luckett

distributor cap/rotor
plug wires

KLR

FWIW, when you're over on both hydrocarbons and NO, it's usually the cat. If you're only missing on one or the other, it's typically a mixture issue (i.e., bad O2 sensor, etc.). If you have a relationship with a p-car wrench in your area, you might ask him whether there is a testing station that he uses that knows how to get the car to pass. There is some discretion in these rolling road tests as to gear/RPM, particularly if you mess around with the tire inflation. This can make the difference if your car is marginal -- these older cars were never made to pass the modern tests. Given that you're failing pretty badly, I don't think that this is going to do it.

Fortunately, when I lived in NYC and had to deal with this stuff, my wrench was also a testing station and would get it done without drama. One can only hope that all of this nonsense will go away over time. In Illinois they've given up on the rolling road test entirely. We no longer have testing for pre-OBD2 cars and for 96 and later cars all they do is check the computer for fault codes. I just got my wife's Acura smogged a couple of weeks ago and it only took 10 minutes, including the wait in line.

Todd157k

Mine failed smog today also. My mechanic buddy told me it's "more than likely the cat" and to swap it with my 83 that just passed smog. That might make it.. for now anyway.

funny you should post this today. I did post a WTB thread to try and find someone that took off a good cat and wants to sell it.

Funn944

Hope you guys in Cali can get your cars to pass. It's almost impossible to find a testing station that "can get you to pass". The stuff you put in your tank wont help with hydrocarbons that high, sounds like it's running to lean (cylinder temps too high) Mine had that problem. Changed the cat, o2 sensor, fiddled with A/F, stuff in the tank........none of it worked. Going to referee is a difficult thing to do as well. I wound up moving out of to a state where there is no testing. GOOD LUCK

944girl

Ok guys....

I just smogged Aug 12th and failed also here are my numbers and what I have done.

1. At 15 MPH (HC) Max 118 Ave 31 Meas 23 PASS
(CO) Max 0.75 Ave 0.10 Meas 0.02 PASS
(NO) Max 799 Ave 237 Meas 1076 FAIL

2. At 25 MPH (HC) Max 93 Ave 20 Meas 25 PASS
(CO) Max 0.63 Ave 0.09 Meas 0.01 PASS
(NO) Max 738 Ave 199 Meas 1012 FAIL

So I just replaced my plugs, O2 sensor, and had the muffler shop put in Magnaflows most restrictive cat.

My test only station told me you look very clean in HC, CO, at both the 15 and 25 but its the NO that failed...so he thinks it was my HIGH FLOW cat that I had on prior to changing it yesterday morning. Wish me luck as I'm going to try it again tomorrow morning with the new stuff on it.

So looking at my numbers do you guys also think it was my high flow cat that failed the 1st time around?

Thanks,
Carolyn

Kevin Baker

What were the dilution numbers on both these cars. Should be 14%. That will tell you if you are lean or rich.

Todd157k

My numbers were almost identical. So are my solotions. I bought another O2 sensor, going to swap plugs AND change the oil. That will make the biggest difference. I also plan on swapping out my cat with my 83. (hopefully they're the same)

Bill

I have been trying to get my car to pass the rolling testy for 3 years now. The usual, HC and CO pass, NOX fail. I have replaced every smog related item with no luck. I spoke to the state referee and got a one time pass due to the money I spent. As I was told, after the one time pass expires, I will again have to get it to pass. If I can't the referee told me I had to crush it! My car is almost perfect. It has only 80,000 original miles on it. I have spent over 30k on it, replacing all the moving parts. Crushing is NOT an option! I told the Smog **** that My daily driver is a Prius, and that I do care about our air. I told him that I have never driven the car more than 5.000 miles a year. Given that my car would have little impact on the environment. I asked him, "you must know that 944's have been having trouble passing"? He admitted that he did know this. Finally..... he told me about registering it in an area that does not have smog requirements. The guy had a heart, and liked Porsches.

