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C30 / S40 & V50 '04-'12 / C70 '06-'13 General Forum for the P1-platform C30 / S40 / V50 / C70 models |
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Performance issues - illusion or real?Views : 1529 Replies : 14Users Viewing This Thread : |
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Jun 21st, 2020, 17:44 | #1 |
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Last Online: Sep 26th, 2021 22:38
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Performance issues - illusion or real?
Hey,
So much like the title says, I'm currently having something funky going on with my V50. It's a T5 automatic from 2004, and I'm not sure if something IS going on, or if it's simply a placebo-effect. Previously, after making a turn (so gearbox probably sitting in first-second gear), I could more or less floor it and it would shoot away. Right now it's still building speed, but I feel like it's not revving as "quick" as previously (perhaps just the gearbox learning/adapting more and more to my own driving style?). Another thing I noticed, was that this issue seemed to be gone after I had the battery disconnected for a few hours while installing some extra lights in the grille of the vehicle. This is probably what's throwing me off the most. Is this just a placebo-effect, or could something be going on that a ECU reset fixes? Oil change interval is at 20kkm and has been driven with roughly 10kkm right now. Engine air filter also looks decent. Any ideas are welcome! |
Jun 21st, 2020, 20:08 | #2 |
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Last Online: Mar 14th, 2024 16:24
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When was your turbo control value last replaced?
These are pretty much consumables and should be replaced every other year (IMO). When they begin to fail you start to see intermittent boost.
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2006 Volvo S40 T5 SE Sport
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Jun 21st, 2020, 21:25 | #3 | |
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Quote:
Is there a way to diagnose this, apart from getting "intermittent boost"? EDIT: Will go get a OBD2 reader tomorrow/Tuesday and come back with some numbers. Need one anyways and should perhaps give me/us some kind of idea what's going on. EDIT 2: Should also be mentioned this only happens when going from a standstill. While overtaking, for example, I got 0 issues. Last edited by Xariez; Jun 21st, 2020 at 23:28. |
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Jun 22nd, 2020, 08:46 | #4 |
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Last Online: Sep 14th, 2021 17:03
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Some fairly common areas to check:
Boost Pressure Sensor (at the Intercooler - mine went bad and really slowed the car down). Turbo Control Valve. Turbo 'Check' Valve (one-way ball valve/flap built into the turbo housing). Fuel Pressure Sensor on fuel rail (this would be my first call). Mass Airflow Sensor. Air Conditioning Load (the compressor saps a fair bit of engine power).
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2005 S40 T5 SE - Manual. Bilstein B4's. (For Sale) 2010 Citroen C4 1.6 HDi (bizarre Gearbox model). 2010 Renault Twingo (refreshingly simple) 2018 Infiniti Q30 1.6T Business Executive (what's this button do?) |
Jun 22nd, 2020, 13:25 | #5 | |
WowIcanwriteAnythingHere!
Last Online: Mar 26th, 2024 16:05
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Quote:
Regardless - there might be a problem as FM and Welton said, check all those and replace if not sure. Boost readout trough ECU will give you some info if TCV is knackered or not, but as mentioned - this thing just fails ever so often so replacing it as maintenance item is recommended.
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2005 V50 T5AWD M66, Stage1 Hilton tune E-focus torque mount, E46 bi-xenon retrofit v2 , (also available in PDF form), DTSC fully-off mod, Brembo discs+ATE ceramic pads |
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Jun 22nd, 2020, 15:54 | #6 | |
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Quote:
1) If the fuel pressure sensor is going, shouldn't the OBD-reader read bad (or erratic) fuel pressures as well? Any ideas what kind of pressure I should expect at idle/under load/etc? 2) In a similar fashion, if the TCV is going, shouldn't the vacuum/boost-gauge be reading quite incorrectly as well? I believe I've read somewhere T5's should generate around 0.6-0.7psi of boost, though not sure how much vacuum should be produced at idle? EDIT: If it matters, the reported average fuel consumption has been lower for some time right now. Granted, it's been warmer outside as well and cold starts haven't been as cold, but while I previously had 10.0-11.0L/100km, it has barely moved from 9.0L/100km currently? Last edited by Xariez; Jun 22nd, 2020 at 15:57. |
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Jun 23rd, 2020, 14:23 | #7 |
WowIcanwriteAnythingHere!
Last Online: Mar 26th, 2024 16:05
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FPS that is going out would trigger engine management light, in most cases, but if you can check the values - from what I remember it oscillates between 400 on idle to 500 on WOT on mine.
if its any help to you - here is a datalog file that I recorded 2y ago, bear in mind my car is s1 tuned so turbo pressure values will be higher, but fuel pressure or TCV behaviour would be similar. EDIT - ref the vacuum, a value of 23.5 rings a bell, I think thats what I have reported by Torque when driving with obd2 adapter active.
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2005 V50 T5AWD M66, Stage1 Hilton tune E-focus torque mount, E46 bi-xenon retrofit v2 , (also available in PDF form), DTSC fully-off mod, Brembo discs+ATE ceramic pads Last edited by LizardOfBodom; Jun 23rd, 2020 at 14:25. |
Jun 24th, 2020, 13:34 | #8 | |
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Quote:
0.7psi is standard boost (IIRC).
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2006 Volvo S40 T5 SE Sport
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Jun 24th, 2020, 16:16 | #9 | |
WowIcanwriteAnythingHere!
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Quote:
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2005 V50 T5AWD M66, Stage1 Hilton tune E-focus torque mount, E46 bi-xenon retrofit v2 , (also available in PDF form), DTSC fully-off mod, Brembo discs+ATE ceramic pads |
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Jun 25th, 2020, 01:42 | #10 | |
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Last Online: Sep 26th, 2021 22:38
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Quote:
The annoying part is that it seems to have gotten slightly (but noticably) different. So perhaps just a "placebo" effect in the end, or just a ECU with reset values that hadn't quite reached it's "learned" state? |
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automatic, ecu, performance, reset |
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