Cadillac Owners Forum banner

1 - 20 of 29 Posts

·
Registered
'97 Eldorado ETC
Joined
·
89 Posts
Discussion Starter #1
Hello all

As the title says, I just failed smog due to high HC

ASM Emission Test Results

C02%O2%HCCONO
TestRPMMEASMEASMAXAVEMEASMAXAVEMEASMAXAVEMEASResults
15 MPH162414.760.11499930.470.030.174096791FAILED
25 MPH155514.800.08336440.440.030.176966233FAILED


I googled/ went through this forum to find out what causes high HC and found
  • HC is raw/unburnt fuel
  • Failing/poor ignition components (plugs, wires, coil, etc) can cause high HC
  • Lean air/fuel conditions and/or vacuum leaks can cause high HC (which only makes sense if it's air lean/fuel rich)
  • Bad CAT can cause high HC
For the last 6 months I've had P0174 & P0171 codes... at first (the first 4 months) the SES light would come on and off, but then it started staying on (for the last 2 months... one of which it sat around waiting for a transmission transplant), so I started trying to fix the problem. The bolts holding down the intake manifold weren't even finger tight so I torqued them to ~7.5 lbs/ft (close to 89 lb/in spec) and the SES light started coming on and off again.

I also had a high pitch whistle so I checked for vacuum leaks, and ended up replacing that backfire relief valve and the intake manifold gaskets (even bought a plenum... my car doesn't even have a plenum, or at least not the rubber one I bought) everything else is fine. That stopped the whistle and the SES light went off and stayed off by itself.

Feeling confident, I took it to get smogged and it failed.

Should I take a chance on the plugs and wires or just go straight for the CAT
 

·
Registered
'97 Eldorado ETC
Joined
·
89 Posts
Discussion Starter #3
Yup... had hard starting issues earlier in 2012 and I replaced the FPR
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,789 Posts
I'd try plugs & wires (probably due anyway). Be sure to use A/C Delco 41-950 plugs.

A failed CAT will trip the SES light and set a DTC.
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,789 Posts
I'd try plugs & wires (probably due anyway). Be sure to use A/C Delco 41-950 plugs.

A failed CAT will trip the SES light and set a DTC.
 

·
Registered
1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
Joined
·
6,737 Posts
An engine running too cool will also raise HC's Thru diagnostics can you verify the engine is getting to 95 C ? Keep in mind once it's fixed, fuel mileage will improve!
 

·
Registered
Black on Black 2001 esc
Joined
·
72 Posts
I had just failed my California bi- yearly pointless take your money inspection for high hc's also

and had no codes new Fpr, intake gaskets, spark plugs and O2 sensors.
It failed smog again after my failed "throw parts at it" quick fix didn't work, so I found a CA approved Kitty kat online, installed it and my 12 yr old car can be on the streets of Cali for 2 more yrs legit .....
 

·
Registered
92 El Dorado
Joined
·
127 Posts
To the OP, I'd recheck the fpr again in case it was a lemon.

Might as well check the other emissions components like the egr (sometimes it can be an intermittent fail w/o dash codes) PCV valve (cheap) and peek at the EVAP all regardless whether it may cause high HC.

Recheck the vac lines.

Make sure you run your car on the freeway for about 20-30 minutes in order to get everything nice and Hot esp. the catalytic converter before the test and keep the car idling.

That will help pass the smog.

I also live in in the state of confusion-california....had to do the same round robin about 2 yrs ago for 'NO' problems.

or just spend alot on a new catalytic converter off the bat and cross the fingers....
 

·
Registered
'97 Eldorado ETC
Joined
·
89 Posts
Discussion Starter #12
Earlier in 2012 I replaced the vac lines, pcv, and FPR... over the weekend I replaced the intake manifold gaskets and backfire valve

How would I check the FPR?

As for spark plug wires... AC Delco as well? Looking to get the plugs and wires from rockauto, looks like I can get all AC Delco for ~$100
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,789 Posts
To check the FPR just pull the vacuum line off the FPR at idle and look for any sign of fuel at the nipple. There should be none.
 

