Runs really rough bad exhaust smell

[woodjamin]

This all started as i was coming to a stop light and slowing down. Engine started bucking and the exhaust started to smell bad. Already replaced the egr valve and the dpfe sensor. New air filter, spark plugs, o2 sensors and cats. Any idea what's causing this? I'm pretty sure the smell is from excess fuel reaching the cats buts who knows. 2002 explorer xlt 4.0 sohc
I was able to get it home about 20 miles. Going up hill the CEL would flash. Codes were reset before i could get my hands on a scanner. Today after changing the EGR and pressure sensor i started it up and it is still running horrible.

 

[woodjamin]

after running the truck for 10min still no CEL. only a pending code of p1151.

 

[TechGuru]

Personally it sounds like a bad spark plug to me. I once had one with a cracked electrode on another vehicle cause my CAT to glow red.

 

[woodjamin]

I'll change them when the weather let's me. Thank you for the reply

 

[TechGuru]

I'll change them when the weather let's me. Thank you for the reply

If you had recently changed them it could just be a fluke that one cracked or something, inspect them and also check your spark plug wires. Does it feel like 1 or 2 cylinders is mis-firing? Note these vehicles have a wasted spark ignition system so if a spark plug wire is getting grounded out somewhere it will kill spark to not one but two cylinders depending on which side of the polarity it is on.

 

[woodjamin]

Yes they were changed last February with double platinum which I now know aren't the greatest. Haven't put too many miles on it since due to other mechanical problems I have since fixed. It does feel like it is misfiring or not firing on all 6. Not sure if that is the same thing. I am waiting for a pack of ngk iridium plugs to come in. How can I tell if the wire is arching to ground?

 

[TechGuru]

Yes they were changed last February with double platinum which I now know aren't the greatest. Haven't put too many miles on it since due to other mechanical problems I have since fixed. It does feel like it is misfiring or not firing on all 6. Not sure if that is the same thing. I am waiting for a pack of ngk iridium plugs to come in.

Get the correct Motorcraft SP500 plugs http://www.rockauto.com/en/moreinfo.php?pk=949946 , funny you say NGK, it was a NGK Iridium that cracked in my other vehicle.

How can I tell if the wire is arching to ground?

Open the hood in the dark with the engine running. You can also try moving the wires around while it's mis-firing and see if there is any change. (I'd use a non-conductive stick)

 

[woodjamin]

i will get those thank you. i took the plugs out this afternoon and cleaned them up one side at a time to see if there was any change. they were really dirty. after firing it up and running for less than a minute it ran way better then went back to the same old shake and sputter. i did pull the wires while running and it did make a slight difference and then again went back to crap. also did a vacuum test and that doesn't seem to be the issue. oh and i did not see any cracks in the plugs.

 

[TechGuru]

Sounds to be running way to rich, MAF sensor could be bad...

 

[woodjamin]

It's possible. I know it can still be working but send false info. On my real my data is saying around 14g/s at around 1200rpm. I did order a new one just in case. I tierd of throwing money at this thing. Was also told and injector could be stuck and is not switching. So looking at some now. Never replaced one of those before and not sure if my scanner can give me the diagnostic info
It's deff running rich
The one potential code. Is p11510 which a lean code from an o2 sensor due to it trying to correct the richness.

 

[Mbrooks420]

Was one plug either much more dirty, or much more clean than the others?

 

[woodjamin]

They were all pretty dirty. Maybe 2 more than others with sludge all the way up to the threads

 

[Joe in NY]

try just unplugging the MAF and see how that goes. OBDII is designed to able to run without the MAF connected. If you have a bad MAF causing the car to run poorly disconnecting it will force default values in place of incorrect values.

 

[woodjamin]

thanks for the reminder. i thought that i had already did that when i was replacing the egr and had the whole air box off up to the the throttle body and it had no effect. but now that i think about it i also had the vacuum line disconnected as well that is right after the MAF. i will try again when this forsaken snow stops here in the north east.

-all plug wires looked ok. no sparks at night. i did inspect the coil, no burnt smell and the only physical damage i saw was a crack in the mount next to the bolt.