Hi all

Can anyone advise the meaning for the icon under the oil temp ? I’m unsure if this should be showing as a negative. 
 

The car is due is first service. 
 

I have tried looking it up with no success.

Turbo boost pressure.

At idle it's in negative boost, what we call vacuum.  If it doesn't increase while driving then there's a problem.

Thanks for the reply it does increase but rarely into positive - does that mean an issue? 

Should I not be driving my car if this continues? 

Just now, krjbrad said:

Thanks for the reply it does increase but rarely into positive - does that mean an issue? 

Should I not be driving my car if this continues? 

It's probably fine.  There are lots of ECU checks done on turbo boost, so if there was a fault it should trigger a warning on the dash.

It will only boost at higher revs on a petrol engine.  So if you always drive gently then it won't increase much.

Yes, mine also usually shows negative. It rarely goes positive unless really giving the car some welly (when my "seat of pants meter" and rapidly changing speedo digits tell me it's accelerating "quite briskly"!) and by that point you should be concentrating on the road anyway.

I don't know how accurate these things are anyway, always considered them a bit of a gimmick tbh!😀

(There are loads of threads around the web on what the standard boost pressure is, but not much help as I've seen figures from 1.4 bar up to 2.2-2.5 had mentioned.)

That is a strange way of measuring things. The pressure in the Manifold after the Throttle (Map) would normally be around 0.3 Bar at Idle and the pressure between the Turbo and the Throttle would be 1 Bar at the same time with no Turbo Boost, it almost looks like Ford are subtracting the Map from the pre Throttle reading and calling that Boost.

If I bring up the Boost Pressure Desired and Actual and the Map in FORScan then those are the readings that I see and they are what I would expect from a petrol Engine.

If I have got that wrong I'm happy to be corrected.

19 minutes ago, Eric Bloodaxe said:

(There are loads of threads around the web on what the standard boost pressure is, but not much help as I've seen figures from 1.4 bar up to 2.2-2.5 had mentioned.)

I think the 1.4 figure is the actual Boost figure not taking into account Atmospheric Pressure and the 2.2 to 2.5 is a figure which includes Atmospheric Pressure, so they are essentially the same thing. 

16 minutes ago, Eric Bloodaxe said:

I don't know how accurate these things are anyway, always considered them a bit of a gimmick tbh!😀

I too had a turbo gauge in a previous car, I always treated it with a healthy disrespect in terms of accuracy, but felt reassured when it bounced right up when having a bit of fun!

 

 

Another thing is if you select the Performance Gauges display rather than Performance Details as per the OP, you get the boost figure in psi, which might appear more dramatic if that's what you want:

59 minutes ago, Eric Bloodaxe said:

Another thing is if you select the Performance Gauges display rather than Performance Details as per the OP, you get the boost figure in psi, which might appear more dramatic if that's what you want:

Out of interest Roger, with the set up that way at Idle does the Gauge show zero or 0.7 of atmospheric pressure which is what the OP's Gauge was showing with it set up the other way?

 

 

 

6 minutes ago, Tizer said:

Out of interest Roger, with the set up that way at Idle does the Gauge show zero or 0.7 of atmospheric pressure which is what the OP's Gauge was showing with it set up the other way?

 

 

 

Lol, not bothered with it for ages! I'll try and remember to have a glance next time I drive the car.

The setup shown on the OPs car is the way a manual boost gauge works when tapped into a vacuum line on a turbo petrol.  (Every 1.8t Golf had one back in my VW days lol!)

There is vacuum in the inlet until the impeller spins fast enough to create boost.  I'd never really considered it as a comparison to ambient before though.

Thanks Tom, it's a bit meaningless though, here is a screenshot of my car at Idle. It correctly shows the Turbo Boost Pressure Desired and Actual as Ambient because there is no boost and the throttled MAP at 30 kPa. 

14 hours ago, Eric Bloodaxe said:

I'll try and remember to have a glance next time I drive the car.

Just reminded myself why I don't bother with that psi "gauge" - it's uncalbrated apart from "30" . As much use as the analogue Speedo dial  around the digital readout which has "0" and "160" .

17 hours ago, Tizer said:

Out of interest Roger, with the set up that way at Idle does the Gauge show zero or 0.7 of atmospheric pressure which is what the OP's Gauge was showing with it set up the other way?

The "Performance Details" screen as in the OP is in bar and the "Performance Gauges" screen is psi.

Anyway, after a quick spin round the shops and recycling site this morning (very exciting!) the screen at idle is as below.

Being unaccompanied by Mrs B on this occasion, purely for research, I used "firm acceleration" (WOT and 5,000 rpm+) on the bypass and it barely flickered. My "seat of pants meter" and traffic rapidly receding in the mirror reassured me that there is nothing wrong with the cars acceleration.

I couldn't find the screen at first but recalled I'd deleted it from the list of options shortly after getting the car and deciding it was on a par with a chocolate teapot in terms of usefulness. I've re-deleted it now!😀😀

1 hour ago, Eric Bloodaxe said:

The "Performance Details" screen as in the OP is in bar and the "Performance Gauges" screen is psi.

Anyway, after a quick spin round the shops and recycling site this morning (very exciting!) the screen at idle is as below.

