harleyhv Posted July 31, 2010 Report Share Posted July 31, 2010 Here is the situation: Happened today and earlier this week. While driving on the highway or street, with engine hot, the car seems to loose its boost for short period of time... It happens when I accelerate hard or gently... it happens while cruise control tries to maintain spped (gentle acceleration)... While cruising, it seems that the boost hits -10 lbs then drops to -20 (lie the car is on iddle) then come back.. same feeling as if I hit the brakes. In acceleration, there is a delay then the boost starts kicking... Other information: * There is no "Check Engine" light on the dash.... * The car has an IPD TCV valve bought 2 years ago (I think). * I upgraded the vaccuum lines a month ago (Sylin' lines) * I have not checked the vaccuum lines as I came back home late tonight... I'll check them tomorrow morning * The car has an Autotech tune which runs fine (up to now) * I have done a quick search and found this link that is similar (although I can hit 13/14 lbs when the boost is good) "Every once in a while, mainly while driving significant distances on the hwy, my car won't boost more then 8psi or so. I'm running a ST tune with new silicone vac lines, and all the intercooler pipes are tightened securely--no leaks. I'm thinking it's either the BCS or the wastegate? Most of the time I can hit full boost without a problem, and when I do get the boost loss it seems to come back after I step on it for a couple of seconds and then coast for a little bit to create maximum vacuum. " http://volvospeed.co..._1#entry1322364 Any pointer would be appreciated. Link to comment Share on other sites More sharing options...
850newb Posted July 31, 2010 Report Share Posted July 31, 2010 Here is the situation: Happened today and earlier this week. While driving on the highway or street, with engine hot, the car seems to loose its boost for short period of time... It happens when I accelerate hard or gently... it happens while cruise control tries to maintain spped (gentle acceleration)... While cruising, it seems that the boost hits -10 lbs then drops to -20 (lie the car is on iddle) then come back.. same feeling as if I hit the brakes. In acceleration, there is a delay then the boost starts kicking... Other information: * There is no "Check Engine" light on the dash.... * The car has an IPD TCV valve bought 2 years ago (I think). * I upgraded the vaccuum lines a month ago (Sylin' lines) * I have not checked the vaccuum lines as I came back home late tonight... I'll check them tomorrow morning * The car has an Autotech tune which runs fine (up to now) * I have done a quick search and found this link that is similar (although I can hit 13/14 lbs when the boost is good) "Every once in a while, mainly while driving significant distances on the hwy, my car won't boost more then 8psi or so. I'm running a ST tune with new silicone vac lines, and all the intercooler pipes are tightened securely--no leaks. I'm thinking it's either the BCS or the wastegate? Most of the time I can hit full boost without a problem, and when I do get the boost loss it seems to come back after I step on it for a couple of seconds and then coast for a little bit to create maximum vacuum. " http://volvospeed.co..._1#entry1322364 Any pointer would be appreciated. Don't waste your time, switch to n/a and be done with it. No more diagnosing these "boost" issues, they're way too expensive to fix, and even then it's just a luxury 4 door, right? Link to comment Share on other sites More sharing options...
TRACStar Posted July 31, 2010 Report Share Posted July 31, 2010 Don't waste your time, switch to n/a and be done with it. No more diagnosing these "boost" issues, they're way too expensive to fix, and even then it's just a luxury 4 door, right? To the OP when using cruise control its normal to go from boost to vac due to changes in load. From the way your explaining your problems it seems like you may not have an issue. Check all your vac lines and report back. Link to comment Share on other sites More sharing options...
SlapShot Posted July 31, 2010 Report Share Posted July 31, 2010 Usually these symptoms describe a boost leak somewhere, but you say everything is tight. You can try adjusting the wastegate a turn tighter and see if it reduces the problem. Link to comment Share on other sites More sharing options...
