1991 Integra's emissions results

An emissions history of Tegger's 'Teg back to top

I'm using US gallons here by the way, not Imperial. And sorry, you'll have to do your own Metric conversions.

		ASM2525 (25mph cruise)			Idle
Date	Item	Limit	Reading	% of limit	Limit	Reading	% of limit
June 2001 175,000 mi April's mpg: 28.7	HC (ppm)	86	32	37%	N/A	N/A	N/A
	CO (%)	0.48	0.06	12.5%	N/A	N/A	N/A
	NO (ppm)	984	222	22.5%	N/A	N/A	N/A
June 2003 209,000 mi April's mpg: 28.0	HC (ppm)	76	14	18.4%	200	13	6.5%
	CO (%)	0.42	0.02	4.8%	1.00	0.02	2%
	NO (ppm)	870	869	99.9%	N/A	N/A	N/A
April 2005 246,000 mi 27.25 mpg	HC (ppm)	66	30	45.5%	200	89	45.5%
	CO (%)	0.37	0.15	40.5	1.00	0.75	75%
	NO (ppm)	757	227	30%	N/A	N/A	N/A
May 2007 287,000 mi April's mpg 27.79	HC (ppm)	66	16	24.2%	200	53	26.5%
	CO (%)	0.37	0.10	27.0	1.00	0.61	61%
	NO (ppm)	757	229	30.3%	N/A	N/A	N/A

Notes:

O2 sensor replaced with new OEM Denso at 173,800 miles (just prior to first test)
Catalytic converter is still original.
There is no EGR system.
Base ignition timing was checked to make sure it was at its correct 16deg BTDC
Oil consumption is currently 1,200 - 1,500 miles per US quart of oil as of spring '07.
All test fuel was 87-octane Esso (Canadian) (octane boosters: MMT until '04, MTBE from '05 up. Esso does not appear to use ethanol yet).
Engine oil was changed just prior to each test, but was 1 month old with 2K miles for '07 test.
Car was driven for one-hour highway speed immediately before each test was done
Government has lowered admissible limits by 30% from 2001 to 2005. No change '05 to '07.
Idle CO for '05 and '07 far exceeds the 0.1% limit specified in the factory manual.

More history and details:

I was curious to see how this car has done since the imposition of emissions testing in the province of Ontario, Canada in my area in 2001, so I saved up all my test slips and was able to compile the chart you see above.

In addition, I have all my gas fillups going back to 1991 (with a gap from 1995 to 2000), so I can determine what my exact fuel mileage was at any point.

Driving is about 85-90% highway for at least a half-hour between cool-downs, and often even longer than that.

This car has ALWAYS had ALL fluids other than the power steering fluid changed once per year, with engine oil changes every 3,000 miles or less, with a Honda filter and Castrol GTX 5W-30 (Mobil 1 as of 2007). Despite winter temps dipping as low as -20F, there is no block heater. The valves have been adjusted every year, and the thermostat replaced every 4 years or so. Air filter is OEM and is changed once per year.

The fuel tank is kept to as nearly full as I can all the time, and is never left below 3/4-full overnight. This being done to minimize moisture in the tank, helping to keep water out of the fuel system. The fuel filter has been replaced once in 14 years. Dirt is not the enemy of your fuel system, WATER is. Water gets past fuel filters.

Spark plugs are changed once a year, distributor cap, rotor and plug wires are changed every five years. OEM parts are always used, except for the plugs which are NGKs.

PCV valve is original. It must not be plugged, because there is no oil in the crankcase breather hose, and the idle drops when I pinch the PCV hose shut. Update:The PCV valve was replaced in the summer of 2005.

The car is started and allowed to sit for no more than 30 seconds before starting out, even in the worst cold weather.

A Motorvac service was performed in October 2001, but otherwise the injectors have never been cleaned or even removed from the intake manifold. Mileage was not affected by the Motorvac service, probably because there wasn't much gunk in there to begin with.

The throttle body is cleaned every year since '05. It was every few years before that..

There is very audible piston-slap when cold. It disappears when hot. Piston slap first became noticeable about 90,000 miles and has gotten louder since. (In very cold weather the power steering pump drowns it out!) It's not a quiet car...anymore.

It's interesting that the gas mileage for Sept/Oct 2000 (roughly the same ambient temps and weather as April) yielded me 29.01mpg with the original oxygen sensor. Mileage immediately afterwards with a new OEM sensor in April 2001 was 28.7mpg. My original oxygen sensor was replaced as a pre-emptive measure before the 2001 test, and was prompted by the fact that the Check Engine light had come on twice in the previous year with an O2 sensor code. In 1995 I saw 26.05mpg with 73,000 miles on the odometer, but that was with 91-octane gas.

Notice also that there has been a steady drop in gas mileage of about 1.25% per year since the new sensor was installed. Some of this drop is doubtless due to Esso's use of the oxygenate MTBE in place of MMT after about late 2003. A further portion is likely partly due to increased blowby.