Being unaccompanied by Mrs B on this occasion, purely for research, I used "firm acceleration" (WOT and 5,000 rpm+) on the bypass and it barely flickered. My "seat of pants meter" and traffic rapidly receding in the mirror reassured me that there is nothing wrong with the cars acceleration.

I couldn't find the screen at first but recalled I'd deleted it from the list of options shortly after getting the car and deciding it was on a par with a chocolate teapot in terms of usefulness. I've re-deleted it now!😀😀

Thanks Roger, that confirms what I expected a Turbo Boost Gauge to show and is the same as the FORScan PID's except FORScan show it from Atmospheric, I still haven't a clue what the other screen is meant to represent.

Your observations about when you get Boost are exactly the same as mine, hardly ever and only at very high Load, not necessarily high speed. I do laugh when I read posts on this Forum that say my Turbo is not kicking in🤣. Maybe the other Gauge set up is for them, they would think there was something wrong if it hardly ever moved, if it is Atmospheric minus MAP then it will move a lot more even in a normally aspirated car.

Your Screenshot also confirms what I said earlier, the Max Boost is around 1.4 times Atmospheric, not 2.4 times, if it was 2.4 times then the Gauge would have gone up to 40 or 45psi.

I also see what you mean about that screen set up being very useful.

Tbf, both of you have 1.5's, the turbo is needed more often on the 1.0...there's no replacement for displacement!  

This video shows a mechanical boost gauge on a 1.0EB working in exactly the way I'd expect.  Around 20 In/Hg vacuum at idle.  And around 20psi boost under load.  I'm still not really sure what's 'wrong' with that. 

 

 

48 minutes ago, Tizer said:

Max Boost is around 1.4 times Atmospheric

I've always taken that (simplistically) as a rule of thumb for a fairly normal level of boost probably because that used to be the equivalence figure when turbo cars were competing in the same class as n/a, e.g. 1000cc turbo = 1400cc n/a.

I do doubt the value of these things - I've always found the tacho much more useful as a driving instrument - and I guess this thread shows why the term "worry gauges" is often used.

50 years ago I found this set up perfectly adequately informative (no turbo of course, and not that much bhp either come to think of it 😀) but good fun nonetheless!

 

39 minutes ago, TomsFocus said:

Tbf, both of you have 1.5's, the turbo is needed more often on the 1.0...there's no replacement for displacement!  

You're right, I'd be much happier with a decent 2 litrel😀

1 hour ago, TomsFocus said:

This video shows a mechanical boost gauge on a 1.0EB working in exactly the way I'd expect.  Around 20 In/Hg vacuum at idle.  And around 20psi boost under load.  I'm still not really sure what's 'wrong' with that.

If a Turbo is producing no Boost it is producing no Boost not a Negative Boost. Knowing the Manifold Vacuum is a bit pointless, it will be the same figure as a normally aspirated Engine until it gets to Wide Open Throttle Valve where the normally aspirated Engine will only show Atmospheric Pressure and not go higher.

Fair enough.  I think we'll have to agree to disagree on this one.

I'd say knowing boost is a bit pointless as well.  I don't think anyone has ever looked at the gauge and lifted-off because there was too much boost on a standard engine.  It's just a gimmick to add to the 'experience'.  Having vac showing on the aftermarket gauge means there's more needle movement which is presumably the point of fitting a visible gauge.

I do agree that showing it as a negative figure on the Fiesta dash is a strange way to do it though.

As an aside, knowing vacuum is not totally useless even on an NA engine.  It was used for a rough MPG gauge on older cars.  So if people want Eco & Boost that could be useful.

Yeah, Distributors had a Vacuum Advance for the Timing as well as Centrifugal Advance and I remember the Carb on my Cavalier had a vacuum Diaphragm for cold starts as well. 

 

On 10/28/2024 at 1:31 PM, TomsFocus said:

This video shows a mechanical boost gauge on a 1.0EB working in exactly the way I'd expect.  Around 20 In/Hg vacuum at idle.  And around 20psi boost under load.  I'm still not really sure what's 'wrong' with that. 

EcoBoom's run around 1.4 Bar of boost?  I guess they need it to make any sort of power being a little 3 pot engine.

I wouldn't bother with anything other than a mechanical boost gauge, digital ones and built in display gubbins tend to not react fast enough.  I'd be inclined to say they're more for show than anything else.

Any petrol turbo'd car, unless fitted with a proper antilag system, will show negative pressure at idle.  The photo I've added was a friends car, was a bit of a rapid, bumpy ride back from Port Seton after a mapping session a few years back.

 

12 hours ago, mickywrx said:

EcoBoom's run around 1.4 Bar of boost?  I guess they need it to make any sort of power being a little 3 pot engine.

That's just for the 125ps version.  140ps maxes out around 1.6 bar of boost iirc.  The turbo tech on the 1.0EcoBoost really was cutting edge at the time.  It effectively replaced the non-turbo 1.8 & 2.0 Duratec as well as the 1.6 Ti-VCT that it was designed to replace.

2 hours ago, TomsFocus said:

The turbo tech on the 1.0EcoBoost really was cutting edge at the time. 

I recall my first test drive in a 125ps ecoboost Fiesta back around 2012/2013. You'll be unsurprised to read I approached it with a degree of scepticism, but I was (and still am) very impressed with the drive.

Great shame about what we now know about other aspects, though as I've mentioned elsewhere, my 140 was faultless for the 5 years I had it.