I have an 02 stock turbo, non x50, and occasionally it'll show .9 on the OBC. I know the internals are okay with that, but do I have to worry about it running lean at that boost level?

There is no tune, the car doesn't act funny, I don't get any warning lights, and it'll stay at .9 for a second or two, then bleed down to .8. I know .7 is normal, and I have no issue with it hitting .8, but is .9 something to worry about?

The realistic part of me is assuming that the computer knows what its doing and to just let it do its thing.

Thanks

 

You're fine. I blew the heads off of my car at 1.5 bar. Sub 1.0 is kids stuff.

 

The computer is what is allowing boost to reach 0.8 even 0.9 bar and in fact every boost level above zero.

The way it was explained to me is the DME attempts to satisfy the torque demanded by the driver via the gas pedal (E-gas). If it can do this with 0 boost so be it. If it requires 0.2 bar or more that's ok too.

Often on the highway when monitoring boost I'll see 0.2 even 0.3 bar without me even thinking about stomping on the gas pedal.

At other times when the torque demand is higher the DME will cause the boost to reach 0.6 bar. Often many drivers see only this level of boost.

But if one really tries he can cause 0.7 bar boost to appear and linger for more than a moment or two though boost does drop off some as RPMs rise.

And under special circumstances -- my experience is at higher elevations -- 0.8 bar even 0.9 bar boost is obtained.

These higher levels of boost are permitted by the DME because the torque demand can't be satisfied by a lower boost and the DME has not encountered anything that would cause it to restrict the boost to a lower level.

All you need be concerned about is making sure you fill up the fuel tank with a proper grade of premium gasoline. In CA all we can get is 91 and my experience is the Turbo engine is "fine" with this. (Well, fine is a relative term as my experience with running 93 octane is the engine loves 93 octane gasoline and low end and throttle response are improved but 91 is all I can get in CA.)

Turbo engines are harder on plugs so don't scrimp or try to nurse a set of plugs beyond their change by date/mileage.

A Turbo uses lots of fuel and the fuel filter is small. Change this on schedule.

And when (if) you ever get a CEL related to an O2 sensor consider replacing all 4 unless they are relatively new and has failed early. (Rare but it can happen.)

In the case of my 2003 at around 132K miles it started registering a CEL accompanied by an O2 sensor error code (I think related to sensor heater problem) and as soon as I could I had all 4 replaced. The engine was running fine before the sensor error. I had just driven it to MO from CA and almost all the way home again (I was in Barstow CA when the CEL came on the 1st time) with no problems. Even after the CEL the engine ran ok all the way home about 300 miles. But after I had the sensors replaced the engine ran noticeably better.

Even though the sensors were "ok" they were under-performing.

BTW, the #1 sensors are wide band sensors to help insure more precise fueling. Proper turbo-charged engine fueling is not to be taken lightly so as with plugs don't scrimp when it comes time to replace the sensors.

Last but not least a Turbo uses lots of air. Change the air filter on schedule.

 

We are above 6,000 ft. elevation here, and I sometimes see .8. A few weeks ago when it was about 20 degrees outside, I briefly saw .9, and wrote that off to the reduced air temperature and the elevation at my location. Had never seen .9 before. Engine is not modified, 35k mi. Due to our elevation, gasoline octane sold here is reduced. So I buy Shell nitro, which is the best available here as far as I know.

Just realized this is my first post here. I have a 2002 Polar Silver Turbo, my sixth P. If you count thr Cayenne and 924. I read this blog often, but don't post much, I guess because I don't know much and haven't experienced many issues with the Turbo. Have lived in Colorado much of my life, before and after a career in the USAF flying club, flying F-101, F-4, F-102, T-33 and others, then flying for an airline for many years.