intermittent check engine light, but no codes?

It could be the EGR, my CE would come on as soon as the engine got warmed up and when I first hit cruise when the EGR would normally turn on. I had my EGR tube blocked as it broke. I got a new tube and the CE went away.

Really the EGR is not something that is hurting the motor performance wise...and your actually hurting your mid load MPG by not having it working correctly. The EGR shuts off at WOT...but I am sure your no dummy to this so I am probably preaching to the choir.

Since you just replaced your O2's, did you reset the EEC by undoing the batt. to clear the KAMFR? If the O2's you had were off a bit, your computer may be having a fit with the new o2's not having a signal that matches the KAMFR (Keep Alive Memory Fuel Reference) from the old o2's.

The_Mustang said:

No, the fancy "Mac" diagnostic machine cleared all the codes that were in the computer. I know this because we did another self diagnostic right after clearing the codes and nothing showed up.

The only reason I don't have the EGR connected to the header is because I'm using the BBK shorties and the factory tube won't fit.

Click to expand...

The egr tube is easy to make... go get a peice of copper pipe... cut the stock one in half and steal the ends. flare the ends with a tubing flare kit and bend it in place works like a charm.

KAMFR is not a code its the fuel trims stored into the EEC's memory...I dont know if a code reader/scanner will reset the KAMFR when it clears the codes.

I am only brainstorming here....

KAMFR is the fuel trims gathered from the o2's and the relation to how much adjusting the fuel injectors need to make to get the A/F numbers the EEC is programed to target. As o2's age they will not hold as narrow of a range and the KAMFR will "drift" over time and become out of range as well.


My "idea" of a possible issue since your new o2's are going to send a correct "tighter" narrow band signal to the eec and it may be causing a fueling mis-match to what is stored in memory as the KAMFR. To reset the KAMFR and test this "idea" you only need to undo your batt +/- terminals and leave the door open so the dome/chime drain any residual power in the system and wait about 1min and reinstall the +/- cables to the batt.

I would say either fix the EGR or get it shut off correctly in the eec with a tune/tuner either way. There are extensions avail. if the stock tube is too short. Otherwise the copper tube method has worked for a lot of people.