Our 2015 LTZ has 175k miles on it and until the past few months has been flawless aside from the Magnetic Ride Control.
We bought it used in 2017 with 80k miles on it and I immediately tuned it (93 Perf/Tow from 5Star) and disabled the AFM. The truck has been great and had plenty of noticeable power gains on the 93 Tune.
It started misfiring a few months ago which is indicated by the flashing CEL; yet we never felt it. I assume the computer mitigated by adjusting timing accordingly. It started to do it more and more so we had the tune adjusted for 91 yet still fed it 93 (assumed we were getting bad/weak 93 fuel). The problem still continued on occasion. Well, next it threw the P0204 (#4 injector circuit/open) code along with the P0300. Once it started throwing the P0204 code, the truck would shake and skip while driving, but you could pull over, shut it down and restart it and it was gone. This became a very intermittent issue at first and then progressively got worse to the point we took it to the shop and they replaced the #4 injector. For about a week, the problem did not occur and then it started again, but still intermittent (sometimes would go days without issue). Continued to drive it for several more weeks just stopping and restarting the engine to clear it out. Finally it progressed enough to the point we took it back to the shop and they replaced the same injector under warranty. Guess what......still continues to do it and this last time it threw a P0202 (#2 injector circuit/open) code; first time I've seen that one and its only done it once so far. The shop is baffled, they are clueless and think its the PCM. I'm not convinced its the PCM. I was convinced it was a possible wire issue as we have chipmunks that get up in the vehicles at the house. The shop checked the wiring and could not find anything suspect. Checked all up under the PCM and the harness leading to the injectors up the backside of the block. Ground on the back of the cylinder heads was good.
If I'm not mistaken the L83 has two fuel pumps? If so, it almost seems as if the high pressure pump is failing under demand and then cuts off only leaving the low side pump to run the vehicle insufficiently for a direct injected engine. A restart resets the pump and cures the problem until the next instance. Seems to be the instances happen mostly under command of power.
Is that a feasible issue? How can I confirm? I have an OBD MXII scan tool which can monitor every PID the fuel injection sees. It will also datalog.
Would the high side and low side fuel trims be indicative? If so, what range should they be? I have not checked fuel pressure yet. What is the spec for that?
Hoping someone else has had this issue and can offer guidance. This is driving me nuts because its driving my wife nuts as its her truck. She wants it fixed or wants a new car. Considering we just paid it off last month, I'm not apt to get a new vehicle for a bit. I'm determined to solve it, but despise throwing parts at things with hope that was it; especially considering the cost of some of such parts.
As a note, we did replace plugs/wires at 150k.
Thanks in advance.
We bought it used in 2017 with 80k miles on it and I immediately tuned it (93 Perf/Tow from 5Star) and disabled the AFM. The truck has been great and had plenty of noticeable power gains on the 93 Tune.
It started misfiring a few months ago which is indicated by the flashing CEL; yet we never felt it. I assume the computer mitigated by adjusting timing accordingly. It started to do it more and more so we had the tune adjusted for 91 yet still fed it 93 (assumed we were getting bad/weak 93 fuel). The problem still continued on occasion. Well, next it threw the P0204 (#4 injector circuit/open) code along with the P0300. Once it started throwing the P0204 code, the truck would shake and skip while driving, but you could pull over, shut it down and restart it and it was gone. This became a very intermittent issue at first and then progressively got worse to the point we took it to the shop and they replaced the #4 injector. For about a week, the problem did not occur and then it started again, but still intermittent (sometimes would go days without issue). Continued to drive it for several more weeks just stopping and restarting the engine to clear it out. Finally it progressed enough to the point we took it back to the shop and they replaced the same injector under warranty. Guess what......still continues to do it and this last time it threw a P0202 (#2 injector circuit/open) code; first time I've seen that one and its only done it once so far. The shop is baffled, they are clueless and think its the PCM. I'm not convinced its the PCM. I was convinced it was a possible wire issue as we have chipmunks that get up in the vehicles at the house. The shop checked the wiring and could not find anything suspect. Checked all up under the PCM and the harness leading to the injectors up the backside of the block. Ground on the back of the cylinder heads was good.
If I'm not mistaken the L83 has two fuel pumps? If so, it almost seems as if the high pressure pump is failing under demand and then cuts off only leaving the low side pump to run the vehicle insufficiently for a direct injected engine. A restart resets the pump and cures the problem until the next instance. Seems to be the instances happen mostly under command of power.
Is that a feasible issue? How can I confirm? I have an OBD MXII scan tool which can monitor every PID the fuel injection sees. It will also datalog.
Would the high side and low side fuel trims be indicative? If so, what range should they be? I have not checked fuel pressure yet. What is the spec for that?
Hoping someone else has had this issue and can offer guidance. This is driving me nuts because its driving my wife nuts as its her truck. She wants it fixed or wants a new car. Considering we just paid it off last month, I'm not apt to get a new vehicle for a bit. I'm determined to solve it, but despise throwing parts at things with hope that was it; especially considering the cost of some of such parts.
As a note, we did replace plugs/wires at 150k.
Thanks in advance.
