Forced Induction High No Levels At E-check

[dustang50]

I have an '02 GT with a KB blower, have had it set up this way for 5 years with no problems. In Ohio you must pass an emissions check every two years. This year I went & it didn't pass because of high NO. Everything I read on this says that it's possibly a temperature issue. I'm not sure if it's because I read that, but the supercharger feels really warm to the touch (can't keep my hand on it for more than a second or it'll burn) and I don't think I've noticed that before. Anyone have similar issues? Is the high temperature of the supercharger normal? Any ideas on how to pass this damn e-check? I changed the SC oil last week & the oil looked fine.

 

[wmburns]

Just wondering. What is the status of the EGR system? Has it been deleted by chance? Consider cleaning the throttle body EGR passageways.

Any DTC codes?

How about the PCV system? Excessive PCV blow by?

Double check the vacuum lines to/from the DPFE. Also the DPFE sensor fails frequently. Frequently enough that if no other reason can be found, I would consider replacing the DPFE for diagnostic purpose.

 

[dustang50]

EGR system has been deleted. No codes. PCV system is in good working order (at least it passes the shake test!). I've passed e-check twice with the exact same setup, nothing has changed. I just took it back yesterday & it failed again, but with higher NO readings. I even went to a closer location thinking that the lower car temp would help.

Where is the DPFE sensor located?

 

[wmburns]

EGR system has been deleted.
Where is the DPFE sensor located?

The MAIN purpose of the EGR system is to lower EXHAUST temperatures in order to reduce NO. IMO it's naive to think that the excess NO isn't related to the deleted EGR system.

As for the location of the DPFE sensor, one would expect that you don't have a DPFE sensor since your EGR system has been deleted.

As for why it passed 2 years ago, how about the motor was two years newer.... Less blow by. More efficient combustion in newer motor. Even different blends of gas could have an impact.

Consider switching to a larger super charger pulley. Pulling some timing. Or re-adding the EGR system.

 

[trinity_gt]

Cats and EGR deal with oxides of nitrogen.

You said it passed in for the last number of years "set up this way." Is everything the same? Did you make any changes (e.g. delete the EGR) since the last emissions test?

Does the car still have the factory midpipe?

How far over the limit is your reading?

How are the other metrics (e.g. CO, HC etc)?

 

[dustang50]

• The only thing that has changed since the last e-check is the drivetrain - new clutch, flywheel, driveshaft, differential, gears - and new coil packs. Everything else is the same.
• The midpipe is a Bassani w/ cats.
• The NO was over by 200ppm the first time, 400ppm (which I believe is almost double the allowable limit) the second time. All other readings were normal/passing.

Could the cats have gone bad? Should I run the car longer & get them heated up more? Could the coil packs be the culprit?

One more question - is it normal for the supercharger to feel hot to the touch? Not sure if I'm just noticing it now or it's always been like that.

I don't drive this car frequently - supercharger was installed at 75k miles, and I'm at 88k now. Not sure if the lack of driving would have any ill-effects. But now I drive it even less - I need the e-check for registration that expired 3 months ago!

 

[wmburns]

Could the cats have gone bad?

The Cats shouldn't affect the NO levels. So heating up the cats more won't make any difference. Remember that it takes high temperatures in the exhaust to create NO. Once created, NO is fairly stable. Which is why the cats don't have any effect.

EGR works by reducing the overall volume of the fuel/air charge. This reduces the overall power of the charge. So anything that reduces the total fuel charge has the possibility to reduce NO. Other options include lower CR, making the AF ratio slightly richer. Don't over do it because excessive unburnt gas could cause a fail in other parameters. Bottom line, if the AF is too far out of adjustment it will create SMOG issues.

I don't really understand the logic of removing the EGR system in the first place. The PCM locks out EGR during WOT. Therefore the EGR doesn't affect performance at WOT.

One more question - is it normal for the supercharger to feel hot to the touch? Not sure if I'm just noticing it now or it's always been like that.

Check the Supercharger bypass valve. I could see if the bypass valve isn't working like it should that could make the supercharger run hot.

 

[trinity_gt]

The Cats shouldn't affect the NO levels. So heating up the cats more won't make any difference. Remember that it takes high temperatures in the exhaust to create NO. Once created, NO is fairly stable. Which is why the cats don't have any effect.

Correction: Proper three-way catalytic converters take NOx and convert it to oxygen and nitrogen (N2) gas along with the two-way standard of CO to CO2 and HCs to water and CO2. A working converter will reduce NOx although if the engine is producing excessive levels due to high chamber temperatures it can be overwhelmsed.

I will suggest that the "high flow" style of converter used in aftermarket midpipes are of little use for emissions reductions, at least not for long. I saw the same thing with my MRT catted H-pipe: Over time the readings got worse and worse until the car failed emissions tests. Replacing the MRT with the factory midpipe resulted in readings that essentially matched those I saw when the car was a year old and bone stock. Factory cats are very good at what they do.

 

[usaf_branham]

Bypass e-check... Get on ohio bmv website and submit a package for collector plates. You'll have to send them an application with pics of the car and receipts for your mods totaling over 5k. I have had the plates for about 2 years, it's a lil more of a pain to get your tags (can't do it online), and it's like $5 more a year... but worth not having to mess with e-check.