Need Help or Advice

[doingdirt]

:exp:1993 explorer 4x4 ,v6,..Problem..Trying to pass California emissions. I have failed twice after the first time I replaced plugs,wires,oil Etc and ran a bottle of "guaranteed to pass" and a tank of premium gas through my explorer and had it tested again to know avail. it passes the high speed above 25 mph but will not pass the low 15 mph test. the results were at 15 mph, NO(ppm)max is 508, ave is 149 , meas was 867, at 25mph they were No(ppm) max is 761, ave is 144, meas was 454 ...Now can anyone help me with what to do as i can not get help from anyone who knows they all want money...do I need cats ,ox sensors, or what i am at a lose and only have 30 more days to repair it or no registration and no plates as I bought it on a lean sale cats,ox sensors come to 400.00 dollars if i do it myself ....Can someone PLEASE rescue me Thank You very much.
doingdirt

 

[dogfriend]

This thread might help you:

http://www.explorerforum.com/forums/showthread.php?t=203278&highlight=NOx

Problems with the EGR sometimes cause high NOx.

 

[deamon3]

Just register it in wisconsin and you don't have to pass anything lol.

 

[Reejerey]

NOx is caused by high combustion temperatures (2500 deg. f or higher). EGR (Exhaust Gas Recirculation) serves 2 purposes. 1 is to "reburn" exhaust gasses, and the other is to lower combustion temps, so you could definitely have an egr valve that isn't opening.

The other issue that can cause NOx commonly is a lean fuel mixture.
things that can cause lean fuel mixture are unmetered air entering the engine (look for vacuum leaks, or air leaks after the maf in the intake air tube) bad 02 sensors (if they get stuck reading rich the engine will try and lean out to compensate) low fuel pressure (the computer thinks its allowing a certian amount of fuel in, but with the low pressure you don't get as much)and clogged injectors (again, it thinks there's fuel going in but there's not).

Carbon build up in the combustion chamber could technically cause you to have NOx issues, but with the premium gas and fuel system cleaners you've ran thru the engine I tend to think that your issue is fuel or air related.

Check for codes, both key on engine off and key on engine running, and get back with me and I'll see what I can tell you.

 

[Vargas]

Reejerey said almost exactly what I would tell you. High NOx readings are a sign of overly lean combustion.

Check for holes in the intake tube between the MAF sensor and the throttle body. That tube can rub against the radiator and develop a leak. Also, the boots on the ends of the tube can get folded over which will cause an leak. Pull the tube off and look for creases on the sealing surface of the boots where they fit onto the MAF sensor and TB.

If the fuel filter looks ancient, I'd suggest replacing it unless you can test the fuel pressure. Filters are cheap, and the fuel filter is an often overlooked maintenance item.

DO NOT throw your money at new cats. Catalytic converters will not solve this problem.

 

[doingdirt]

I know this might sound bad but I am having trouble finding the DPFE sensor and the EGR valve on my explorer. I have a Chilton Manuel and know what an egr valve looks like Damn I am 55 and have been doing mechanics for 40 years but I can not find them to save my ass 1993 Explorer with v6 , AC, power everything can you help me locate these items. I know it has to have them hiding somewhere amongst all the other crap on this motor.
Thank you

 

[doingdirt]

1993 explorer egr valve

so what do you do if their is no egr valve as i was told there was no egr valve on a 1993 explorer v6 until 1995

 

[Verno]

Actually the 94's had EGR, but that is irrelevant. You need to focus on the lean burn now that you have eliminated EGR from the picture.

 

[Maniak]

Actually the 94's had EGR, but that is irrelevant. You need to focus on the lean burn now that you have eliminated EGR from the picture.

Ditto.. Time to look for vacuum leaks etc.. un-metered air can make it run lean (air going into the motor that the computer can't see).

~Mark

 

[doingdirt]

could it be ox sensor not switching/system rich left or front h2so-fuel control ?

 

[Reejerey]

it could be an oxygen sensor stuck rich. back probe the oxygen sensor wires at the ecm with a dvom and see if its switching.