Knock and high NO readings

Shrouded

Registered User
It's a 1993 super coupe, the car has 200,000 miles on it, the engine and transmission was rebuilt in the past 50,000 miles and the car has been well taken care of. I've been trying to troubleshoot this knock recently and I take it to get smogged and the NO emissions are high, around 700 ppm. I've done the KOEO test and it didn't pull any codes, I did the KOER test a few times and once it registered some weird numbers like 6225 and 67225, but the rest of the time it registered okay.

I'm thinking it could be the MAF, O2 sensors, or knock sensor. It knocks when under medium to heavy acceleration, particularly when going up hills. I've tried putting some of the engine cleaner in it and then used a full tank of gas and the knock is still there, as are the high NO readings.

Any sort of ideas on how to know exactly which sensor might be bad or any other causes for this knock?
 
Thanks for the quick reply.

What EGR stuff is there to check? I own the Ford manuals and I can't find any EGR valve or anything for this year Thunderbird SC. The cats should be fine, the rest of the readings for the emissions test are still very low. I'll try cleaning the MAF and see if that works tomorrow.
 
It is possible the car does not have EGR. The SC's were back and forth with that equipment. It is very well hidden if it does have it. Almost have to remove the wiper cowl to see it. My 94 just passed with the EGR not opening (code) although the NOx where high because of the EGR it was still in spec.

My 93 5.0 bird was pinging under load. I cleaned the MAF and it took care of that.

Here's the thread in the FAQ's with what years have the EGR http://www.sccoa.com/forums/showthread.php?t=12482
 
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smog

if your NO is high that means your cats are bad or is running hot if you find a way to make it run cooler you will pass been there n done it...;)
 
what is the number you have it hit for nox vs what you did? high nox is due to excessive combustion chamber temps. I would expect a check engine light to be on if you get high nox due to the 92 sensors indicating unable to bring emissions into line. Bad o2 sensors thus could lead to this if they are reporting everything is fine even when it is not.

plugged cats could cause this as well.
 
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