1991 240sx fails smog test HI no at 15mph

[demerske]

Hi all,

My smog test today leaves me clueless. Everything passed great except my NO at 15mph.

It was 1517 and the max allowed is 559. But the NO at 25mph was only 91 and the max allowed is 516. The smog tech was nice enough to test again but the numbers were about the same.

So what could cause this HUGH discrepency in NO measurement between 15 and 25 mph?

The smog tech thinks my egr valve is not lifting at 15mph although when I put my finger under the egr valve and rev the engine it lifts ok.

Any suggestions would be much appreciated...
Thanks

[compactfean]

I would recommend cleaning out the channels in the intake mani for the egr. Does the engine try and die when you manually lift thr egr when idling? Its a common problem on the ka motors after alot of miles.

[demerske]

I don't think I ever cleaned the egr intake channel (not sure what it is) but I have pulled off the egr many times and cleaned it and also cleaned out the pipe from the exhaust manifold to the egr. The engine stumbles at idle when I lift up on the egr valve, but I don't know if the engine stalls. Should it?

[compactfean]

Ask asoomal where the pictures are at on this post, there pretty detailed.
egr-help-t539477.html

[demerske]

Well I just checked my egr valve while the engine was idling and when I lift up on the valve the engine idles a litle rough but no where near to the point of stalling. So maybe my channels are blocked. I seem to recall that years ago when I lifted up on the egr valve my engine stalled. This could explain why at 15mph not enough exhaust gas was being recirulated due to the blockage

[Zenki_Kid_]

did this ever get fixed. i am currently having the same problem

[compactfean]

What have you done to try and fix this? all the info needed is here.

[Dimitri]

Last Saturday I failed high NO (Max 565 / Measured 579) .
Some facts: Car had not been driven since before Christmas, since the water pump failed.
Last time it was filled with gas was probably sometime in early November 2012.
Oil had not been changed in a while.
I got in and drove to the testing place and turned the engine off while I was waiting for about 15 minutes.
...and it failed.

Here is a list of what I did to "repair" it in the order everything took place:
Changed Spark Plugs.
Replaced a cracked vacum line that I stumbled on afer changing spark plugs. (It was causing it to run rough but this problem didn't show up until after changing the spark plugs.)
Added half a bottle Berryman Smog Pass Protection to the 1/4 tank of gas that was in the tank (about 3 or more months old gas) - drove around for about 7 miles and let it run in the driveway for about on hour.
Run almost an entire bottle of Seafoam through the brake booster vacum line @ 2 am in the morning
Took it in for and Oil change
and Coolant flush (I'm sure it has nothing to do with passing but I wanted to have it done since I just installed a new water pump)
Filled tires with air (40 PSI all around)
Filled up with fresh gas.
The following day I warmed it up in the driveway for about 15-20 minutes, mostly idling and keeping it revved up to 2000 every so often for a couple of minutes at the time.
I took the "long way" to the testing place driving in low gear (about a 7 mile trip in street traffic)
I left the car running while we did paperwork (no wait this time) probably less than 10 minutes.
...and it passed! (Max 565, measured 439)

Oh yeah, I also wore my favorite red jacket!