Well I don't like making another thread, but I think that it may get enough discussion to get its own seperate from my other 'project' thread. With larger injectors going in one truck, the current 238/100 hybrids are going in another.
Just so happens to be a 02 SuperDuty with a PMR engine. Now with all the past talk of more HP or larger nozzles and the resultant window to wave "hi Mr. Crankshaft"
on a PMR engine, it's got me a little worried, but I'm pretty confident I'll have it working. I have my single shot timing(fairly conservative) related maps copied/grafted in the SD file. Then grafted in the pulsewidth map I had working on the OBS. The PW map for the hybrids I started with has flow detuned to basically match output of an AA injector across the entire map.(that was because I was initially seeking a like-stock file when I started tuning the injectors for the OBS).
Now is where I started looking a little closer, and perhaps I should have done this when tuning for these injectors the first time. Being a little more cautious for the PMRs got me looking closer though. For the most part, my PW map for the 238/100 is
fairly close to stock. Hybrids needing a little more PW here, little less there, but the big changer is up top, the PW map for AA stock and the hybrids starts deviate a lot more for me for MFDs >70. The hybrids can flow equally to stock AAs about .5ms quicker. I suppose I should pull some timing, unsure of how much. Took me a while to figure it out
, but after staring at the ICP desired, SOI, and PW(namely the change in PW), I pulled some timing from all RPMs down to about a MFD of 70 using the rotational time calc that Bill has made for excel. At 3000 RPM and high MFD, with a shortened PW of .5ms, to have injection 'end' at the same time, 9* of timing would be pulled. When at 1000 RPMs that drops to 3*. (just so happens that PW difference was equal at that MFD over varying RPMs, it was not always like that so it wasn't always 1/3 less timing to pull at 1000RPMs).
Now I thought I found something that could likely have caused issues, and it was the biggest difference I could find when going with larger nozzles. If you raised the PW map in those areas MFD>70 and they match more like stock PW length, timing wouldn't really need to be pulled. For most, PW probably wouldn't be decreased to limit HP like I have, unless you were to say make an economy tune. My guesses are either what I
seemed to have found or just too aggressive low RPMed fuelling, lotsa torque.
Anywho, thats my thoughts for the night
, if anything else talking(writing) about it helped. Just thought I'd post it to get some additional opinions, hoping to avoid a windowed block myself, and if it helps others avoid one too even better!