Emissions vs grade of gas ?

Emission test in NJ are almost as tough as California these days (special thanks to former gov. Christy Whitman for selling out for more highway funds). I have inspection on my 88 Cherokee coming up next month and I want to do everything I can to pass on the first test, or the State wants to see repair bills from an authorised emissions testing garage that the work was done (more BS). I just did a complete tune up and it runs well even though It has 170,000 miles.
Here's the question...Does the grade of gas affect emissions testing at all ? I know a better grade of gas helps engine perfomance due to better control of the burn, but would regular gas give a lower emissions since it ignites faster ?
Thanks for any input.

Using the wrong grade may have more of an effect than changing grades because of carbon buildup and an accompanying compression shift.

That quick burn might affect the NOx readings. If I remember right, the quick burn has a higher temp and raises the NOx.???? You should double check me on that one though!!!????

Using the wrong grade may have more of an effect than changing grades because of carbon buildup and an accompanying compression shift.

That quick burn might affect the NOx readings. If I remember right, the quick burn has a higher temp and raises the NOx.???? You should double check me on that one though!!!????

Thanks, JD

I've been using regular which I believe is typically 87 octane since I've had the Cherokee for the past year. Does anyone know what the recommended octane rating is on an 88 w/ the 4.0L engine ?

Emission test in NJ are almost as tough as California these days (special thanks to former gov. Christy Whitman for selling out for more highway funds). I have inspection on my 88 Cherokee coming up next month and I want to do everything I can to pass on the first test, or the State wants to see repair bills from an authorised emissions testing garage that the work was done (more BS). I just did a complete tune up and it runs well even though It has 170,000 miles.
Here's the question...Does the grade of gas affect emissions testing at all ? I know a better grade of gas helps engine perfomance due to better control of the burn, but would regular gas give a lower emissions since it ignites faster ?
Thanks for any input.

I just had my 97 Sport done in California on the dyno test...It has 124K on it and I had plugs and wires refreshed last year...the NSS was rebuilt to prevent a check engine light....I use regular gas. The important thing is to get the Cat good and hot...so I had it checked after a 100 mile freeway drive back from Sacramento. Passed easily, but cost $140.
This is the test reserved the smogiest areas in California.

Couple of tips:
Change the air filter, put in fresh oil (I prefer synthetic), and clean the throttle body plate to get a good idle. Use some Techron in the gas about a tank or so before you go for the injectors. Oh yeah tighten the valve cover and look over the PCV equipment. The gas cap get checked out here also for sealing (just buy a new one).

I just had my 97 Sport done in California on the dyno test...It has 124K on it and I had plugs and wires refreshed last year...the NSS was rebuilt to prevent a check engine light....I use regular gas. The important thing is to get the Cat good and hot...so I had it checked after a 100 mile freeway drive back from Sacramento. Passed easily, but cost $140.
This is the test reserved the smogiest areas in California.

Couple of tips:
Change the air filter, put in fresh oil (I prefer synthetic), and clean the throttle body plate to get a good idle. Use some Techron in the gas about a tank or so before you go for the injectors. Oh yeah tighten the valve cover and look over the PCV equipment. The gas cap get checked out here also for sealing (just buy a new one).

Thanks Aloha, Good tip - I'll get that cat conv warmed up good for the treadmill test. What's Techron - injector cleaner ? I have the old Redix (sp?) Multiport system on my 88 and just want to be careful with it. I'll get the cap replaced - I hear people fail for that all the time.

Try this link:

http://www.chevron.com/products/prodserv/fuels/techron/techback.shtml

I use a large bottle of concentrate in the Jeep with a full tank.