Failed emissions! Help!

[ALXTTA 1]

Failed IL IM240 test for the second time in my TTA, and am looking for advice [note that all values below are GPM.] The car is in great shape and runs well w/22k mi and ran a 13.4@103 last summer at Route66 w/a crappy 2.2 60' in 90+ deg heat and very high humidity (pump gas and street tires.) Only mods to the car at this point are K+N, jacob plug wires, adj fp reg, adj wg, valvecover breather (replaced with stock cap before tests), 3" cat, 3" edelbrock cat back, and thrasher 93 chip (replaced w/stock chip before tests.) FP was left at 45 (line off.)
Here's the lowdown. I took it for the first test w/o realizing that the stock cat had been previously gutted (doh!) It also had a bit rough of an idle. It failed w/an HC of 3.6 (limit .80) and barely passed CO w/14.2 (limit 15.0.)
This is when I checked the cat and found it gutted, so I replaced it w/a 3" high flow unit. I also replaced the (lazy) Bosch O2 sensor w/an AC Delco and replaced the spark plugs (AC R42LTS's, gapped at 0.35".)
The idle improved quite a bit, and the idle vacuum reading on the autometer boost gauge went from 12-13 to 15-16.
Took it back for the second test, only to fail again! This time, it read HC 1.88, CO 8.7, and CO2 347. (NOx is not read on their tests.)
I know that the high HC indicates unburned fuel, but I'm not sure why this would be. I'm hoping to get some TL readings to help sort it out, but I have very little time left to get it to pass. I've thought about lowing fp, but I don't understand how this would help on a closed loop system (unless BLM's are off the chart) and would think this might even hurt results by worsening the injector spray pattern? Any help appreciated.

 

[2QUIK6]

You indicated the Thrasher was replaced with the stock chip right, cause the Thrasher operated in "open" loop at idle and will fail, had the same problem, but passed easily in my TTA after replacing it with the stock one.
*
Also, are you failing the high speed or the idle test?
If the idle test, then crank the IAC screw till your idle rpms are around 900-1000, that helped my tuck with a TPI ignition pass after failing miserably the first go around at 650rpm idle.
Also, make sure the cat is hot, leave car running if you have to to keep it hot.
There maybe something else wrong if you cat is good and you have the stock chip in. Any scan tool numbers?

 

[Turbosix6]

45 psi on the reg sounds high for the test - I would turn the reg down at least 5-7 psi - Also, is it possible for you test the emission levels without putting the car on the state computer?? Lastly, you might want to try a hotter plug and a bottle of that inspection pass additive they sell at the auto parts store.

good luck

 

[ALXTTA 1]

2quik6 - Yep, swapped in the stock chip for both tests.
The IL test doesn't really have an idle and high speed test. They have a dyno test that is ~5 minutes, that's supposed to simulate city driving in the first half and highway in the second (with accelerating, decelerating, and cruising 0-55 mph.)
From what I can tell, HC's were lowest during steady acceleration and cruising, and worst during short blips of acceleration.
One concern you mentioned that I did think of -- while I was doing the gascap test (during the entire test of the car in front of me), they had me shut the car off. The engine stayed warm, but I wonder how much this allowed the cat to cool off?
I'm hoping to get some TurboLink #'s...but my only laptop (from work), is Win2k with no floppy drive!

turbosix6 - I thought that a stock TTA fp regulator was 45 psi??
I would like to find somewhere to take the test before I go back for the official one, to make sure it will pass this time -- and I will pour some form of alchohol (gtp, heet, etc) to the tank before I test it again.

One thing I did forget to mention - when I changed the plugs, the old ones looked OK. They did have a thin, dry, "copper-ish" colored coating on the electrodes...if this indicates anything?

 

[FJM568]

What brand of plugs did you put in and what are they gapped at???

 

[ALXTTA 1]

The new plugs are AC R42LTS (the stock plugs), gapped at .035".

 

[sam87]

High HC indicates carbon deposits. I suggest using some xylene or GM top engine cleaner to clean intake & combustion area.

 

[Scott231]

As is always the combination to pass emissions:

1. Change the oil and filter the morning of the test (BIG help)
2. Use fresh O2 sensor
3. Run an Emissions chip (I sell 'em for only $15 shipped)
4. Fresh, factory recommended plugs
5. Ensure EGR opertion is proper.
6. Cleaning the injectors with a pressurized solvent is also a very good idea.
7. Replace fuel filter if it is well-used.
8. Air Filter should be cleaned if using K&N style filter, otherwise replace paper filter.
9. Consider replacing PCV if it is well-used.
   [/list=1]
   Doing the above will give you a greater than 95% chance of passing the emissions test assuming your engine mechanicals are in good order.
   
