Tuning Issues!!! - Bad Emmitions, Failed Tests

[erik]

I think we should have a "tuning" topic. See my frustration on the Misc. under 'Emmitions Problems'. Not only is it important to tune for WOT imo, but it's important for the 'everything in between' as well. The emmitions place is probaly a good as place as any to fully tune your car, BUT it gets expensive and tedious after not being able to correctly diagnose the problem quickly.
Most town driving and autocross raceing is needed for a FULLY (all rpm and power range) tuned car. And I realize that the S-afc is not alwase the best tool for diagnosing it. Just tweaking it untill you find a fair approximation to what your car needs for the full range for fuel and air.
Some have had good luck with a TMO datalogger. Others have had good luck with a wide band O2 sensor. I have the TMO but no wide band O2 sensor, just the factory one. But I figured the TMO logger would have told me something. I guess I don't know how to read it fully, yet. All things are relative. Timeing, trottle position, RPMs, intake temps, duty cycle, etc.
I know a lil enough to say I have a fairly good report here: So why is my HC's bad???????????
You get the gold star for figureing it out.

erik:p

[Van]

What are your fuel trims? Lo, Mid and Hi...

[erik]

- 140% across the board. On high, med. AND low. No changes during run.
- A cycling .04-.98V on the O2.
- The AFC was set at -15% a/f mix for low and -9 to 0% at the high throttle up to 5500rpm.
- High/low throt points were 65 and 80%.
- Max rpm run was 3594 rpm.
- Timing was at 9 at idle and thru the test was ranging from 17 to 39 during accel and decel.
- Injector pulse width is from a 2-4milicycles.
- Coolant temp at 198deg.
- Barometer was a steady .83.
- Air temp for intake was 109deg.
- Karmens at peaks of 300 to 400hz.
- Virtually no knock. 1 count.
I guess they are just looking for a factory car setup. I know many modded cars run rich. But this is ridiculous. Even after bringing my setup to near stock cond. again.

[Van]

Originally posted by erik
140% across the board. On high, med. AND low. No changes during run.
I guess they are just looking for a factory car setup. I know many modded cars run rich. But this is ridiculous. Even after bringing my setup to near stock cond. again.

That 140% means that you are WAY lean, so lean that the ecu can not gain control. IMHO, this is why you failed emissions.

Too lean of an a/f mixture will sometimes result in an incomplete burn, raising CO and HC. There is your HC that is just a bit out of whack. How close was your CO?

What other fuel trims have you set-up to go thru emissions?

We should meet up sometime soon and I'll see if I can help you tune her before you get her all the way back to stock and sell her, hehe.

[erik]

From a 15.3 CO to the last attempt at 3.7. Passing is a 20.
I datalogged the 3rd attempt. Last mondays 4th attempt I figured on passing and didn't bother to ask if i could log that one.
Anyway. The 3rd time that has the readings mentioned above are with the afc to -15% from 1000-7500rpms. The high was at -9% from 1000 slopeing gradually up to 0% at 5500rpms. It then took a stronger swing to +17% up at redline.
The 4th run was a lil different in AFC settings. I just dropped the high setting to full -15% so everything was consistently right there. But I threw in the stock fuel pump, new wires, reconnected the crank case breather, and turned down the boost a lil more to a max available 12psi. .. Running 85 oct. again. (Maybe now I should run 91oct??)
That being said... The 4th run was way lower in the HC.,CO., and the NOx than the 3rd run. Even the CO2 was just a smidgin lower as well. The HC's went from 6.0 down to 2.8 for a passing score of 2.5. .. I was sooo close!
Apart from that I am definitely missing/hesitating under load still, and I think it's ignition relevant. Although, it could be just running to lean like you said.
I have never messed with the timing on this car. I wonder if advancing it would actually harm it? (note the readings stated above) I still think It could be the coil or some throt sensor or something in that genre. No? Because the testing mostly looked good on the charts. I wonder since the places that it didn't, it was sporadic, I'm thinking it could be the higher throt position that it wants to miss. And the lower rpms it just wants to bog and hesitate. Sounds like a timing issue.

[MaxDraco]

Hey Erik - how's it going ?

Do you have a CAT installed for the emission tests? If not, try that - it'll make a world of difference.
MD.

[XakEp]

i know this sounds bizarre, but get a load of this...

My friend's car couldnt pass emissions. It was putting out too much CO2... The dealer couldnt figure out why, nothing...

It was the fucking GAS CAP. No joke! The cap wasnt allowing air back into the tank, forcing the car to fuck up its idle fuel trims. How do we know it was the gas cap? We replaced it and the car passed with flying colors...