Hi All;

I recently replaced timing belt after belt broke and now engine idles poorly. It runs fine at all other ranges, just idles poorly and CEL shows misfires on clyinders 1 & 2. Could this be minor valve damage? I double checked timing marks and #1 & 2 intake cam was slightly retarded. correcting this issue helped idle some but still is rough. Do I need to replace some bent valves or could perhaps this smooth out in time?

 

OBW, the only other thing replaced was coil pack and plugs. Which I replaced after timing belt to see if that was problem.

 

Thanks in advance;

 

Wayneb

You should check compression. That will tell you if you have bent valves. If you broke a belt on an EJ25 you most likely have bent valves, they are interference engines.

there is most likely some valve damage, it definitely won't go away with time. but just in case check these items:

 

compression test may be off if the cams and crank aren't aligned perfectly. i would make sure those marks are dead on. if you removed any of the cam sprockets, then make sure you didn't accidentally put the wrong cam sprocket on the wrong cam (someone else just did that recently).

 

wires are more likely be the culprit for cylinder misfires then spark plugs - try swapping the wires and see if the misfire stays with the cylinder or moves with the wires. did you use NGK spark plugs. on this motor you should only use NGK plugs and OEM Subaru wires.

 

if it is bent valves and you plan on fixing, at least you'll have new head gaskets too.

[...]idles poorly and CEL shows misfires on clyinders 1 & 2. Could this be minor valve damage? I double checked timing marks and #1 & 2 intake cam was slightly retarded. [...]

There isn't a common intake cam for cylinders #1 and #2; those cylinders are at the front of the engine, but in opposite banks. The cylinder positions, facing the engine from the front of the car, are:

3-4

1-2

 

If you're certain that the timing is correct now, then it's unfortunately possible that there are damaged valves. As subaru360 suggested, a compression test should reveal that.

 

Although changing the timing belt shouldn't be related to this, a bad ignition cable on either #1 or #2 (due to the wasted spark configuration) could cause misfire on both. However, that would likely show up to a degree at engine speeds above idle as well.

Check your plug wires. This happened to me after I rebuilt the motor in my OBW...