Smog test - 1992 Ford Ranger

[Mihail Milkov]

There are many knowledgeable people here so I thought I'd ask for advice on how to pass the smog test on the 1992 Ford Ranger that I bought a week ago. It's a 3.0 V6 with a 5-speed manual and an unknown number of miles (could be 130K or 230K and I was told it's engine has been replaced).
So far the only thing I've changed on it are the engine oil and the air filter. The spark plugs look clean.
Today I smogged it and didn't pass the emissions. Here are the results:

(Measured/Max)
At 15 mph, 1701 rpm
HC 242/127
CO 0.75/0.78
NO 2229/1031

At 25 mph, 1855 rpm
HC 81/108
CO 0.18/0.99
NO 857/891

I've typed in bold those readings that exceed the limit. Any guesses on what might be the problem(s)? Can anyone recommend me a smog test repair shop? I live in Moorpark.

Thanks for your help!

Mihail

[Christos Adam]

Hi Mihail

I think high CO usually means the wrong air/fuel mixture. In this case, it is running on the rich side.
I also read that when your CO level is high it will usually bring HC along with it.
I think it's very possible to be the O2 sensor.

here is what I found:


Carbon Monoxide (CO)*
CO is created when gasoline is not completely burned. High CO ( running rich ).

A list of common causes of CO related smog check failure:

1. Timing is not a big factor in CO production but check it anyway. Everything helps.

2. On older Carbureted vehicles you can have problems like a partially stuck choke plate.This is the moving steel plate on the top of your carburetor.

3. A leaking power valve on your carburetor can cause high CO and Smog Check failure.

4. A faulty carburetor can cause high CO and Smog Check failure.

5. A dirty air filter can cause high CO.

6. A common cause for high CO is a faulty Oxygen Sensor. This sensor tells the computer how to fine tune the air fuel ratio.

7. Other sensors like the M.A.P.sensor , C.T.S. sensor or the Air flow meter can also effect the CO level.

8. A faulty air injection system can cause high CO. This is the Smog pump and related components.

9. A faulty Catalytic Converter can cause high CO and Smog Check failure.

10. If your car has been running rich ( high CO ) you should change your oil after you get it repaired. When you have rich condition all the fuel cannot be burned, you start to saturate the motor oil with CO and HC. This in itself can also cause a rich condition.

[John Stimson]

HC = hydrocarbons. If those are high then the fuel isn't being burned completely. Could be running rich. Could be a bad catalytic converter.
NO = nitrogen monoxide. Those come from breaking down the nitrogen in the air. Could be running hot. Could be a bad catalytic converter.

I am not an expert.

[Mihail Milkov]

Thanks for the replies. Yesterday I replaced the spark plugs and the engine is running smoother now. Hope it helps with the emissions.
As for the oxygen sensor - wouldn't it cause the "check engine" light to turn on if it is not working properly? Currently the light is off and I don't think I have any fault codes - otherwise the smog technician would have flagged them.

[Christos Adam]

Thanks for the replies. Yesterday I replaced the spark plugs and the engine is running smoother now. Hope it helps with the emissions.
As for the oxygen sensor - wouldn't it cause the "check engine" light to turn on if it is not working properly? Currently the light is off and I don't think I have any fault codes - otherwise the smog technician would have flagged them.

I heard that when they get old they start malfunctioning w/o necessarily throwing error codes.
By the way do these things get bad if you leave them outside exposed in air?
I have a 02 sensor for the miata which has been laying in my garage for a couple of years now - when it was removed was working fine (it was 6 months old back then but I decided to go with a WB02). Anyway this is a generic sensor witch I had to put in the miata harness - if you feel that might be useful to you, you can have it for free (but again I'm not sure if it has been destroyed by been exposed to air and dust for so long).

[John Stimson]

I wouldn't expect an oxygen sensor to go bad just sitting there. It's probably the heat and the exhaust gases that kill them.

[KJ Christopher]

By the way do these things get bad if you leave them outside exposed in air?

It isn't exactly in a vacuum when installed on your car.

[Lily Liu]

Check your timing but it's very likely that you need a new cat. How many miles on it and is it a CA cat?

It took us 5 tries until we passed the CRX. At least it's free until you pass. The time it passed we had put in a new cat. Oil change, timing, and O2 sensor replacement didn't make the car pass smog.

[Jayson Woodruff]

Usually a poor tune is the start to the problems. Poor tune => unburnt fuel => over work/kill cat => smog fail. Then when you correct the tune, the cat is still roasted.

Jay W

Check your timing but it's very likely that you need a new cat. How many miles on it and is it a CA cat?

It took us 5 tries until we passed the CRX. At least it's free until you pass. The time it passed we had put in a new cat. Oil change, timing, and O2 sensor replacement didn't make the car pass smog.

