Digital Posted June 21, 2011 Share Posted June 21, 2011 Hi fellas, a strange problem with an NA: with WOT the engine holds back at arround 4000rpm and up. It's almost like some sort of limiter but that's not possible off course. It's not stuttering, but really almost like somthing is pushing the car back(figurally speaking). Also, when warm, the idle is real unstable. Timingbelt and sparkplugs are recently changed, not by me. Could wrong timing cause this specific problem arround 4000rpm and up? Quote Link to comment Share on other sites More sharing options...
David P Posted June 21, 2011 Share Posted June 21, 2011 How long since the fuel filter has been changed? Quote Link to comment Share on other sites More sharing options...
Digital Posted June 21, 2011 Author Share Posted June 21, 2011 No idea. Worth a try indeed. But this problem came overnight so it's a bit strange. Quote Link to comment Share on other sites More sharing options...
kill1308 Posted June 21, 2011 Share Posted June 21, 2011 iirc Homer had a similar problem with his NA a while back, might be worth speaking to him. Quote Link to comment Share on other sites More sharing options...
Neil-NA Posted June 21, 2011 Share Posted June 21, 2011 Have you checked if the valve in the throttle body is connected and working properly, not too sure if it would cause the issue you are having but its worth a quick check. Quote Link to comment Share on other sites More sharing options...
Homer Posted June 21, 2011 Share Posted June 21, 2011 From your orignal description it sounds a little more serious than just a dodgy butterfly hose, is the rpm actually struggling to go above 4krpm or is it just a lack of power? Is the car an auto and is it the same in all gears? Assuming it is just lack of mid range: As mentioned above, check the vac hose under the intake manifold is still secure. It is VERY difficult to get to and near impossible to see, so you have to look very carefully for it. There is a small valve directly underneath where the intake after the throttle body splits into two, this should have a vac hose attached. If the vac hose is missing both throttle butterflys remain open causing a loss of mid range power. For me it was very noticable after plugging it back in. Here you can see the before and after dyno (Ryan found the disconnected hose between dyno runs!) Quote Link to comment Share on other sites More sharing options...
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