Good catch!
Higher RPM (4000+) detonation?
- Thread starter 01rangerxl
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Originally Posted By: OVERKILL
Originally Posted By: 1kickbuttranger
Unless it jumped to another wire/tower... then that could detonate pretty bad.
True. But you would expect that to happen at all RPM, not just high RPM
Plus, the title would have said 'runs on five cylinders and detonates'.
Originally Posted By: 1kickbuttranger
Unless it jumped to another wire/tower... then that could detonate pretty bad.
True. But you would expect that to happen at all RPM, not just high RPM
Plus, the title would have said 'runs on five cylinders and detonates'.
After some more test driving (ie driving it like I stole it), I noticed some detonation again, but high RPM performance is GREATLY improved with the new coil, and the detonation seems mild now...like it might just be from the 87 in the tank, or maybe it does have some carbon on the heads since it was apparently running worse than I thought. Misfire symptoms (loss of power, flashing CEL) are all gone.
I think what I was hearing before was a combination of detonation and misfiring. It was bad, and loud. Sounded like something bad was about to happen to the engine.
Doing some digging online too, those Denso plugs were probably one or two heat ranges too hot for the FFV engine, and so were the Motorcrafts I put in initially. I went to a colder heat range Autolite APP103 today. The original plug, SP-495, is colder than the plugs most parts stores show for the truck in their computer systems. Runs beautifully with the APP103s. Unfortunately SP-495 is hard to find...it was apparently for FFVs and supercharged vehicles, while most everything else got SP-432.
What gets me is how good it ran most of the time with that cracked coil and hot plugs. It's hard to diagnose things like this on this truck/engine because it usually only rarely shows the symptoms even when you know something is up. I kind of felt like it didn't have as much power as it used to, but it still ran so smooth and didn't give a CEL. The times it has thrown CELs in the past, it still ran fine. It's also weird how it was like flipping a switch...it didn't gradually get worse as RPM increased, it was fine at 4100 RPM or so and sounding like it was about to shoot a piston out at 4300 RPM.
I'm looking forward to putting some E85 in it again, but the station was sold out of it tonight because it was cheaper than regular gas. Not sure if that's just due to people with FFVs opting for the E85, or if people with non-FFVs think they figured something out (until they have to replace most/all of their fuel system).
I think what I was hearing before was a combination of detonation and misfiring. It was bad, and loud. Sounded like something bad was about to happen to the engine.
Doing some digging online too, those Denso plugs were probably one or two heat ranges too hot for the FFV engine, and so were the Motorcrafts I put in initially. I went to a colder heat range Autolite APP103 today. The original plug, SP-495, is colder than the plugs most parts stores show for the truck in their computer systems. Runs beautifully with the APP103s. Unfortunately SP-495 is hard to find...it was apparently for FFVs and supercharged vehicles, while most everything else got SP-432.
What gets me is how good it ran most of the time with that cracked coil and hot plugs. It's hard to diagnose things like this on this truck/engine because it usually only rarely shows the symptoms even when you know something is up. I kind of felt like it didn't have as much power as it used to, but it still ran so smooth and didn't give a CEL. The times it has thrown CELs in the past, it still ran fine. It's also weird how it was like flipping a switch...it didn't gradually get worse as RPM increased, it was fine at 4100 RPM or so and sounding like it was about to shoot a piston out at 4300 RPM.
I'm looking forward to putting some E85 in it again, but the station was sold out of it tonight because it was cheaper than regular gas. Not sure if that's just due to people with FFVs opting for the E85, or if people with non-FFVs think they figured something out (until they have to replace most/all of their fuel system).
OVERKILL
$100 Site Donor 2021
Well too hot a plug could certainly be a contributor to pinging! Gotta love those parts store cross reference/look-ups eh? LOL!
Keep us posted on how it is with the new plugs.
Keep us posted on how it is with the new plugs.
I figured something in the ignition but not something like that, good catch finding that.
I tried the TT plugs on a couple of beaters and wasn't satisfied with the longevity or the performance, in a waste spark system they seem to have the lifespan of a house fly.
I tried the TT plugs on a couple of beaters and wasn't satisfied with the longevity or the performance, in a waste spark system they seem to have the lifespan of a house fly.
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