Yes, my paranoia was not unwarranted... I failed my emissions test today. I even swapped my JWT ECU with my stock ECU earlier in the afternoon. I went for a "spirited" 20 min. highway cruise. When I got to the testing station, my car was pulled in and run about 5 min. after I got there.

My hydro-carbons was a pass but close!
I failed the NO test... by a BIT...



The guy said that it might be my EGR. Now the problem with EGR is that a diagnosis is a pain in the a$$ because there are so many things to look at and there is no guarantee that any of them might be the cause of the problem! Even on the org I am unable to find any links on how to test the EGR system. I haven't checked my FSM yet. Even so, that is just a guess... it could be my stock cat for all I know! But considering that the fail was so marginal, I might be able to get away with something smaller.

I need some help and suggestions on where to begin. There is a shop behind the emissions test centre that will do an EGR system test for $140... check all hoses, valves, etc... but I am hesitant to pay that much... but I don't know what else there is, for me to do!

 

Ive heard of guys gettin entire EGR system cleanings at Nissan for around $140-$200. So definetly dont spend $140 to have it checked..

For kicks, go back tomorrow and see if maybe youll pass on another machine..I failed for brakes once with my last 81' CJ-7 Jeep....well after i failed I turned right around and went back and said I had them adjusted...they tested them (different person, different machine) and I passed..that was NJ

good luck
-matt

 

Did you have to let your car idle for 5 minutes? I would have been inclined to shut it off, until I was called. Then give it a little gas in neutral before you get hooked up.

 

I turned the car off while I was waiting.

I did pass the idle tests though... it is the 40 km/h test that I failed the NO on.

 

i have to get my emissions tested also. Is there anything I can do to clean the egr system?

 

I wouldn't have shut the car off at all. If you have a day or of free time you could clean the EGR yourself.

 

Well I think you suppost to leave the motor running the whole time.

 

Maybe you failed cause the ECU wasn't plugged in long enough? Maybe not just trying to help you out.

 

Your mechanic is probably right about it being your egr system. The cat does not control NO emissions. NO is controlled by combustion chamber temperature. A high combustion temperature results in high NO production, and the egr is used to lower combustion temperature during cruising (which is why they test at 40 km/hr). Your problem is probably due to a clogged egr valve or pipe.

 

You should have let the car idle and not turn the car off. The cat needs to be hot and so do the O2 sensors. Not sure how long you left the car off though so that may or may not be what tipped you over the edge. There are some gas supplements that can help if you are just failing by a little.

 

Put the JWT ECU back in. I have a moded 300ZX TT and passed with flying colors...the guy even checked 2x because the reading were so low.

The other thing is put the stock y-pipe back. The pre-cats are for NO at startup.

 

buy a fuel additive that's called pass-emissions made by CRC, or somethinglike that, it helped me pass. and an oil change. good luck.

 

Just to clarify, the car was only off for about 5 min. as soon as I got there... I thought that idling the car for any amount of time would only increase temps. so when they did the 40km/h test, the NO readings would have been higher... ?

Th JWT ECU advances timing, so according to the mechanic, it would have made my NO reading even higher... otherwise he was going to let me pay to retest on the spot.

I have done a search on cleaning EGR system on the org and there are little to no threads discussing exactly how to do it - most guys do not want to touch it with a 10 ft. pole it seems. Is it really that difficult to do?

Emissions aside, are my HC and NO readings a little high even if they were on the pass side? Is all that affecting performance at all?

 

Is that just a band-aid fix or does it actually clean out the combustion chamber to reduce NOX?

 

Speedemn I have diagrams of the whole EGR. Looks like that's all you'll need to get it done. At least it shows all the parts involved.

 

Yeah man that would be awesome... my e-mail addy: speeedemn@hotmail.com

 

hey could I get a copy of that also? dmangru01@verizon.net

 

I passed my emissions easily with the JWT ecu. Not sure, but I thought it also tweaked the Air/fuel maps to run more lean (which will only help you with emissions).

 

http://www.wivip.com/3_5_1.PDF

 

Wait a minute... I called JWT to confirm, because I switched the JWT for my stock ECU and the tech guy there gave me the impression that the a/f ratio is richer but only at WOT... so in my case of the 40 km/h roll on test, it would not be a factor, either way...

So is it lean or rich? I was thinking lean too but switched ECUs because the tech at JWT said rich... ugh maybe I should just go back with my JWT ECU and run it and I should pass!

 

I have a JWT ecu. In closed loop mode (which is what it will be in at 40 km/hr and at partial throttle) and at idle the afr is perfectly stoichiometric. Or rather, the afr oscillates slightly above and below stoichiometric.

Like somebody, said, high NO may be a cat problem, but it is more likely due to a clogged or malfunctioning egr.

 

Egr testing is very basic. Feel under the valve for the diaphragm. At idle, push the diaphragm all the way up and it your vehicle will cut off. That means your passages are clean enough. Rev it a few times and you should feel it flutter a bit. That means vacuum is going to the valve.

Do you have a high flow cat? Those suck at reducing emissions. Use 91+ gas if you are not. Running too lean will cause your no readings to go up. Running rich will cause it to go down.

 

band-aid fix, but it works great. you only have to do it once a year?
It may not be your egr system and egr valve hardly ever breaks down....

 

But it gets clogged up like a mother, that's why you need to at least clean it.

 

For me since i'm in california... they have recently or for not so long updated their smog tests. IT is a B!tch.

I failed 3 times =X. First time it was knock sensor and the o2 in the cat because that was the reading from ecu. Second time after changing those i still failed and had them diagnosed my car leading it to cat (car sound from Warpspeed), then got cat repalced. third time failed cuz the EGR clearing but passed all emisions.

I had a carsound cat which kept failing my emissions. The HC and the NOX "NO" was the problem. They replaced it with a 3 way version cat (lowers HC CO NOX) and it passed smog but not the EGR clearing. No readings from the ECU at all. The mechanic then read to me from this manual from the CA gov that the Nissan 96-99 had problems with the EGR clearing a lot. Well in CA for all I know so far. So he is sending and scheduling me with a "referee smog place" ran by the gov so I can pass the smog test for sure.

I also took the time to go to Nissan Dealership Auto Service to ask them for a sheet on how to clear the EGR for a nissan maxima 96 A/T and it was so hectic. Like 7-9 different stages in warming up your car and then a 2nd run to finish it. It was like 30 min + work and each stage has it's own rules and timeframe. =/ I told the guy why is it so hectic and the guy said that's why we have guy working on it for 2.5 hrs at times. It is probably much easier if you have a dyno style track or soemthing to run on.

=[

 

this is when its good to have a friend who does inspections

 

can i get a copy of the diagram as well thx email urmab1@nyc.rr.com

 

How many kms do you have on the car? Basically cat's are only good for approx 200,000kms by then they are so plugged up there's no way it'll pass without changing it.