I bought a rusty 95 XJR as donor for the engine and it never seemed to have the power a 300hp car should - it never seemed as fast as my 94 6.0 V12 XJS for example.

Now that I have the engine out and am looking closer at it, I noticed the front knock sensor wiring was not plugged in. It never had a code or MIL light on, so will it have much effect on power? The manual says that it shroud have thrown a code, but didn't say what effect no knock sensor would have.

I'm wondering if I will need to dig deeper once I have the engine installed in my project car.

 

From what I understand 95 was very early in the OBD 2 codes from being shown and refined . This is different then the engine regulation that looks at this signal and retards the spark timing as how it is used .

Recommend just plug it in and let it go . There is a youtube video on how to test them .

While your in the area and up the air might consider replacing the gaskets on the coolant water rails , oil filter housing gaskets , and oil pressure sender . There was a 95 TSB on changing the camshaft over from a 110 degree overlap to a 14 degree overlap for better idle quality and if the mod has been done there is a marking somewhere in the TSB :

http://www.jagrepair.com/images/TSB/...%20Changes.pdf

Looks like normally aspirated engines only

Save the MAF and manifolds from the original engine .

 

Diagnosing a disconnected knock sensor was one of the hardest electrical faults to diagnose. The impendence of the device is very high and the signal level is very small. However, I can't explain why a fault code was not logged. If a fault code was detected, I think the software retarded the ignition timing as knock could no longer be detected. After 24 years, I can't remember precisely how the knock diagnostic Failure Mode Effects Management (FMEM) software worked. if it was active, then that might explain an apparent reduction in engine performance.