Has my car been re-mapped?

[coldcuppatea]

I've just changed my 2015 Focus ST for a 2008 GTI. As I expected, the Golf doesn't feel as punchy as the Focus and I was considering getting a remap. I thought I'd get an idea of pre-remap data by doing some logging from the OBD2 port this evening. I was surprised to see the boost apparently peaking briefly at up to 25psi and holding 18 to 20 psi. From what I had been reading, I was expecting it to hold around 15psi.

However, I assume that if it's had some sort of "stage 1" map, it should have around 230bhp / 230lbft, which I would expect to feel similar to the Focus, but it really doesn't.

Can anyone shed some light on the boost levels? Does OBD2 report accurate levels?

Thanks!

[pudding]

Standard boost is 0.9 bar iirc, so likely mapped.

It may not be a brilliant map and the Golf is a lot older than the Focus, so it's probably not a fair comparison. 

[Dan_FR]

Do not forget that almost all OBD logging using the MAP sensor provides absolute pressure readings, so you need to subtract approximately 1 BAR of atmospheric pressure to get the true positive 'boost' reading.

Subtracting approximately 14.7PSI from your readings sounds exactly like standard to me, with about 10psi peak settling down to around 6psi by the redline

post the data here if unsure

[coldcuppatea]

Thanks chaps. I'm pretty sure that the boost values that are being output are corrected for atmosphere. The logs also include inHg for absolute manifold pressure which, when converted to PSI, were reading 14.4 psi higher than the boost value at the same point in time.

Unfortunately the data logger only seems to write one line of data per second, so the finer points are lost. I've plotted out a run from stand still through 1st, 2nd and 3rd using the launch control. 2nd gear (points 6, 7 and 8 ) are fairly representative of what I was seeing in the instant read out (18.5psi, 19.7 and 17.3).

There is a big spike to 29psi showing, which I'm guessing isn't good.




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[Madone]

Do not forget that almost all OBD logging using the MAP sensor provides absolute pressure readings, so you need to subtract approximately 1 BAR of atmospheric pressure to get the true positive 'boost' reading.

Subtracting approximately 14.7PSI from your readings sounds exactly like standard to me, with about 10psi peak settling down to around 6psi by the redline

post the data here if unsure

Spot on Dan, fell into the absolute reading myself many moons ago. That sounds like stock levels to me also

[coldcuppatea]

Do not forget that almost all OBD logging using the MAP sensor provides absolute pressure readings, so you need to subtract approximately 1 BAR of atmospheric pressure to get the true positive 'boost' reading.

Subtracting approximately 14.7PSI from your readings sounds exactly like standard to me, with about 10psi peak settling down to around 6psi by the redline

post the data here if unsure

Spot on Dan, fell into the absolute reading myself many moons ago. That sounds like stock levels to me also

See post above. Absolute inHg and Boost PSI are different by 14.4 psi...

I'll try again on the way home and log both:

[coldcuppatea]

Definitely boosting to 20+ psi / 71 inHg Absolute Manifold Air Pressure. So either it's been remapped or something is amiss. Couple of questions if anyone knows:

- Is there anything I can check that can cause the car to generate too much boost?

- Is there any way to find out what map is on it?

- Would it make sense to get it re-remapped so I know what is on it.

Thanks!


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[AJP]

If it doesn't feel like 230bhp, you'll want to get that sorted anyway, whether it's got a remap on it now or not.

So yeah, if it was me I'd be getting it booked in for some software that you know is safe, and you know is giving you proper power. Any remap worth having should give you more like 245bhp minimum and upwards of 280lb/ft.

Just make sure you've got the usual suspects sorted prior to the remap - dv, pcv and cam follower.

[Dan_FR]

I'm not convinced. What OBD tool are you using?

The turbo will not sustain 15+ psi at high rpm, even at higher stages of tune. You have an issue with your data logger I'm sure

[coldcuppatea]

I'm using a WiFi OBD2 dongle and logging with OBD Fusion on iOS. I do have a Chinese ScanGauge copy kicking around somewhere. It doesn't log but might be worth me plugging it in and seeing what that says.

I think the suggestion of just getting some known software put on the car is probably sensible to be fair.


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[pudding]

The boost is all over the place according to your app.  Can't be very pleasant to drive like that!  A huge boost spike is typical of a Revo map but other mappers like the more aggressive approach also.

You can tell if it's been remapped with VCDS, by looking at a byte called "Flash count".  Standard should be zero and every time the ECU gets flashed (remap), the count goes up by 1.  You can't tell what's actually been done to the map without special software because remappers encrypt their code.

VCDS is the way to go.  You can data log many sensors and output them into a pretty Excel graph.  Where are you based?  I'm sure someone with VCDS is pretty close to you.

I would initially data log:-

Requested boost pressure
Actual boost pressure
Mass Air flow (do a hard pull to the redline in 4th, or 3rd if you don't have the road space)
Requested fuel rail pressure
Actual fuel rail pressure

From those things we can quickly see if it's been remapped.

Standard boost is 0.9 bar and VCDS is metric, and the MAP sensor is upstream of the intake, so will not record vacuum (inHg).

Standard rail pressure never exceeds 115 bar, so if you're seeing 120+, it's definitely mapped.

And finally, divide your peak MAF reading by 0.8 to get a very close approximation of BHP.

Does your app record fault codes?  A faulty N75 valve can cause an overboost condition and a broken PCV and / or dump valve can cause an underboost condition.  That's why VCDS is great because you can compare requested to actual to see how far adrift things are.

So yeah, buy yourself VCDS!  The best forensic tool for VWs out there 

[coldcuppatea]

Thanks very much for all the input everyone. I'll look at get the VCDS as that is seriously appealing to the geek in me.

There are currently no fault codes showing so I'll take a look at logging the suggested items.

However, I've emailed R-Tech to see if they can get me in at the end of the month!


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[AJP]

Thanks very much for all the input everyone. I'll look at get the VCDS as that is seriously appealing to the geek in me.

There are currently no fault codes showing so I'll take a look at logging the suggested items.

However, I've emailed R-Tech to see if they can get me in at the end of the month!


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You might be better phoning them. They usually have a 5-6 week waiting list.

[coldcuppatea]

Booked in for 11th May at R-Tech. Fingers crossed that the big waiting list is testament to their apparently stellar reputation 

[Dan_FR]

It is mate. You won't be disappointed