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Mystery Problem


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2000 Boxster Tiptronic (120,000 miles) wouldn't start, mechanic said the oil seperator was cracked and needed replacing. OK. CEL fault codes were saying it was the oxygen sensors but they were recently replaced, along with the Mass Airflow Sensor. Car still wouldn't start, so mechanic decided the crankshaft speed sensor needed replacing. OK. This appears to have fixed the starting problem but the car now ran rough, so the mechanic replace the plugs, coils, sleeves, etc. This accomplished nothing, car still runs rough and the mechanic decided it has something to do with the transmission so he checked the fluid level (slightly low) and he topped it off. Now the car is leaking transmission fluid and still running roughly. Mechanic doesn't know where to go next without fault codes to guide him, anyone got an idea what's going on? Please reply soon, I'm almost out of money. Thanks in advance - rPm

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Elaborate about your patient. (When you said it wouldn't start, it still cranked no?), is it misfiring? listen at the tail pipe for little poofs, you can feel them to with your had in front of the exhaust pipe to. If it is, is it even & steady or arbitrary hit an miss. Does it run rough all the way up to the recline. Again abitrary or even.

Is it just slugish but still running smooth? Did it die on you or did you just wake one morning to a little surprise? Doing anything weird last time you drove it?

Regards, pk

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2000 Boxster Tiptronic (120,000 miles) wouldn't start, mechanic said the oil seperator was cracked and needed replacing. OK. CEL fault codes were saying it was the oxygen sensors but they were recently replaced, along with the Mass Airflow Sensor. Car still wouldn't start, so mechanic decided the crankshaft speed sensor needed replacing. OK. This appears to have fixed the starting problem but the car now ran rough, so the mechanic replace the plugs, coils, sleeves, etc. This accomplished nothing, car still runs rough and the mechanic decided it has something to do with the transmission so he checked the fluid level (slightly low) and he topped it off. Now the car is leaking transmission fluid and still running roughly. Mechanic doesn't know where to go next without fault codes to guide him, anyone got an idea what's going on? Please reply soon, I'm almost out of money. Thanks in advance - rPm

:welcome:

Sorry, without fault codes - everything is a guess. Any good mechanic will tell you that.

Beg, borrow, or buy a tester and report the fault codes back here and we will try to help.

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2000 Boxster Tiptronic (120,000 miles) wouldn't start, mechanic said the oil seperator was cracked and needed replacing. OK. CEL fault codes were saying it was the oxygen sensors but they were recently replaced, along with the Mass Airflow Sensor. Car still wouldn't start, so mechanic decided the crankshaft speed sensor needed replacing. OK. This appears to have fixed the starting problem but the car now ran rough, so the mechanic replace the plugs, coils, sleeves, etc.

Sounds like your "mechanic" is throwing parts at your car, and at your cost. For a car that won't start, O2 sensors, AOS, or MAF won't keep it from starting, but will make it run rough or smoke. The CPS is the key that tells the computer how to control the ignition and fuel. If it is running that rough, it should be throwing codes. Borrow an OBD reader to see what codes are present and let us know.

An idiot check would be to disconnect the battery for a bit, then reconnect, should reset the ECU, but won't clear most codes.

You need to find a different mechanic, quickly.

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At 120k, an AOS replacement would not surprise me at all, but you might get a read(ie durametric software or equivalent) of the DTC's off the car's ECU. Having said that, the ignition switch assembly failed on our 01 without emitting any DTC's. You might suggest your tech also check the clutch switch(or brake switch if tip).

regards

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He says in the first post that the mechanic read the CEL codes, but that they're now gone after his first repairs, and he now has now codes to guide him. At least that's how I interepreted it.

I've had a pretty massive vacuum leak from a cracked oil filler tube that made the car run terrible, but I still never had a code. That's why I was guessing vacuum leak.

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A vacume leak is a good possibility. There's a good old fashion way he could use to find vacuum leaks himself. Sounds scary but not even, (I'd explain why but...).

Simply get a can of spray starter fluid (with the little "mini straw" extension). Fire up the motor, and start selectively shooting focused blasts at all the suspicious vacuum connections and devices. When you hear the engine surge a little (takes a second to register) and it's predictably repeatable, bingo. there's a leak.

Regards, PK

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A vacume leak is a good possibility. There's a good old fashion way he could use to find vacuum leaks himself. Sounds scary but not even, (I'd explain why but...).

Simply get a can of spray starter fluid (with the little "mini straw" extension). Fire up the motor, and start selectively shooting focused blasts at all the suspicious vacuum connections and devices. When you hear the engine surge a little (takes a second to register) and it's predictably repeatable, bingo. there's a leak.

Regards, PK

This post brings back good memories of finding vacuum leaks with my dual 48 IDA's on my good old VW Bug when I was in college...exactly how I use to do it as well. I was running a 2276, which was just a blast. There was just something about seating the manifolds once they were ported and polished and getting those 13mm nuts to seat on the 8mm studs. It always seemed as though there just wasn't enough surface area to close the vacuum leak. Those were the good old days! If I had to find a vacuum leak today, I'd do it just as you've described.

I hope the originator of the post finds success getting his car going...sounds like a new mechanic may be the hot ticket.

