As mentioned, a high NOX reading is usually the result of a bad EGR or worn cats.

On a bit of a different note, I got my 86 inspected yesterday at a local gas station and I was talking to the guy running the inspection. He mentioned a newer C6 that came in and wouldn't pass emissions. He said a lot of the older cars aren't passing either. Makes me wonder if it's the cars, the standards or the test equipment.

When he did mine, he let all the tests run at idle and never brought the car up to the RPMs the test was looking for. He seemed to know how to get around it.

 

Took a look at my exhaust and it appears she's running a little rich. I found a lot of carbon on the tips. So i'm thinking of replacing the o2 sensors. Im also going to check the resistance of the injectors.

 

Did a scan of my engine while at different speeds and temps. Best I can see it is running rich at lower rpms and lean at higher rpms. I get some codes flashing for 1 record at a time but nothing stays red as a thrown code. Shows the egr opening and closing throughout the run and the o2 sensors fluctuating quickly(but I am told this is normal). How should the histogram chart for datamaster look? I have alot of red and some green but a lot less white. Should I focus on the injectors?
Thanks for any help!

 

this has been going on for a month.. since you have an lt1 its a 20 min job to change injectors.. let me send you a set, put them in and go to inspection..
if it passes or you like the way the car runs. buy them. if not send them back and reinstall the multecs.

 

pm sent to fic

 

I've read nothing but excellent posts about FIC. If I wasn't sold already, that response right there would have done it!

When I'm ready to change over to the Bosch III's I'm calling FIC

 

Vacuum leak.

Vacuum leak.

Just like bczee, suncr, cevetteboy said.

It will cause rich too, tho' not constant, as the revs do their yo-yo thing. Rich, lean, rich, lean, ...

The computer reads air, feeds gas, burns. Some unread air is getting in on a vacuum leak, and it burns as a lean mix. O2 reads high, feeds some extra gas, and the revs come down, cause there's too much gas/not enough air. The rich condition varies as does the revs.

Ever tune the jets on a carb? Reduce the gas, and the revs increase up to a certain point. Increase the gas, and the revs go down.

 

The good news...Put the new injectors in and the vette is running sweet. It didn't necessarily run bad before but it seems smoother and a bit more power. I have not had any idle issues when hot either. Ran a scan and it is running slightly lean. Before it was extremely rich at idle and low rpm's and really lean at WOT. I am hoping to get it to E-check thursday.

The bad news is I decided to clean the MAF, IAC, and throttle body and put it back together and idle was high, getting a DTC 22 (tps low voltage). Seems the TPS decided to turn inside 90 deg. and will not mate up with the throttle plate. Anybody have this happen?, seems weird. I am trying to locate one ASAP but no one has one in stock. Oh well with some luck I should have one by Thurs.

I also wanted to thank Jon from FIC injectors. He saw my problem and took it by the horns and sent me some injectors to try no questions asked. Now thats proactive customer service. I don't know if it will get me passed the emmisions check but my car was definitely not running like it should and the computer was working like crazy to adjust the fuel mixture. I'll probably buy the injectors even if I don't pass yet as it was definitely part of the problem.