P006A code - advice needed - been fighting with it for 6 months

[glenn_mca]

Hey folks.
I'm hoping someone can offer some advice here:
I have a 2014 ST180, which is pretty extensively modified, i hadn't changed any parts for more than 3 years when all of a sudden i got an "engine malfunction - service now" error on the dash.

The code is P006A (Correlation issue between MAF and MAP sensors) and it us a UK (euro spec) car, thus it uses the maf reading for fuelling and what not

The car had been running perfectly until this code appeared.

What I've done so far:

• Checked intake for leaks (fine) - turbo elbow seems to not seal perfectly against the turbo but apparently this is normal and most (all?) aftermarket elbows don't even come with a gasket
• Replaced the dump valve (turbosmart) with a supposedly more reliable GFB DV+
• Pressure tested the inter-cooler (again fine, no leaks)
• Inspected all piping for breaks, loose connections or holes, all seem solid and tight
• Replaced MAF sensor
• Replaced MAP sensor (the upper one, on the intake manifold, not the lower one on the cold side boost pipe)

When the issue happens:
This is the weird part, the code thrown would suggest some sort of boost leak, however, the code only appears, putting the car in limp mode if i drive at half (anything other than full) throttle.
If i turn the car off and on, then immediately drive it hard at full throttle, the code will not throw, but as soon as i slow down and start to drive at anything between 1 and 99% throttle, the code will throw and the car will go into limp mode.

Has anyone experienced an issue similar to this before? I don't know what else to check, everything i look at seems to work fine and any parts I've replaced have made no difference.

Thanks in advance.

 

[lemonjs]

I had the same code, but replacing the Turbosmart BOV with the DV+ resolved it.

Do you have a boost tap installed by the MAP sensor?

 

[glenn_mca]

Hey, thanks for the response. I saw some success stories with the same solution, that's why I replaced the turbosmart with the gfb.
I did have a boost tap under the map sensor originally, but i removed it along with the turbosmart valve when i was replacing it as the tap for the vacuum line was no longer needed.

 

[glenn_mca]

A quick update on this incase anyone is googling in future.
I chatted with GFB (manufacturer of the recirc valve that i fitted) and they said:

OK with the upgrades (Hybrid Turbo) that you are running and the generic stage 3 map, I pretty sure the car is reacting to the way the DV+ works on low boost if you are rolling on and of the throttle although the ECU is telling the Dv Solenoid to open the GFB DV+ due to it mechanical operation (spring behind the brass piston) is staying shut, retaining boost in the system which the MAF & MAS are seeing and thus out of manufacturer parameters and setting of error codes.

So before you set of the parts cannon I would suggest to run the DV+ without the spring behind the brass piston, this will revert the DV+ back to standard factory operation but still giving you fantastic boost holding and longevity of life.

We see this with a lot of Hybrid Turbo cars with generic mapping, ecu reacting to the GFB and the way it retains boost.

If this does not cure the issue, I would be looking at the wastegate and checking it’s operation, plus also better to get the car on the dyno to see issue happening in live data this will show exactly what the issue is.

This sounds reasonable to me. When I get a chance I'm going to remove the DV and remove the spring then refit the DV.
I'll post any updates that I have in here.

Some other areas that I need to check after a discussion on Facebook are:

1. Fuel evap pipe may be blocked
2. Boost solenoid
3. Maf housing size (I believe uk/euro spec FiSTs need a 70mm maf housing, pretty sure this is fine but I need to measure and make sure)
4. Turbo elbow (to fix this issue I think the turbo needs to be removed, trying to work at the back of the engine is useless if trying to fit a gasket to this, I suspect the faces of the turbo and elbow that meet together may not be truly flat, leaving a gap, some sanding and good gasket paper should fix this.)