What gives??

First it was idling too high. The dude said that that's what was causing it to run too hot to pass NOx. It was idling at about 2k. It started doing this after I took off my throttle body and cleaned it a few months ago. A new IAC didn't fix it, so I just turned the screw in a little, and that brought my idle back down to a healthy one. I went ahead and kept the new IAC.

Well, I took it back for a rematch, and the tech said that now it's even worse! Still too much NOx! He suggested that it might be an EGR issue. The EGR is only about 1.5 to 2 years old. It still runs kinda hot. Hotter than it used to. I've tried so many things to fix the heat issue (within the past year or so). New fan relay, new temp sender(?) [behind the valve cover, pass. side], flushed the block the best I could, new thermo, new water pump... This brought it down to where it barely goes past 220. It seems this is the best I could do.

Now what?

Thanks

 

Oh BTW... 89 'bird VIN S

 

The high idle is probably caused by a vacuum leak created when you removed the throttle body. That could also cause a lean condition which will cause nox to go up. I would try a new tb gasket and see if that helps.

 

Fixed it!

It was a dry-rotted and broken off vacuum line junction completely killing the vacuum to the EGR valve.

Passed emissions with flying colors!

Thanks, Dank!

 

You didn't get a code for the EGR?

 

The egr isnt a feedback type. Feedback types have a potentiometer that tells the ecm how far the egr is open. On our system all the ecm can tell is if its electronically working eventhough it may not be mechancally working.

 

Probably.

Before I found the leak, I would get the check engine light after it would warm up (about 15 minutes of driving). Now, was that a code 34 (EGR)? I don't know, I don't have a code reader. But I'm begining to think that it was, because since I fixed the leak, I haven't gotten the check engine light once.

No, not once!

So to answer your question... Probably.
Actually... Most likely.
The more I think about it, the more I think it was a code 34.

 

You can use a paper clip or piece of wire to pull codes