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White smoke AND hard brake pedal at same time?

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Hey guys...

Went out yesterday morning to start my 1997 boxster with 65,000 miles, backed up my drive-way and the brake pedal wouldn't depress...barely got the car to stop. Thought it might be a one-time problem so I (cautiously) drove to stop sign...same problem. I turned back for home and white smoke started pouring out of the exhaust. Parked it and took other car to work.

Went out this morning to start it and engine had rough idle. Gave it a little gas and she stalled...white smoke the entire time.

I am aware of the white smoke at start-up, but this is different.

Any ideas??? I'm finding it odd that both the brakes and smoke happened at the same time.

Never had any problems with this car and the day before...she ran perfect. HELP!!!! :)

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Low vacuum because of AOS failure. Try starting the car and let it idle; while it is running, try to remove the oil filler cap. If it is very hard to remove, your AOS is toast and has to be replaced (do not drive the car in this condition as you could easily hydraulic the engine). Do a search; this is a DIY project................

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Both, the brakes suffer due to lack of vacuum (provides the "power" in power brakes) caused when the AOS craps out, the smoke is oil being pulled into the engine through the failed AOS. It is also why you have a rought idle.

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Sounds like your brake booster has failed due to water intrusion

into the booster. The cowl drains clog and the early cars don't have

an adequate boot to seal it out. There is an update to the boot that

requires a few more pieces than come with the new "TRW" booster.

To see if this the case, remove the plastic cover for the booster and

master cylinder and carefully pull the 90 degree plastic vacuum valve

out of the grommet on the booster. Look inside and you will likely see

a lot of rust. I've done about 10 now and usually the master is bad.

The white smoke is water going into the engine.

hope this helps, Tony

Edited by tony.mccabe
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  • 2 weeks later...

So...you were both right :thumbup:

Replaced AOS, cleaned MAF, and changed out air filter. Cleared codes. No more white smoke and running smoother.

The brake booster plunger, thanks to a heavy rain and tree debris, was under water. I cleared the drains and the brakes are working...but not well.

Drove her to work and the idle at each red light was high (1100rpm). Check engine light then came on (p0506...low idle?)

My questions are could the vacuum assist to a faulty brake booster be the culprit or ???? ...and... why p0506 when idle is high?


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P0506 is usually associated with a sticking idle air control valve, which bleeds air into the intake to control idle speed conditions; sort of “controlled vacuum leak”. The IACV can often be cleaned of accumulated crud and placed back into service, but that does not always work and replacement becomes necessary.

That said, considering your vacuum booster issues, you should also be checking it to be sure you do not have rust out problems causing a vacuum leak there that is upsetting the IACV.

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