surging at idle and high nox

[Paul Lengyel]

Need some help with my 86 GN stock. At idle when I first start car it seems to surge and hunt. When I put it in gear it stalls. I also just took it to emissions and it failed with very high nox. The nox readings were a little over 2000. I hope someone out there can help. It also has a slight rough idle when warm, but doesn't stall. I looked for vacum leaks and founbd none. The coil pack was changed hoping that was the problem. The egr is working properly and the car has new plug wires (GM) and a new O2.

 

[Oldsmobuick]

I'm struggling with a similar problem.

See my postings from the past few days.

It seeks and surges in open loop until it warms up.

Also I have failed emissions with nox.

I, however, have a vacuum leak (hear it), and 2 open vacuum lines open. I don't know where they go yet!

My nox was measured in gpm 4.05 actual versus 3.20 allowed.

I can tell you by the curve of stoichiometric fuel ratio, that nox means lean! You have to get it on the rich side to have low nox.

Look carefully at fuel supply, injectors, fuel filter, etc.......
No vacuum leak, so that will help!

Also take a look at the emissions link one of these guys sent me.
It really helped!

Maybe we can fix this together?

 

[WarpSpeed]

That means it's lean, of course.

Probably pirate air. Air getting in that the MAFs isn't seeing. Might look closely for holes in the 3" flexible tube that goes to the turbo. Also, check the tube running from the valve cover to the turbo(if equiped.) Maybe even a really faulty pcv valve.

 

[Paul Lengyel]

surging/high nox

Thanks Oldsmobuick, I will make those checks and if I find the problem with my car I will pass it on to you. The emissions here in Connecticut must be like yours and they are a pain in the you know what.

Paul

 

[Paul Lengyel]

surging/high nox

Thanks Warpspeed, this is something I have not checked. I will check the hoses in the AM and pass on the results. It seems as though I am having a simular problem that Oldsmobuick is having, so maybe between the two of us and the help we get we will be able to solve the problem.

Paul