2G N/T: intermittent rough idle and knock

[evers310]

I cant seem to figure this one out. I have a '98 RS wit h170k miles on it. While driving one day last week the engine suddenly started knocking really bad and it lost power. I had a friend tow me home. The number 3 spark plug electrode was gone so I'm guessing the knocking was detonation. I replaced the plug and when it's cold the engine will start fine but after a minute or so it will start idling rough and knocking again. When it does this the cylinders will become very wet with gas. If I let the engine run for a while it will start sounding normal again.

This is what I've done so far:

Changed the timing belt
changed the coil pack
changed the Crank angle sensor
reset the ECU

I'm getting a few error codes from the ECU, the main ones are

P0303 - cylinder 3 misfire
P0300 - Multiple cylinder misfiring
P1494 - Manufacturer specific error ???

I had another one that started with P13xx but I cant remember it now.

When using the scantool program from scantool.net all the real time readings seem to be all over the place, even when it's running smoothly.

Is my ECU going bad or what?? Anyone have any ideas??

 

[evers310]

Ok, I just gor two more error codes.

P0172 - fuel trim too rich (bank 1)
P1390 - Octane adjust pin out of range

Is it possible I got some bad gas or is this a fuel system problem?

also, as soon as I got these errors it started knocking really bad continously.

 

[evers310]

I've been monitoring the fuel trim and I've noticed something. The 'short trim fuel bank 1' normally sits at -5 at idle, when it starts knocking and missing it drops to -25. I have to raise the idle to keep it from dying and it comes up to around 7 or 8, when the knocking and misfiring stops it will go back to -5 again.

Could this be a partially clogged injector? bad sensor? I have have just lost my job last week and dont have the money to keep throwing at this, any help is GREATLY appreciated!

 

[evers310]

One last update, I took it out on the road and opened it up a few times and it cleared up! I went and got some injector cleaner and octane booster and filled it up with super. I've been driving it for 3 days now, the only thing I notice is that it idles a bit rough every once in a while.

anyone have any ideas what this could be? I'm afraid of it happening again.