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That's awesome! I'm head over heels in love with the LFX engine for swaps. Such a great platform and the aftermarket will hopefully start catering to it a bit more because of how common it is becoming.
This might be a bit premature as it's untested and recently discovered, but I thought maybe I could get some feedback on this idea.
I might have figured out "a" solution. I don't know if it's "the" solution. This is at the moment just a thought experiment, untried, untested.
I ran across an alternator controller datasheet last night, and much to my surprise, I found out that a lot of the major companies (ST, NXP, OnSemi) have alternator controllers. I haven't yet identified the controller in the LFX, but I have identified the voltage regulator.
Above you can see in the data that there is a "vset 13.8" data point - so pretty obviously, default voltage 13.8v.
This opened up another avenue of discovery - that these are known as "denso hairpin" alternators, and of course they have some compatible parts - there's actually an entire catalog of bearings, rotors, diodes, etc -
vset 14.35v. Now I'm willing to bet it might need some additional wiring to excite, I need to hunt down which honda's that came in to figure out what additional wiring mods will need to be done - and you can crossreference that part number and find it for about $30 on ebay, and probably cheaper if I venture into aliexpress territory. Swapping out the regulator isn't for the faint of heart, but honestly, if you're installing an LFX you're probably plenty qualified to open up an alternator and swap this part out.
edit: I should also mention there are a number of different regulators available that look like they will fit, so I'm not sure if the honda one I listed is the way to go. https://store.alternatorparts.com/in...-one-wire.aspx for example looks like it fits the regulators physical format with a different plug and rear shield, but it's a 1-wire alternator with a 15v output. (BTW, don't know if I would use this - 1 wire alternators have a tendency to not charge until running a higher RPM, at least thats what I remember from installing one on my 66 galaxie many years ago).
Last edited by gooflophaze; 03-19-2020 at 12:23 PM.
Another route to explore - seeing if there's another alternator that fits but has a different voltage regulator. I've identified the drive end cover - 21-82147 - and googling through that, it looks like 2004+ cadillacs w/ 2.8 + 3.0 + 3.6l motors share the same housing with a slightly differently clocked plug - but it's still digitally controlled. This expands the alternator pool beyond what rockauto has listed as cross referenced parts goes (for 2012+ camaros), and explains why some of the LFX engines have plugs that come out of the side instead of the back. GM 25751145 if you want to see what I'm talking about.
The LFX alternator is a **** to open. I destroyed one already, but admittedly I have no idea what I am doing with these alternators and my solution is usually a bigger hammer.
Well now that I have that datasheet in hand, I think I see why my PWM circuit didn't work - so I might have two options available after some testing. One will be a "set this trimpot while looking at a multimeter" circuit board, hopefully I can build it out of a 555 without having to resort to something that needs to be programmed. The other will be the honda-ish regulator - but I think it's 3 nuts to get back plate off, then 3 bolts for the regulator and one bit that needs to be uncrimped/cut off and recrimped/resoldered on.
How did you guys end up wiring your pump? I used one big relay like Cujoels wiring, I didn't bother using the power train relay output,
this isn't going to matter for the rest of the wiring? playing around on my test bench
How did you guys end up wiring your pump? I used one big relay like Cujoels wiring, I didn't bother using the power train relay output,
this isn't going to matter for the rest of the wiring? playing around on my test bench
Hi Cameron - I'll refer you over to my wiring post. https://www.miataturbo.net/build-thr...-87186/page13/ - basically I added an inertia switch from a ford inline to the fuel pump relay that is just powered by the ig1 circuit.
Well now that I have that datasheet in hand, I think I see why my PWM circuit didn't work - so I might have two options available after some testing. One will be a "set this trimpot while looking at a multimeter" circuit board, hopefully I can build it out of a 555 without having to resort to something that needs to be programmed. The other will be the honda-ish regulator - but I think it's 3 nuts to get back plate off, then 3 bolts for the regulator and one bit that needs to be uncrimped/cut off and recrimped/resoldered on.
Curious if you made any more progress on the alternator.
Yes and no. I have all the information I need - a peer recently (like, literally a week ago) clued me into the canbus values needed for ECM alternator control (untested - I trust they're correct, but I need to do my own verification) - and I have a basic idea for a standalone controller that may be cheaper / easier to produce / GM agnostic - I'm still weighing pro's and cons to that approach, and decided that unfortunately it is definitely gonna be more complicated than a simple 555. It got deprioritized on my end because our own hard start issue virtually disappeared once we realized our 10micron inline fuel filter was clogged, which annoyingly, behaved *exactly* like low voltage. I was in the garage with my o-scope and a bench power supply powering the engine electronics, varying voltage and trying to find more or less the exact threshold at which brownout protection kicked in, and it got to a point it wasn't firing at 15v - "well that just doesn't make any sense.. could it.. not.. be the battery?"
