pfbz

I'd really like to know more about how Ford's electronic boost control handles altitude...

On a simple mechanical boost controller, usually the waste-gate is triggered by the rise in manifold pressure vs. ambient pressure. Which means you would get perhaps a 15 PSI boost over whatever the ambient pressure is, so ~30 psi at sea level, about ~27 psi at a mile-high.

Ford and most OEM turbos surely use more modern electronic boost control. I'm sure they are looking at the MAP (Manifold Absolute Pressure) sensor, temperatures, throttle position, knock sensors, and a bunch of other variables in determining the boost pressure, and from what I hear, they adjust boost quite a bit. Those who have added boost gauges see it going all over the place, dumping boost at shift points, etc. It's been reported that people see about 15 psi as maximum boost.

My curiosity is really about maximum boost at altitude... Does the EcoBoost add additional boost at altitude to achieve the same absolute manifold pressure as would be obtained at sea level?

A standard aftermarket boost gauge would measure relative boost, not absolute pressure, so if Ford was doing this, you would see MORE than 15 psi on a boost gauge at altitude.

Any thoughts?

taylori

I wish I would have had a guage hooked up while I was in colorado with my ecoboost. From what I could feel before the turbos came into boost the engine would be pretty gutless. Once in that RPM range where the turbos were helping it felt normal as ever. The reason a N/A engine loses power as you go higher in elevation is that the air is thinner and the engine isn't capably of pulling in as much air. A turbo engine is going to force whatever pressure it is set at into the engine. This is why Turbo engines do not lose power (or lose very little) at high elevations. I'm going to assume your max PSI will stay the same.

pfbz

Not that simple.
The question is relative psi (gauge pressure) or absolute psi (MAP).

taylori

yeah that didn't make much sense after I read it. sorry. What I meant was (I'm assuming it does compensate for altitude by having the MAP psi as close as possible but still within safe parameters based on my experience driving a mile high) that the ECU should be allowing the turbo to boost a bit more to achieve it's desired MAP and power ratings.

Mrtea

i've wondered this in other applications where there are claims of overworked turbos from the factory. Running an extra 2-3psi (roughly) for those at altitude all day long, on a turbo already maxed out at sea level doesn't seem quite right. Have to wait for someone with a gauge/scanner to check i guess?

pfbz

Exactly...

I don't doubt that Ford's ECU could run the turbo's harder to completely compensate for any altitude, up to say 10,000 feet, but the real question is do they? They clearly have pretty sophisticated boost management, much more than "always open waste-gate at specified pressure", and I'm just curious to figure out how they handle altitude.

I suppose the best way to find out would be to look at OBDC MAP data at different altitudes and see if a pattern can be spotted.

Deerhunter4

My boost numbers were not any higher at altitude (10,000 ft). I have an electronic gauge.

Mrtea

when you drive at that altitude, car power on, is your mechanical (all be it electric) showing neg boost pressure, or vacuum as it were? so car off, the gauge reads -5, but when at full boost, it reads the same 15psi (no clue what stock is) as it does down at sea level?

meaning that it's spinning the same as someone running 20psi at sea level

pfbz

What kind of electronic gauge?

An aftermarket gauge with some sort of sensor in the manifold? Or something that is reading the MAP data through the OBDC port?

What I really want to know is was it reading absoute or relative boost... the central question.

Deerhunter4

It's reading the MAP data through the OBD port. It's a Bully Dog Watch Dog monitor.