·
Registered
'97 Eldorado ETC
Joined
·
89 Posts
Discussion Starter #14 (Edited)
Quick update, I re-tested at a different smog station and failed again... I brought the car in hot (it sat for a couple minutes while he took down my info and I handed over the keys), replaced the plugs and wires, checked the FPS, and everything else is good... I'm now under the impression that I must now bend over and get a CA Legal catalytic converter to lower my HCs

Here are the results of my latest run:
ASM Emission Test Results 01/21/2013​

%CO2%O2HCCONO
TestRPMMEASMEASMAXAVEMEASMAXAVEMEASMAXAVEMEASResults
15 mph149614.90.0499660.470.030.134096733FAIL
25 mph156214.90.0336330.440.030.106966220PASS


Here's the results from the first smog I had done earlier in the month:

ASM Emission Test Results 01/07/2013​

%CO2%02HCCONO
TestRPMMEASMEASMAXAVEMEASMAXAVEMEASMAXAVEMEASResults
15 mph162414.760.11499930.470.030.174096791FAIL
25 mph155514.800.08336440.440.030.176966233FAIL


There's definitely improvements (except for CO/CO2, they went up a little bit), but I barely passed the 25 mph HC test at the max and was still 17 ppm too high on the 15 mph HC test.

The smog station I went to this time was owned/operated by an older gentleman who seemed like he knew his stuff. He told me that I may have a degraded cat as it's the 170k mi old OEM cat... So sure it may not sound bad, smell bad or throw codes, but it takes a long time for it to drop the emissions. He went on to explain that bad cat codes only pop-up on the 2000+ models
 

·
Registered
'14 ATS Premium with 3 pedals | Past: '13 ATS Performance & '99 Seville STS
Joined
·
5,847 Posts
So could you guys eventually discover what kitty kat means?
 

·
Registered
92 El Dorado
Joined
·
127 Posts
The second test was at lower RPMs FWIW. Maybe that helped.

I wonder if its running too rich? Does the on board computer allow you to test the fuel injector banks? (or have it put on a 'scope')

Try to find out whether its running too rich.
Also my FPR did not leak fuel when the vac hose was removed, however, once uninstalled it did stream out of that port. It had to be replaced.
So MAYBE its the FPR.

Heck if its cheap and simple to replace, go to bat again before diving into a Catalytic converter.

When my Eldo failed CA smog (for NO) the mechanic instantly said "Cat. Converter". It was not that !

These guys or a mechanic can read and interpret the numbers in order to infer a probable cause. Like running too rich or lean etc... Good luck !

oh yeah, lazy O2 sensor(s) ?? don't know how that would affect a particular set of readings but 'lazy' does happen. Use on board computer to check O2 sensor activity. Get the FSM.
 

·
Registered
'97 Eldorado ETC
Joined
·
89 Posts
Discussion Starter #17
I have a some questions

1. Does the grade of gas being used during a smog test make a difference?

I've been running 89 octane (CA mid-grade) for a while and during both smog tests, from what I understand, the pcm/ knock sensor compensates for the lower octane and retards ignition... should I use the recommended 91 octane premium unleaded? (I have a '97, so it says premium only under the gas gauge and on the fuel door) The only conceptual problem I have with using higher octane fuel is I remember higher octane meant more HC, so wouldn't using a higher octane make matters worse?

2. High HC is said to be caused by excess fuel in the exhaust, would changing my air filter increase the amount of air let in the engine and result in more efficient fuel combustion (less wasted fuel)?

3. Would cleaning the throttle body and/or IAC help improve the the air/fuel mix?

4. I dumped a bottle of Lucas' tune-up in a bottle fuel treatment and injector cleaner, could that help lower HC after this tank?
 

·
Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
·
68,495 Posts
1. It would not hurt to run a 93 octane for a week or so before a test. The slight difference in your 89 and 93 should not make a difference ...... but ......
2. IF the air filter was unattended for quite a while maybe - just maybe - but the engine controls works to keep fuel mixtures within design specs at all times.
3. Cleaning the TB once a year, particularly on the pre-2000 engines, is always a performance and economy plus.
4. Instead of various additives (not recommended in your owner's manual by GM) try a 20 oz. bottle of Chevron TECHRON once in 5,000 miles. GM recommends Top Tier gasolines (Google it) and TECHRON is a component in them.

Just before an emissions test get the car out on the highway and run the snot out of it - get it and the exhaust system hot and, using aggressive accelerations, cleaned out.
 

·
Registered
97sls,09dts
Joined
·
880 Posts
If you google smog checks in ca or similar you will get alot of information.

They have cheap hand held scanners as low as 20 bucks that will tell you if you are ready for the check. mike
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,789 Posts
Are you sure all the vacuum lines and fittings are tight? Sure sounds like you have a vacuum leak somewhere.
 
1 - 20 of 29 Posts
Top