Emissions (NOx) on '90 S13 hatch

[Alfador]

This is the same problem I posted a while back in this threadhttp://forums.nicoclub.com/zerothread?id=153586

I bought the EGR solenoid (cost me about $100 for just the part) and the damn thing still fails. As a matter of fact the NOx went up

Old info (GPM):HC - 0.57CO - 8.99N0x - 3.63 (the limit for this was 3.0)

New:HC: 0.51CO: 10.016NOx: 3.376 (again, limit 3.0)CO2: 353.94 (no limit, but they tested anyway)

The CO did go up a few grams but I'm not sure how significant that is, and the HC stayed about the same but I'm pissed that after that the damn thing went up.

Okay, now something else that has become apparent to me since then is that the person who had the car before me did 1 very stupid thing (well perhaps several but only one that matters here). He didn't do a good job mounting the injen intake, and as a result there is a gash in the pipe worn from vibration against the radiator . I Have since taped this off temporarily but could that be responsible for this problem since the holes are behind the filter and MAFS?

Also as you mentioned before about the exhaust as you mentioned before, I am hesitant to address this just yet but if a lack of back-pressure does appear to be the actual problem would it work to get a silencer or two (double tipped exhaust) and put them in just for the test? I'm sure I could find one that robs enough flow to restore the backpressure if thats the real problem. I'm trying to get pictures of the exhaust and intake but I dont really have access to a camera right now. Thanks in advance.

EDIT: I forgot the title rule, so if someone could change it to match I'd appreciate it thanks.

[NISTECH]

yes the leaks behind the maf can make the car lean out. I am not 100% familiar with the type of measurements they use on the 240IM test in your state. So if you could post the limits of the other gases that would be helpful.

[Alfador]

Limits:

HC___2.00CO__30.00NOx__3.00C02 measured but no limit

They're supposed to list the average for a passing vehicle of that type but they generally don't.

[NISTECH]

Just playing the numbers game here. You readings are about 25% of passing I would say your not running lean based on that. I think you just have an egr problem. If you can hook up a vaccum gauge teed in between the BPT and EGr valves , position it so you can see it while driving, see how much vaccum your getting to the EGR. Typical is about 5". If not that is you problem. You then need to test it again before the BPT to see if the vaccum is available before it. If so your BPT hose may be burnt or your lacking the back pressure in the exhuast to close the vent in the BPT. If all you vaccum checks turn out ok you need to test the egr diaphram by applying vaccum tot he valve. It should hold vaccum and cause the car to nearly or completely stall. If it doesnt stall but does hold vaccum you may have restricted passages for the egr flow in the intake.