Last edited by gooflophaze; 03-29-2021 at 09:52 PM.
Yes and no. I have all the information I need - a peer recently (like, literally a week ago) clued me into the canbus values needed for ECM alternator control (untested - I trust they're correct, but I need to do my own verification) - and I have a basic idea for a standalone controller that may be cheaper / easier to produce / GM agnostic - I'm still weighing pro's and cons to that approach, and decided that unfortunately it is definitely gonna be more complicated than a simple 555. It got deprioritized on my end because our own hard start issue virtually disappeared once we realized our 10micron inline fuel filter was clogged, which annoyingly, behaved *exactly* like low voltage. I was in the garage with my o-scope and a bench power supply powering the engine electronics, varying voltage and trying to find more or less the exact threshold at which brownout protection kicked in, and it got to a point it wasn't firing at 15v - "well that just doesn't make any sense.. could it.. not.. be the battery?"
I spent an hour today looking at possible one wire alternators that would fit in the oem mount. No luck, although one of the transverse powermasters is only an inch off (#477501). Emailed a couple custom alternator rebuilders and asked just out of curiosity if they could convert my oem alternator into a one wire configuration. I doubt it, but who knows.
The denso VRM swap I mentioned earlier in the thread is probably on-par / easily done by an alternator shop. Looking at it again, I'm seriously wondering if the cadillac one is the same VRM in my LS3, and if so, all it needs is an exciter wire + resistor to turn on..
The denso VRM swap I mentioned earlier in the thread is probably on-par / easily done by an alternator shop. Looking at it again, I'm seriously wondering if the cadillac one is the same VRM in my LS3, and if so, all it needs is an exciter wire + resistor to turn on..
Hell yes! We might be on to something. Will report back as soon as I get more info about a possible conversion.
Crossreferencing "IN6003SE - Voltage Regulator, Self Exciting (one wire) for Buick (2004-2005) , Cadillac (2001-2005) , Pontiac (2004-2005)" and looking at what models might possibly use it, I started on Pontiac (cuz smallest range) and it looks like it's a 2005 Bonneville - same bolt positions on the VRM that identifies it as a Denso.
Browsing some Bonneville forums about control schema I can't find much - but there are some complaints about it outputting 15.6-15.8 which seems to indicate it does operate like a one-wire alt with a bad fail-safe condition. Looking for more verification, 2001 Cadillac Deville and Seville -
Little more information on the forums about failures, same 'fail-high' (15.5, 15.8v) scenario, but did found "failed (low voltage/no output), replaced, now 14.4"
and just for reference - camaro alternator - you can see some of the plastic shell might need to be trimmed to accommodate the plug (or swapped out completely, since denso horseshoes are supposed to be modular?), but the VRM bolt pattern is a match.
Goof, not sure if you have seen this. Seems highly relevant to your efforts. Skip ahead to the section: 2-Way Connector External Regulating Alternators
Sorry to revive a stale thread, but this seems like the best place to put some information for future reference.
Gooflophaze was kind enough to pass on this bit of potentially-useful info via PM, with regard to sending an alternator demand over the CAN bus:
I found this awhile back but have not had time to test it at all - so at your peril -
0x3f1 - 250ms strobe - Byte 1 is the Requested Alternator PWM Duty (Generator Regulator Setpoint Duty Cycle Request) (0-255) Duty Cycle = n*100/255. Set byte 7 to be 0x6e = 15 degrees (c) Outside Air Temp (also ties in). There's also a valet speed limiter the packet in there as well, but the details are 'fuzzy at best' when you're looking at the 20th page of a google search. Also be aware that the charge duty is just that, it's not a closed loop control system.
I used an Arduino with a Seeed CANbus shield to try this out, but I had no luck. I can receive CAN messages from the PCM so there isn't any issue with the connection. I get 13.6 volts no matter what I send. Here's my code, for the curious:
#include <SPI.h>
#include "mcp2515_can.h"
const int SPI_CS_PIN = 9;
const int CAN_INT_PIN = 2;
02-18-2020, 02:34 PM
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