RandyR

I'm fairly new to boxter world ......customer came in today complaining about a running issue. Turns out she has an inconsistant idle hunt and an inconsistant cough when accelerating from a stop. No check engine light. I can poke around but I thought I'd ask around for any common notorious problems to start looking for. She is schedualed for next week to come in. Any ideas?

Ray S

Check out the links in post #4 of this thread.

https://rennlist.com/forums/boxster-and-boxster-s-986-forum/366798-oil-pressure-and-engine-idle-questions.html

senna21

Let us know if cleaning the Throttle valve clears up the problem.

nickg

mine was a bad maf..did same thing. MAF fixed it

Macster

vacuum is a symptom of air/oil seperator (AOS), although not all fail with this symptom. Hoses from intake to AOS can collapse too.

If you can examine throttle body and butterfly valve. Any oil wetness or oil in port just downstream of butterfly valve another sign of AOS trouble.

Be very careful with car/engine if you suspect AOS because running engine can subject the engine to hydraulic lock if failing AOS allows engine to ingest oil. And this can happen.

Surprisingly, during the time my '02's AOS was going bad no CEL.

But it started with a mild hesitation -- just enough to make me think engine was getting tired (this at 80,000 or so miles) -- and soon to follow a mildly hunting idle. Just 100 or so RPMs either side of normal (700 or so).

Only when AOS got real bad and engine smoking quite heavily did I give up my atttempt at diagnosis and flat bed car to dealership. (AOS failures at that time were relatively still rare and I knew nothing about them at the time.)

When I called dealership/service and described symptoms service advisor told me about AOS -- though not in any detail -- and cautioned me to avoid driving car. Another owner with a car going through the same symptoms at the same time as mine ignored warning and engine locked up and was ruined. (And it was his car (Lapis blue, too, same as my car!) on rack that had AOS removed and cut apart to show me what went wrong with my car's AOS when I stopped in at dealership to check on car's health before heading out west for a job interview.)

My '02 survived and after AOS, spark plugs, some bottles of Techron (and a perhaps unrelated to the AOS failure an O2 sensor that I had to replace) the engine has gathered another 90,000 miles since that time apparently none the worse for the experience.

Sincerely,

Macster.