Another stupid d-jet question:, Related to a new 2.1 tune: defining terms- what constitutes "part-load vs full-load" and other mysteries |
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Another stupid d-jet question:, Related to a new 2.1 tune: defining terms- what constitutes "part-load vs full-load" and other mysteries |
DRPHIL914 |
Nov 29 2021, 08:06 AM
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#1
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Dr. Phil Group: Members Posts: 5,766 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
calling all d-jet masters ! OK so yes, ive read Anders etc and maybe missed it along the way, but how or what constitutes a part-load condition? I am trying to get my d-jet MPS dialed in on the 2.1 build. and it had been running really well, but just a tad lean still, so after going back and reverifying my timing and other settings, checking plugs aftera 750 mile trip, its really close and realizing i was probably a bit low on the fuel pressure i made that correction and then set out to do some local highway driving to test it out, and really felt good, but maybe a bit rich at low end, idle and what i was thinking would be part-load. BUT i think i over corrected on the MPS and now i went from being in the 12-12.5 range at idle and also cruising at 3000-3400rpm, i now am running light at about 14 on that mid-range cruising. it is good on WOT so i dont want to mess with that(full load stop) . i should have left well enough alone because i will probably be a bit heavy at idle and low end with this motor, due to a more performance minded cam profile etc. point is, what is part-load? if i am reading my AFR meter , lets say at 3000rpm- 3400rpm and cruising on the flat, that would be part- load condition correct? so i dont want to make it more rich at cruise or on WOT, so how can i isolate the mid range or par-load to enrich it with out messing anything else up. i already messed this up trying to just lean it out slighty and over corrected. if i adjust the inner screw by itself it changes both part and full load. the outer screw in will richen part load i believe lean out full- load. the Anders chart doesnt really address it. - also i feel i cant really get idle right, it seems too rich but that might be the way the motor will be, not sure. the MPS is a rebuilt one with Tangerine kit and adjustor screws, so easy to access and adjust using the Tangerine tools. I may be at the point of just going dual webber with 44 IDF's, and forsaking the d-jet - OR a more modern programable EFI...... i just dont think i am getting the most power out of this motor that i should or would with better air intake and A/F mix. intake is somewhat restricted on a stock d-jet and the injectors can only give you so much fuel. i did see somewhere anders wrote that the stock set up could support a build up to 2270 even with the proper changes( not sure what that means either), anyway first question is - part load definition. then how to proceed to get this mid-range or par-load adjusted into a better mix with out making idle even more rich(or WOT either) Thanks for the help. Phil |
rjames |
Nov 30 2021, 12:29 AM
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#2
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I'm made of metal Group: Members Posts: 3,924 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
QUOTE Part throttle cruising can be leaner than 14.7 and be ok since you are not loading the engine. In my old CFI mustang it will bounce around 14.3-15.3ish while cruising. When we were tuning it on the dyno (tangerine setup as well) part load settings seemed pretty good. That seems a lot leaner than what I've heard others here recommend for the type IV. |
emerygt350 |
Nov 30 2021, 07:56 AM
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#3
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Advanced Member Group: Members Posts: 2,087 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
QUOTE Part throttle cruising can be leaner than 14.7 and be ok since you are not loading the engine. In my old CFI mustang it will bounce around 14.3-15.3ish while cruising. When we were tuning it on the dyno (tangerine setup as well) part load settings seemed pretty good. That seems a lot leaner than what I've heard others here recommend for the type IV. Yeah, I saw that after digging through the archives. I really wish it were easier to change the part load and wot individually. I also wish at idle they would have really bypassed the MPS altogether. Not sure why they wouldn't. They have the TPS and the ECU knob. I guess on earlier years the knob isn't an option. I think I need a vacuum gauge as well. I suspect changes in diaphragm position might be contributing to my strange lean early rich late WOT issue. |
DRPHIL914 |
Nov 30 2021, 08:38 AM
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#4
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Dr. Phil Group: Members Posts: 5,766 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
QUOTE Part throttle cruising can be leaner than 14.7 and be ok since you are not loading the engine. In my old CFI mustang it will bounce around 14.3-15.3ish while cruising. When we were tuning it on the dyno (tangerine setup as well) part load settings seemed pretty good. That seems a lot leaner than what I've heard others here recommend for the type IV. Yeah, I saw that after digging through the archives. I really wish it were easier to change the part load and wot individually. I also wish at idle they would have really bypassed the MPS altogether. Not sure why they wouldn't. They have the TPS and the ECU knob. I guess on earlier years the knob isn't an option. I think I need a vacuum gauge as well. I suspect changes in diaphragm position might be contributing to my strange lean early rich late WOT issue. like i have written on that chart at the bottom, if you tighten the outer screw while holding the inner one, you will enrich the part-load and lean the full load out some and that sounds like thats what you need to do. would be so much easier to doe this while on the dyno rather than the stop go etc but thats what i did last night and am getting much closer to where i was. my mistake was thinking i could see that part load by just reving the motor sitting but thats not going to work you have to have some load. and if you get to the point of low and middle load and cruising is where we want it, but full load is off, then you can make a slight adjustment to the full load stop with out moving inner or outer screws. way better to start off with it at least at the factory setting, and go from there. also pull the plugs and see what they look like, thats going to tell you a lot too. @emerygt350 |
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