Eric,
Love your work! Congrats on the new truck!
I have what may be a simple issue but has stumped everyone for a long time:
1997 Mustang GT – 4.6L – 300K miles (yes, 300K on the original engine/trans) – COMPLETELY stock! (yes as unbelievable as that is on a 90’s Mustang)
PROBLEM: It has a spark-knock (pre-detonation) issue pretty much since the early 2000’s. It will not run on regular unleaded gas without spark-knocking, especially when putting it under a heavy load (pulling hills, etc).
I took it to Ford who said the ECM was reading octane levels at 93 so they re-flashed it back to 86. This fixed the problem for about 2 weeks, then the spark-knock was back. I have confirmed the correct temperature spark plugs were installed (OEM), otherwise I have been running high-octane (93) gas nearly its entire life to combat the issue. Also, there is no knock sensor on this car.
Other than that, it has been a great car and was my daily driver through my 20’s and 30’s. Now that I am in my 40’s it is my project car BUT the spark-knock issue always bothered me.
I have had a wild idea that there is a lot of carbon build-up causing higher compression ratios in several of the cylinders but that’s a stretch, I know.
Have you ever heard of this issue? Any other ideas?
Many thanks and keep up the good work!
Kelly
Atlanta, Georgia