I'd take it to a pro and let them take a look at it.

you can end up wasting more time/money trying to fix it yourself if you don't know what you're doing - whereas the pro might be able to troubleshoot/diagnose it ASAP.... as they know the car inside/out....

good luck and I HOPE that the problem is something not too $$$...

[Oaktown 986]

Originally Posted by tonycarreon

i don't want to presuppose your mechanical skills or troubleshooting prowess. however at some point ( if it were me ) i would stop trying all the "do this, do that" and get a professional opinion.

that said, have you checked the oil level?

http://986forum.com/forums/showthread.php?t=24415
http://986forum.com/forums/showthread.php?t=24564
http://sites.google.com/site/mikefocke2/checkenginelightcausedbymassairflowsensor

well, i have more time than loose change, and i have other autos, so it's not a rushed deal; i'd rather have the car out of commission then pay $1k for something that I could have done myself. That being said, after I pull some spark plugs this weekend, and see what's going on up there, I believe I'll have some clarity on whether this is totally catastrophic, or simply a case of lacking spark.

Also, I fear that if the engine is blown, I'd rather buy a Raby then deal with sending it to a dealer for $200 plus towing fees when I'm going to need to also send it to Raby and fork up a whole lot right there.

Jon

[Lucky]

Based on what you've shared so far regarding the failure (just stopped, no unusual noises, etc.) and your attempts to diagnose, my best guess is the crank position sensor (CPS) has gone bad. As a result the engine computer has no idea where TDC is for each cylinder and can't determine when to fire the spark plug.

The only other reasonable possibility is a huge vacuum leak. One of the AOS hoses could have come loose or some other hose of a similarly large size. Check everything that connects to the intake system -- both ends of each hose and the hoses themselves for splits/cracks.

It is unlikely that the coil packs are bad. All 6 don't fail at once.

[Oaktown 986]

Originally Posted by Lucky

Based on what you've shared so far regarding the failure (just stopped, no unusual noises, etc.) and your attempts to diagnose, my best guess is the crank position sensor (CPS) has gone bad. As a result the engine computer has no idea where TDC is for each cylinder and can't determine when to fire the spark plug.

The only other reasonable possibility is a huge vacuum leak. One of the AOS hoses could have come loose or some other hose of a similarly large size. Check everything that connects to the intake system -- both ends of each hose and the hoses themselves for splits/cracks.

It is unlikely that the coil packs are bad. All 6 don't fail at once.

Thank you; this post has given purpose to my weekend: shall report tomorrow on findings for the AOS or any other hoses that are split, cracked, or disco'd.

[ARModen]

I had similar problems. It ended up being bad gas. The gas wasn't igniting properly and the computer attempted to correct for that by wildly adjusting the timing. There was no visible water and the gas easily lit with a match, so I ended up tearing a lot of the car apart looking for the problem. In frustration I had it towed to a shop where they dumped the whole tank and started over and it fired right up. On the up side the whole thing only cost me $500 including the tow.

http://987forum.com/forums/showthread.php?t=23121&page=4&pp=20&highlight=waterlogged

What I did might help.

[ARModen]

I believe people are directing you to the intake/maf based on the O2 sensor errors. These are more likely caused by the misfires. Gas that's not completely burnt in the cylinders when they misfire ends up partially burning in the exhaust manifold. This gives the O2 errors and can lead to cat failure.

I think the misfires can either be caused by incorrect timing, or an electrical/computer issue. If it was a timing chain issue, you'd probably just have errors on one bank. If it was an IMS failure (both chains) you'd hear your valves high fiving your pistons. So probably electrical/computer related. Of course that's 90% of the car!

For fuel, I'd check and make sure you have pressure at the test connection when the car is cranking. A pressure tester at autozone is only about $20. It connects to a test connection on the passenger side fuel rail. You can position it so it's visible from the drivers seat while you're cranking the car over. You can rent a set of "noid lights" for free ($20 deposit again autozone) and check the fuel injectors at the same time in almost the same location.

Electrical problems usually have lots of symptoms in cars that are so dependent on electronics. Have you had issues with any of the following not working: alarm, remote, windows, top, radio, lights? Dirty battery terminals or a failing ignition switch can cause your problem, but usually come with a dozen other issues.

Computer issues can be checked with a durametrics or shop tester. If you're able to read codes with a regular OBD2 scanner then the DME is probably working. It may still be the cause of the problem if it's getting bad inputs. A bad MAF should cause it to run like crap, but shouldn't throw off the timing because it affects fuel/air ratio not timing. Failed cam/crank sensors are more likely to cause misfires because they are timing inputs.

