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A little back story: I bought my 04 MSM off a forum member around this time last year and have really enjoyed the car. Previous ownership installed the Big Enchilada kit and the car has a Hydra 2.7 remote tuned by Ken Hill. About 93K miles currently.
Over past year I have noticed a stutter when under throttle that has only gotten worse and worse. It seemed to happen randomly at first with no correlation to the amount of throttle or engine speed. More recently, it has almost always occurred at over 60% throttle and over 4500 rpm. Wanted to figure it out so I pulled out my computer and dug into the Hydra data logging. Here's the first run I did 3rd through 4th gear WOT:
I got one stutter in third and then a bunch more after shifting to fourth. I realized that rpm and throttle were probably two important things to display so I ran again, 3rd through 4th WOT
And now I wish I hadn't. No stutter in third but in fourth it stuttered atleast three times. Immediately after this run, I heard a bad ticking sound (similar to HLA tick in NAs but a bit louder).
Any input as to what the ticking sound may be and as to why the knock sensor is going off would be much appreciated. Some things to keep in mind is that the car stutters under load only about a fifth of the time and that I have never been able to detect any knock with my own ears. CEL has never flashed to indicate the ecu went to back up fuel and timing tables but that is what I suspect is the cause of the stuttering. Also, knock threshold is also set at 0.16V and goes down to 0.1V after 2000rpm. Really, really, really hope I did not just bend a rod.
I would do a compression at least to rule out any rod issues if you think that's the case. A hiccup or miss under higher load usually speaks to a weaker ignition system, or something in the ignition starting to fail. I would log the following things:
You can also modify the output for the check engine light to turn on if the timing is being retarded for whatever you like - greater than zero degrees for example - as well as for high coolant temp, and nearly anything else you can think of etc.
The knock voltage range on the Hydra is very limited on the NB sensors and I've seen evidence of knock on values as low as 0.07V. I usually set the threshold at .06V.
Over the course of the car's life, the stock pistons progressively bent and eventually started to contact the crank and/or the oil squirters under higher loads. I believe the knock sensor detected this and cut spark which was the "hesitation." Pistons had zero evidence of knock or detonation when I pulled the engine apart. #3 rod was the most bent. Doesn't matter too much anyways now because I put forged internals in over the summer, went to an EFR 6258, and switched to MS3. Car should be running again very soon.
Over the course of the car's life, the stock pistons progressively bent and eventually started to contact the crank and/or the oil squirters under higher loads. I believe the knock sensor detected this and cut spark which was the "hesitation." Pistons had zero evidence of knock or detonation when I pulled the engine apart. #3 rod was the most bent. Doesn't matter too much anyways now because I put forged internals in over the summer, went to an EFR 6258, and switched to MS3. Car should be running again very soon.
Sounds good - sorry you weren't able to get more support sooner.
03-25-2020, 12:15 AM
Datalogging Woes
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