Cel # 0170 On '95 Es300

[mark lang]

Any suggestions on this problem?

My '95 es300 with 175K miles started running rough and showed 0170 on CEL. I replaced plugs with no change. Then I did front and rear O2 sensors, still no change. I've checked all hoses and replaced some, including PCV. I cleaned the MAF.

A mechanic told me it was the igniter, I replaced that with used, it seemed to get a little better but still misses and hesitates, particularly going up long hills.

This is the engine with one coil per cylinder.

Thanks

[mark lang]

Any suggestions on this problem?

My '95 es300 with 175K miles started running rough and showed 0170 on CEL. I replaced plugs with no change. Then I did front and rear O2 sensors, still no change. I've checked all hoses and replaced some, including PCV. I cleaned the MAF.

A mechanic told me it was the igniter, I replaced that with used, it seemed to get a little better but still misses and hesitates, particularly going up long hills.

This is the engine with one coil per cylinder.

Thanks

A couple weeks later and I'm still chasing this problem. Cylinder 3 (closest to the battery) plug is always fouled. Black but not wet. I've swapped the coil but plug stays black. How can I tell if it is the injector?

Thanks

[mark lang]

Well, I think the mystery is solved. Replaced the fuel pressure valve and all the problems went away. This is the vacuum operated valve at the end of the fuel injection rail (closest to the battery). I noticed I was getting gas on the vacuum side of the valve and I knew there was something wrong.

What with all of the hose replacement, throttle body and MAF cleaning, new plugs and generic O2 sensors I've done the car is running better than ever.

Hope this helps someone.

[blk_on_blk]

I'm sure that will probably help me troubleshoot at some point. Thanks for following up on this. All this kind of information of symptoms vs. the fix is extrememly helpful to me and others.

Thanks again for posting the solution!!!