[Christos Adam]

By the way do these things get bad if you leave them outside exposed in air?

It isn't exactly in a vacuum when installed on your car.

LOL true KJ, it doesn't make any sense but I read this in the installation of my WBO2 ... I might be able to find the document to rescue some of my dignity "I think it was saying not to be exposed to air when is not working" (which again doesn't make sense but anyways...

[Bob Beamesderfer]

1992 is OBD I, not sure if they plug into the diagnostic port on those. O2 sensor and cat are likely culprits. I'm pretty sure your truck has fuel injection, so none of the carburetor related issues apply.

[Will Kalman]

It isn't exactly in a vacuum when installed on your car.

Unless

[Mihail Milkov]

Thanks to all for the useful tips!
To answer some of the questions. It is port fuel injection, the mileage is probably 230 K (it shows 30 K on the odometer) and I was told that it's on it's second engine.
Oxygen sensors are 1-wire, 2-wire, 3-wire or 4-wire. Before I buy a replacement oxygen sensor, I guess I should look to see how many wires come out of the one that's already there?

[Jayson Woodruff]

Before I buy a replacement oxygen sensor, I guess I should look to see how many wires come out of the one that's already there?

Yes, as they're very different in price too.

Jay W

[Jeff Shyu]

my 87 toy pickup had similar problem when i tried to smog it last.

shop was convinced it's a O2 sensor problem. turns out, exhaust leak at the header collector, that never got completely sealed when i had to replace the cat due to theft.

not saying that's what's going on with the ranger, just throwing it out there.

[Bob Pl]

I had an 89 Bronco 2 v6 2.9l, very similar. Failing. New 02 sensor did squat.

New cat fixes all, mine was a double bubble (expensive) cat.

Maybe a cheaper aftermarket cat would clean it up.

or this, which I would have tried if I knew about it.

http://www.asashop.org/autoinc/june2007/techtips.htm" onclick="window.open(this.href);return false;

Like the heat cycle on a MAF wire only on a BIGGER scale.

Have a fire extinguisher handy.

[Max Hayter]

I had an 89 Bronco 2 v6 2.9l, very similar.

OJ - is that you?

[Bob Pl]

I had an 89 Bronco 2 v6 2.9l, very similar.

OJ - is that you?

If the cat don't fit, you must aquit (or fail smog).

[Jayson Woodruff]

I had an 89 Bronco 2 v6 2.9l, very similar.

OJ - is that you?

Come on you foreigner. OJs wasn't a '2'.

Jay W

[Christos Adam]

Hey guys, isn't a program sponsored from California for older vehicles that can't pass test?
If I recall correctly a friend of mine with an old volvo was telling me that if the repair is very expensive you pay a maximum of $500 and the rest will been paid by the city...

[Jeff Shyu]

i think you have to go through quite a few hoops to qualify for that.

[Bob Beamesderfer]

i think you have to go through quite a few hoops to qualify for that.

Need to take estimate and car to the BAR referee.

[Mihail Milkov]

i think you have to go through quite a few hoops to qualify for that.

Need to take estimate and car to the BAR referee.

I just read on the BAR site that you don't qualify if the vehicle is undergoing a transfer of ownership, which is my case.

[Kristoffer Gjevre]

...smog test on the 1992 Ford Ranger that I bought a week ago...

...
I just read on the BAR site that you don't qualify if the vehicle is undergoing a transfer of ownership, which is my case.

Not that this will help, but it seems like the seller should have provided the current smog certification, unless the you bought it from a close relative...

http://dmv.ca.gov/vr/smogfaq.htm#BM2535" onclick="window.open(this.href);return false;

Smog Information
...
When a vehicle is more than four model years old, a seller must provide evidence of a current smog certification except when one of the following occurs:

* The transfer occurs between a spouse, domestic partner, sibling, child, parent, grandparent, or grandchild.
* A biennial smog certification was submitted to DMV within 90 days prior to the vehicle transfer date (a vehicle inspection report may be required for proof of certification).

Smog certifications are good for 90 days from the date of issuance.

When a car is sold, who is responsible for the inspection?

The seller is required to provide the buyer with a valid smog inspection certification at the time of the sale or transfer. Smog certifications are good for 90 days from the date of issuance.

The inspection is not required on a transfer if a biennial smog certification was submitted to DMV within 90 days prior to the vehicle transfer date (a vehicle inspection report may be required for proof of certification).

NOTE: Smog certifications are not required for transfers that occur for a gasoline powered motor vehicle that is four or less model years old. (Determine the oldest-qualifying year model by subtracting three from the current year) the four or less model years old rule does not apply to diesel powered vehicles. A smog transfer fee will be collected from the new owner.

[Arthur Grant]

May be the reason it was up for sale.