I did some research and found that there are regions that do not require smog checks. So I purchased some land in Nevada with no smog requirement. I am taking the car to Nevada next weekend and will register it there. Then I will drive back to Calfornia and drive the car legally, with my Nevada Plates. Screw California.

CRUSH IT........Bite me!

KuHL 951

I said it once and will say it again: Xylene is your best friend come Cali smog time. Don't ask me why it works but I've used it on so many cars I can't remember. I got the info years ago from the Jeep Forums that tend to mod their cars pretty heavily also. The 951 just doesn't have a lot of wiggle room under the current CAL smog regs even if running well...the Xylene seems to help all the residual fuel to burn off completely lowering emissions across the board. When I am done with smog I top the tank off to dilute any adverse effects on the cat or seals. This is on a car that has a good O2 sensor, clean plugs, a newer cat, and runs great otherwise...the Cali standards are just set too high for an older car

Yummybud924

well I have to smog my car here in BC in a week and I have a feeling it will fail, my mechanic told me it runs a bit rich.

I've heard putting methyl hydrate, or methyl alcohol in the gas will help you pass but I'm a bit scared about doing this. I've read that it can destroy all your rubber fuel lines and seals and I don't know if it can damage my engine.

I'm thinking of getting 10 litres of gas on a nearly empty tank and putting one litre of methyl hyrate in so it would be close to a 10 percent mixture of alcohol but I'm not sure if that is enough to help it pass.

smog is a major pain when you have an older car. On my old 924 I had to spend like 350 bucks to have it finally pass.

smog doesn't even make sense to me. A small 4cyl engine can fail smog because it's a tiny bit over the limit for that engine and vehicle while a hummer can pass because it's within it's limits.

Todd157k

Is that available at paint stores?

FRporscheman

Roger's in Germany so I'll fill you in on his car (the '89 NA). It's not stock. It has MSD ignition, A completely custom exhaust with a high-flow cat, light flywheel, light pulleys, throttle cam. I don't know if it has a chip.

Yeah screw california and it's dumbass smog bs. They pinch us for our little 4-banger efficient cars while diesel trucks AND cars get to belch plumes of smog into the air, unchecked. THAT doesn't make sense. I like that Nevada idea.

Andial951

Hello all............writing from Berlin.

I will give the Xylene a shot........and maybe at the same time use that addidtive that is supoosed to gaurantee you will pass.

Arash......what would you pay for a 944 Euro bumper???

quinnfiske

The Xylene idea is interesting. Does it help across the board (HC CO NOx) or only specific gasses? Has anyone done any back-to-back comparison on this? We definitely need some tools to help us with this issue. The trial and error method everyone uses is not good enough.

I would like to have access to a gas analyzer. They seem to cost a fortune and the goofy state I live in (think cheeseheads) tests you in grams/mile rather than ppm or %.

944girl

Hi all I'm back....

Well I smogged my car again today and guess what it failed again...its my (NO)

So here are the numbers with new O2 sensor and Magnaflow high flow cat only (NO) since that is the issue.

Done: 8/12/07 (NO) Max 799 Ave 237 Meas 1076 (15 MPH)
Max 738 Ave 199 Meas 1012 (25 MPH)

So on Tuesday I changed out my cat to another Magnaflow the most restrictive universal cat they make and still have my new O2 sensor and today 8/16/07 here are my numbers.

Done 8/16/07 (NO) Max 799 Ave 237 Meas 1140 (15 MPH)
Max 738 Ave 199 Meas 1115 (25 MPH)


This has all been done at the same test only station...I'm going to go to a different test only station. If this doesn't work...then I must go to a referee and also get a waiver and figure out what to do next. This is a brand new re-freshend motor from bottom to top with only 7,000 miles on it and its still failing (NO). It makes my want to cry...I'm so discusted with the whole thing.

I feel your pain Bill...I'm not going to crush mine either...I have babied this car and spent like you a lot of money to keep it looking and running nice.

Carolyn