so i failed the my test todaypassed everthing but "NO" ppm at 15mph barely passed at 25mph. 15mph: "%C02 = 14.2" "%02 = 1.2" "HC(ppm) tested at= 53, max = 110" "CO% tested at .01, max= .71" "NO(ppm) tested at 970, max 772" the smog guy said its my egr, either its bad, or it doesnt have enough back pressure to open, because of my full exhaust" headers, highflow cat, and flowmaster muffler, it should be good because i replaced it 3 months ago and it has about 1,000 miles on it so i;m guessing it doesnt have enough back pressure to open, what does everyone else do to pass smog? is there a better egr valve i can use or what, the one i have on there now was from autozone, "wells egr132" theres no way i'm putting all my stock exhaust back on so what can i do , i know some one else has had this problem before, i guess i'll do some more searching and hope i find something but if anyone has any ideas please help me, thanks- scott -

Put the stock chip back in it, get the car fully warmed up, then take it in for the test.

i tested it with the stock chip and i had driven the car for 20-30 minute befor, to get th cat nice and hot, thanks for the reply though

so i did some more searching and i;ve come up with some possible culprits, i may be running a little lean, is there any way to richen it up a bit withought tunning maybe bumping up the fuel pressure, i allready have it 3/4 off the way up to maximum, was about 1/4 of the way up stock.

also when tested i was running 2 deggres advanced timing, would setting it back to 0 give me a noticible drop in N0x ? thanks again -scott-

learn is good. your probally running rich, that will fail you.

Running lean is what will help cause too much NOx. Definitely retard the timing back to stock.

do you think pulling it back 2 degrees " at TDC" will it cut off 200 points of NOx or should i set at like 1 degree retarted " 3 degrees total"

plus what grade of fuel would be best , i always use 91 from mobil/chevron, would 87 be better or even the 100 octane racing fuel at 76 its 5 bucks a gallon but i can aford $15.00, 3 gallons, to pass smog any suggestions

is ther another type of egr i can use, the original one was a negative pressure, would a positive pressure or non pressure egr help me? is there another egr i can use that will work with my low restriction exhaust, part numbers? i know someone else has to have had this problem so what the fix? -scott-

your not that far off, so you are getting at least some EGR. normally if the EGR valve isn't working at all NOx is much higher than what you have, usually at least 1500 PPM or higher.
not knowing what your per cat CO is, i would say you are a little lean.
you may have some combustion chamber deposits which raise compression some & also can cause per ignition which raises NOx.
setting your timing back 3 degrees i think may be enough for you to pass & you will still be within the + or - 2 degrees that Cali requires. a small timing change can make a big difference. also pulling a little timing in most cases bumps CO up a little bit which will also help lower combustion chamber temps.
bumping up your fuel pressure a little can also help, but i would try the timing first & see where your at.
as far as fuel goes, stay with what you have been using for now.

a non back pressure type valve would be best.

bam..... that what i was looking for, thanks so much DENN_SHAH, sounds like some good advice, i ran a product, called g2p, guranteed to pass, but the guarantee is only worth so much, $8.00, i use fuel injection cleaner products prety regulary, and always buy good gas, so i'm probaly not to dirty internally, for a 19 year old car. so i guess my plan goes as follows some good old chevron 91, set my timing 1 degree retarted, 3 degrees from where i am now and about the non back pressure type egr where can i find one? part numbers? what vehicles came equipped with one? thanks again for the advice much appreciated - scott-

as to where to get a non back pressure EGR valve, i can't help you.
as far as i know, the factory back pressure Delco valves all have a letter at the end of the part number on the valve, N for negative & P for positive, with the non BP valves having no letter at the end of the number.
you may be able to get one just by giving them the number off the valve without a letter.

