MSefi.com read only forum (Jan.15,2018)

hi, i've tried searching all over for an answer for this and i have not found any, and i dont think they even have support for the diypnp on forums. first of all, here are some details about my car engine and such. engine: 2jzge w/ 2jzgte cams, diypnp kit n76, i'm using tuner studio to interact with it since thats all i can use, spark type wasted spark (controlled by high current drivers in the diypnp), 1400cc low impedance injectors, e85 fuel, 24-1 trigger wheel mounted on the exhaust cam. i own two megasquirt units, and i'm VERY close to just giving up on this thing and getting my ms2 that i have on my flow bench to work with my car.

here's the problem, as the title says i have a very unstable vr sensor reading... i can use the same trigger wheel and sensor on my lathe (which currently is setup to run 600rpm) and it just jumps about 200rpm up and down. when my car is cranking, it barely has any signal and its unable to even fire on a cylinder. the signal just comes and goes when cranking... it will read maybe 300 rpm, then zero, then it wont register any, then sometimes it does. the vr sensor is about as close as physically possible, and its lined up correctly. its set up so that tooth one is at the sensor when the engine is at tdc on cylinder 1. i've tried resistors, different amounts of teeth, different pickups, etc... same result. the only one that looked promising on the lathe was the 24-2 setup in tunerstudio as a 12-1 at crank speed. obviously it showed 1200rpm but it was much more stable than anything else. i've tried that setup to no avail also. so, i'm out of ideas.

ps: i checked every sensor and the function of every injector, and ignition coil on my bench, all were working... just the vr sensor is jumpy. and i also cant use toothlogger, since i dont think tunerstudio has it. the graph of the ignition signal on there was not consistent though. i hope someone can help me here. thanks in advance.

I'd say you need to get hold of a 'scope and look at the signal all the way through the chain.

trakkies wrote:I'd say you need to get hold of a 'scope and look at the signal all the way through the chain.

i actually was kinda thinking of checking that wiring. hrm, i'll try just only wiring that up on some spare connectors i have on my bench. if anyone else has an idea feel free to chime in.

so, i ended up switching to another combination in hopes of things working... ofcourse no good outcome. now i'm running just the vr sensor and wheel on my lathe. the sensor is the crank sensor found on a 2jzge with vvti and the crank wheel is for the same engine and is a 36-2. so far i've tried a 24-2, a 24-1, and a 36-2 all with the vr sensors designed for them... i sent in my 36-2 tooth log to DIYAutoTune, they said it looks great... however, the ecu still shows the rpm jumping all over the place... 200 rpm in either direction. i dont really know what the heck < thanks for the auto edit! to do anymore. its frustrating to know that this stupid issue is the only thing keeping my engine from running and there's basically nothing i can do about it. makes me almost want to figure out how to make everything work on the stock computer... at least i know that it would run with that. the datalog just shows the signal bouncing all over the place. about 200 rpm up and down. i'm about ready to give up and sell this thing if an answer doesnt come very soon.

I know how frustrating it can be!! The best way to find your problem is using a dual trace scope. I picked up a Fluke scope meter and it was very valuable in understanding the circuit and what I was getting. I am using an MSD crank trigger and it worked flawlessly on my first MSII. The new one I built, didnt like it. I found that the way form from the MSD was a bit different and the chip used in the newer one, was different than my first MSII. I found that going back to the old chip helped my problem. I only found it by using the scope. Watching the input create the output and making changes.
I used a 24v dc scooter motor to spin a spare crank trigger and bench tested it till it worked!!
I hope that helps..
Dick