Help! Car failed smog today

[fairlesstj]

My 93 failed the HC part of smog test today 15mph 59HC max Mine 61
At 25 mph 34HC max Mine 40HC. The shop owner says they need to start with a diagnostic $180 and then he tells me cars that are so close are the hardest to figure out. Says most cars with similar problem run $400 - $500 to get straightened out. but tells me the good news is if I let them do the work they retest for free. Does this sound right? Should I drop it off on monday? I just need a little advice here.... What if they get $500 in and still wont pass? First time I have dealt with this shop had to go there cause test only center but is a gold shield CA certified so they can work on it......My ruby beauty is starting to get to me. I should have paid alot more and got one with alot less problems,,,,,,,,

 

[93Rubie]

Wow, that margin is not much. Unburned hydrocarbons could be a lot of things. How was the other gas levels CO, CO2, etc...

Does the car run and perform otherwise ok?

Also, I would check around and see if this shop is on the up and up. Never hurts, see if they have had any experience with older Corvettes as well.

 

[fairlesstj]

Wow, that margin is not much. Unburned hydrocarbons could be a lot of things. How was the other gas levels CO, CO2, etc...

Does the car run and perform otherwise ok?

Also, I would check around and see if this shop is on the up and up. Never hurts, see if they have had any experience with older Corvettes as well.

test results 15mph %CO2 14.6 - %o2 0.3 - CO max 0.49 Mine 0.34 NO max 692 Mine 601
25mph %CO2 14.6 - %o2 0.2 - CO Max 40 mine 28 NO max 711 mine 490

I am gonna try stuff I got at autozone guaranteed to pass I think it was called or somthing like that. I filled up 91octane and and added 2 bottles of this stuff gonna run the tank out refuel than go test. At a different place. Wish me Luck. Oh and otherwise car and engine run strong real nice. Thanks Rubie for the reply

 

[boomdriver]

test results 15mph %CO2 14.6 - %o2 0.3 - CO max 0.49 Mine 0.34 NO max 692 Mine 601
25mph %CO2 14.6 - %o2 0.2 - CO Max 40 mine 28 NO max 711 mine 490

I am gonna try stuff I got at autozone guaranteed to pass smog or somthing like that. I filled up 91octane and andded 2 bottles of this stuff gonna run the tank out refuel than go test. At a different place. Wish me Luck. Oh and otherwise care and engine run strong real nice. Thanks Rubie for the reply

usually High HC means its rich, bad inj or tune or bad/old Cats. Sometimes when a cat is holding you back, you can add a qt or 2 of alcohol (everclear, painters alcohol, any strong-straight) to a few gallons of regular gas, NOT premium and run it as hot as it will get and test again.
I pass a Ca test with NO cat and just some alcohol in the gas...or maybe lots of alcohol....I forget.
Lean it a little if you can, that will help. Also check the ign timing,.

Good Luck...
I'll be doing the same battle in Texsass next month.

 

[fairlesstj]

Thanks for the input BoomDiver I appreciate all the input I get.

 

[ßill]

Check with BennyC at AutoStart in Elk Grove.
He cured the smog problems I had with my '90 ZR-1.
Oh yea he has a '95 ZR-1
916 714-2886

 

[Pete K]

My 93 failed the HC part of smog test today 15mph 59HC max Mine 61
At 25 mph 34HC max Mine 40HC. The shop owner says they need to start with a diagnostic $180 and then he tells me cars that are so close are the hardest to figure out. Says most cars with similar problem run $400 - $500 to get straightened out. but tells me the good news is if I let them do the work they retest for free. Does this sound right? Should I drop it off on monday? I just need a little advice here.... What if they get $500 in and still wont pass? First time I have dealt with this shop had to go there cause test only center but is a gold shield CA certified so they can work on it......My ruby beauty is starting to get to me. I should have paid alot more and got one with alot less problems,,,,,,,,View attachment 3508

If I understand you correctly, they have provided a price for likely repairs, before performing the diagnostic procedures?
If so, run from this shop.
Their ethics sound questionable.
How anyone can throw a number at something without any clue as to what has tested bad suggests to me they were fishing for an easy victim.

 

[boomdriver]

If I understand you correctly, they have provided a price for likely repairs, before performing the diagnostic procedures?
If so, run from this shop.
Their ethics sound questionable.
How anyone can throw a number at something without any clue as to what has tested bad suggests to me they were fishing for an easy victim.

Thats EXACTLY the problem with these smog test/laws...they leave the consumer wide open to crooked auto repair businesses that can legally rob the consumer because they can basically trade a certificate for a $500 (repairs to be determined later) invoice...and once failed, you're trapped. Many states enter the failed test into the system so its seen by the next test station so they can look for the repairs, some of which the owner is not allowed to do, so they want to see the paper-work (ransom receipt).
Some states (Ca used to) had a guide that had a maximum that someone had to spend on their car to get it passed but that still allowed for lots of consumer rip-off. It was just limited, so the state officials went home thinking they protected the public...uh-huh.

Smog law is fine. I like air that I can;t see...

