Guest Guest_turbo brick Posted June 21, 2004 Report Share Posted June 21, 2004 Hey everyone i need yoour help,I have an upsolute ecu in a 1997 t5 with a stainless exhaust.My problem is this,when i put my foot down the boost rises hard to 15 psi then just as the rev counter hits 3500rpm the boost drops to 5 psi then goes back up to 15 psi at 4000rpm.so it hapens hardley at in 2nd it doesnt even have time to drop,in third it happens once and in 4th its happens a couple of time but on the freeway in 5th it happens lots.I have replaced all the hoses that run from the boost control soilinoid and the hose that runs from the inlet manifold to the inlet pipe.I have even tried a different MAF diverter valve,boost solinoid valve.I have even tried a friends ecu and it does exactly the same.I just dont know what else it could be actuator ,the thing i dont understand is that it holds the 15psi of boost after its finished around.thanks in advance.P.S it wont let me log on here Link to comment Share on other sites More sharing options...
lax01 Posted June 21, 2004 Report Share Posted June 21, 2004 sounds like a boost leak...check your vacuum hoses... Link to comment Share on other sites More sharing options...
Guest Guest Posted June 21, 2004 Report Share Posted June 21, 2004 which 'vac' lines,I already said that that i have replaced the one from the inlet manifold to the inlet pipe and the hose from the comp housing to the BCS the hose from the inlet pipe to the BCS and the hose from actuater to the BCS.Where are the others <_< Link to comment Share on other sites More sharing options...
freeskier8585 Posted June 21, 2004 Report Share Posted June 21, 2004 they are everywhere :ph34r: Link to comment Share on other sites More sharing options...
Guest Guest_turbo brick Posted June 21, 2004 Report Share Posted June 21, 2004 they are everywhere and they cause chaos lol Link to comment Share on other sites More sharing options...
Turbo Brick Posted June 21, 2004 Report Share Posted June 21, 2004 It seems like a boost leak would continue to be a problem even as RPM rose. My friend had this same problem on his bone stock '95 850 Turbo. The car would pull hard all the way to about 4k then it would just set right around 4000 RPM for a few seconds, then it would pull out to 5200 just fine. I diagnosed it as spark blow-out and sure enough, the previous owner's mechanic had replaced the spark plugs with cheap Delco units. I changed them back to stock Volvo platinum plugs ($40) with a gap of .028 and now it runs great. If you changed your plugs recently, they could be causing your problem. Link to comment Share on other sites More sharing options...
Lackey R Posted June 21, 2004 Report Share Posted June 21, 2004 Turbo BrickI have a 96 850R, and had the same problem with my Upsolute ECU. I had Bill put different software on it 3 times, the first 2 had the same problem, the 3rd worked fine, but my boost would not rise above 11 PSI. The first 2 programs would hit 15 before it spiked. I have to admit, I am pretty disappointed with my 11 psi, so I had a MBC installed, and The boost hits about 14 now. IT worked fine all week, and today on my way in, it would spike and then drop down to about 7 psi, then rise again slowly to 12Don't know whats up with it either, according to my mechanic my vaccum lines are fine. Just wanted to let you know your not the only one-Mark Link to comment Share on other sites More sharing options...
Guest Guest Posted June 21, 2004 Report Share Posted June 21, 2004 i have put an MBC onit to see if it will hold boost and it holds 1 bar fine,but it may well be that the spark is not good around those rpm and by putting the mbc on and removing the ecu from the equation it does'nt do it.I would run an mbc but i am not a fan of them at all they kill your top end and if somthing does go wrong the ecu cannot back it down.Keep the ideas coming Link to comment Share on other sites More sharing options...
Guest Guest_nik850r Posted June 21, 2004 Report Share Posted June 21, 2004 i have a similar problem. I have an ipd chip and then put on a mbc. didn't like the mbc so i took it off. while my car was getting worked on the wastegate was adjusted. I changed my vacuum lines to make sure that wasn't the problem. but it still runs funny. 1st gear will hit between 11 and 15 psi, and then when it switched into 2nd it will it 20 psi drop down to 13 and rise back to 15 psi. would the wastegate cause this problem. Link to comment Share on other sites More sharing options...
Guest Guest_turbo brick Posted June 22, 2004 Report Share Posted June 22, 2004 I was wondering if it could be the wastgate actuator!!but it holds boost ok up top,today i replaced the cap and rotor arm but no luck I guess the next thing is plugs. Link to comment Share on other sites More sharing options...
