KuHL 951

Yeah, another stupid failed smog post. I just got back from smog testing my 86 951 at the same 'test only' facility I've used for years. It failed miserably in every category except HC at 25mph. I'm talking a car that passed 2 years ago with the same set-up except I swapped the stock airbox on this time. I'm thinking the O2 sensor is toast and the cat is probably burnt out from running rich. The car was fine 2 years ago with the same VR K-26/8 chip and 3-bar FPR. I have another cat section and 2.5 FPR I can throw on but not sure if that is enough. I'm not sure if changing the FPR will make it too lean at 15/25 mph with the VR chip or not. I've added xylene on a past test with good results but I've heard it can make the NOx go up dramatically. Any thoughts always appreciated?

15 mph:
HC: max allowed 133, measured 222
CO: max allowed .82, measured 2.32
NO: max allowed 1125, measured 111

25 mph:
HC: max allowed 108, measured 121
CO: max allowed .62, measured .89
NO: max allowed 955, measured 1177

Eastep

move to NC, any car older then 1997 is emissions exempt :P

Yabo

older than 1997? WTF!

Edit to add insight: Last time failing across the range happened to me, it was a cat. I don't recall which vehicle though, I"m pretty sure it was the 944.

KuHL 951

Thanks for the insightful help guys

Wipeout

This sounds like my '85 when I registered it up in Oregon. It'd passed the CA smog the previous year, then failed up here miserably. Replaced O2, didn't even register on the smog test it was so perfect. There's extra witchcraft I'm not familiar with on turbos, though.

xschop

Xylene is good, but Acetone is the secret. 3oz acetone/10 gal. pure petrol. don't use Ethanol blended gas.

Eastep

acetone?...like paint thinner!? for real!?

xschop

Yes, I run it in that conc. in all my vehicles. On the fuel injected vehicles which atomize the hydrocarbons well, it is not noticed much at the pedal, But out the tail-pipe analyzer..... NOX is nada.
On my carbeurated bikes, there is an increase in horsepower because of the complete combustion that it causes of the hydrocarbons. The Acetone molecule is a turbo-charged propane if you will, with it's own double bonded oxygen (liquid turbo)

m73m95

lol, +1 on the acetone. Its cheating, but it works.

Did you drive around for a while before your test. Your cat has to be plenty hot to pass some tests.

alex

I know a guy who knows a guy.


/JK





maybe...

KuHL 951

Thanks. The cat was heated up well for 25 minutes of driving with several hot runs and then backed right onto the dyno, fan in front of the IC. I'll give the acetone a look but I think xylene has a lower flash point which should make it burn even cleaner. I'm not sure about the ethanol blend comment above but I think all gas in Cali has ethanol so that's a no starter. I've run xylene in the car several times when I raise the boost on real hot days or go on a fun run and it makes a huge difference in performance and exhaust smell.

I'm sure a new O2 sensor will make the biggest difference of all. Is the O2 sensor more critical for low rpm fuel control than higher rpm? Since my emissions improved some at higher speed it has me wondering. Is there a way to test the O2 with an ohmmeter at the plug. I've tested them on a BMW but that was years ago and my memory sucks. Something about the hot/cold difference and how fast it dropped at idle.

xschop

Shell stations seel 100% petrol here. Ethanol causes higer Nox cobustion byproducts.

Eastep

so basically paint thinner in your gas tank is like doing sea-foam yes? this work on an N/a car

xschop

works just as well on NA cars

Calmchaos

Yeah there is a way to test the O2. Its not an exact test but it works.

Warm the car up so the O2 sensor is nice and hot. Then unplug the sensor. Set your Ohm-meter for 2000mV or something of the like.
Connect one end of the meter to the male pin on the sensor wire (should be 2 female pins and one male), and connect the other end to the negative of the battery.
It should read somewhere between 500mV and 850mV ish. Now richen up the mixture either with propane or w/e you wish that will make it rich. The sensor should now read above 900mV. Now lean the mixture by disconnecting a vacuum line at the intake. The sensor reading should quickly drop to 200mV or less.

Mine was bad and it read 880mV at all times. I replaced my O2 recently, and while it was a huge improvement I only got close to passing NJ emission.
My n/a is currently only slightly lower than yours. I passed everything but the CO%. I need .50 and got .82.

Oh yeah... im pretty sure clarks also says to run the engine at 2500 rpm during the test. But I've tested good and bad sensors, and the test proves efficient at idle too.
All testing done on my 86 n/a if it makes a difference.