[Oaktown 986]

Originally Posted by ARModen

I believe people are directing you to the intake/maf based on the O2 sensor errors. These are more likely caused by the misfires. Gas that's not completely burnt in the cylinders when they misfire ends up partially burning in the exhaust manifold. This gives the O2 errors and can lead to cat failure.

I think the misfires can either be caused by incorrect timing, or an electrical/computer issue. If it was a timing chain issue, you'd probably just have errors on one bank. If it was an IMS failure (both chains) you'd hear your valves high fiving your pistons. So probably electrical/computer related. Of course that's 90% of the car!

For fuel, I'd check and make sure you have pressure at the test connection when the car is cranking. A pressure tester at autozone is only about $20. It connects to a test connection on the passenger side fuel rail. You can position it so it's visible from the drivers seat while you're cranking the car over. You can rent a set of "noid lights" for free ($20 deposit again autozone) and check the fuel injectors at the same time in almost the same location.

Electrical problems usually have lots of symptoms in cars that are so dependent on electronics. Have you had issues with any of the following not working: alarm, remote, windows, top, radio, lights? Dirty battery terminals or a failing ignition switch can cause your problem, but usually come with a dozen other issues.

Computer issues can be checked with a durametrics or shop tester. If you're able to read codes with a regular OBD2 scanner then the DME is probably working. It may still be the cause of the problem if it's getting bad inputs. A bad MAF should cause it to run like crap, but shouldn't throw off the timing because it affects fuel/air ratio not timing. Failed cam/crank sensors are more likely to cause misfires because they are timing inputs.

Your input is quite useful and well thought out, and highly appreciated. I've been using a standard OBDII sensor, and my O2 codes have been active for a couple months (I don't drive it all that much, figured I could let it slide until winter). WIth that in mind, I will also get the pressure tester and start there; these $20 testing solutions are great to isolate this, and the tools will be forever saved for use with future vehicles (my audi is a troublemaker even though it's only 3 years old).

All the electronics on the car have been in perfect working order; however the battery did recently die after I was gone in South America for 3 weeks. Perhaps something is bad in the charging system?

Jon

[ARModen]

Batteries can do some crazy things to modern cars that depend on a very steady voltage. The speedometer in my S-10 used to warn me when my battery was going south. If the speedometer started bouncing around it meant that I'd better park somewhere good because I was not going to get it to start up again. Corrosion on the terminals of my 944 used to cause complete electrical failure. I'd be cruising down the highway at night and the entire car, headlights, taillights, dash light, engine would all go black. I'd have to coast to a stop then it would fire right back up and work fine for a few more days.

[Oaktown 986]

Originally Posted by ARModen

Batteries can do some crazy things to modern cars that depend on a very steady voltage. The speedometer in my S-10 used to warn me when my battery was going south. If the speedometer started bouncing around it meant that I'd better park somewhere good because I was not going to get it to start up again. Corrosion on the terminals of my 944 used to cause complete electrical failure. I'd be cruising down the highway at night and the entire car, headlights, taillights, dash light, engine would all go black. I'd have to coast to a stop then it would fire right back up and work fine for a few more days.

New battery has been called in and is awaiting me for after work today at the local store.

we'll see what this does, then move on to the fuel pressure testing.

Thanks!

Jon

[ARModen]

Lol, I'd have just cleaned it first.

[extanker]

Originally Posted by ARModen

Lol, I'd have just cleaned it first.

its okay..he "charged" the battery to your name

[Oaktown 986]

Originally Posted by extanker

its okay..he "charged" the battery to your name

So... of course. I changed the battery after autozone tested it, and put in a new one. It now starts and drives, albeit with some loss of power. I'm going to jack it tomorrow and pull a plug and see if I can get a clue as to what's going on...

[Oaktown 986]

Update:

Some loss of power is a pretty consistent loss of power in every gear. It drives, but is slower to rev, and on the freeway cannot get past 65 MPH. I've parked it back in the driveway. It's got 92k and the original MAF.... I'm thinking that after looking at all the other high mileage cars on this forum, that could be the culprit?

J

No codes are being thrown right this moment, and the engine does make a backfiring noise if I gas it too hard to "overcome" the loss of power

[Oaktown 986]

BUMP.

Who says MAF is the likely culprit?

Jon

[Keith Newby]

Isn't the common test for a bad MAF to disconnect it...If the car runs better it's a bad MAF?

[extanker]

with the money ya saved you can have the brakes fixed