Thread: Unstable combustion troubleshooting

I had 2x different 4.2 AEM sensors go bad in about a year on each. One was on the mustang probably 24" from the turbo. The other was on the automatic RR G20 and was probably 36" from the turbo. I really hope the 4.9 lasts like I have heard. They are supposed to last up to 10 years on OEM applications is what I think I read... I'll have to go back and look for that article.

Do you know the manufacturer of the 4.9 sensor that went bad? Where there any markings on it? Just asking because some places are selling the Chinese $40 units.

This is way too close!! I would install it about 18-24" from turbo outlet.

"Weld the bung at least 24 inches downstream of the exhaust port
outlet (after the collector), or 24 inches after the turbocharger if so
equipped. The bung should be welded before the X or H pipe if so
equipped."

from the innovate manual.

Yay, somebody read the manual!

yes, it absolutely did.

Update time

New sensor arrived, it was very physically different:
-Different styled tip, open instead of multiple holes drilled in it
-More heat resistant wrapping around the cabling (gray vs black on old sensor)
-More stamped numbers on it, along with "MADE IN GERMANY"

This makes me believe that the first 4.9 sensor I had was some early/chinese version. Hmm...

Oh, combustion is spot on now! Closed loop is much more rapid, AFR swinging beautifully between 14.5->15.0 .I'll post up the re-SMOG results later next week.

Haha, that made me almost dizzy

OP, forwarding this to my bro who knows a ton about this stuff, see if he has any tips

Did you buy the old one from a AEM dealer or somewhere like ebay?