Glad to see the USMB is Back!

 

98 2.2 Impreza 5 sp 262K with about 160K on the engine.

 

It's been running rough for a while, noticeable at idle, with more shaking the a smooth Subaru engine should have. Until the last few days, there have been no codes over the last 8 months I've noticed this.

 

The codes posted P0301 and P0303, miss fire on 1&3.

 

I've checked and done the following to get it running right.

- New NGK Plugs,

- Air Filter

- Swapped Plug wires

- Fuel System Cleaner

- Checked for vacuum leaks

 

None of these fixed the problem, although slight improvements were noticed. This has been a very slight problem until the last day or so.

 

With the codes showing, I pulled the plug wires one at a time, all produced a drop in RPM.

 

I pulled the injector plugs one at a time, #3 produced little or no change in idle. Ohm the injectors, all were 11.7 Ohms.

 

I had another coil, so I swapped them, no change.

 

I had a set of 2.5 injectors, so I swapped them, slight change still rough.

 

I can hear a Pop Pop in the exhaust.

 

I'm going to do a compression test and check the timing marks tonight.

 

What else am I missing?

 

Thanks, Larry

i chased something similar a little while ago on my 96 Leg. EJ22 and i turned out the connectors for the fuel injectors were swapped so obviously it was injecting fuel at the wrong time....worth a quick check....as for the plugs and wires im assuming you you used OEM?....to check for the vacuum leaks did you do a vacuum test?...if not i would do a vaccum test and see what you get.....

I'm not sure you're missing anything - be interesting to see if one side has slipped valve timing. You could try holding a small stip of paper to the tail pipe. If it tries to 'suck in' that could mean a valve is open when it shouldn't be. I dunno if that trick works if timing is off by just 1 or 2 teeth though.

 

Maybe there is a fuel pressure/delivery problem?

When you say you "swapped plug wires".... what exactly did you do?

 

The EJ engines like new plug wires about annually. OEM or NGK are recommended.

 

1/3 use the same side of the coil (wasted spark ignition) so that vaguely points to an ignition failure - I would normally suspect the coil but you swapped that out.

 

GD

You might try adding a good quality fuel injector cleaner to a tank of gas. Use the good stuff that cost about $5 or $6/can. The cheap stuff is worthless.

whe did you last replace the fuel filter?good to do every couple years anyway.

Does that year have soild lifters? If yes have they been checked / adjusted?

I pretty much have it down to #3 not firing due to lean fuel. I thought I had it a few times when I did the following, but the problems comes back on #3 cylinder.

 

Cleaned all the Engine Connectors

Cleaned the MAF and then swapped in one I had (seem to help the most)

New Subaru Plug wires, no change

 

Pinch the fuel return line and the RPM increases some so I'm going to tee in a pressure gauge and change the filter. My Manual says 2.6 to 3.3 PSI for fuel Pressure is that correct?

 

Full system voltage at the Injector 14.2 Volts engine running. When I have the rough running at Idle pull the #3 injector plug has no effect on the RPM.

 

The plug is white as can be, lean. More after I test the fuel pressure.

Thanks for the ideas, Larry

New Fuel Filter, Fuel pressure 30+ PSI, my gauge pegged at 30. It ran all the way down to 10PSI when I disconnected the fuel pump plug.

 

Compression test is next, followed by a leak down test.

Compression test 160 all the way around. 6200' here in Colorado Springs.

 

I pulled the outside timing covers looks like its a tooth off. I will come apart Sat.

Timing belt was off a tooth on both cams, so I suspect the crank jumped a tooth. New Belt and It's running Great. Thanks for the feedback. Larry

i suspectit might jump again it its the original tensioner and ifler. Those parts will last 120K, (2 timing belt changes) but wont usually last nush beyond that. Just something to keep an eye on if it happens again.

 

nipper

Yep I replaced both of them. Thanks Larry