Hello,
I am in need of help what to check next. 99 SL1 260,000 is failing emission for NOx.
I was researching on SaturnFans.com but the site has been down for four days.

-Noted the HC is higher than normal for this car, but it still passes for HO.
Previous years this car was (GPM):
HC 0.18 CO 0.00 CO2 288.3 NOx .99
-6 months ago car got new:
PCV, TPS, MAP, idle control valve, O2 sensor, temperature sensor, ignition coil packs, spark plugs ( BKR4ESA-1) and wires, and ICU.
1st test
HC 0.59 CO 4.76 CO2 249.0 NOx 3.36
-After 1st test, I sea foamed throttle body, sea foamed gas, sea foamed crankcase, new oil change, new air filter, cleaned EGR, and put half gal 99% alcohol in 1/4 tank. 2nd test were basically no change:
2nd test
HC 0.6 CO 4.8 CO2 288.3 NOx 3.2
-After 2nd test showed no change I bought a new EGR, cleaned exhaust port from EGR to muffler (compressed air and brake cleaner). And did a quick spray down on the hoses to look for a vac leak, but didn't see anything.
Third test:
HC 0.68 CO 4.67 CO2 257.3 NOx 1.98
-Third test was much NOx improvement but still failed.

Limits
HC 0.80 CO 15.0 CO2 ---- NOx 1.50

Sorry I don't know how to convert GPM to PPM, but the general idea still applies.
----Car has no codes, (there is fraying starting on the flex pipe between manifold and cat - could this be leaking and causing my issue?)
The fact that the HC and CO2 are higher than normal tells me something is unhappy. Before I buy a new catalectic I want to eliminate everything else.

On-board monitoring:
Test $02 Data: Pass
Test $04 Data: Fail (TID: $04 CID: $20 ; Limit 512 Results 63232 (Steady State catalyst test bank 1))
Test $07 Data: Fail (TID: $07 CID: $0d ; Limit 768 Results 64256 (EGR decel test -or- Full EGR intrusive idle test MAF Out of range low))
Test $0E Data: Pass

The above to me hard to understand.
Are these results legit or is there something wrong with my software? I say that because I read somewhere that numbers could be hitting the limit in a 16-bit word if they are scaled using signed 2's (or was it 1's) complement math. If this sentence doesn't make sense then disregard.

-What should my MAP be reading (Pa)?
-Will check STFT and LTFT tonight but how should I perform this test properly? I know to look for ą10
Can I be in neutral or do I have to be driving in gear?
Should I check LTFT at a few different RPMs or at WOT?
-Anything else I could check while I'm in there?

Thanks in advance!

 

Do they test this car on a dyno? If so is it simulating a road test? I have not had a car smog tested in 44 years since I left California. We tuned cars to HC and CO only. Just started with four gas analyzers and I switched to Diesel repair. Now they are the major pain to get right. Gasoline trucks are easy.

 

Your mode data is telling you bank one failing.
Replace your front O2 with the denso equivalent of the OEM part. Don't remember the part number but I probably have an extra on the shelf. Don't know who has the OE contract for front O2 sensors for an AC Delco aftermarket, but I highly doubt denso was the low bidder.

The reason I suggest this sensor in particular is because it is identical to OEM, also known as OEM.. Back in the day, if you bought one at the dealership, you'd open the Saturn/GM box and find a denso part. Didn't even bother getting them private labeled after a while and people had caught on anyway and were just by the denso somewhere else for 20 bucks less.

In my experience, the Bosch front O2s specified for the s cars were shayt and ran even richer than the car does normally. Dumping gas hence higher emissions.

Since the hydrocarbons are also high, you may also want to do an injector leak test to see if extra fuel is sneaking its way in through a leak. The front O2 response on these vehicles directly determines the pulse width for the injectors.

Additionally, how much oil do you burn per 3000 mi?
If it is excessive, the extra emissions maybe coming from burning oil in the cat.

It's an SL1 IE SOHC. Didn't burn oil at the rate the dohc did, but at that mileage you're likely going to have ring wear, oil control ring seizure, and valve guide seal issues.

Wet and dry compression test May shed some light on the overall health of the engine.
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Actually I need to be careful because the 99s and up had the precat so the front sensor is likely not identical to the one used during the rest of the '90s. However I would still find the denso equivalent of the GM part and use that. I don't know if RockAuto still stocks the front O2s for the s cars. Maybe I'll go have a look.

 

The number one thing that produces NOx is heat and compression. Is EGR fully working? Carbon buildup?

 

Appreciate it! I will start there and see what happens.
And yes it does burn quite a bit of oil and I think it has some blow by. It could use a oil catch can. Replaced the head 60k ago but didn't open the short block.

I do have a Bosch O2 in there now so I will order a Denso. RockAuto suggests it is the same O2 for 1995-2002.

 

I replaced the EGR before smog test 3 but it is aftermarket. The desired EGR graph and the EGR performance graph are mirrored fairly close. I suspect there is a lot of carbon build up, I cleaned ports best I could but haven't been ambitious enough to take the manifold off to clean in there too.

 

If you don't clean the pipe leading to The EGR, the new EGR will end up like the old EGR much faster than you would ever want it to.

The following involves listening to raw exhaust and potentially having carbon laden goo expelled in a somewhat unpredictable manner. Wear hearing protection.

Quite hillbilly, but it does work.

Perform at your own risk:

Get the engine up to operating temperature. Turn off the car.
Remove the EGR. Spray a liberal amount of carb cleaner into the pipe leading to the EGR. Whether you can see it or not, it is caked with carbon deposits. Do not spray half a can into there at once. Remember it is combustible and will accumulate in a hot area. In other words, don't make a bomb.

Let it sit for 5 to 10 minutes as it loosens the carbon.

Unless you want carbon goo on the underside of your hood and who knows where else in front of the vehicle and under the hood, wrap a thick towel around where the EGR mounts. You need to leave some slack for when the engine is running and the exhaust exits that pipe.

Hold the towel tightly or if you dare, come up with a way to secure it over the EGR port. Personally I never let go of it. Where heat protective gloves. Put on your ear protection and wear eye protection

Have a friend crack and start the vehicle. No exhaust equals loud.

What's the vehicle starts there's usually an initial slug of dissolved carbon and maybe some engine stumbling and combustion of residual carb cleaner in the exhaust feed to the EGR.

Don't let go of the towel

Have your friend pulse the throttle up to about 3,000 RPM repeatedly, then run it there for 15 seconds, and a final pulse or two to 3k. Keep your head out of the way should the towel get away from you. Hot raw exhaust is not something you want blowing in your face.

Turn off the vehicle. Remove the towel being sure to invert it so that the goo doesn't come running down on everything.

Examine the goo of your labor, knowing that none of that will end up in your EGR.

I'm sure there are more civilized ways to clean out the carbon from that pipe. I'm simply passing on something that was suggested to me and absolutely keeps the EGR, new or cleaned, from quickly getting deposits.

Don't do it inside your garage if you can do it outside due to a very small fire risk and keep it extinguisher nearby, and hope that people down the block are not home to hear it and call you in for a noise complaint. Or bribe them with beer etc.

Again, perform at your own risk. I'm two for two and not dead, so there's that.

 

LOL!! You da mann