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Dreaded Flashing Check Engine Light 100K


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There I was...just tooling down the road. One mile from my exit, cruising, no rush. Check Engine Light came on and flashed and kept flashing until I could safely get off the road, I could feel the engine falter but no loud noises. After turning off the engine, I have not tried to restart as of yet. I'm waiting to get a reader for the codes. I wish I had them for you. I replaced spark plugs and MAF at 90k but the coil packs are the ones that came with the car when I got it in 2005 at 47K miles as well as the oxygen sensors. 

 

While I was waiting for the tow truck driver to arrive, I did a cursory look over the engine and where I could see and feel, I couldn't see any vacuum lines misplaced or other signs of visual distress (as if) but the Y-tube wasn't solidly connected to the air/oil separator. There did not appear to be any signs of oil or sludge from the Y-tube or the air/oil separator. I don't think it would trigger a flashing CEL, but I know a loose gas cap can trigger a solid CEL.

I'm leaning towards a coil pack failure as opposed to oxygen sensors. It's my opinion only that if an oxygen sensor was beginning to fail, I would have only a solid CEL rather than a Flashing CEL. Maybe the Y-tube and air/oil separator lost their connection enough to trigger the event, but something tells me that's wishful thinking. 

To get to my question, now that you read the details (thanks) I hope I didn't damage the engine/catalytic converters from the time it came on to the time it took me to safely get off the road, but in any event, would the weight of the flashing CEL be towards a failed coil pack or an oxygen sensor? I realize there maybe other factors, but I'm curious to hear your opinions from experience to assist me in evaluating the problem.

Thanks in gratitude 
David

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A flashing CEL is a critical issue, and may be more than a simple misfire, which rarely causes the CEL to flash, but rather just illuminate.  Get the codes read, preferably with a Porsche specific scan tool and let us know what you find.  Without the codes, anything is speculation.   Good luck.

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P0300 & P0343 are the two codes I have. 

 

P0300 Random Misfire
P0343 Code (Camshaft position sensor A Circuit High Input. Bank 1 or single sensor)

 

Fuel system 1 : CL

Fuel system 2 : CL

Calc Load 27.1%

ECT 180F

STFT B1  15.6%

LTFT B1  2.3%

STFT B2 15.6%

LTFT B2  0.8%

Eng RPM 3280

Vehicle speed 68mph

 

So, replace 996-606-106-02 to remedy P0343? And P0300 would be an oxygen sensor before the cats or a cracked Ignition coil(s)?
 

Edited by zodman
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1 hour ago, zodman said:

P0300 & P0343 are the two codes I have. 

 

P0300 Random Misfire
P0343 Code (Camshaft position sensor A Circuit High Input. Bank 1 or single sensor)

 

Fuel system 1 : CL

Fuel system 2 : CL

Calc Load 27.1%

ECT 180F

STFT B1  15.6%

LTFT B1  2.3%

STFT B2 15.6%

LTFT B2  0.8%

Eng RPM 3280

Vehicle speed 68mph

 

So, replace 996-606-106-02 to remedy P0343? And P0300 would be an oxygen sensor before the cats or a cracked Ignition coil(s)?
 

 

Codes are probably related, but the P0343 is often more a wiring issue than a replacement:

 

P0343 Camshaft Position Sensor 1 – Above Limit

Potential causes:

– Short circuit to B+

Check the connector/wiring.

Check signal wire from DME control module, pin III/20, to CMP sensor for short circuit to B+.

1. Connect special tool 9637 to wiring harness (DME control module connector).

2. Remove connector of CMP sensor.

3. Connect voltmeter to special tool 9637, pin III/20, and ground.

Switch on the ignition.

Display: 0 V

If battery voltage is displayed, check wiring harness for chafing and pinching damage.

  
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Due to the fact I don't have special tool 9637, where would I find someone in the San Francisco Bay Area to loan me one to test? I can't find any online.

If a broken wire is the culprit, could new ones of the same gauge be routed along the harness and rigged that way to the DME since replacing the harness would be a nightmare?

If the Sensors are on both sides of the engine, if you clear the codes and swap the sensors out with each other, would that cause a different number error code, ruling out the wires being the fault but the sensor?

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10 hours ago, zodman said:

Due to the fact I don't have special tool 9637, where would I find someone in the San Francisco Bay Area to loan me one to test? I can't find any online.

If a broken wire is the culprit, could new ones of the same gauge be routed along the harness and rigged that way to the DME since replacing the harness would be a nightmare?

If the Sensors are on both sides of the engine, if you clear the codes and swap the sensors out with each other, would that cause a different number error code, ruling out the wires being the fault but the sensor?

 

Tool 9637 is one of Porsche's Unicorn tools, it is called a pin out box for diagnosing electrical issues in the harness.  These things cost a couple of grand, and the last time we looked the wait time to have the elves in the Black Forest build one for you was about two years.  It is not going to be easy to find.

 

The harness can be repaired, but with a couple of caveats: The wire gauge and colors should match for later diagnostic purposes, and the replacement should be soldered and heat shrinked, never crimped (low voltage sensor signals are very suseptable to line resistance, which is common with crimped connections).

 

You can always swap the sensors, but as the code is specific to a harness issue, the code would not likely change.  You would probably better spend your time jury rigging the wiring harness electrical tests looking for the short.

