A45 m133, p0108

[etapp01]

Hello,
can anyone help me to find why I'm getting P0108 Manifold Absolute Pressure/BARO Sensor High?
I belive the settings shouldn't set the fault code but still it does.
Fault code isn't the problem but the fact that it is hitting boost limit and and the Limp home with very limited boost...
Mods: LITTCO L500 turbo (good for >500hp), 100-cell downpipe, Airbox mod with large bore adapter to turbo.
Thanks!
Peter

[chevota]

Here's my guess.
I'd lower my temps with the cooling fan too. No point in starting a run when the eng was as hot as possible. I also set the trigger to Water, no oil, so it responds quicker

1.jpg2.jpg3.jpgFan.jpg

[etapp01]

Very valuable input.
Funny but I can't find the Max TIP error before over boost map except by searching in Navigation, makes me wounder if there are more maps I haven't found yet :-)
Will test shortly, Thank you!

[chevota]

Do you have this selected?

Adv.jpg

[etapp01]

Yes I have, thanks!

[etapp01]

Now I have tested with the additional changes.
Unfortunately I still have the throttle shut.
Attached is new settings, log and picture on where it shuts the throttle.
Grateful for any ideas.

[chevota]

In that picture, where you have the line, I'd say you let off the gas.
Prior to that, on the far left where that double hump is, I'd say you hit the rev limiter. You hit it, it shut down, shifted, then recovered. Not sure why it isn't shifting before that, but I suppose you could adjust the rev limit.
Mine was doing that too, but usually only in 1st gear where it would rev too quick and the stupid computer can't shift in time. So I raised it, plus set the recovery rpm much closer to hardly any delay.

Rev Limits.jpg

[etapp01]

I pretty sure I had the pedal to the metal, Pedal is still 100% in this picture.
Rev limiter is because I was running manual shift, my mistake...

May I ask what set up you are running, boost level and power if you measured it?
Thanks!

[chevota]

The data has random delays so it's pretty hard to tell what is happening when, so you either let off first, or it cut power and you let off a fraction of a second later. By looking at it I'd say you simply let off.

I try to keep boost under ~22 but it can't control boost for shyt so it's all over the place. Apparently a "safe" boost for my car is 17-18.
My car details are in my signature.

Power I don't know because changing certain things to make more power will skew the torque reading to read low. The Normalizer is the main one, so they say, so if you reduce it 10% then the reading is 10% low. In my scanner I have two torque readings, one is what the ecu thinks it is, the other is that x 1.111 to bump the # back up. There are other things that screw up the reading too.
Someone said messing with the Spark MBT screws it up, and who knows what else does. I have no way of checking, unless I buy some dyno time, which is expensive and ultimately pointless imo.
On the other hand I've had the power reading go way up as well. Not sure what I did but for a while it said I was making 800ftlbs with a peak of 812. In reality it was probably making more like 500, based on the boost.

Ultimately I simply shoot for the boost I want, adjust spark to just shy of retarding with whatever fuel I have, and set lambda to lean-ish but seems safe?
What boost and lambda is safe is subjective, imo. People say boost for my eng should not exceed 18, and lambda should be .800, maybe even richer. Well, more boost is more power so that 18 is pretty difficult to comply with, and .800 costs me power.
A leaner fuel mix nets more power and better throttle response, but under heavy load you need extra fuel for cooling. Ironically, when I add more fuel, the exhaust temps go up. It doesn't necessarily mean my cly temps are hotter, but if there is no O2 then how does more fuel make a hotter exhaust? So all I can do is wing it and hope I'm adding enough fuel to cool, but not hurt power too much. The .800 hurts power a lot, so I try to keep it closer to .850, which is considered dangerous to most. Imo the direct injection allows a leaner mix, and combustion chamber design and material are a factor, so I believe .800 is an outdated #? Maybe I'm just ignorant but in an old school engine it will start to ping when it's not rich enough, mine actually pings when I add fuel. So it may ping just a hair, or none at all at .850, then ping more at .800. Very confusing, but to me ping is a result of to much heat, so no ping seems to say you're good to go?

This brings up another question I've always had but rec'd zero answers; the Lambda sensor cannot read fuel or fuel mix, but instead bases it's value entirely on O2 levels. So if Stoich of 14.7 uses ALL the O2, then how can it possibly read a richer mix?????? It likely needs more like 14.3 to 14.5 to really get all the O2, but the point is no O2 is no O2, so how does it read a richer mix?

I've been meaning to add Methanol injection to cool it better, but too lazy and haven't installed it yet. I actually have two, the thought was one for pure Meth and one for pure water. With water doing the cooling I expect it will drop the Ex temps and cool the cyl better, and no weird stuff, but we'll see.
I think the more boost you have the more you need something like that, and I mean you. Speaking of you, you named your tune xxxxx stage_3, what does that mean? Did you buy a stage 3 tune of some sort and now you're tinkering with it? If so, details about it, and post the oem tune, please.

I figured you were in Euro. I'm in the US. I don't have your engine so I won't be able to help much, just the basics.
Best too keep everything here on the forum so others can bennie from it, and share thoughts. As you can see the forum is all but dead, but there are a few here.

[outlaw_50]

You are overboosting which causes Low Fuel Rail Pressure and the car triggers P0108 to keep the car safe.
If you desire more boost then you should work on you fuel system.

