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850 / S70 & V70 '96-'99 / C70 '97-'05 General Forum for the 850 and P80-platform 70-series models |
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S70 T5 OverboostViews : 6245 Replies : 58Users Viewing This Thread : |
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Apr 3rd, 2012, 17:43 | #51 | |
Volvo Nutcase
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If you don't want to be treated like a child then I suggest you stop acting like one. Let's cut the drama queen crap for a moment: Say the OP followed your advice, went to Volvo and got them to do the work (i.e. change the vac hoses connected to the BCS). They would have done the work and taken £100 off him. On his drive home the OP tests the car out and finds that it is no different - it still reaches peak boost and then spikes on gear changes. Would you refund him his £100? Would you even apologise and admit you got it wrong? Somehow I doubt it. A big part of this forum is about saving people money. To do that you need to give good advice. If you are going to give advice that you have learned 2nd hand then that's fair enough but you should make sure that the circumstances in both cases match. This thread should have been done and finished at post 2 when the query was answered correctly. If you wanted a discussion about your opinion then that's fine, even beneficial for the forum, but you should have posted an OPINION not a FACT. If you don't know the difference between fact and opinion then you should look it up in the dictionary. It's nothing personal, if anyone posts a fact that's incorrect then I or someone else WILL post to correct it, it's how forums work. By all means put me on your ignore list but remember this: if you post incorrect information then either myself or someone else is going to correct it, there's no getting away from that. So grow up, learn from your mistake and move on.
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Andrew 1998 S70 T5 CD AUTO Previously a 1990 240 GLT-R |
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Apr 3rd, 2012, 17:56 | #52 |
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it is a sad day when members have to point out the correct information over and over again and still the Trolls come out to play thank you Andrew for your help in trying to put it into perspective for the OP. the T5 that i had did exactly that.spiked on gear change
mike
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Mar 12th, 2020, 04:13 | #53 |
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1995 850 T5 A/T overboost when shifting at or near WOT.
Ok, I know I’m bringing up an old topic again, but my 1995 850 T5 is doing the same thing. I don’t have actual boost numbers because I’m going by the factory gauge that does not have numerical values. When under full or near full throttle, there is a momentary spike in boost when the car shifts. It is an Automatic Transmission car. There is a slight but very noticeable pop in the exhaust when it happens as well. Now, my understanding as the difference between a manual and an automatic car when it comes to shifting with a turbo is that when you shift a manual, you let off the gas obviously. This causes a cut in air, fuel, and also opens the CBV, BOV, DV, whichever you like to call it which releases the boost to prevent a lean condition when the throttle is reopened after the shift and also prevents damage to the throttle body and intercooler piping due to the sharp increase in boost when the throttle is suddenly shut and the turbo is still spooled. Now, with an automatic transmission, obviously you do not lift the throttle when the car shifts. As the engine’s RPM increases, so does the turbo’s RPM because the faster the engine is turning, the quicker it uses the air so the turbo has to spin faster to maintain the boost level at whatever setting it is. Now, when the transmission shifts and the engine’s RPM suddenly decreases, the turbo is still spinning fast enough to maintain say 11 psi at 5,500 RPM but now the engine is only turning 4,000 RPM. There is a spike in boost before the turbo slows back down to the necessary RPM to maintain 11psi at 4,000 RPM. This is a normal thing to happen but, if I was the manufacturer and I was programming the ECU (The Bosch Motronic ECU is a VERY GOOD ECU), I would program it to open the TCV right at the shift to fling the wastegate wide open to drop the turbo’s RPM at the same time the transmission shifts. The ECU and TCU communicate constantly so the ECU HAS to know when the transmission is going to shift so it can react properly. It’s either I would program for the TCV to fully open (basically run straight mechanical wastegate instead of holding the boost out of the wastegate’s reference hose and bleeding the excess into the inlet pipe before the turbo) or I would do what VW does on their DSG cars and I would cut the ignition and fuel right at the shift. Now, on my car, all of the hoses to do with the wastegate and TCV are brand new and I’ve recently replaced the turbo as well. This condition has stayed throughout the hose and turbo changes. To me, this is either a normal operation which has been compensated for in the ECU to add more fuel and drop timing right after the shift, poor programming of the ECU if there is not a compensation, or a lagging TCV. The latter seems the most likely. So, does anyone have any experience with the Heavy Duty TCV from IPD? I am getting ready to have the ECU flashed with IPD’s software and I would like to know if this is something that needs to be corrected before I have to flash done. Obviously the flash is going to raise the requested boost in the ECU so this spike is going to be exaggerated after the flash and I really don’t want to cause damage or blow the engine because of it. Or, does IPD’s software compensate for this issue? If they have addressed this issue and the problem doesn’t happen on their software, there may not be anything to worry about. Another note: this really seems to be most significant when the car is in “Sport” mode, probably because the shift logic is different and the ECU and TCU are running a more aggressive map for everything. Sorry for the novel you all had to read and I hope I wasn’t ambiguous with anything.