1988-305-tbi, any chance of getting a confirm/deny on if retarding 3 degrees worked for you or not. I have a new exhaust setup and will be changing a few other things before my inspection date and would like to know in advance what to change if I fail. Thank you

havent done it yet..... probaly later on this week, and ill post the results as soon as i hear pass/fail, i'm also going to fill up with 87 octane, i figure since i'm pulling the timing i should also use the appropiate fuel

bad news... so i decided to pull my timing today, and when i went to check it it was already at 0, i retarded it 2 degrees, but i thought i was 2 advanced, so this means that when i failed my test originally i was already at factory settings, i'm going to play with the egr valve 2morrow and hopefully it passes, if not i got to pay some corrupt smog guy $150 to pass it

I remember when I went last year my car would not pass. They had to change some hoses in which was what made it pass, but also, the retarted my car a bit. When I got the car it sounded like it had a nasty cam in it and didn't scoot around to good, so I took it back and had them advance it and now she runs like a charm. But ya, maybe you have some dirty hoses if the timing retarting doesnt work.

sso.... bad news...i failed again, but even worse

so i pulled 2 degrees of timing and went back and things got worse

15mph: "%C02 = 13,9" "%02 = 1.5"

"HC(ppm) tested at= 84, max = 110" "CO% tested at .01, max= .71"


"NO(ppm) tested at 1158, max 772"


i realized there might be a culpritt holding me back.. my car is running hot as hell.... i have a 160 thermostat and the fan was switched on the whole time..., during the test my car was running at 200+ degrees, my car used to always run cool, but the original waterpump went out and i replaced it with one from auatozone and now my car always runs hot. with the old pump, in the summer time 110 degree weather the car would run at 160 degres all day long as long as the fan was switched on, but since the water pump change it runs at 200 degrees with the fan switched on all the time, all i changed was the water pump and this happened, the smog guy told me that the car might pass if the opperating temp was much lower, so now i;m gonna try a new water pump, if this fails i'm just going to shoot myelsf in the head

finally passed...... nox went from 1158 to 451.....i pulled the orifice washer out of my wells egr valve to allow more flow and i passed with ease, but i barley passed hc's tested at 108 max was 110, so i'm running at bit rich now.... but since i did the egr mod my car is running awesome much more power at wot and just crusing i give it 1/2 the gas and it runs just the same, long story short a working egr is impotant for power and i'm sure my mpgs will go up too

Do you know exactly what the higher air flow did to effect the emmissions? I've failed 3 times down here in san diego and even replaced to the wells egr with no difference. I run about 1200 NOx readings. How is the more air flow making you run rich? I plan on taking the washer off and also replacing the egr solenoid to see if that can helpl me pass.

HC is unburned fuel which can be cause by a miss, low compression, excessive blow by, dirty or contaminated oil, too lean or too rich.
CO is the indicator of rich or lean.
your HC probably went up because either the EGR valve is flowing a little too much or your a little lean, or maybe a little of both.
its hard to say for certain if you are rich or lean with out pre cat gas readings & not knowing how well your AIR injection system is working.
the EGR system works by letting a little exhaust gas into the motor which cools off the combustion process.
with all other things being good, too much EGR & you have a lean misfire with high HC, not enough EGR & you have high NOx with low HC.
running a little on the lean side can also be a cause of high NOx.

as an example, ULTM8Z posted these numbers up in DYI PROM a few days ago,
cold cat before light off
HC => 2108
O2 => 3.5%
CO => 3.18%
CO2=> 10.3%

hot cat after light off
HC => 50
O2 => 0%
CO => .08%
CO2 => 15.3%

by the first set of numbers he is running a little rich, but with a good cat it cleans up quite well.
i see a good cat because of the change in his O2 & CO2 readings.

Hey guys thanx for the help. I put the egr valve on with no washer and installed a new solenoid and passed with flying color. NOx was at 149 and max is 779. I was dealing with this problem for a month a half.

hello guys, im new here so please bare with me, i read all of your threads and kinda understand that my problem can b fixed by messing with the EGR and pulling the washer out. Now, im not car tech so i have no idea what the EGR is, i took my car to get tested today and failed with the following readings:

@ 15 MPH:
HC: max: 93, read: 55
CO: max: 0.50, read: 0.05
NO: max: 595, read: 1272 "FAILED"

@ 25 MPH
HC: max: 61, read: 24
CO: max: 0.41, read: 0.00
NO: max: 498, read: 655 "FAILED AGAIN"

Now im not sure if this info can give you any idea of what is going on with my car or what i can do to fix it. I dont want to take it to some asian mechanic thats only going to lie to me and do stuff thats only going to mess up my car, or do extra stuff just to get money outta my pocket.

PLEASE ANY HELP WOULD BE APPRECIATED AS I NEED TO GET MY CAR GOOD THIS MONTH SINCE MY REGISTRATION NEEDS TO GET PAID...

THANK YOU !!!