All the best,

Bill :beer:

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He says in the first post that the mechanic read the CEL codes, but that they're now gone after his first repairs, and he now has now codes to guide him. At least that's how I interepreted it.

I've had a pretty massive vacuum leak from a cracked oil filler tube that made the car run terrible, but I still never had a code. That's why I was guessing vacuum leak.

Yes, that's why I titled it "mystery!" There are no fault codes. Thank you, Tex

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He says in the first post that the mechanic read the CEL codes, but that they're now gone after his first repairs, and he now has now codes to guide him. At least that's how I interepreted it.

I've had a pretty massive vacuum leak from a cracked oil filler tube that made the car run terrible, but I still never had a code. That's why I was guessing vacuum leak.

Yes, that's why I titled it "mystery!" There are no fault codes. Thank you, Tex

Many thanks for all the suggestions, here's the latest update: Mechanic now says that the seal between the torque converter and transmission is bad, that's why it leaked when topped off. When fluid level drops below the level of the seal car runs rough but leak goes away. Question is now, do I replace just the seal or has the tranny been damaged and needs replacing as well? Hate to pay for labor twice, your suggestions and comments are greatly appreciated. - rPm

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Has he demonstrated this to you? Don't know anything about tips but if it's in neutral, can't see how fluid level would make a dif.

PK

Yes, car on lift (back tires off the ground), start car, engage emergency brake, shift into drive. Will not leak in neutral, only when transmission is circulating fluid in gear. While driving, the hesitation feels like the engine is running roughly but it is the transmission slipping because of the leak and low fluid level (according to the mechanic). Makes sense to me, but sounds like you're not buying it?

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Has he demonstrated this to you? Don't know anything about tips but if it's in neutral, can't see how fluid level would make a dif.

PK

Yes, car on lift (back tires off the ground), start car, engage emergency brake, shift into drive. Will not leak in neutral, only when transmission is circulating fluid in gear. While driving, the hesitation feels like the engine is running roughly but it is the transmission slipping because of the leak and low fluid level (according to the mechanic). Makes sense to me, but sounds like you're not buying it?

I would advise you to be very careful using starting fluid to search for vacume leaks. just a small amount coming into contact with a high voltage spark will have you running for an extinguisher in a hurry. As a minimum, keep a charged water hose handy with a fine mist setting.

I also would suggest another opinion from a mechanic that is more familiar with your car. Good luck.

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BoB C welcome aboard.

That sounds very, prudent & sensible and deserves a short but honest discussion Don't take it the wrong way and go away and never come back as I might sound harsh. I think we might both might learn something, You will have to work through some challenging, grammar misspellings, and sentence structure (dyslexia)

So, Have you ever seen an arch in your engine bay? If so where did it come from?

I owned, rebuilt and sold awful lot of cars years ago, about 25-30 in all. Paid for my schooling selling them once got them shi[ shape, I got to own and drive a lot of cars no starving college student should be seen in. I'll tell you though, to get those things up from the dead and ultimately running sweet (they usually came to me on flatbeds in pretty sorry shape) took an elluva lot of starter fluid (among many, manyother things), to make them sing and sell.

Basically what I observed in those days was that the stuff never stuck around long enough to catch fire. I think you could probably flick matches into the spray, a foot from the nozzle, all afternoon, and never see any pyrotechnics. It either dissipates or vaporizes shortly after leaveing th can. I have only seen a flame when deliberately screwing around with a lighter, right in front of a spraying nozzle. It's a big flame, but only till the very instant you shut it down. Then it's gone. poof with out a trace

My theory is, and I think its a good one,Its extremely volatile, can be ignited at very low temps, but, only when the conditions ar perfect. The occures in only to places 2 in it's journey to the spark plug from the nozzle(I've studied this suff a bit), that's at the nozzle & when It's Sucked in to vacuum/manifold system. That's due to it's critical A/F value the starter fluid needs to ignite, (Our cars have a 14:1, A/F ratio nothing burns well if at all to far from that ratio.

In the can, the fuels compressed with very little air, it's way off. Way, way to rich to burn. Start spraying and at about an inch out, its mixing with air, now close enough to it's A/F value that it can ignite. But maybe a foot away , It has dissipated some and vaporized and now theirs way to much air to let the it ignite, The A/F value has tilted to the other extreme.

(Jeeze, did I say a "short ...discussion") At the other end its going to start to return to its flammable A/F ratio as it' sucked into the manifold it starts to equalize it's ratio with that of the fuel there at 14:1, good enough to burn. ( but note, Its really whisked away fast into the manifold where it's safe from your arc. Once in the cylinder with correct a/f ratio, its compressed and ignited and boom. I'ts more flammable and explosive than fuel, but again, only at the a very good stoichiometric value (A/F ratio). It has that value just outside the can and in the vacuum system but not dilute wit air wafting around the engine bay,

Just an educated guess but it makes sense doesn't it? Other wise, odds's are by now, what was left of my head would be out in the stratosphere somewhere.

But, your correct, if your not comfortable around the engine (or, one with engine?) have someone else do it. The beauty is it's really, really fast and the alternative require $$ equipment and more time $$. I gave my Box the once over after some extreme mods to it's plumbing. In 20 mins or less I found and fixed four leaks an checked dozen more.

Regards, PK

Edited by pk2
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