[etapp01]

The data has random delays so it's pretty hard to tell what is happening when, so you either let off first, or it cut power and you let off a fraction of a second later. By looking at it I'd say you simply let off.

I try to keep boost under ~22 but it can't control boost for shyt so it's all over the place. Apparently a "safe" boost for my car is 17-18.
My car details are in my signature.

Power I don't know because changing certain things to make more power will skew the torque reading to read low. The Normalizer is the main one, so they say, so if you reduce it 10% then the reading is 10% low. In my scanner I have two torque readings, one is what the ecu thinks it is, the other is that x 1.111 to bump the # back up. There are other things that screw up the reading too.
Someone said messing with the Spark MBT screws it up, and who knows what else does. I have no way of checking, unless I buy some dyno time, which is expensive and ultimately pointless imo.
On the other hand I've had the power reading go way up as well. Not sure what I did but for a while it said I was making 800ftlbs with a peak of 812. In reality it was probably making more like 500, based on the boost.

Ultimately I simply shoot for the boost I want, adjust spark to just shy of retarding with whatever fuel I have, and set lambda to lean-ish but seems safe?
What boost and lambda is safe is subjective, imo. People say boost for my eng should not exceed 18, and lambda should be .800, maybe even richer. Well, more boost is more power so that 18 is pretty difficult to comply with, and .800 costs me power.
A leaner fuel mix nets more power and better throttle response, but under heavy load you need extra fuel for cooling. Ironically, when I add more fuel, the exhaust temps go up. It doesn't necessarily mean my cly temps are hotter, but if there is no O2 then how does more fuel make a hotter exhaust? So all I can do is wing it and hope I'm adding enough fuel to cool, but not hurt power too much. The .800 hurts power a lot, so I try to keep it closer to .850, which is considered dangerous to most. Imo the direct injection allows a leaner mix, and combustion chamber design and material are a factor, so I believe .800 is an outdated #? Maybe I'm just ignorant but in an old school engine it will start to ping when it's not rich enough, mine actually pings when I add fuel. So it may ping just a hair, or none at all at .850, then ping more at .800. Very confusing, but to me ping is a result of to much heat, so no ping seems to say you're good to go?

This brings up another question I've always had but rec'd zero answers; the Lambda sensor cannot read fuel or fuel mix, but instead bases it's value entirely on O2 levels. So if Stoich of 14.7 uses ALL the O2, then how can it possibly read a richer mix?????? It likely needs more like 14.3 to 14.5 to really get all the O2, but the point is no O2 is no O2, so how does it read a richer mix?

I've been meaning to add Methanol injection to cool it better, but too lazy and haven't installed it yet. I actually have two, the thought was one for pure Meth and one for pure water. With water doing the cooling I expect it will drop the Ex temps and cool the cyl better, and no weird stuff, but we'll see.
I think the more boost you have the more you need something like that, and I mean you. Speaking of you, you named your tune xxxxx stage_3, what does that mean? Did you buy a stage 3 tune of some sort and now you're tinkering with it? If so, details about it, and post the oem tune, please.

I figured you were in Euro. I'm in the US. I don't have your engine so I won't be able to help much, just the basics.
Best too keep everything here on the forum so others can bennie from it, and share thoughts. As you can see the forum is all but dead, but there are a few here.

I been thinking of these time delays on the a few times but in this log I'm pretty sure I let off as a result of the ECU closing the throttle, if I come to that I need more support on it I simply make a new log where I'm sure :-)

Okay, I thought you where also working on an A45 but then I understand. Power question was only to understand if we were on par with the tunes. I have the luxury of having access to a dyno I was part of designing and running weekly for a few years. I like to use it for reference and stay of the roads for some high speed test...

I would sing to 0.8 (at high boost) any day since that keep engines alive for me the last 30 years of tuning but I also realize that 0.85 probably is more accurate for the modern engine designs. Interesting that you observed more pinging on 0.8 than on 0.85, needs to be investigated!

Lambda richer than 1...the question larger that the meaning of life...I started using lambdas in the early 90:th and read a bunch of papers on in through the years but never understood how how the remaining oxygen can be correlated to a generic fuel/air mixture. there will of cause always be some unburnt oxygen in the exhaust no matter how much fuel you dump in there.

Water Meth/Eth is something I have been using on and off since the first turbo conversion I did in 1993, absolutely great where used the right way!

Stage 3 is some kind of commonly used naming online...not my preferred naming being an old guy...
How I usually interpreters it:
Stage 1 => Software only
Stage 2 => Software, downpipe, air filter
Stage 3 => Software, downpipe, air filter, larger turbo

I'm based in Sweden.

Thanks!
Peter

[etapp01]

You are overboosting which causes Low Fuel Rail Pressure and the car triggers P0108 to keep the car safe.
If you desire more boost then you should work on you fuel system.

Thanks for the input, really appreciated!

[etapp01]

Latest news...I think I overlooked the gearbox (TCU settings).
Awaiting an adjustment of the torque limitation, seams to be a 600Nm (440 US unit I got it right) and dropping at 5000rpm. This is where I expect to be when the ECU close the throttle on me. Adding some fuel pressure as to outlaw_50 advise might just get me to the next stage.
Update will come.