Tb205gti
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« on: June 06, 2022, 01:12:55 PM »
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I have bought myself an Audi Q3 2.0 TFSI 211Bhp Quattro - and I'm diagnosing it before I start remapping it.
I have logged requested boost vs. actual (as the car felt sluggish below 2.500 rpm)
Now, the N75 valve is at max 96.5%, but boost is only about 0.5bar at 2.000 rpm - but requested is at 0.8bar.
I have just replaced the DV - made very little difference, I have pressure tested the PCV - working just fine.
Now, is this nornal for the TFSI ? or am I looking at an issue that needs to be sorted ? No fault codes, good milage, no rough runing etc.
Log is attached.
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« Last Edit: June 07, 2022, 04:40:30 AM by Tb205gti »
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curamrdan
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« Reply #1 on: June 06, 2022, 01:36:08 PM »
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On first gen EA888, with higher milage is common that WG flapper guide become loose and starts to rattle => actuator tension is lost => more and more laggy boost until underboost DTC shown in end cases.
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cherry
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« Reply #3 on: June 06, 2022, 10:20:24 PM »
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For me it does not look tooo bad, compared to a similar car. This should be IHI turbo with D5S manifold cast, so maybe there is a crack in wastegate seat. Borgwarner cast is more temperature stable.
The actuator for borgwarner turbo does not fit to IHI, the actuator from IHI does not have a thread to adjust. Even not sure if you can remove it from lever.
Btw at which rpm is the AVS switch?
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cherry
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« Reply #4 on: June 06, 2022, 10:28:24 PM »
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Ah it seems from partnumber this engine is without valvelift...
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Tb205gti
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« Reply #5 on: June 07, 2022, 01:05:05 AM »
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Cool, thanks for your replies.
The car has only done 138.000Km, so not what I would call high milage - but it has been remapped by ABT previously.. When I bought it the remap had been overwritten by Audi, so the only signs left were the tons of ABT stickers all over. (engine cover, side mirrors, rear view mirror etc.). I do not know how much power it has been running, but since it is ABT, I'd expect fairly mild stage1. It has standard air intake and downpipe.
As far as I can see the original turbo is: 06J145713F, not sure if this has the adjustable actuator or not?
Other things I suspect could be a cause, not sure if it is relevant or not.
- Carbon build up in the inlet
- Poor N75 valve, not giving full vacuum to the actuator (?)
- Something else holding it back - ignition retard, lean mixture ? (What should I log to get the full picture ?)
Also; if it is the actuator without adjustments, can I replace it for one with - keeping the pre-load as close to original as possible?
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« Last Edit: June 07, 2022, 01:42:45 AM by Tb205gti »
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prj
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« Reply #6 on: June 07, 2022, 01:56:38 AM »
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For me it does not look tooo bad, compared to a similar car. It looks very bad. I added a pic to show how it looks on a functional car when remapped. Note how much boost it makes at much lower DC. Carbon buildup will only increase the amount of boost because engine flow is worse. N75 usually not broken on these. Only two things to check really - wastegate loose or not and whether the bypass valve is diaphragm style and the diaphragm is torn, that'll do that as well. Both of these could be done already, especially the wg flapper check it's easy to just reach down there and check if it's loose. Actuator not adjustable. |
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Tb205gti
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« Reply #7 on: June 07, 2022, 02:56:28 AM »
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It looks very bad. I added a pic to show how it looks on a functional car when remapped.
Note how much boost it makes at much lower DC.
Carbon buildup will only increase the amount of boost because engine flow is worse. N75 usually not broken on these.
Only two things to check really - wastegate loose or not and whether the bypass valve is diaphragm style and the diaphragm is torn, that'll do that as well.
Both of these could be done already, especially the wg flapper check it's easy to just reach down there and check if it's loose.
Actuator not adjustable.
That is a massive differenc, yes. :/ I replaced the DV as I suspected it - it was so cheap that I just bought a new piston type one. It turned out the old one also was a piston type, so no diaphragm. There was oil in the plug - but I suspect this is fairly normal after some time. Changing the DV did not really make a difference, so last thing to test is the WG. It doesn't rattle though - but it can be leaking anywho. |
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prj
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« Reply #8 on: June 07, 2022, 03:24:09 AM »
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If you move it up and down and it doesn't have play in it, then you also need to pressure test the entire inlet incl. the manifold.
Can be done by removing the turbo outlet hose and pressurizing that way or removing intercooler hose and pressurizing from the intercooler (but then have to inspect the turbo to intercooler hose also).
These cars don't have a MAF, so if there can also be a massive boost leak without any faults thrown.
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prj
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« Reply #9 on: June 07, 2022, 03:28:52 AM »
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Actually... I just looked at this sorry excuse of a "log" in csv form...
Do a full pull from 1500 to 6000 rpm. Might be nothing wrong with it.
Name the log a proper name, save only this one pull into the log.
Your nr1 lesson is to learn to make logs.
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Tb205gti
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« Reply #10 on: June 07, 2022, 03:36:36 AM »
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Actually... I just looked at this sorry excuse of a "log" in csv form...
Do a full pull from 1500 to 6000 rpm. Might be nothing wrong with it.
Name the log a proper name, save only this one pull into the log.
Your nr1 lesson is to learn to make logs.
Yup - this is not a "proper" log - this is just some testing during my commute. (primarily doing pulls in high gears from 1800-3000 rpm). Problem is, that the laws here is that the police can take your car on the spot if you're speeding. And getting a proper log where the turbo has time to boost properly requires you to be in a high gear = exceeding the speed limit quite rapidly. :/ Best option is to test it on the dyno, but finding a 4wd dyno is not the easiet part around here  |
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Tb205gti
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« Reply #11 on: June 07, 2022, 03:45:53 AM »
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btw - there is a pull from 1500 to 6300 rpm in the file, but it is not in a high gear IIRC.
EDIT: Just did a more thorough comparison of your graph and mine - there is not a lot of difference at 2.000 rpm.. I'm at approc 0.5 - and you're at 0.55. Once we go higher the remapped one makes much more boost - but that is a natural when remapped. My concern is below 2.500 - but looks like there is not a big difference after all.
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« Last Edit: June 07, 2022, 03:55:17 AM by Tb205gti »
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prj
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« Reply #12 on: June 07, 2022, 03:52:53 AM »
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That actually looks more or less ok.
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Tb205gti
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« Reply #13 on: June 07, 2022, 03:58:22 AM »
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That actually looks more or less ok.
I tend to agree - I'm just surprised that they do not make more boost below 2.500 rpm - it is way less that requested. But it looks like your remapped has about the same boost as my standard - below 2.300. |
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Tb205gti
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« Reply #14 on: June 16, 2022, 07:09:54 AM »
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I found out why the car was driving "funny". Changing gears too soon, extremely soft gear changes (more gentle than a classic auto), being completely slow below 2.5000 rpm - but fine'ish above. It had an ABT "piggyback ecu" fitted. It was well hidden under the scuttle panel. I have now removed it and now it runs like a factory car again. Proper DSG gearchanges, that not always happens below 2.000 rpm, and no sudden torque explosion at 2.500 rpm. ..next step, get my file written in bootmode |
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