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airtite
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« on: February 03, 2022, 10:52:52 PM »
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Hi All
I bought the above non runner, it had the steering lock actuator issue and an ecu issue. I have another exact same car, so I did an immo defeat on the working ecu so I could swap it between the 2 while sorting out the issues. After sorting out the ecu it had a turbo actuator fault so I bought a new turbo actuator and had it programmed by audi using the vas 6395, the actuator fault is now gone and there are no longer any other engine fault codes.
Now when I drive the car it drives fine for about 200meters and then goes into soft limp with little to no power, the ecu is not storing any dtc's related to the engine or trans although the gear changes are very erratic and harsh compared to the other q7, if I stop the car and key off and key back on the car drives fine for a minute or 2 and then back into soft limp, I have no idea where to look from here?
Any ideas?
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prj
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« Reply #1 on: February 04, 2022, 01:46:44 AM »
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Most likely software is not stock and fault codes are deleted in it.
Another issue you can have is EGR valve jamming, but that usually throws a code.
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terminator
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« Reply #2 on: February 04, 2022, 06:29:25 AM »
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And I would add it's overboost.
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airtite
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« Reply #3 on: February 05, 2022, 02:01:08 AM »
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Most likely software is not stock and fault codes are deleted in it.
Another issue you can have is EGR valve jamming, but that usually throws a code.
Thanks PRJ software is stock, the ecu is from my other q7 with immo defeat the ECU that was on this car was faulty water damage, I did post previously about that ecu and the chksum, and supply voltage issue. I will reflash it again with the stock file to double check, yup had egr issues on the other q7 and that does throw a code and usually check engine light, thats whats weird here is there is no faults and no check engine light. What I am noticing more now is that it seems to happen when the car is at normal temp when its cold it doesnt do it straight away, the gear changes are also very jerky when it happens. I changed the gearbox oil yesterday but that hasnt made any changes. |
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airtite
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« Reply #4 on: February 05, 2022, 07:14:57 AM »
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what measuring blocks in vcds can I log to try and isolate the issue? I dont really know vag diesels that well.
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terminator
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« Reply #5 on: February 05, 2022, 02:30:14 PM »
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I would log 11.
In most cases if there is no more limp after you restart the engine, it's an overboost condition. From my experience.
And I would check all temperature sensors.
If tmot is too high there will be also no DTCs but the restart won't help and max rail pressure will be too low.
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Geomeo
Full Member
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« Reply #6 on: February 05, 2022, 03:16:43 PM »
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When you say the ECU was water damaged what state was it in? Is the connector that plugs in to it maybe have corroded contacts?
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airtite
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« Reply #7 on: February 06, 2022, 10:54:15 PM »
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Hi
from what it looks like is someone left the rubber gromet off of the top of the ecu housing and water got in there, it wasnt sitting in water if that makes sense. I have cleaned the contacts with electrical cleaner twice to make sure they are good.
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airtite
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« Reply #8 on: February 06, 2022, 10:56:19 PM »
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I would log 11.
In most cases if there is no more limp after you restart the engine, it's an overboost condition. From my experience.
And I would check all temperature sensors.
If tmot is too high there will be also no DTCs but the restart won't help and max rail pressure will be too low.
just 11? max rail pressure is fine while driving even in limp I have checked that. what is noticable is that as soon as the car gets to temp the gear changes become very hard and erratic would a gearbox issue put the car into a soft limp without logging a fault? |
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airtite
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« Reply #9 on: February 08, 2022, 10:35:33 PM »
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I am leaning more towards an issue with the 09D gearbox valve body having an issue, its just strange that its not logging anything.
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airtite
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« Reply #10 on: February 10, 2022, 09:51:38 PM »
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not a gearbox issue, had the valve body swapped with a serviced unit and new oil and filter. The gar changes are now smooth as silk but the loss of power when warm still persists. I am trying to do a log but by the time I get somewhere that I can do a 4th gear wot log the motor is warm and already in limp.
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airtite
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« Reply #11 on: February 11, 2022, 01:06:32 AM »
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log attached, I did 3 logs. 1 x 3rd gear (limp mode), 1 x 4th gear (limp mode), then managed to stop and key off and key on the car and then log a full accelerator run (no limp)
any help please, I am running out of ideas here... its the 1st vag car that hasnt logged a fault when in limp and confirmed flash is stock file.
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airtite
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« Reply #12 on: February 11, 2022, 02:24:51 AM »
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the only thing that looks out of place to me is the "Temperature prior - Precatalytic Converter" doesnt change and is at 551 all the time
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prj
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« Reply #13 on: February 12, 2022, 03:41:35 AM »
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the only thing that looks out of place to me is the "Temperature prior - Precatalytic Converter" doesnt change and is at 551 all the time
Flash stock SGO, stop screwing around. Learn to make logs, what the f... is that file? You've been on here long enough to know how to make a third gear pull. |
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airtite
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« Reply #14 on: February 13, 2022, 11:04:16 PM »
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Flash stock SGO, stop screwing around.
Learn to make logs, what the f... is that file? You've been on here long enough to know how to make a third gear pull.
As I have said a few times now, it is the stock file loaded on there, and the 1st log was a 3rd gear pull, then the 2nd was a 4th gear pull but like I said the car is already in limp at this point.... if you look at the timestamps between when pedal position was at 100% you will see that there is a gap when the log was stopped and then resumed. |
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« Last Edit: February 13, 2022, 11:15:47 PM by airtite »
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