Another 1991 Fails CA emissions... Help!

[tccrab]

There is a member here that used to own a SMOG shop in Sacto.
He'd be the one to nail this down.
I'll dig him up if he's still around.

TomC
"Crabs"

[Shinto]

Originally Posted by gbrtng

The audible pinging is a clue - it's running lean with advanced timing. Maybe a failing injector or knock sensor. What gear do they run the 15 and 25 mph in?

I'm not sure what gear, as the test is about as hands off as it gets. I'm not allowed in the service area. That's why I gave the listed rpm (I'd guess 2nd).

Originally Posted by gbrtng

Also, has CA lowered the NOx limit recently?

It's against federal law for them to change the limits for the model year car to be lower than what was originally approved, but it wouldn't surprise me if they did. They keep making the testing increasingly hard to pass and thinking up new ways to fail cars. They actually pressure tested the GAS TANK in the '78 Trans Am and failed it on that (as well as other tests).

This last go round the smog machine actually gave NO feedback to the operator in terms of emissions -- only rpms and speed. We didn't know it failed until the test was over and it printed out.

I also see more and more data printed out every time I have a test done, regardless of model year. (Ask me what I REALLY think of this in an uncensored forum... Starting to remind me of a certain country in Europe in the late 1930's...)

How do I test the knock censor and injectors?

[tccrab]

Found this in the archives:
http://www.zr1netregistry.com/forum/...read.php?t=131

I'm trying to remember the guys name who owned the SMOG shop down in Sac, "BennyC" keeps coming to mind.
I've checked the archives here and I don't find him so it must have been on that "other site" long before I got the boot.


TomC
"Crabs"

[jonszr1]

boy sure makes me glad that our county doesnt have to test unless we sell the car .you might think about finding a freind in sonora that would let you register the car there

[Paul Workman]

Originally Posted by gbrtng

The audible pinging is a clue - it's running lean with advanced timing. Maybe a failing injector or knock sensor.

I agree w/ gbrtng that the pinging is the clue that it is running lean, and or the spark is too advanced(?), especially if it is pinging on 91 octane. Marc H can provide you with a chip that will bring the fans on while the temps are a little cooler. Cooler would help N0x, but too cool and HC will creep up - it is a balancing act. 10º cooler (both fans coming on at around 206-210) might do it for ya.

Anywayz...I would do a dynamic scan/data logging to see what other clues might pop up before I started changing this and that in hopes the problem goes away. BTDT.

P.

[gbrtng]

I asked about the NOx limit because Hib was complaining about CA lowering it several years ago - and what to do to help the 94-95 cars with EGRs. And it would be to your advantage to scan the system before throwing parts at it.

[Dynomite]

Originally Posted by Shinto

I'm not sure what gear, as the test is about as hands off as it gets. I'm not allowed in the service area. That's why I gave the listed rpm (I'd guess 2nd).

Holy smoke WOW....Now I know why I am registered in South Dakota

[tomtom72]

I'm not trying to be a wise guy. I live in NYS, in the NYC/Metro-suburban area and we have strict smog regs like CA. We even do this roller loop test at 15 & 25 mph.

Anyway, two inspections ago the place called me up to give me the heads up that my car wouldn't pass the NOx test. We don't have "state run smog inspection stations". We have auto repair shops do the testing. I went over and found that I had left the power key in the "Full Power" position.

Just a shot in the dark!

[RKC]

I have a 1990 that gave me fits getting pass smog. Here are my results from my first failure.

15 mph / 2294 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 51 (limit 110)
CO: 0.01 (limit 0.71)
NO: 868 (limit 772) ***

25 mph / 2450 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 41 (limit 85)
CO: 0.01 (limit 0.59)
NO: 987 (limit 711)

After I passed:


15 mph / 2190 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 109 (limit 110)
CO: 0.10 (limit 0.71)
NO: 611 (limit 772) ***

25 mph / 2440 rpm
CO2: 14.7 (no limit)
O2: 0.2 (no limit)
HC: 52 (limit 85)
CO: 0.01 (limit 0.59)
NO: 667 (limit 711)

I passed the test after using fuel injector cleaner, changed the oil, replaced the spark plugs, and cleaned the air filter. I used Chevron gas. My engine has 45,000 miles and blows a little oil on startup.

I did have new bullet cats on SW headers. The cats may have helped ,but they didn't help it pass the first time. I also have 4.10 gears in rear.

One major difference I noticed is the RPM's at 15 mph. In your test, you're barely off idle at that low RPM. Nearly 900 fewer than mine. About 350 RPM's less at 25 MPH.

Also, I'm not sure of the reasons, but in passing the NO portion of the test, I very nearly failed the HC portion. I tested on a summer day. The technician had the car running for nearly 20 minutes before and during the test. With the aftermarket radiator it ran very hot at idle. I subsequently swapped it for a stock radiator and dramatically improved the idle temperature. My point being, the engine coolant temperature had to be extremely high during the test.

Also on the first test failure, they failed me on my gas cap. I replaced it with a new one. Don't know if that would cause any actual exhaust emissions change, but on a newer OBD II vehicle of mine it set an error code that I couldn't solve until I finally replaced the gas cap. It immediately cleared the problem and never reset.

[RKC]

I'm sorry, but I failed to mention that I failed the first test with an aftermarket PROM. I managed to buy the last stock PROM for a 1990 in the Chevrolet system. They shipped it all the way from Maine. I'm certain that must have played a large role in passing.