   Good Luck

 

[gofstbuick]

I worked on the I/M240 project in CA. The one thing I noticed is many people that had aftermarket EGR valves installed had HC problems. The problem is that those aftermarket EGRs that used restrictor washers may over regulate exhaust gas flow into the combustion chamber. If the flow is excessive, then it puts out too much of the combustion and since the engine ingest fuel (in the form of HC), the spark plug fires the mixture and the EGR introduces too much inert gas (spent exhaust), the HC does not burn and thus you have excessive HC. So even if you have enough spark to burn the mixture, if there is not enough O2, the mixture will only burn up to the supply of O2. What kind of O2 content is left? I/M240 is a brutal test, and relies on the engine running almost perfect. CA uses ASM 2525 and 5015, and you can get away with things that you would have problems on I/M240. Also, the gas benches on an I/M240 analyzer are lab grade and measure in exact grams per mile, whereas the benches in CA take a sample and average it.

 

[ALXTTA 1]

Thanks for all of the info, guys.

Scott - What are the differences in your "emissions" chip vs a stock chip?

 

[Ryan87GN]

If you want an easy solution, and lazy people work at the emissions testing place than it is easy. Just loosen up the exhaust to create a little bit of a leak. I dont know about your area emissions checks but in my area the employees dont even check for a cat. If you still cant pass it find somebody to bribe that can "make it pass"

HTH
Ryan

 

[gofstbuick]

Ryan87GN
If this is the I/M 240 system I worked with, that may not work, because this a constant volume sample system that draws the whole sample though the system and stores it in a bag and breaks the sample down into a percentage. The suction on the end of the probe is pretty strong.
Additionally, a report I'm reading appears that Ohio is using a idle test with ASM2525 (one portion of the CA test). I/M 240 is a different test, a 240 second test that runs the vehicle over 50mph. 2525 is a constant speed test wiht a constant load (25% of vehicle weight at 25 mph for 90 seconds. If you violate the drive trace for 2525 the emission result drift is not that critical and the violation period is quite liberal. If you don't drive the trace properly on I/M 240 (like not driving the trace smoothly), you may encounter problems, even though you don't have any drive trace violations. With I/M 240, who cares if the cat is installed, b/c if the cutpoints are anywhere close to federal test procedure (FTP) standards, if a cat is not installed or working properly the test will show. I don't mean to sound like a jerk about this, but I worked on the CA project for 2 years and I think I have a pretty good understanding of I/M 240

 

[ALXTTA 1]

Gofstbuick - You're right, they do no visual inspection whatsoever. Since this is the case, would putting my valve cover breather back in actually help lower HC's by venting them underhood instead of into the exhaust? Or would it make emissions worse?

 

[gofstbuick]

Unless your'e running extremely rich, having the closed pcv system intacted should not affect your emissions enough to fail. If the crankcase is full of fuel from a rich mixture, running the mixture through the combustion process may yield rich reading. I kind of looks lean. do you know what kind of egr valve is installed?

 

[ALXTTA 1]

No, I'm not sure. I'll check that along with a few other things (including, hopefully, some TurboLink numbers), tonight or tomorrow morning.

 

[ALXTTA 1]

gofstbuick - Checked the EGR valve, and it's the original GM part. It also looks like the PCV is original (I'll replace the PCV, to be safe.)

I'm going to take it for another test today (I'm also going to change the oil right before I go)...I have almost no time left to get it to pass. Since I need to lower HC as much as possible, I went ahead and lowered FP to 43 (line off.)

So which would have lower HC readings: stock cap or breather on the valve cover (oil fill hole)?

Should I dump in a bottle (or 2, or 3) of some sort of alky (g2p, heet, etc)???

 

[gofstbuick]

Stock cap closed pcv system (I gonna contradict my post from yesterday), b/c the extra fresh air from an open system may do wierd things to your mixture. The alcohol probably won't hurt. I hope this post is not too late.

 

[ALXTTA 1]

Argh!! WTF? I took it for another test Friday and it failed again! Luckily, I was able to take a "practice" test for $20 so it won't count against anything, but still...I'm back to square one. I lowered the FP to 43, replaced the fuel filter, changed the oil right before I took it, and put in a bottle of that g2p...only to fail worse than ever (4.6 HC, ~15 CO)!! Actually, I think the low FP was a mistake, it seemed to throw it out of tune. I think I'm going to have to suspend the plates so that I can keep my license because I'm out of time (my own damn fault.)

Sooo...assuming that putting the FP back to 45 will get me back to 1.8 HC and 8.7 CO....how do I get my HC down 1 stinkin gram per mile? Any more suggestions? I think that gofstbuck has the right idea, that's the HC are from a source other than a rich mixture...but what??

 

[gofstbuick]

Lets try two things. One try blowing propane under the EGR valve and see if the idle changes (you may have a leaking EGR diaphram). the other thing is the engine may be too lean, so slightly richen the mixture, by increasing FP (but don't go crazy). Do you have some type of scantool?. Also, you can call me at 916-255-4217 (7:15-4:15 pacific daylight time)