Kw521 Posted August 27, 2010 Share Posted August 27, 2010 i noticed this recently and I do not know if it is normal. but upon driving my car(usually at slower speeds 35 and under and im not fully accelerating my car seems to pick up and then slow down then pick up and slow down. It seems my turbo wants to boost then it doesnt. Is this normal? Link to comment Share on other sites More sharing options...
moncur_6 Posted August 27, 2010 Share Posted August 27, 2010 What RPM/Gear? Link to comment Share on other sites More sharing options...
Kw521 Posted August 28, 2010 Author Share Posted August 28, 2010 3rd gear around 3k or little less Link to comment Share on other sites More sharing options...
Kw521 Posted August 28, 2010 Author Share Posted August 28, 2010 there are no check engine lights either....could it be a messed up A/F ratio? Link to comment Share on other sites More sharing options...
Kw521 Posted August 28, 2010 Author Share Posted August 28, 2010 No one has any input on this? Link to comment Share on other sites More sharing options...
Kw521 Posted August 29, 2010 Author Share Posted August 29, 2010 I have narrowed it down to either one of these problems with the car. There are no CELs' thrown so I cant troubleshoot it. The car slightly is stalling under minimal throttle. I am going to check with my Access Port today and watch my boost levels and then watch my fuel levels to see if the car is running rich then leaning out. If it is boost oscillation how do I fix it? Link to comment Share on other sites More sharing options...
ehsnils Posted August 29, 2010 Share Posted August 29, 2010 Also check that you have sufficient fuel pressure under load. It may be that the fuel pump can't keep up for some reason. Link to comment Share on other sites More sharing options...
ehsnils Posted August 29, 2010 Share Posted August 29, 2010 Merged threads since they are on same car/topic. Link to comment Share on other sites More sharing options...
Kw521 Posted August 29, 2010 Author Share Posted August 29, 2010 Ill have to check the fuel pressure on my Access Port as well thank you. The car under hard accel though gets up and goes so I don't know if that could be a fuel pump? And if it is boost oscillation I read that it is something with the waste-gate needing to be adjusted. Would an aftermarket one be a better option? Link to comment Share on other sites More sharing options...
ehsnils Posted August 29, 2010 Share Posted August 29, 2010 I'm not sure that there is a sensor for the fuel pressure or if you need to connect a separate gauge. I suspect that it's one of the sensors that we want but doesn't have since the fuel pressure is considered to be sufficient for standard setups of the cars. The risk of boost oscillation - it can be, but I would like to rule out other things first since boost oscillation isn't really that common or it would have been listed a lot more often here. Also note that if you have a custom intake it can be the culprit - resonance effects can be a headache, or it could be a "stupid" thing as the air intake being too weak and partly collapsing and therefore choking the car. Another item can be a custom or damaged exhaust. Also check for the possibility of a prankster partially plugging your tail pipe. The wastegate is usually integrated with the turbo, so that would mean that you have to replace the turbo. Another factor that pops up is the possibility that you are seeing the first signs of a turbo failure. Link to comment Share on other sites More sharing options...
Kw521 Posted August 29, 2010 Author Share Posted August 29, 2010 I just checked on my AP the A/F ratio while driving and it jumped around like crazy and checked the fuel trim cycle and it jumped around like crazy as well. Link to comment Share on other sites More sharing options...
ehsnils Posted August 30, 2010 Share Posted August 30, 2010 There can be two O2 sensors, one before and one after the cat. The one before shall oscillate and the cat will make it average out so the second should be stable. But a sway can indicate that one of the the O2 sensors are bad - like getting bad readings when it gets too hot and then goes back to normal. However - before you throw money at an O2 sensor I would say that you should check the air intake and replace the air filter to make sure that you don't have any constrictions there that messes up things. Squirrel living in the airbox or a plastic bag that has found it's way into the intake. Link to comment Share on other sites More sharing options...
Kw521 Posted August 30, 2010 Author Share Posted August 30, 2010 Ill check my air intake....but the intake I have on my car is literally less than a month old....im kind of wondering now if it is an 02 sensor...if so ill be relieved Link to comment Share on other sites More sharing options...
ehsnils Posted August 30, 2010 Share Posted August 30, 2010 OK, so you don't have a stock intake. Have you done a tune since you changed the intake? If not then that's probably your problem. If possible - try to go back to stock intake and see if the problem remains. Link to comment Share on other sites More sharing options...
Kw521 Posted August 30, 2010 Author Share Posted August 30, 2010 I have been tuned since the stock intake. Ill find out what it is here soon. I got a hold of my tuner and sent him the log he will look and see Link to comment Share on other sites More sharing options...
Kw521 Posted August 31, 2010 Author Share Posted August 31, 2010 Also if it is the case that it is the O2 sensor is it okay the drive the car? Link to comment Share on other sites More sharing options...
ehsnils Posted August 31, 2010 Share Posted August 31, 2010 It can put some strain on the cat, but otherwise it shouldn't be any big issues with it. Link to comment Share on other sites More sharing options...
Elliott1080 Posted September 11, 2010 Share Posted September 11, 2010 I have the same issue. Just purchased the car yesterday. I love the car and have wanted one for several years. Had a Forester for eight years. Have you solved the issue yet? I have a 2005 Limited gt with a 2006 motor. Someone blew the motor during a test drive and the dealership had to replace it and take a loss. Link to comment Share on other sites More sharing options...
Kw521 Posted September 12, 2010 Author Share Posted September 12, 2010 it turns out its a vacuum leak for me. check your hoses and your bpv or where your intercooler connects Link to comment Share on other sites More sharing options...
moncur_6 Posted September 13, 2010 Share Posted September 13, 2010 I have had similar issues around my TMIC with small leaks around the hose. Not the greatest design IMO but luckily I'll be buying a front mount in the next 6 months Link to comment Share on other sites More sharing options...
Elliott1080 Posted September 13, 2010 Share Posted September 13, 2010 Thank you, I'll take a look. Link to comment Share on other sites More sharing options...
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