2005 Boxster S (987) AOS
Discussion
Hoping to get some advice. Firstly I'm no mechanic! A while ago my car started smoking on start up. I replaced the AOS but when I came to do it I noticed that the hose that should be attached at the top was not connected to the right place. Having never worked on the engine before I initially couldn't work out what was wrong but after a while and after trying to order a replacement hose I spotted the problem. The hose that should be attached to the AOS is blanked off. The AOS is now goes to the top of the engine where an extra nozzle has been fitted. My question is, why would anyone reroute the hose to where it has been done in the photo and will this have an effect on the car? It is still smoking on start up despite replacing AOS (normally the day after a longer journey, not shorter ones). The car runs very smoothly and no smoke whilst driving. Any suggestions gratefully received.
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Hi the only reason i think this would be carried out,is to stop any oil getting into the maf sensor.
The 987 seams to suffer maf sensor issues due to the change in the angle of the pipe from airfilter to throttle body,as it runs down hill towards the airfilter.This will cause oil residue to run down the pipe into maf.
Chris
The 987 seams to suffer maf sensor issues due to the change in the angle of the pipe from airfilter to throttle body,as it runs down hill towards the airfilter.This will cause oil residue to run down the pipe into maf.
Chris
My advice is to route the hose from the AOS to the intake correctly. The AOS needs the low pressure from the intake to function correctly. The low pressure helps lower the boiling point of water in the oil to help keep water build up in the oil down.
Be sure you use the proper hose. If the hose is too soft it can collapse and this then disables the AOS. The hoses must remain open for the AOS to do its job.
That hose being routed incorrectly suggests to me a hack.
I am not familiar with the car but is the MAF located on the floor of the intake? In all cars I'm familiar with the MAF is up high and even if there was some oil in the intake at where the MAF resides I couldn't see how the MAF could get fouled. In the case of this particular model is it hard to imagine the oil running the other way, against engine air flow, and fouling the MAF.
For the smoking if the AOS for some reason emitted some oil vapor this can collect on the intake walls and if heavy enough can take some time to burn away. When my Boxster suffered its first AOS failure the engine exhaust was dripping with oil. The service manager at the dealer told me it can take some driving to elmiinate the oil through out the engine from the intake through the exhaust system. He said in some cases it can around 50 miles of driving. Highway driving is not necesssarilty the best driving either in this case. Around town driivng is preferred as teh engine runs hotter and the intake stays hotter due to heat from the engine and a warm intake then helps any oil become more liquid and thus it can be pulled along and into the engine. The exhaust system likewise gets plenty hot throughout the system not just at the headers/converters.
Be sure the oil level is ok. If the AOS wasn't connected properly the oil could have become contaminated with water which can raise the oil level. If you haven't done so already it might not be a bad idea to change the oil and of course ensure the oil level is correct.
Be sure you use the proper hose. If the hose is too soft it can collapse and this then disables the AOS. The hoses must remain open for the AOS to do its job.
That hose being routed incorrectly suggests to me a hack.
I am not familiar with the car but is the MAF located on the floor of the intake? In all cars I'm familiar with the MAF is up high and even if there was some oil in the intake at where the MAF resides I couldn't see how the MAF could get fouled. In the case of this particular model is it hard to imagine the oil running the other way, against engine air flow, and fouling the MAF.
For the smoking if the AOS for some reason emitted some oil vapor this can collect on the intake walls and if heavy enough can take some time to burn away. When my Boxster suffered its first AOS failure the engine exhaust was dripping with oil. The service manager at the dealer told me it can take some driving to elmiinate the oil through out the engine from the intake through the exhaust system. He said in some cases it can around 50 miles of driving. Highway driving is not necesssarilty the best driving either in this case. Around town driivng is preferred as teh engine runs hotter and the intake stays hotter due to heat from the engine and a warm intake then helps any oil become more liquid and thus it can be pulled along and into the engine. The exhaust system likewise gets plenty hot throughout the system not just at the headers/converters.
Be sure the oil level is ok. If the AOS wasn't connected properly the oil could have become contaminated with water which can raise the oil level. If you haven't done so already it might not be a bad idea to change the oil and of course ensure the oil level is correct.
Not to steer away from the topic but is there an early warning for AOS fail? My 2000 (2.7) never smoked since I owned, maybe a slight a few seconds tiny smoke if from a cold start (like 4-5 days sitting).Thinking of replacing with the next oil change for like 6 months later, since it's a fairly cheap replacement anyway.
Many thanks for your very comprehensive reply Rockster. I had wanted to put a new hose on when I replaced the AOS but had nothing to sort out the added nozzle with or to blank off what would have been a hole underneath it. I will however get everything g rerouted as it should be soon!
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