AverageVolvo Posted July 31, 2010 Report Share Posted July 31, 2010 He is asking about vacuum. IE -10 and -20. He is confusing boost with vacuum on his gauge. Egr purge valve can cause this. Visually Check your intercooler hoses. Start with the throttle body hose and upper hoses. :unsure: :unsure: Link to comment Share on other sites More sharing options...
harleyhv Posted July 31, 2010 Author Report Share Posted July 31, 2010 Thanks for the replies guys. I'll check the lines tomorrow Am and report back on findings (if any).. Link to comment Share on other sites More sharing options...
volvoskiah Posted July 31, 2010 Report Share Posted July 31, 2010 My IPD TCV went bad so put your stock one back in and try it Link to comment Share on other sites More sharing options...
harleyhv Posted July 31, 2010 Author Report Share Posted July 31, 2010 Update: * Check the vacuum lines to/from TCV: ok however, I was unable to reach the vacuum line under the turbo on the turbo side but if I understand this correctly, if it was unplugged, the car would not boost at all. * check vacuum to/from boost gauge sender: ok * check intercooler pipes to/ from hot/vcold side: ok. Now, I have to locate the old TCV valve... hopefully I kept it. will update shorthly. Link to comment Share on other sites More sharing options...
harleyhv Posted July 31, 2010 Author Report Share Posted July 31, 2010 Update: * Found the old TCV and installed it. * Went for a drive and it took 5 minutes and a couple of acceleration runs in an industrial park nearby for the car to "get used" to the TCV. * Acceleration is not as smooth as expected. * intermittent boost issue happened twice on slow acceleration during a 10 minutes highway drive. * I'm going up north over the weekend (1.5 hrs drive) so I'll be able to further test it. * Will update after drive (if my daughter let me use her iphone.... ) Link to comment Share on other sites More sharing options...
harleyhv Posted August 3, 2010 Author Report Share Posted August 3, 2010 Update: * The Old TCV valve did not make it on saturday. I had to put back the IPD TCV in place. The car was bucking with the old TCV and I could not trust it for the drive up north and we had to go. * The car has the same behavior. on slow acceleration while cruising to maintain speed (usually gauge shows -10 so the turbo has not kcicked in), the pressure drops to -20 and goes back to -10 (like a yo-yo). If I press the gas gently, same behavior.... no acceleration an If I press harder, the boost kicks in and the car accelerate. * This behavior is random but always on slow acceleration from cruising (no turbo involved). * other points: * the car starts ok when cold. * the car is difficult to start when hot. If I start the car normally, the car stalls (like no gas is going in). I have to give some gas to ensure that the car starts. Once started, it's ok. * I parked the car on an incline (driveway going up) on Sunday and the car would not start again. I had to put it on neutral, get the car on the flat and start it. * I have the "service" light but it goes off after a while.... it's been there for a couple of months so I don't think that there is a correlation. * The gas pump has never been changed to my knowledge * I have cleaned the ETM two weeks ago and the iddle is smoother. Some things point towards a faulty TCV valve The hot starts issue may point elsewhere. So I'm at a dead end right now and I'm going to have it checked tomorrow morning to see if any codes are present. Will kpee you updated. Link to comment Share on other sites More sharing options...
harleyhv Posted August 3, 2010 Author Report Share Posted August 3, 2010 Update: * Went to get the codes on the car. Here are the codes found: ECM-6806 Turbocharger (TC) control system flow fault. Flow too high/low ECM-902A Throttle unit communication. Signal too high or signal missing. ECM-903F Throttle unit, internal fault. Signal too low or signal missing. ECM-912A Engine control module (ECM) communication. Faulty Signal. Everything points to the ETM. and on my way back, I received the infamous "Engine system - Service Required" message.... Looks like I'll have to replace it (under warranty) I have attached the diagnostic printout for those of you interested (it's in French though) Link to comment Share on other sites More sharing options...
harleyhv Posted August 8, 2010 Author Report Share Posted August 8, 2010 Final Update: * The ETM was replaced under warranty. * The car was scanned at the dealer 1st. * New codes were found (above the 4 initially identified) and had to be investigated.... which kept the car at the dealer overnight. * The Tech discovered that the ETM connector had also a short creating the additional codes. * Total Cost: 0$ Lol I nearly fainted.... told my volvo technical advisor that I would frame this invoice to remember it with some tears in my eyes..... and my autotech tune has been erased... which should not create too much problem. I wanted to upload the OEM settings before bringing the car to the dealer but it has been raining cats & dogs over the last week and since I don't have a garage.... uploading mapping files in the rain was not my cup of tea. Link to comment Share on other sites More sharing options...
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