MirXas
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« on: July 17, 2022, 09:53:03 AM »
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Hello. I have a problem with a completely stock 1.8t 225hp S3 BAM engine. Its constantly overboosting, sometimes so much that even throttle plate drops to 40% when going WOT. Parts I've tried replacing with known good ones - n75, bov valve and solenoid, whole turbo k04-023 (used one, but with original one was the same), MAF, MAP. Vacuum and boost pipes have been checked OK, N75 piping is good, no leaks. All solenoids actuate during VCDS active tests. No fault codes. Software is tuned 210hp 8N0906018J and with SAI and rear o2 off, but I've also tried with 8N0906018CB 225hp known good file - same $hit..
Any ideas ?
Attached logs.
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« Last Edit: July 17, 2022, 11:19:27 AM by MirXas »
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nyet
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« Reply #1 on: July 17, 2022, 10:51:01 AM »
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"known good" in what way? When did this start happening? was the car ever running right with this turbo/wg/tune?
WGDC just isn't dropping. wg look to be a bit tight for that dc vs boost, unless your lines are totally busted (which they don't seem to be).
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MirXas
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« Reply #2 on: July 17, 2022, 11:43:15 AM »
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Parts that were working fine in the same configuration, same engine but in another car. Tried maybe 4-5 different n75 solenoids, even new ones, from different 1.8t engines. Same with blow off valve, now it's running a new OE valve.
Actually, this car was never running right, it always overboosted to some degree. K03s (dont ask why an S3 had a k03s in it), new chinese K04-023 (which blew up instantly when the boost spiked), used OE K04-023, now another used OE K04-023, all the same story. Even the ECU was changed with another one, particularly from a BAM engine. Tried numerous different softwares, 210 225hp, EGT and rear o2 off or on, it doesnt matter.
Another thing i forgot to mention - when i disconnect the n75 solenoid, it only boosts up to 0.3bar. Isnt that a bit low ? I'll try loosening up the wastegate a bit, see if that helps. If i wont be able to find whats wrong with this cursed car, i'm thinking of a manual boost controller hooked up in parallel with the n75, to bypass some pressure in to the wastegate and keep it more "ready" to open.
Were these log variables enough ?
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« Last Edit: July 17, 2022, 12:23:16 PM by MirXas »
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nyet
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« Reply #3 on: July 17, 2022, 12:41:53 PM »
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Add all the PID variables.
MBC is a waste of time, dont do it, you'll just get dtcs anyway.
with n75 disconnected, .3 does seem low, while it indicates the lines are working fine (which is a good thing), it makes it hard to believe your wgs are too tight.
you're going to want to significantly pull WGDC if you can via IMX, if only to see if you can control boost with the N75 at all.
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denniss112
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Audi TT 99' | 180+HP FWD
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« Reply #4 on: July 17, 2022, 02:29:07 PM »
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The wastegate actuator on the turbo is very well known to break. Also the k03/k04's have a have thin exhaust turboside which make cracking insanely easy. I had to replace mine but all the garages and second hand turbos are cracked.
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denniss112
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Audi TT 99' | 180+HP FWD
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« Reply #5 on: July 17, 2022, 02:31:58 PM »
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This was my old one. As you can see it will crack towards or from the wastegate all the way inside.  |
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MirXas
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« Reply #6 on: July 18, 2022, 12:07:35 AM »
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I hardly doubt that its because of a cracked turbine housing.. It should underboost then, not overboost all the way until redline. Besides, this happened with all turbos, even with a new chinese k04 - same thing (yes, i know that wastegates are smaller than OE on those).
I'll log PID's then.
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adam-
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« Reply #7 on: July 18, 2022, 12:42:03 AM »
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What's been changed in software? Request is high - is IMX/PID related stuff stock?
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MirXas
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« Reply #8 on: July 18, 2022, 01:04:44 AM »
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Adam, I havent looked at what is changed in this tuned 210hp software (boost request is obviously higher, tho), but we've tried numerous stock 210 and 225hp files with no success - constant overboosting and n75 not "catching up".
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