MmmBoost
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« on: March 01, 2011, 11:36:10 PM »
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Hey guys,
I need some help here. I'm working with my AMB 1.8T running a GT2871R on Eurodyne Maestro 7 software. I am increasing the boost level past the limits of the stock MAP sensor. However, when doing so, The ECU isn't adding the correct amount of fuel into the cylinders because it doesn't think the boost is anywhere past 22 PSI. Fueling is fantastic below 22psi.....not so much after.
Now I know I'm certainly not the first and only person running more boost than the MAP sensor will allow, so my question is......How are you guys adding a sufficient amount of fuel past the MAP sensor limit to keep O2 corrections reasonable?
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julex
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« Reply #1 on: March 02, 2011, 12:10:16 AM »
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Hey guys,
I need some help here. I'm working with my AMB 1.8T running a GT2871R on Eurodyne Maestro 7 software. I am increasing the boost level past the limits of the stock MAP sensor. However, when doing so, The ECU isn't adding the correct amount of fuel into the cylinders because it doesn't think the boost is anywhere past 22 PSI. Fueling is fantastic below 22psi.....not so much after.
Now I know I'm certainly not the first and only person running more boost than the MAP sensor will allow, so my question is......How are you guys adding a sufficient amount of fuel past the MAP sensor limit to keep O2 corrections reasonable?
Fueling has nothing to do with MAP Sensor readings unless you're running MAFless tune. IF this is the case, there is no workaround since ECU cannot properly calculate amount of air entering the engine. Case closed. If you're running standard tune, you're probably pegging your MAF, which means you're exceeding its reading limit. The maf reads 0-5v and there is MAF map that translates that into amount of fuel entering the engine. Traditionally the way to fix this issue is to get bigger maf housing and move the maf sensor. Once in larger housing, same amount of air will generate lower reading on the sensor so you just multiply all the air/volt map values by increase in surface area of cross section between old and new maf and you're done. Maestro has maps for both V8 MAF with bosch element and 90mm Ford Lightning housing with Hitachi element as well as Audi TT MAF housings/MAFs. Should help mitigate some issues you're having. |
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« Last Edit: March 02, 2011, 12:13:07 AM by julex »
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MmmBoost
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« Reply #2 on: March 02, 2011, 12:35:18 AM »
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Thanks for the quick reply.
I'm running a stock TT25 MAF. Brand new. My MAF readings are not pegged out. I do have a 3.5" MAF that I could move to, but I don't think the flowmeter is the issue.
Whenever the boost hits 2500+ mbar i'm getting massive (+) O2 correction. In some cases I'm getting boost spikes at 800 kg/hr which is nowhere near the limits of the TT225. Once the values come back down below 2400 fueling settles out. All the way up past 1000 kh/hr of airflow.
I'm stumped....
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« Last Edit: March 02, 2011, 12:53:35 PM by MmmBoost »
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overspeed
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« Reply #3 on: March 02, 2011, 11:42:42 AM »
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For me, it looks like the BTS protection... try to play with KFFDLBTS and KFDLBTS instead of KFLBTS and FBSTABGM.
there is a theorical EGT map (can
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nyet
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« Reply #4 on: March 02, 2011, 12:01:10 PM »
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Whenever the boost hits 2500+ mbar i'm getting massive (+) O2 correction. In some cases I'm getting boost spikes at 800 kh/hr which is nowhere near the limits of the TT225. Once the values come back down below 2400 fueling settles out. All the way up past 1000 kh/hr of airflow.
Log calculated EGT. |
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MmmBoost
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« Reply #5 on: March 02, 2011, 12:52:59 PM »
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When I say O2 correction I don't mean that the ECU is dumping fuel to protect itself. I mean that it's correcting in order to reach desired AFR. Have a look at this log and you can see what I mean. There are a number of short pulls with different boost levels. notice what happens when boost exceeds the MAP limit. I just switched to larger injectors, so things are still a little rough. https://spreadsheets.google.com/ccc?key=0Aoetxfc9e1KpdHZ3SFpGUEwxeHVQQndPQlFDYmxib0E&hl=en&authkey=CMCs0uMM |
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overspeed
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« Reply #6 on: March 02, 2011, 01:50:31 PM »
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there is something wrong, in lines 49, 50 51:
the MAF drops, TPS drops (is this TPS or the pedal position ?) and the ignition gos -3
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MmmBoost
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« Reply #7 on: March 02, 2011, 02:09:55 PM »
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That was me letting off the accelerator pedal.
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nyet
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« Reply #8 on: March 02, 2011, 02:20:47 PM »
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When I say O2 correction I don't mean that the ECU is dumping fuel to protect itself. I mean that it's correcting in order to reach desired AFR.
O2s are ignored openloop (desired lambda!=1) |
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MmmBoost
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« Reply #9 on: March 02, 2011, 02:45:08 PM »
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Not so on my ECU.
O2 correction is always used. From idle to WOT. The beauty of Wideband ME7.5
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julex
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« Reply #10 on: March 02, 2011, 02:52:27 PM »
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I don't think that your MAP limit has anything to do with the situation.
I think that your problem is with improperly scaled MAF map. You're running lean anywhere over 3.5k while at WOT. Your actual lambda keeps creeping towards 1.0 and ECU is eventually trying to correct it by increasing fuel corrections. You running lean happens way before you hit the MAP limit.
It almost seems to me like you put in larger maf housing without properly scaling the MAP. The ECU thinks it sees much less air than there is actually entering the system and it goes leaner and leaner.
How are your block 032 fuel trims? I think you will find some hair rising values in there.
If your MAF map properly scaled for TT housing.... or your injector constant proper for the injector size? Either one or both is out of whack.
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« Last Edit: March 02, 2011, 02:54:51 PM by julex »
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MmmBoost
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« Reply #11 on: March 02, 2011, 03:09:33 PM »
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Well I am using a brand new, off the shelf TT225 MAF sensor and housing.
I selected the TT225 MAF profile in the Eurodyne software, so unless the MAF linearization curve is incorrect in the software, I can't see how else it would be mis-reading.
BTW my 032 blocks are within 1% of zero.
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julex
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« Reply #12 on: March 02, 2011, 04:50:13 PM »
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Well I am using a brand new, off the shelf TT225 MAF sensor and housing.
I selected the TT225 MAF profile in the Eurodyne software, so unless the MAF linearization curve is incorrect in the software, I can't see how else it would be mis-reading.
BTW my 032 blocks are within 1% of zero.
Check main fuel correction and injector compensation tables. In my experience, they might have weird values in them. |
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MmmBoost
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« Reply #13 on: March 02, 2011, 05:11:08 PM »
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What do you mean "weird values"?
Are you working with Maestro also?
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julex
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« Reply #14 on: March 02, 2011, 09:35:57 PM »
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What do you mean "weird values"?
Are you working with Maestro also?
yes. Default maps has some values which are not normal for stock ECU in there. I would advise resetting all of these since they are very custom to some car/injector setup tapp programmed in the past. The 660cc map tapp distributes for S4 for example has lots of custom stuff in there which causes the car to run at like 10.5 AFR up top, whatever lambda it is (0.68 or something). There are main fuel corrections and injector corrections which are much higher than needed for properly tuned car. Now S4 doesn't have wideband so it just runs like that but if he sneaked something like that into default tune for your car, it would cause havok with your wideband O2 corrections. For S4, This is pig rich which works since the car is fast but not as fast as when you lean it out fto 11.8 without meth or 11.4 or so with meth. |
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