Help! Failed my emissions test! - Problem found!

[Bigerik]

Having had a thought in the back of my head that there might be a problem, decided, for the first time ever, to take my car in about 6 weeks early for the E-Test. Of course, it failed.
Only reading that was high was NOx.
Pass was 390
My test result showed 560.


All the other test were well under.

EGR is the most likely culprit, I would guess. But I am certainly open to other ideas or suggestions.

The car was hot - 1 hour of driving in city traffic prior to test.
Plugged in my code scanner and got no codes. Coolant temperature outside of the test centre showed 218 degrees.
My Cat is new.
O2 sensor is about a year and a half old - proper Delco sensor
Plugs have about 20K miles on them - 10 months? NGK TR55's. Wires are new.

Again, any thoughts would be appreciated.
Thanks!
Erik

[Bigerik]

More info. These are all my test results:

Limit Reading
HCpp 54 12
CO% .30 .07
NOppm 396 560

[willwren]

EGR would throw a code, and most 3800's will pass emissions WITHOUT the EGR regardless (including 92's which didn't have one other than L67's).

Cat, O2, and plugs/wires. A random misfire can cause this. I'd trust the cat, but even the O2 could be causing this, regardless of age. There are 'freaks' out of the little ac delco boxes.

Inspect your plugs. Pull all 6, lay them out in order, and let's see a pic of them.

[agrazela]

More info. These are all my test results:

Limit Reading
HCpp 54 12
CO% .30 .07
NOppm 396 560

Low HC, Low CO, High NO all point to lean A/F...maybe a vacuum leak? Maybe a tired out O2 sensor?

Like wren said, check the plugs for signs of lean operation.

[Bigerik]

The vacuum leak I would doubt, as the things idles VERY well. Watching the tach on the test computer showed a range of about 20 rpm, from 720 to 740. Pretty consistant.

Will start doing some checking this weekend. Probably get a new set of plugs anyway.
Do plan on pulling the EGR and giving it a check.

[Bigerik]

Ok. Got some pics of the back three plugs:



Looks to be running a little lean. Fronts looked better.

[Bigerik]

Just bumpin this.
All help appreciated.

[azu]

I would rule out EGR. Double check that O2 sensor. Make sure the wires on it do not touch anything. I had similar problem with a bad miss and found the wire was too close/touching metal bracket causing false O2 sensor readings. Good luck!!! BTW my plugs looked just like your plugs do.

[Bigerik]

I would rule out EGR. Double check that O2 sensor. Make sure the wires on it do not touch anything. I had similar problem with a bad miss and found the wire was too close/touching metal bracket causing false O2 sensor readings. Good luck!!! BTW my plugs looked just like your plugs do.

Thanks!
I will certainly check that out. Looks like only the rear bank is running a little lean.

Talking to some of the local guys too. Apparently a bunch of them have had trouble with Magnaflow Cats. Gonna check that option out too.

[willwren]

I've never seen an issue with a magnaflow cat on a 3800.

EVER.

[Barry]

I never tried this, but here in Minnesota, when they used to do E tests, I heard many times talk that if you failed, put a half can of Sea Foam in your gas tank when it is about 1/4 full. Drive at least twenty minutes and then get tested. It was said that this could get you through. It wouldn't fix your problem, long term, but may get you through in a pinch if you cannot find a solution to your problem. The Sea Foam in your gas will not harm anything. Just thought I would mention it, not necessarily advocating it. I never did it because I never had a problem passing.

[Bigerik]

I never tried this, but here in Minnesota, when they used to do E tests, I heard many times talk that if you failed, put a half can of Sea Foam in your gas tank when it is about 1/4 full. Drive at least twenty minutes and then get tested. It was said that this could get you through. It wouldn't fix your problem, long term, but may get you through in a pinch if you cannot find a solution to your problem. The Sea Foam in your gas will not harm anything. Just thought I would mention it, not necessarily advocating it. I never did it because I never had a problem passing.

Thanks for the tip. I will keep it in mind if needed.

however, I would really like to get my car running right. I'll get this thing figured out....

[Bigerik]

Well, I actually took it in to a real garage to have it diagnosed.

I had been talking to a LOT of people connected to emissions testing up here, and EVERY one said with the numbers I have, the catalytic convertor is bad. A couple of them mentioned the Magnaflows having frequent issues without being prompted.

Took it in for the test, and I gotta say what they did was very interesting. They drilled a hole in the pipe in front of the cat and measured emissions there. Then the tested after the cat. The results were interesting to say the least:

At idle, my car is running so well that I passed WITHOUT a cat:

Curb Idle:
_____ Limit ___ Reading
HC _____ 200 ____ 101
CO ____ 1 ___ .57

So, all that tune up stuff is working well.

At 40 km/h the result was a little different:
____ Limit ____ Reading
HC _____ 54 _____ 96
CO ___ .3 _______ .46
NO ____ 396 ____ 1192

They said these numbers were very impressive and showed that the car was running really well.

When they tested after the cat, they found:
_____ Limit ______ Reading
NO____ 396 ____ 598

Now, they said a good running cat should knock a minimum of 1000 points off the NO figures. Mine was was only reducing me NO number by about 600.

What does this all mean? Well, in my car. it certainly appears to be the cat. Based on the discussions I have had with MANY people in the industry up here, universal or high flow cats are very commonly the issue when the results show up like mine (Good HC and CO. Poor NO). Does this mean that all Magnaflow cats are bad? Hardly, but there have been enough bad ones found in Ontario testing that it is considered common for them to cause a failure.

Hope this helps someone else in the future.