Sages,

I’ve been trying to track down two annoying issues which may or may not be related, 1) a rich fuel mixture (since May of 2015), and 2) a possible Knock sensor issue.

So yesterday before the big game I removed the intake manifold and started trouble shooting the knock sensor. Following the FAQ I was able to test through the “Physical checks:” and “Electrical Sensor and Wiring Checks:” sections and nothing jumped out like there was an issue. I did not, however, get to the “Sensor Testing procedure:” section as I was running out of time. My question on this section is where to attach the LED tester to? I know one end goes on the +12 volt side of the battery, but I am confused as to where to attach the other end of my tester.

While I was in there I did notice that the PCV oil trap was coming apart, which may explain the rich fuel mixture, and most definitely explains all the oil that I’ve noticed on that side of the engine. Ugh!

Since I was running out of time I opted to put it all back together and here is where the gremlins came into play, and lets not forget Murphy!

I started it up and it just ran and continues to run like crap, almost like it’s not running on all 4 cylinders.

So today I did more troubleshooting.

With the engine running, I first unplugged all four spark plug wires, one at a time. I got a change in idle for all BUT the last one, the one next to the rear firewall. I then checked the rotor and I have spark on that cylinder, but it makes no difference whether it is plugged in or not. I’ll have to check that wire once everything cools down more.

I then unplugged each fuel injector, one at a time, and I did get a noticeable change in RPMs on every injector each time one was unplugged and then plugged back in.

Next, I took a can of brake cleaner and started spraying everything around the intake manifold and here is what I noticed. The idle increased when I started spraying the last two injectors next to the rear firewall. I also got an idle change on the two small hoses that run into the throttle body, and it appeared that I also got a change when I sprayed around the new intake manifold gasket that I put on last night. Why that is happening is beyond me. At this point I ran out of brake cleaner and then opted for a spray bottle filled with just water. By using the water I did not seem to get as much of any type of change in idle except for the second fuel injector closest to the rear firewall. When that was sprayed the idle did increase.

So I’m thinking I need to, at a minimum, replace the O-rings on the injectors, and secondly replace the PCV oil trap which is coming apart. Only then will I be able to diagnose what other leaks I may have. I believe if I can get these leaks to go away then my rich mixture should also go away and my MPG should improve. As far as the 4th cylinder not having any effect on the idle when the spark plug wire was pulled, I will further investigate that as well, but only after I’ve replaced the above mentioned items. I also believe that once this is done, I’ll most likely have to reset the idle.

Any thoughts on what I’ve discussed above, and most importantly, anything that I may have over looked?

Thanks in advance,
Matt