'92 Ranger failed smog test.

[ZMan]

Went to get my truck tested today so I could get plates on it. It failed. It was high on Carbon Monoxide (11.4, limit is 1.68), and Hydrocarbons (201.2, limit is 151). I just put a brand new Magnaflow Cat on it last week, and I have maybe 20 miles on it. The people at the station said the new cat is probably the cause because its not burned in yet. This sound feasible? I do have an intermittent check engine light that I haven't tested yet, but definitely will now.

 

[Andy D]

it is running rich , did the NOx pass? If you dont fix that, you will shorten the life of the cat.

 

[ZMan]

Ya it passed with a 93.9, limit is 956.0

 

[ZMan]

I just pulled the codes, and it is definitely running rich..
522-(O) Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault - PNP
171-(M) Oxygen sensor not switching - system was at adaptive limits - Single, Right or Rear HO2S - Fuel control
173-(R,M) Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S - Fuel control
179-(M) Fuel system was rich at part throttle Single, Right or Rear HO2S - Fuel control

I do have a new O2 sensor in it, changed it with the cat.

 

[Mazda]

Did you just drive over there and have it smoged. How far of a drive? My opinon is cat was not hot enough.

You will want to go on a really good drive before you take it in to smog. With a new cat something like 45 min highway speeds to get that sucker good and HOT.

Call the smog station before you go and tell them you will be there in like 45min to a hour and see if they can retest right when you get there so it doesn't have any time to cool down..

Do this and it should pass for you....

 

[scotts90ranger]

yeah, that's the proper way to get ready for a smog test, but if he's got codes for it running rich, that aint helping a thing

I say spray the MAF down to clean it and check the fuel pressure regulator vacuum hose for fuel to try to take care of those codes.

 

[lil_Blue_Ford]

I suppose it's always possible that an o2 sensor could be defective even being brand new....

I'd check the fuel pressure regulator and then see if I could trace the o2 sensor wiring a bit to see if maybe it's damaged or anything (it is plugged in right? I know it sounds stupid but....)

 

[adsm08]

Clean the MAF.

Lean codes are tricky, lots of things can set lean codes. The only things that can set a rich code is either too much fuel or not enough air. And it isn't likely to be not enough air.

 

[ZMan]

I suppose it's always possible that an o2 sensor could be defective even being brand new....

I'd check the fuel pressure regulator and then see if I could trace the o2 sensor wiring a bit to see if maybe it's damaged or anything (it is plugged in right? I know it sounds stupid but....)

I suppose that could be, but it was throwing codes before I put the o2 sensor in it, though I didn't check them until Friday. I'm going to trace wiring for sure, we actually have a newer Mustang in at work getting a whole new engine harness because mice got to it over the winter and it's throwing a bunch of codes.

Did you just drive over there and have it smoged. How far of a drive? My opinon is cat was not hot enough.

You will want to go on a really good drive before you take it in to smog. With a new cat something like 45 min highway speeds to get that sucker good and HOT.

Call the smog station before you go and tell them you will be there in like 45min to a hour and see if they can retest right when you get there so it doesn't have any time to cool down..

Do this and it should pass for you....

i drove it to work that day, then drove to the station after work, the one I go to is a 20 minute drive from work at about 60mph, and usually when I go there I don't wait at all since its out in the boonies. I got another temp tag yesterday so I'm going to take it on a few long drives before testing it again.

yeah, that's the proper way to get ready for a smog test, but if he's got codes for it running rich, that aint helping a thing

I say spray the MAF down to clean it and check the fuel pressure regulator vacuum hose for fuel to try to take care of those codes.

Clean the MAF.

Lean codes are tricky, lots of things can set lean codes. The only things that can set a rich code is either too much fuel or not enough air. And it isn't likely to be not enough air.

