4 cly accord. Will run with a slight hesitation continually and then sometimes it will not start. It starts and stalls immediately. I forced it to start by feathering the gas and running it at high idle until it would run by itself at idle and then it was fine. Drove for 100 miles without any problem. However this problem happens randomly and is getting more consistent. There are no check engine lights or codes and the car has 139K on it. Any thoughts on what I should try to look for. I don't smell gas and I don't see any signs of leaks. I was thinking ERG or fuel pressure regulator, but I don't really know.

 

A sticking-open EGR valve might lean the engine enough to cause idle problems. Try disabling the EGR by removing and plugging vacuum line. If problem is resolved, EGR should be replaced or cleaned carefully.

A sticking Idle Air Control Valve might cause some of these symptoms. If sticking closed, idle may be too low and engine dies. However IACV would not affect drivability once above idle.

good luck

 

Still have the sporadic problem and it is getting worse. Once it is running - no problem. When I shut down for a while, starting problem begins. Connected an OBII code reader and it came up with a PO420 code citing catalytic system. I don't see and leaks in the exhaust system. Car has 135K miles - was going to replace the upstream & downstream O2 sensors with Denso replacements - think it might help?

 

Engine operates in open loop (w/o O2 sensor input) so replacing O2 sensors seems unlikely to help.

Did you check EGR valve for sticking open? Does rough running occur every time on cold engine.

P0420 is unlikely to be cause for your problems.

good luck

 

RegMike,
Since you are not getting any CEL codes do you hear the fuel pump prime? I am leaning towards a fuel delivery problem. Have you tried checking fuel pump pressure? The 4 cyl is suppose to be between 38-46 psi at idle with vacuum hose attached and 47-54 with vacuum hose detached. The fuel system hold pressure after 5 minutes should be between 30-40psi.
Let us know what you find out.