slight intermittant miss--help

[beige97camry]

slight miss at idle but not always. originally I had a po401 cel pop up, drove a few days with cel until I could check it out. while leaving a fast food place car started stumbling at idle like egr open, I checked egr, modulator, vvs, hoses, and replaced vvs and others were ok. miss and stumble still there and p0301=misfire #1 cel light. I replaced plus with denso oem and new wires for good measure. initially it seemed ok but then started intermittant miss at idle and rpm drop from 800 to 600 rpm, under full throttle runs great and NO CEL. any ideas to look at now as I am stumped. thanks.

97 camry 2.2 4 banger

[fenixus]

have you cleaned IAC valve?

[beige97camry]

clean, no crud, deposits etc. looks like new. other ideas, only notice when in gear and very slight and only now and then.

[fenixus]

if it happens to only 1 cylinder then maybe the fuel injector is dirty.
if you have and OBD2 scanner capable of showing live Fuel Trim levels, you could do a balance test, basically on running engine and scanner hooked up, you disconnect electrical connectors from each injector one by one and every time you note how the fuel trims react when compared to the base reading (all plugged in).
when you find the one which doesn't change much after unplugging then it's the dirty one.

[Mike Gerber]

^ I have to agree a dirty fuel injector is the next most likely cause. You could try adding a good fuel injection cleaner like Chevron with Techron to the gas tank and see if that helps the problem.

Also, make sure where that number 1 spark plug wire goes in to the coil, that there is no corrosion. If there is, clean it and use some dielectric grease in there before reinstalling the plug wire.

Mike

[beige97camry]

cel shows egr flow not enough-po401, already replaced vvs, modulator passed all, test, so did egr, done according to toyota service manual. any ideas....how do I tell if egr is slightly open???

[fenixus]

if all vacuum lines are good and electrical ground point on the back of engine (VSV uses it) is tight and clean, then try this:
DIY : EGR Valve removal

note, you will need a small 6'' crest wrench (adjustable) if you are going to remove valve together with exhaust pipe section (bolts to that pipe very often break off or strip).
you will also need 2 gaskets to manifold, get them from dealer.

my valve didn't survive the cleaning, or rather disassemble, so I had to get a new one, revised design (black top), no more trouble with EGR (I had intermittent power loss upon acceleration). old valve was terribly sticky and rusty and squeaky.