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In reading a few other posts related to the P0343 code, there are a few that had suffered breaks in the camshaft chains/timing chains as being the causal agent(or horrid aftermath), a few others had the sensor at fault or the contacts leading to the sensor. Can I simply pull the green plugs on top and rotate the crankshaft to make sure the chains and the timing is still good? Would I need to drain the oil at all?

Would the crankshaft move at all if the chain is broken?

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If yours is a 2001 Boxster, pull the green plug on the exhaust side of the head on the passenger's side and rotate the engine by hand (clockwise ONLY) using the bolt in the crank pulley.  When the engine is at TDC, the slot in that cam should be straight up and down in the plug opening.

 

As the crank drives the cams via the chains, yes the crank would move if the chains were broken, but the engine would be trash as there would have been massive piston to valve contact. At that point, codes would be irrelevant.

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1 hour ago, JFP in PA said:

If yours is a 2001 Boxster, pull the green plug on the exhaust side of the head on the passenger's side and rotate the engine by hand (clockwise ONLY) using the bolt in the crank pulley.  When the engine is at TDC, the slot in that cam should be straight up and down in the plug opening.

 

As the crank drives the cams via the chains, yes the crank would move if the chains were broken, but the engine would be trash as there would have been massive piston to valve contact. At that point, codes would be irrelevant.


That's the lower one right behind the passenger seat correct? Would I need to drain oil first? And the third question, I read that the crank would move, but the cams wouldn't if it's trashed correct or wouldn't line up vertically once at TDC?

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Correct on the cam plug location.

 

An oil drain is not necessary, with the engine off there is little oil in the cylinder heads.

 

If the chains have failed, the engine will not run, and even turning it over would result in bent valves, and the engine would not be able to complete one rotation.  These are interference engines, meaning that if the valves are not opening or closing at the correct time, parts start hitting and it is all over.

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1 hour ago, JFP in PA said:

Correct on the cam plug location.

 

An oil drain is not necessary, with the engine off there is little oil in the cylinder heads.

 

If the chains have failed, the engine will not run, and even turning it over would result in bent valves, and the engine would not be able to complete one rotation.  These are interference engines, meaning that if the valves are not opening or closing at the correct time, parts start hitting and it is all over.


Well I removed the lower bottom plug and the cam slot was at 7o'clock for three full clockwise rotations and never budged moved at all. I'm trying not to curl into a fetal position, or otherwise turn to drinking. I took good care of it over the years...Changed oil often, replaced the IMS, replaced the shocks, the clutch, the top, the aos, the maf...yada yada....then it gets a frikken heart attack and dies....And I just bought her new ignition coils and spark plugs for her birthday....sniff....

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9 minutes ago, Ahsai said:

Sorry to hear that. Seems like you did all the right PM and regular maintenance. Any warning like debris in oil, strange noise, etc?

 

No warnings, just driving down the freeway. Light kicked on flashing then loss of power. I limped it off the freeway for safety. Never had debris in oil filter from previous changes. Checked oil pan at 88K was clean. If the cam isn't moving I don't know if there's any hope to saving anything if it's an interference engine. Once those chains go you're foicked.

What are JFP in PA's thoughts or Loren's?

If I could get it up my inclined driveway into my garage, I'd consider swapping out the engine, but that is a problem as there isn't any way to get it inside.

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18 hours ago, JFP in PA said:

Correct on the cam plug location.

 

An oil drain is not necessary, with the engine off there is little oil in the cylinder heads.

 

If the chains have failed, the engine will not run, and even turning it over would result in bent valves, and the engine would not be able to complete one rotation.  These are interference engines, meaning that if the valves are not opening or closing at the correct time, parts start hitting and it is all over.


Well I removed the lower bottom plug and the cam slot was at 7o'clock for three full clockwise rotations and never budged/moved. I'm assuming the engine is foicked. What would you do in this situation JFP? It's a 5-chain 3.2 986 engine with a double row LN upgrade. 

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I would start by removing the oil filter and cuttingt it open; if it is full of metal, you will need to drop the engine for further examination.   If the cams are not rotating in sync with the crank, I would seriously doubt the news is going to be anything good......

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It would help us advise you if you mentioned the skill level(with M96) of whoever will do the work. I mention this because it seems probable that you will need a replacement engine. That is a task requiring some significant equipment, skill, time and money.Will you do all the work or your Indie?

Ahsai's suggestion of removing the Bank1 scavenge pump seems the best initial course of action because the seemingly failed chain is easily exposed by removing just 4 bolts that retain the pump.You should see it on the Ex cam sprocket

An alternative would be to remove (catch oil !!) the chain tensioner nearby -32mm size. Stick your finger in the hole to feel for the floppy/broken  chain.

The potential problem with a broken chain is the very hard debris of the broken chain pieces & of the thrashing chain on related plastic and aluminum parts. Finding all  of that abrasive/clogging debris will be difficult even with a full dismantling of every part of the engine. If you have a full flow filter(LN?) that may help. Usually the cost of such work far exceeds the cost of a good used engine. 

For options, you could try L.A. Dismantlers for a used 3.2 , Woody (itsnotaNova on 986 Forum) or Fleabay ,maybe Craig's.

Good Luck with your sad project .I am just recovering from a similar one.

Edited by Schnell Gelb
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