However, The way they are enforced and regulated stink of United States Congress involvement....:ugh

For all of us that think we have it bad....
Japan is MUCH tougher....There, they do not tune up a car, they replace the engine at 30,000 miles to pass their smog laws. Thats where all these used engines come from that you see in the papers..."Used Japanese Engines"...its a huge business with a endless supply of cheap low miles engines for every Japanese model car there is..They are not good enough to run over there but they are fine for here.

 

[WhalePirot]

Comments refer to a different engine than my signature

While Ruby car may be older than when I did this, my car passed quite easily long ago, by just resetting the ECM. Seems it had learned some bad things with the minor mods installed (headers, mild cam). The code it showed was related to no tire rotation with high RPM, but all the gas numbers improved.

Does the car have mods?

In my case the more aggressive cam dropped the manifold pressure causing the ECM to add fuel for what it thought was an open throttle.

 

[Clive]

Stuff Doesn't Work

That "Guaranteed to pass" stuff doesn't work. I tried it on a vehicle I had and it didn't make a difference. I think it pads the profits of the manufacturer by people who buy it to pass the test and they still fail. Sort of like the stuff they sell that just about guarantees new engine performance from a worn one. Modern day snake oil really.

As for your car, find a shop that has a good reputation from Corvette folk and go there. They know Corvettes and you'll probably get a better deal in the long run. Hard to quote a repair bill without first doing any investigative work.

Hopefully it won't be a difficult repair. I had one car (not a Corvette) that took 2 weeks of work to make it pass. DPO* had cut some wires that we didn't find for ages. Computer was going nuts to correct the readings to spec.


*Dumb Previous Owner

 

[Schrade]

Can you get a data scan of the engine in open loop?

Some grain alcohol in the tank will boost your burn temps, lower the HC count, since you are so close to the threshhold.

If your EGR has a carbon-fouled pintle, the exhaust gases could be holding down the burn temps also (this will show as a lower than normal NOx count (way under limit), and a longer than normal EGR duty cycle in the scan).

 

[fairlesstj]

While Ruby car may be older than when I did this, my car passed quite easily long ago, by just resetting the ECM. Seems it had learned some bad things with the minor mods installed (headers, mild cam). The code it showed was related to no tire rotation with high RPM, but all the gas numbers improved.

Does the car have mods?

In my case the more aggressive cam dropped the manifold pressure causing the ECM to add fuel for what it thought was an open throttle.

No mods and just got the ecm back from being rebuilt by cardone

 

[fairlesstj]

Check with BennyC at AutoStart in Elk Grove.
He cured the smog problems I had with my '90 ZR-1.
Oh yea he has a '95 ZR-1
916 714-2886

thanks I will check with him

 

[fairlesstj]

Thanks everybody for the replies

 

[fairlesstj]

Can you get a data scan of the engine in open loop?

Some grain alcohol in the tank will boost your burn temps, lower the HC count, since you are so close to the threshhold.

If your EGR has a carbon-fouled pintle, the exhaust gases could be holding down the burn temps also (this will show as a lower than normal NOx count (way under limit), and a longer than normal EGR duty cycle in the scan).

Kinda new to all this dont know of where I could get the scan done might get some grain alcohol though

 

[cjericsen]

OIl change

My 93 failed the HC part of smog test today 15mph 59HC max Mine 61
At 25 mph 34HC max Mine 40HC. The shop owner says they need to start with a diagnostic $180 and then he tells me cars that are so close are the hardest to figure out. Says most cars with similar problem run $400 - $500 to get straightened out. but tells me the good news is if I let them do the work they retest for free. Does this sound right? Should I drop it off on monday? I just need a little advice here.... What if they get $500 in and still wont pass? First time I have dealt with this shop had to go there cause test only center but is a gold shield CA certified so they can work on it......My ruby beauty is starting to get to me. I should have paid alot more and got one with alot less problems,,,,,,,,View attachment 3508

Sometimes an oil change can help clear up that slightly high HC%.

 

[froggy47]

Get the cats REALLY HOT & go for the test. If you have to wait, run the engine at very fast idle to keep cats hot.

 

[fairlesstj]

I just changed oil but also I had just put the rebuilt ecm in the day of the test. Some of the things I have been reading says that can be part of my problem.

 

[lt496]

My 93 failed the HC part of smog test today 15mph 59HC max Mine 61
At 25 mph 34HC max Mine 40HC. The shop owner says they need to start with a diagnostic $180 and then he tells me cars that are so close are the hardest to figure out. Says most cars with similar problem run $400 - $500 to get straightened out. but tells me the good news is if I let them do the work they retest for free. Does this sound right? Should I drop it off on monday? I just need a little advice here.... What if they get $500 in and still wont pass? First time I have dealt with this shop had to go there cause test only center but is a gold shield CA certified so they can work on it......My ruby beauty is starting to get to me. I should have paid alot more and got one with alot less problems,,,,,,,,View attachment 3508

Might want to just try another station to test it...

 

[LLC5]

I just changed oil but also I had just put the rebuilt ecm in the day of the test. Some of the things I have been reading says that can be part of my problem.

With the HC numbers you posted it sounds like a weak catalytic converter or that the cat wasn't hot enough during testing. I would try froggy's advice and make sure that the cat is up to temps by driving on the freeway for 20+ minutes before testing and keeping it hot during waiting for the test. Good luck with it.