The car:
1995 Ford Escort LX station wagon. 1.9L four cylinder engine, automagic transmission.The problem: The engine runs well most of the time, starts well, idles well. The problem is that on the highway, at 45mph+ speeds, the car bucks and sputters sometimes. The problem seems to be EGR related. It occurs when the EGR valve opens (or should open).
Things I've tried: I disconnected and plugged the vacuum line on the EGR valve, and the bucking and sputtering doesn't occur. I get smooth running, but I also get more pinging under moderate loads, and I get a check engine light because the computer can tell the EGR valve isn't really opening when the solenoid provides vacuum to it. The codes indicate an EGR problem (obviously because I disonnected the EGR valve and plugged the vaccum line).
I picked up a good condition used EGR valve from a parts yard, and I thoroughly cleaned the carbon gunk out of that valve, getting it looking very clean and almost new. I tested this valve and it works and seals properly when closed, flows well when open. I installed it and it didn't fix the problem. The old valve looked very similar with some carbon buildup in it, but it functions properly. The EGR pipe that the valve attaches to also had scaley carbon stuff in it, but with the EGR valve disconnected from the pipe and the engine running, there was exhaust coming out of the pipe.
I really don't want to just "throw parts" at it. The budget is tight right now. What can I check next?
-- Racer X
1984 VW Jetta Diesel GT 1992 Mazda Miata 1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy) 1995 Ford Escort (Hey, it was free) 1983 VW Rabbit GTI (ITB racer) 1988 Mazda RX-7 (Soon to be ITS racer) 1992 GMC Topkick (portable garage for racecar[s])