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Typical MAF readings and boost pressure for standard CR170 ?


muddyboots

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Hi all

 

Just for geeky interest, I've been keeping an eye on typical maximum MAF readings and boost pressure over the last week.

 

Car is a 2011 CR170 Yeti, still standard.

 

Peak airflow reported by the MAF seems to be around 145 g/s.

Peak boost pressure tends to be 37psi (2.55bar). Subtracting atmospheric pressure (I assume 1bar?) gives a boost level of 22.5psi / 1.55 bar.

 

Just wondered if anyone with similarly geeky interest had ever monitored theirs, and know if this sounds about right for a standard CR170 ?

 

Have been using the Torque Pro android app (£2.95) on my phone, and a £10 chinese wireless bluetooth OBD dongle. A cheap setup that works a treat, although it can't access as many things as VCDS sadly (DPF temp readings for instance).

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Not been checking MAF figures but can do later.

 

Torque pro is reporting peak boost of 22.8 psi as per http://www.briskoda.net/forums/topic/303885-torque-users-show-me-your-cr-fuel-rail-pressures/

 

I've been using Torque Pro with a cheap bluetooth for years but have just started using an OBDlink wifi one http://www.scantool.net/obdlink-mxwf.html which was a lot more money and seems to perform exactly the same. The reason I got it was wanting to go wifi as torque pro seems to get in a pickle if you make a call using bluetooth.

 

It's a shame these things can't do the full VCDS thing - actually I'm not sure if it's can't or just don't. I've no idea if it would be possible; I suspect if it was there would be an app already

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A fellow geek in the Yeti forum, hurrah :)

 

I presume that peak boost figure of 22.8psi is corrected to deduct atmospheric ?

 

I did briefly see mention of adding custom PIDs to Torque, not sure if that means you can extend it to read further VAG channels or not. Like you say, I suspect someone would have done it already if possible - having said that, I've not really looked..maybe they have !

I'd like to be able to see DPF readings (temps, soot loading etc) as it's much easier to pop my phone on the dash mount and monitor stuff than it is to use the laptop with VCDS.

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A fellow geek in the Yeti forum, hurrah :)

 

I presume that peak boost figure of 22.8psi is corrected to deduct atmospheric ?

 

The boost figure is exactly as Torque Pro reports it (as per my screen grab in the other link). I can't remember if Torque Pro have separate displays for boost and manifold pressure. I'll have to have a look later

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From this morning's commute:

Intake 37.0 psi

Boost 22.3 psi

MAF 161.9 g/s

Hmm that's interesting. Your MAF reading is nearly 20g/s higher than mine.

 

I presume those readings are from some full load use right across the rev range ?

 

Thanks for this.

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Hmm that's interesting. Your MAF reading is nearly 20g/s higher than mine.

 

I presume those readings are from some full load use right across the rev range ?

 

Thanks for this.

 

Gyp - would you be able to log a few more journeys ?

 

Reason I ask is that most of the UK had quite a cool start this morning; when I took my readings the temps would have been 15-20ºC.

Just wondering if the cooler weather this morning resulted in denser air and you seeing higher mass air flow readings than I did.

I doubt it'd make that much difference, but a few more readings should confirm, if you're able to.

 

Boost pressure readings look pretty much identical to mine.

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Hmm that's interesting. Your MAF reading is nearly 20g/s higher than mine.

I presume those readings are from some full load use right across the rev range ?

Thanks for this.

Early this morning, full throttle through the gears, up a big hill, 8C

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Gyp - would you be able to log a few more journeys ?

Reason I ask is that most of the UK had quite a cool start this morning; when I took my readings the temps would have been 15-20ºC.

Just wondering if the cooler weather this morning resulted in denser air and you seeing higher mass air flow readings than I did.

I doubt it'd make that much difference, but a few more readings should confirm, if you're able to.

Will do.y3uzu9a4.jpg

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Journey home last night:

 

Ambient temp: ~16ºC

MAF peak: 146g/s

Intake: 37psi

 

Journey in this morning:

 

Ambient temp: ~8ºC

MAF peak: 148g/s

Intake 37psi

 

So, it seems the intake pressure is well regulated, have never seen it climb above 37psi, which seems identical to yours Gyp, so that all looks normal.

 

Still wondering why the difference in peak MAF readings.

Last night, the journey included a number of opportunities for prolonged, full-load operation right across the rev range, and most of the time it never went above 142g/s. Only once did it peak at 146g/s.

Similar story this morning, generally 143 was the maximum, but a single peak of 148g/s.

This is generally around the 4500rpm mark (give or take, eyes are more focussed on the road!).

 

The turbo is providing the same level of boost pressure in both cars, yet mine is flowing roughly10% less air.

In my mind, that means there's more resistance to flow somewhere ?

Either that, or something's changed in the engine, inlet or exhaust design to flow more freely - mine's a 2011 model (will check the engine code), yours is a 2013 I think Gyp ?

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Cheers Gyp :)

 

11ºC this morning.

Got a peak MAF figure of 146g/s - so it's looking fairly consistent.

Shortly after that reading, it started doing another regen; I wondered if the airflow would increase at all after the regen had completed - but no, I couldn't improve on 146g/s. 

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Possibly. Possibly not. Awful lot of traffic light Grand Prix tonight. I'll have a go at graphing it at the weekend to see if these are just instantaneous values or sustained (the phone was in the glove box to avoid me being distracted by it)

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