'92 Explorer Sport, High NO (PPM) - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Micky_B · 06-19-2010, 20:42

She's an old truck but i love it. It runs great most of the time, has 309k miles, and i'm planning to rebuild it. It has been coast to coast, border to border, everywhere...recently it has a stuttering problem. runs great, then will bog down and eventually misfire. then once it misfires, it is back to running good. It does this occassionally and usually at low to mid rpm. Just today it failed california smog testing with high NO (PPM). Max allowed is 859 / mine is 1015. Could this all be linked? i'm thinking sticky valve?? Also today i replaced the coil pack and that seemed to help with power, but still bogging down and misfiring.

**Bert** · 06-19-2010, 21:25

NOX is controlled by the EGR valve. The ports may be plugged and not letting enough flow. You can put vacuum to the valve with the engine running and see if the engine runs rough or stalls. If so, the EGR is working okay but maybe the control isn't. As for the rough running, that could be variuos items. Maybe the EGR is sticking. You can do this test to see if you get any codes. http://fordfuelinjection.com/?p=13

Micky_B · 08-25-2010, 12:53

ok took awhile to get back to this..but this year explorer has no egr valve. i have looked all over, crawling under and over. Also as far as the running rough i'm thinking there is an electrical problem. I pulled the codes this morning off it and it's all over the chart. the codes read: 157, 158, 171, 172, 181, 185, 186, 187. everything is coming up as over voltage and under voltage.

**Bert** · 08-25-2010, 15:02

With all of those codes, it's more than likely a connection problem Check all connections. Clear the codes and rerun it. See if the same codes or only some come up.