Guest GUest Posted June 22, 2004 Report Share Posted June 22, 2004 sounds like a waste gate problem. like waste gate opens too far, lets too much boost out. i'm not to familiar w/ volvos but on saabs you can adjust wastegate dump. good luck Link to comment Share on other sites More sharing options...
Guest Guest Posted June 23, 2004 Report Share Posted June 23, 2004 you can adjust the W/G on the volvos,but i cannot imagine that it is it,if an upsolute ecu saw to much boost at 3.5rpm because your w/G was would in would it cut back to W/G pressure anyone???????anymore ideas anybody :blink: Link to comment Share on other sites More sharing options...
EOBD Posted June 23, 2004 Report Share Posted June 23, 2004 The Boost Control Solenoid (BCS) has the sole purpose of acting as an electronic control pressure ‘bleeder’. We are all aware of how the solenoid works.What you are experiencing in respect of varying boost levels is a feature ‘inbuilt’ to the design of the ECU and the firmware running on it. The Volvo’s are like many similarly designed vehicles utilising a turbocharger. The wastegate actuator is designed to open at a boost pressure of around 5 – 6 psi. The BCS is added so that the boost pressure can be increased to a much higher value, usually 11-12 psi.The normal operation of the ECU is to allow the car to run at the full 11-12 psi. It achieves this by cycling the solenoid open and shut. This cycling is done via the Pulse width modulation method and the ECU averages out the load and performance requirements of the driver input, coupled with sensor readings. However two factors have an overriding influence on the cycling of the BCS. They are namely knock detection and WOT input.If severe knock is detected for a specific duration then the ECU will increase the close time of the BCS thereby restricting boost to that allowed purely by the wastegate. This is to protect the engine as an increase in knock, coupled with high boost levels, can cause the engine to fail. Once an ECU enters into this state it can take some time for it to resume normal operation so as to speak. This is because the ECU is always trying to give the maximum amount of ignition advance at all times. In a knock situation where it has to effectively shut off the BCS to restrict boost it needs to ‘satisfy’ itself that the knock scenario has now passed. It does this by reference to advance ignition tables indexed to RPM and MAF inputs. Some other calculations are done to ensure that the knock factor is no longer a risk. Generally speaking low octane or ‘bad’ fuel can aggravate this aspect of ECU control of the BCS. Another consideration is that of WOT. Under this condition, and near to maximum performance, the ECU will reduce the boost as full boost is no longer required. Further more the ECU does not update many of its long term fuel, ignition, boost and knock tracking values in the WOT state. Therefore, to ensure the ECU does not over do things and allow the engine to possibly fail, it backs off boost as a simple precaution. It may be the case that the engine is okay at this level of boost and therefore does not need this reduction, however the ECU is programmed such and therefore does as it is simply instructed. As the ECU can track long term knock in the engine, if some other external factor, such as bad plugs or ignition problems exist that cause the ECU to ‘see’ engine knock, the long term knock factor is updated accordingly. Now when the engine goes on boost this long term knock factor is applied and if still evident the ECU will reduce the maximum amount of boost permissible. From this it is therefore possible that a continuous amount of nominal engine knock off load can have a severe limiting factor on the overall boost the ECU permits when engine load and hence boost rises.If the pressure hoses etc are all in order it may well be worth your time checking on the likes of plugs, ignition leads and even the ignition control circuit as already discussed. In addition it may be worth checking to ensure the knock sensors are functioning correctly on the engine. Have you thought of checking the mechanical state of the engine? I recently experienced a modified Impreza turbo which was restricting boost under load. The fault was down to an after market exhaust down pipe lightly tapping on the engine block, and the knock sensor was picking this up! Link to comment Share on other sites More sharing options...
Guest Guest Posted June 23, 2004 Report Share Posted June 23, 2004 Thanks for the detailed response EOBD,i have just done the cap and rotor so i will do the plugs,Your response is interesting because it only happens at WOT.I had a good look around the block today on a ramp and there is nothing,that i can see touching the engine that should'nt be.Ho can i check to see if the knock sensors are working??If i unplug them it will go into a safe mode will it?? Link to comment Share on other sites More sharing options...
EOBD Posted June 23, 2004 Report Share Posted June 23, 2004 There are a lot of factors that can cause engine knock which would go into page upon page. However to test the knock sensors you can look at this PDFKnock testingGo to page 3 and have a look. You will need a scope to do this unfortunately, and reference data for the knock sensor outputs. I can see if I have the Volvo stuff at hand. Can you confirm the exact year and model of Volvo you have? Link to comment Share on other sites More sharing options...
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