2001 3.0 V6 Taurus. Problem is when I first start the car up in the morning, or anytime the engine has completely cooled down, and I shift into gear whether it be drive or reverse it surges without touching the accelerator pedal. Once the engine warms up the surge disappears. It also has a rough idle while stopped in drive. Other than that the car performs flawlessly on the highway at highway speed. Acceleration is not affected. I was thinking maybe a Differential Pressure Feedback EGR, or and EGR valve or IAC Valve. Any possible solutions?
I replaced the Differential Pressure feedback Sensor, the one right next to the EGR Valve and that seems to have taken away the rough idle when its hot and in drive. Currently letting the car cool down so I can see if the surge is still there.
Sounds like a sticking (dirty) iac and/or vacuum leak(s). Next time the idle surges, tap the iac with the handle end of a screwdriver and see if it normalizes. If so, might remove it and try cleaning it up with throttle body or brake cleaner spray before purchasing a new one. If rough idle returns, i would start searching for vacuum leaks.
It does not surge when idling, only after I put it into gear, it will be like that for a few minutes until the engine warms up. And the rough idle is back after I put the DPFE sensor in. Not as bad, but here and there I will notice it. So maybe it was a part of the problem but not the whole thing. So maybe an EGR valve? I am leaning away from it being an IAC, I looked up some symptoms and really only one of them matches. I have the EGR valve for it, just debating putting it in
Last edited by DaveMerl04; 04-03-2011 at 09:29 PM.
You can test the egr valve by removing its vacuum line at idle and replacing it with a piece of scrap sampling hose. Suck on sampling hose opening valve and egr flow to the manifold. Engine should stumble or stall verifying valve is operating properly. Remember, there should be no egr flow at idle or wot (wide open throttle). Why did you change out the dpfe sensor? Were you getting a po401 code? A faulty one should not affect idle or cause the surge youre describing.
I would put the IAC valve on.....its easy not a lot of money and it will do strange things with the idle if its not working right. Ford did have a lot of issues with these on the taurus and other vehicles