Failed Smog Across the Board - Interpretation
 

Warning - Hand holding needed...

My brother just failed across the board on a busted ass 95 Probe V6. This stuff is Egyptian to me, so can someone please give me their interpretation and solution for passing this CA smog test.

Thanks.

Attachment 209536

The interpretation is -> he needs a new catalytic converter because his current one is broken

Without actually contributing any useful information, let me just say that this is one of the more impressive failure I've seen. He managed to exceed the limit by a considerable amount in all three rated categories, and by a factor of 2x to 3x in both HC and NO! I am truly humbled by his sociopathic disregard for life on this planet. :bigtu:


Seriously, though. The numbers are somewhat confusing. HC (hydrocarbons) is unburnt fuel and is generally symbolic of an overly rich mixture. NO (oxides of nitrogen) are typically by-products of excessively high temperature or pressure in the chamber during the combustion event, and are usually indicative of an overly lean mixture. So a simplistic interpretation here is that your brother's car is both too rich and too lean at the exact same time.

Ok, so what can be done here...

High NO is often caused by a malfunctioning EGR system. So clean and inspect that.

I'm thinking that the high HC might be a by-product of some funky injectors. If he's got one injector that's flowing considerably more (or less) than the others, then the engine will over-compensate the "good" injectors to achieve an acceptable average AFR, and thus the engine will be both rich and lean.

I would recommend that he put some time and elbow grease into the EGR system, and some money into a new cat and O2 sensor(s)- it goes without saying that these are automatically suspect on an OBD-I vehicle of this age.

If the car still blows bad numbers, then the injectors might benefit from a visit to the Sexy Nurse Clinic.

Yeah. What he said! :giggle:

joe, couldn't you have a clogged injector and an ECU that reads that as "lean--inject more fuel" until it's rich in some and lean in others?

also google.
Emissions Testing

Isn't that what I just said?

yes. i saw the word "funky" and my brain shut down.

Kenzo, without knowing the state of tune of the vehicle the list of culprits could span a small book.

I would ask:

How many miles on said vehicle?
Is it a v-6 or 4cyl?
When was the last time a complete tune-up including spark plugs and wires and distributor cap and rotor (I think the Probe has one) air cleaner etc. was performed?
Does the engine run smooth or rough (misfire)?

The readings above suggest a vehicle that might be experiencing lean misfires which would cause high combustion temperatures leading to those very high levels of NO (oxides of nitrogen) combined with the high CO and HC (essentially raw fuel).


Tracing gas emissions problems is difficult at times and specially with high mileage vehicles (which this seems to be the case here). I suggest checking the basics but you might have to end up taking it to a pro at the end. After all they will have the 5 gas analyzer to verify any repairs.

Tony

Good point. If it does have a distributor, then a new cap & rotor should be on the list as well. Might as well do the plugs & wires while you're in there too- they're cheap.

High HC = misfire.

The fact that the O2 doesn't go to zero despite the excess means the cat is weak. The cat should be consuming all the O2 in order to oxidize the CO and HC. Don't replace the cat until the other problems are fixed - else the new cat will suffer.

The fact that NOx is high suggests a lean condition - the misfire could be a lean misfire.

Things to check:
bad O2 sensor - check if it's cycling
if not, check for bad temp sensors or a bad AFM

curious how the car runs?

He sold the car yesterday morning. He's probably better off selling it since he doesn't wrench himself.

The numbers above are what you end up with when the cat converter is shot. That's it. No need to guess about running rich or about EGR being broken, etc. :)