My friend's 2002 honda odyssey minivan has recently developed a weird idle issue. When I start the van it sounds like its hesitating to start and then the idle is a tad bit high and then sounds likes it "hiccuping" or mis-firing. The weird thing is that the van isn't reporting any check engine codes so I guess its not really misfiring.

The plugs are new (installed only 6 months ago by me) and the car is in overall good running condition. 181, 000kms.

Filters are clean, no corrosion damage of any sort that I can see.

I thought that maybe a leaking intake manifold gasket would be the culprit but the thing is how would something like that develop out of nowhere?

I've also check the IAC valve by unplugging it thinking that maybe it was trying to overcompensate the idle and not working right but even when unplugged the idle speed goes higher but you can you hear the engine "hiccuping".

Ideas?

Thanks

 

Sounds like a stuck open EGR valve. If you didn't put NGK plugs in it you need to take the plugs out and install the correct ones.

 

if the EGR is stuck open wouldn't the van throw a CEL code?

One more note worth mentioning: When i unbolted the top cover the intake plenum there was a lot of carbon and small pools of oil in the intake runners which I thought was a tad bit weird.

Plugs are NGK platinum ones.

 

Not always. The last one I had on a Pilot didn't throw a check engine light.