KJL

I have a 95 ZR1 and am having problems passing the Nox part of the emissions test again. Am wondering if E15 would be OK to run for the test?

I have replaced the fuel line o-rings but am concerned about the Fuel pumps and other fuel system components.

Dominic Sorresso

What mods if any?

KJL

Many Mods.
Fuel pumps are stock, injectors and seals are good for at least E10 fuels.
Headers and exhaust, after market CATs.
EGR removed
4.10 gears w/Ram dual disk & light weight flywheel
Top end ported
Marc's Performance Chip
Marc's Emissions chip

Passed last year easily but this year it was very hot when I had the car tested. The tech had no clue as to how to use the rollers so the car sat there and idled for nearly 30 minutes as he had to read the manual. All I did last year was run some CRC through it. It did fail the first time but passed easily the second time. I though it was mainly due to the fact the car sat for year while I was workinng on it. I was very surprised how badly I failed the NOx portion of the test this year....I hope the OA temps had something to do with it along with the car idling for so long.

Rkreigh

yeah, I've mixed up some emissions cocktails to lower the nox but it's not really going to help much unless you run e85 and tune it

the more alchy you run the car leans out and the o2s richen it back up and you get misfire which is terrible for emissions

ask me how I know

if you get it just right it might help on the early cars the injectors don't like alchy in the fuels so increasing it doesn't help

but that is a slow not a fast death as the injector windings break down

KJL

The injectors are new and should be OK.

Dominic Sorresso

u should think about reconnecting the EGR.

billschroeder5842

Yep, this will make a difference.

I'm not sure on the gas, but having your car idle for 30 minutes is not helpful; needs to be way hotter.

Funny that GA smogs these old cars. In Texas you share a beer with the technician and he signs the papers.

Rkreigh

get a dyno operator that will work with you

they will use the dyno to get it hot and then run the test with a good foot and you'll have a fighting chance

also clean out the top end with a few spirited runs at the lt5 tends to be a carbon machine

dyno one and you'll see I stood about 25 foot back of my car and after the first run I looked down and my jeans were peppered with carbon flecks

the strokers tend to run a bit rich to project the engine and lugging them around with big cams doesn't do much to keep the engine clean

now after you get out of jail, do your best to run the car hot

my dyno operator "dug the car" so he could put the thing in test mode and not send in the results to see if my "cocktails" were working

in the old days I had a 98 HC standard, the old LSV with failing random ss cats didn't hit the new 48 HC standard VA was nice enough to impose on the old gal. So Dr. Phil actually has the answer here

he rigged up some hideous restrictive 3" cat and flex pipe mod.

but in reality, that's what's needed is hot and fresh cats to clean up the breath

if you have factory cats, and low miles, that's good, but the headers and dinky little bullet cats aren't the answer here

and yes, hook up the egr

also find a friendly shop to work with, buy and put on brand new cats, and see what the old gal will do on the breathalizer

if the dyno guy will let you warm it up, all the better!!!

KJL

Finally got around to testing after running some cat cleaner through and filling with a fresh tank of gas. I did try running with a few gallons of E85 but it did not help much. This time I hooked up a tube to the cruse control vacuum port and metered in some windshield washer fluid. This dropped my numbers the most.

25/25 Test Nox Reading: 998 Allowed: 796 Diff 202
50/15 Test Nox Reading: 1096 Allowed: 897 Diff 199

I am going to replace cats and try again. The original are aftermarket and I have no idea how old they are. This would be the next easiest and cheapest thing for me to try. Maybe I will wrap them in insulation to keep them as hot as possible. Temps are supposed to be in the 20's here next week.

Dominic Sorresso

KJL

I assume it is just E10. I just filled her up with regular 93 Octane gas. It passed last year so it is very odd all of a sudden my Nox number have nearly doubled. Nothing has been done top the car since it was inspected last year.. I am also running an emissions chip from Marc.

Dominic Sorresso

ccmano

Did you hook up the EGR?
H

Paul Workman

That was going to be my suggestion too.

Paul Workman

Not to be a "Pit Nicker", but "E85" is 15% ethanol, 85% gasoline. "E15" would be just the opposite ratio proportions...NO?

KJL

C6_Racer_X

Locate and fix all vacuum leaks and you'll probably pass the NOx test.

Also test the O2 sensors and replace all of them if any are slow or "stuck". Use a volt meter to backprobe the connector for best results. I'm not sure if the data link speed on your 95 is fast enough to get a good reading from the ECM for that.

Dropping the thermostat temp one step (10°F to 15°F) might also help some.

Also make sure the EGR system is operating as designed. I see you've got it bypassed or removed. EGR may be necessary to pass the test.

E15 might make NOx results worse. More oxygen in the fuel won't really help a lean mixture which is causing high NOx. It depends a lot on how the engine electronics are tuned.

C6_Racer_X

It's definitely the other way around. E15 is 15% Ethanol. E85 is 85% Ethanol.

ccmano

EGR was designed back in the day specifically to control NOx. Without it on these old engines you have little chance of passing.

Be glad your not in California. They keep raising the NOx requirement (though they deny it) to weed out older cars and get them off the road. Are you sure your state isn’t doing the same thing?

H

KJL

Their published values have not changed. These not-to-exceed values are printed on the report.