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Mar 12th, 2020, 10:08 | #54 |
Volvo Nutcase
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It shouldn't be popping in the exhaust on gear changes. I'd have a look and see if you have an exhaust leak first of all - my mx5 (miata) popped and sounded like a rally car with antilag, especially on overrun, when I had a small leak at a joint in the exhaust. I've never had any popping in the exhaust on the volvo.
Personally I don't think it's poor mapping at all on the factory ecu, I find the shifts and power delivery to be extremely smooth, certainly on a par with other younger autos I've driven. Time has moved on of course and there may well be better ways of mapping the gear changes now but this is only because other aspects of engine management have advanced such as coil on plug with individual cylinder monitoring and VVT as opposed to what we have which is cylinder firing driven directly off the end of the camshaft (via the rotor arm/dizzy cap) with a single coil providing power to the plugs - they did the best with what they had at the time. I run the IPD TCV, it has not made a difference to me but I have not had a remap. I've not noticed any difference in boost levels in sport mode. It just makes the gearbox hold a lower gear for longer (and burns more in fuel) so when you put your foot down it does "feel" more aggressive. If you have queries on the IPD map you really ought to direct those to IPD to get the best answers and have a look on the american volvo forums as there should be some reviews out there.
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Andrew 1998 S70 T5 CD AUTO Previously a 1990 240 GLT-R |
Mar 12th, 2020, 16:36 | #55 | |
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Mar 13th, 2020, 07:40 | #56 |
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Hi ColoradoSoul03
I haven't read the whole of this old thread (it's such a long one), and I don't know anything about 850s. But on a 1999 V70 AWD Manual using a VIDA Dice diagnostic device I noticed some spiking on gear change. No popping or any other noticeable problems. The diagnostic device let me watch boost pressure and also the turbo control valve duty cycle. I replaced the TCV (replaced with known good), which I don't think made any difference but what greatly reduced the spikes was replacing the vacuum line check valves. That car had two. You can test them by blowing. They should let air through one way, but not the other. Cheap to buy (I bought non volvo). While you are at it, might as well replace various vacuum lines if they need it. Make sure you install them or their replacements the same/right way round, and keep the same connections to the TCV. I went on to check some other similar Volvos, and found quite a few failed check valves. HTH Steve
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V70 2.5 Turbo AWD Man. 1999 Red V70 2.5 10V Auto 1998 Green C70 T 20V Auto Conv. 2001 Blue, C70 T5 Auto Conv. 2000 Blue V70 2.5 Turbo AWD Auto 1998 Green, V70 2.5 10V Auto BiFuel 1999 Red (scrapped) V70 20v Auto 1999 Green (scrapped) Last edited by SteveSarre; Mar 13th, 2020 at 07:42. |
Mar 14th, 2020, 22:54 | #57 |
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In other news...you're still alive, Andrew! Long time no see...!
cheers James
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Mar 15th, 2020, 18:29 | #58 | |
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Yes still alive although life keeps finding increasingly inventive ways of being difficult for me. I might try to get to castle Combe this year (if it's on). I suppose if we have a gathering at the current time one led by a doctor is probably the way to go....
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Andrew 1998 S70 T5 CD AUTO Previously a 1990 240 GLT-R |
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Mar 16th, 2020, 17:21 | #59 |
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I think that's true for most of us!
No word on CC this year. The Doc has been having a rough time of it with family health problems, so it might have having a year's hiatus. Will be good to see you as and when! cheers James
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VOC 300-series Register Keeper '13 V70 D4 SE Lux '89 740 Turbo Intercooler '88 360 Turbo Intercooler '84 360 GLT '81 343 GLS R-Sport '79 343 DL '70 164 |
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