I'll do that. I removed the stock airbox and put a cone filter on it. The only reason I did that is because I put a MAF housing off of a 3.0l on it, since they are a little bigger once you trim the center out, I had it and the cone filter laying around, but didn't have a stock airbox laying around. It DOES have the original MAF sensor though. I'm pretting sure the stock airbox had 2 vacuum lines going to it, am I correct? I eliminated one, since there was 1 spot to put a vacuum line on the cone filter adaptor I had. Could this cause an issue? I'm not really sure what I eliminated to be honest with you, I couldn't find anything under the hood when I was looking tonight. The truck runs fine, not rough or anything. If it comes down to it, I'll go to pull-a-part and get a stock airbox off of a 2.3 or 3.0 truck and find out where all the vacuum lines go.

 

[killj0y]

Get it close to stock for the test and before that clear the codes and take it for a drive. Then see if it still throws codes

 

[lil_Blue_Ford]

Offhand... I forget what exact purpose the vacuum lines to the air box are for. IIRC they connect to a little gizmo in the lid of the box, almost want to say that it's some sort of control for the vent on the stock supply line to supply warm air (air off the exhaust manifold) to the engine in cold temps or something like that.

I never had it connected up on my choptop, doesn't throw a CEL. I just have the vac ports that I don't have in use capped off on the manifold. I don't know about smog though, it's not required where I live right now (thankfully, it's downright expensive for a smog test in PA).

 

[--weezl--]

i would run a bottle of injector cleaner through it... a poor spray pattern could leave you with unburnt fuel... even though you're not technically running rich, there could be unburnt fuel exiting the cylinder, which is exactly what HC is... i would dump a full bottle of some super strong injector cleaner in, and do it with minimal fuel in your tank, and run the crap out of the motor until you are virtually dry, then top it up with 87 octane... (yes i know everyone recommends 91+ octane for smog testing)

the higher the octane rating, the longer it takes for the fuel to burn, which means you have a greater chance of unburnt fuel exiting the cylinder... low octane fuel burns fast and aggressive, though it has no more actual energy than high octane fuel does... the other thing that may help is low octane fuel tends to have more ethenol in it, and if i'm not mistaken, ethanol is NOT a HC string, which in theory, means that if you get 201.2ppm HC, with straight fuel, and then switch to e10 ethanol (10% ethanol) your fuel going in is only 90% HC, which will effectively lower your reading to 181.08ppm... the other thing you can do, now i make no claims as to if this will work or harm/not harm your truck... but you can put methyl hydrate in your tank, it is sold at gas stations as a water remover, usually a little 6oz bottle for 7 bucks... don't bother with that... go get a gallon from a hardware store's paint department, usually around 12$... dump that into the tank, it again, not HC string, so literally lowers your HC reading right there also!

i was recommended about 1/4 gallon of methyl hydrate for 5 gallons of fuel or something like that... i dumped in 1 gallon for about 3 gallons of fuel... my 88 tempest ran just fine, absolutely no effect on driveability, and no CEL either...

again, i take NO responsibility if something happens... do so at your own risk, i did not have any issues doing it in my vehicle, but that does not mean you will have the same results

though i usually lean towards a bad o2 sensor when i have rich/lean issues, never personally had a bad o2 (out of the box) though... so hard to say...

 

[ZMan]

Thats some interesting info there weezl, not quite sure if I'm all about trying it, but we'll see how desperate I get. After resetting the codes and driving it its still coming up with 173. I just poured some lucas injector cleaner in it but haven't driven it, I usually use seafoam, but I have about a half gallon of lucas, figured I would just use that and save myself $8.

 

[OilPatch197]

Good spark and good plugs?

What is the maintenance record of the truck? Usually cats last the life of the vehicle.(unless their stolen!)

BTW when you installed that O2 sensor, DID YOU USE ANTI SEIZE? You are supposed to use a special conductive anti-seize, using grey could cause a bad ground to the exhaust.

 

[scotts90ranger]

a '92 uses a 4 wire, not an issue

I'm thinking it might be the MAF housing change, the engine has no idea how much air is passing through the sensor although I think with a larger housing it would think it has less air and make it a little lean

That's all I got right now