WJM Posted July 28, 2005 Share Posted July 28, 2005 1996 Legacy Outback Wagon 204,000 miles on it All original engine/tranmsission Here's what its doing... That was a few weeks ago...NOW the dip is starting at 3000....and continuing until 5500. It has a new knock sensor, and all the other sensors are working correctly. No CEL's at all. I am running sythetic oil, Motul 5w30 8100 series, the timing belt is only about 50k old. Coil-wire-plugs are approx 25k old, replaced about 8 months ago. Air filter is fresh. O2 sensors are same age/mileage as the ignition stuffs. Ive run seafoam thru it...to no affect. C16 fuel did nothing. I did 20+ dyno runs that day swapping things out and trying stuff and nothing worked....and now it is getting worse. any ideas? Quote Link to comment Share on other sites More sharing options...
Cougar Posted July 28, 2005 Share Posted July 28, 2005 Have you checked the fuel pressure? I wonder if the fuel pump is having a problem. Quote Link to comment Share on other sites More sharing options...
WJM Posted July 28, 2005 Author Share Posted July 28, 2005 it appears to be fine as well. When i first got the car, it was happening between 3 and 4 initially....eventually that kinda dissapeared...then resurfaced in the 4~5 range...now its getting worse. its a very consistant thing....and if you keep it in a gear, going up hill you can ease the pedal to the floor and still have gradual full power...but as soon as you get past about 95% throttle, you feel the power suddenly drop off...back the pedal off 5% or so and it comes back. But there's still a loss form only going 85~90% WOT..... Quote Link to comment Share on other sites More sharing options...
rguyver Posted July 28, 2005 Share Posted July 28, 2005 it appears to be fine as well. When i first got the car, it was happening between 3 and 4 initially....eventually that kinda dissapeared...then resurfaced in the 4~5 range...now its getting worse. its a very consistant thing....and if you keep it in a gear, going up hill you can ease the pedal to the floor and still have gradual full power...but as soon as you get past about 95% throttle, you feel the power suddenly drop off...back the pedal off 5% or so and it comes back. But there's still a loss form only going 85~90% WOT..... it sounds like the TPS (throttle position sensor) check that its reading at WOT (wide open throttle ) Quote Link to comment Share on other sites More sharing options...
Cougar Posted July 28, 2005 Share Posted July 28, 2005 I'm not sure how you can eliminate the fuel pump being the problem by appearing to be ok, unless it has been pressure tested while the problem is happening. If the pump really is ok then I would check the throttle next, as was mentioned. If that is ok then I would check the intake manifold for a leak. Quote Link to comment Share on other sites More sharing options...
WJM Posted July 28, 2005 Author Share Posted July 28, 2005 it sounds like the TPS (throttle position sensor) check that its reading at WOT (wide open throttle ) thats a big negative there ghostrider..... The A/F's would go lean where the dip is if the TPS wasnt working. I'll still check it to be safe....but I dont think thats it. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 29, 2005 Share Posted July 29, 2005 i'd check the MAF sensor and TPS sensors. does this have a hotwire type MAF sensor? i'd pull the sensor and check the very very thin wires to see if any are broken. a broken strand can give very similar problems and not throw any CEL codes. not likely but it is possible the timing tensioners are weak or the bolts holding them are stripped and not holding tight enough. under light load there is no problem, at higher RPM's the tensioner gives away under the higher load, temporarily *changing* your timing. this problem will also get worse as the tensioner or bolts get worse. more likely for the item to just fail, this scenario is very rare but possible if you're striking out everywhere else. Quote Link to comment Share on other sites More sharing options...
WJM Posted July 29, 2005 Author Share Posted July 29, 2005 MAF is next item...I did clean it and it looked fine....going to swap it soon to compare. if you note the DYNO GRAPH....there is no loss up high...its only at a certin RPM point/range...so that thows that theory out. Quote Link to comment Share on other sites More sharing options...
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