Cylinder 5 misfire, and now cylinder 8 and a random misfire... suggestions?
Here's the skinny...
5.9L with about 158K miles on the engine. I had been getting a cylinder 5 misfire and random misfire so I swapped out the plugs (some of which looked like they had been HOT), wires (two were badly corroded), and distributor cap and rotator (bot in bad shape). The misfire codes went away for all of 15 or 20 mins. This is what I'm getting now:
P0305 Cylinder 5 Misfire Detected
Fuel Sys 1: CL
Fuel Sys 2: CL-Fault
Calc Load: 29.41%
STFT B1: 0.00%
LTFT B1: 2.34%
Eng RPM: 832
Veh speed: 26mph
P0300 Random Misfire Detected
P0308 Cylinder 8 Misfire Detected
So, I was thinking this could be the #5 fuel injector, but now that the random misfire has returned, I'm not so sure... I'm going to pull the injectors and plugs to see if they are burned up or anything is fowled, but I'm fairly certain its not the manifold gasket leaking by... any suggestions? I don't know what that Fuel Sys 2 is, but it's making my pocket book nervous...
thanks for the help in advance...
What was the throttle position when the code set? Have you checked the plug condition? Oil fouled plugs would cause a misfire and being those two cylinders are toward the rear making them prone to oil fouling from a leaking plenum pan gasket. What about the rest of the secondary ignition system?
I just got done pulling the plugs, injectors, injector rail, and scoping the cylinders and injection manifold. The plugs are clean, no fouling/funny smell/temperature damage. I have ran electrical checks on the ignition system running and off. so far nothing is wrong.
The injectors looked pretty nasty, but they all passed resistance and operational checks. when the injectors open, I get free flow from each of them (I don't have a test stand to see if they have good spray patterns and how well they are flowing at operating pressure though). I took the cylinder 5 injector and put in cylinder 1. I figure if there is a gremlin in there it should show up on cylinder 1 now.
Any ideas on the secondary fuel system? is that the fuel return system?
well... Re did the wires and ignition system, cylinder 5 is still missing though. At this point I'm considering the possibility of a cracked head or bad valves. Time for a leakdown test I guess... :-(
Check for a broken valve spring too, since it won't show up on a leakdown test.
Symptoms: some vehicles may exhibit this symptom:
Various single cylinder misfire (1, 3, 7,) ad especially 5 and/or 8
NOTE: This rerouting procedure should be performed before any other misfire, surge, or spark knock repairs are attempted.
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