how to lower hydrocarbons for emissions test ?

[jaker04]

I am looking for advice on how to pass smog as my car failed. it's a Honda Accord 95 with 166k miles. Before this test my car was in the shop for 2 months so it was not driven often. I often drive city only, not highway. I only drove 10 minutes to city for this test from a cold start.

test:
15 mph
hydrocarbons max is 61, I measured 66

25 mph
hydrocarbons max 37, measured 70

tech said I had unburned fuel due to high hydrocarbons.

After this, I added a whole bottle of Redline SL1 to 1/4 tank and 93 Shell Octane gas to a full tank. I have been driving over 200 miles so far, mostly all highway. Should I use Guaranteed to Pass or Isoheet after I exhaust this full tank of gas? Or is driving all highway now enough to burn off the unburned fuel? I check my exhaust and see black soot build up.

 

[spasm3]

So many things figure into this. Mileage since last spark plug change? Does it burn oil ? Any fault codes, or is the check engine light on ? What was it in the shop to have done ?

We need more info.

 

[proveitwithdata]

I am looking for advice on how to pass smog as my car failed. it's a Honda Accord 95 with 166k miles. Before this test my car was in the shop for 2 months so it was not driven often. I often drive city only, not highway. I only drove 10 minutes to city for this test from a cold start.

test:
15 mph
hydrocarbons max is 61, I measured 66

25 mph
hydrocarbons max 37, measured 70

tech said I had unburned fuel due to high hydrocarbons.

After this, I added a whole bottle of Redline SL1 to 1/4 tank and 93 Shell Octane gas to a full tank. I have been driving over 200 miles so far, mostly all highway. Should I use Guaranteed to Pass or Isoheet after I exhaust this full tank of gas? Or is driving all highway now enough to burn off the unburned fuel? I check my exhaust and see black soot build up.

does your state exempt vehicles with obd 1/1995 or 25 year rule?

 

[mk378]

Really need to see all 3 pollutant numbers relative to their limits. For example, if it's running rich, CO will also be elevated (though maybe not over the limit) and NOx will be unusually low.

Make sure the temperature comes up to the normal level. If the battery has been run down dead or disconnected for service, it's a good idea to drive a significant amount before testing to let the computer re-calibrate fuel trims. Though that may not be important on OBD1.

 

[chemman]

I would at the very least change the engine oil and filter, fill up with a Top Tier gasoline with 10% ethanol and then add 3 bottles of Iso-Heet (the stuff in the red bottle) to further oxygenate the gasoline, and then drive on the highway for about an hour before getting the emissions tested.

 

[slacktide_bitog]

Welcome to BITOG

You might need an oxygen sensor. That would be my best guess

 

[Rand]

I would at the very least change the engine oil and filter, fill up with a Top Tier gasoline with 10% ethanol and then add 3 bottles of Iso-Heet (the stuff in the red bottle) to further oxygenate the gasoline, and then drive on the highway for about an hour before getting the emissions tested.

or he could put in a gallon of e85 instead of the isoheat?

 

[KrisZ]

If only hydrocarbons are outside the test values, then it could be an issue of just getting it burned off. I would give it some beans on the highway, maybe stay in lower gear to bring the RPM high. Also make sure the vehicle was driven for at least 20-30 minutes before doing the test.

 

[chemman]

or he could put in a gallon of e85 instead of the isoheat?

Maybe. I do know an individual who used the 3 bottle of Iso-Heet to pass emissions testing in Connecticut and it worked really well. OP might not live in an area with E15.

 

[nthach]

Air/fuel ratio has an impact on HC. Check for vacuum leaks, bum O2 sensors, check the valve adjustment. Hondas don’t use MAF sensor, so the ECU is using MAP with manifold vacuum values to sense how much air is entering the engine.

Also, for older cars you do need to pre-condition the cats - go on a long drive, smog check must be done with the cats hot.

 

[jaker04]

My CO%
15mph max .52 measured .33
25 mph max max .50 measured .48

My NO PPM
15mph max 493 measured 65
25mph max 516 measured 101

After failing, I recently changed my oil with Penzoil yellow bottle 5W-30. I checked my spark plugs and they were clean. they were changed 50k miles ago. My car was in the shop for a new radiator, radiator fan, and new coolant. On the day it failed my top coolant hose had a hole and leaked out coolant. I changed my O2 sensor around 40k miles ago. Yes, my car was burning oil excessively, Could my older and low oil yield the high hydrocarbons? I have no error codes or check engine lights on my dashboard.

 

[spasm3]

My CO%
15mph max .52 measured .33
25 mph max max .50 measured .48

My NO PPM
15mph max 493 measured 65
25mph max 516 measured 101

After failing, I recently changed my oil with Penzoil yellow bottle 5W-30. I checked my spark plugs and they were clean. they were changed 50k miles ago. My car was in the shop for a new radiator, radiator fan, and new coolant. On the day it failed my top coolant hose had a hole and leaked out coolant. I changed my O2 sensor around 40k miles ago. Yes, my car was burning oil excessively, Could my older and low oil yield the high hydrocarbons? I have no error codes or check engine lights on my dashboard.

Ahhh. Burning oil will raise hydrocarbons. I would put in a thick oil , and have the cats really hot ( run it good and hard to burn any oil in the exhaust, longer drive in lower gear, as mentioned above. Run the fuel tank down really low, and put in 2 gallons of E-85 ( close to where you are inspecting and after the Italian tuneup ). Fill up and dilute it after the inspection.

 

[jaker04]

how do I get my car to burn less oil? I already changed my oil with Penzoil 5w-30.

 

[chemman]

You could run some 10w40 or maybe some 20w50 (if you can find it). Heck just run straight 30, that should take care of it for a short duration.

 

[Chris142]

Change the oil. It really does help.

 

[Lubener]

High HC is a lean miss, high CO is a rich running engine.

I had a couple cars which I had to cheat to get them to pass. Like Chris142 stated , change oil and do not fill your gas tank prior to testing. Use a top engine cleaner like GM's top engine cleaner. Tune up the engine and change out hardened vacuum lines which could be causing a lean miss (high HC) . High HC, make sure fuel system pressure is at specs and change the fuel filter. Prior to test time, get the cat. converter good and hot . This is what got me to pass. Using vise grips, pinch off your PCV hose before pulling in the check station. When CO is high too, I would just pull out the PCV and just let it suck air.
Unfortunately, these old cars are held to a standard which can be difficult to achieve and you do whatever you have to do to get them to pass without putting a huge amount of money into them.

 

[Plawan]

how do I get my car to burn less oil? I already changed my oil with Penzoil 5w-30.

Check /change pcv valve. Run chemtool b12 through gas tank or a cat cleaner. Do a motor flush and change oil again and go on highway and drive it like it’s stole for a good while ). If that doesn’t work I think someone mentioned possible o2 sensor?

 

[Marcozi]

If the car has and OBD2 port, scan the engine computer for codes. I suspect you've got a vacuum leak and/or bad oxygen sensors.

 

[Rand]

Maybe. I do know an individual who used the 3 bottle of Iso-Heet to pass emissions testing in Connecticut and it worked really well. OP might not live in an area with E15.

I mentioned e85, The e15 near me isn't close to 15% most of the year one gallon certainly wouldn't change much.

 

[Blueshound]

Check exhaust pipe temp with a temp gun before and after the cat. There should be a significant increase in temp. If not, your cat is hollow (or dead) and you probably need to replace it.

Edit: Full operating temp