View Full Version : difference between the late (86) 5m injector reisitor pack and the 7mgte units??
07-15-2008, 04:20 PM
I don't have alot of access to the exact specs between the two, and am needing info fast. How bout it guys with the 7mgte swaps, did you swap over the 7m injector resistor pack with it??? has it been verified that you can run 440's on the mkII setup? I'm guessing the plugs are different, and I have no idea of what the 7m one looks like compared to the 5m except a crappy google image I found. I am searching to find the answers, so sorry if it has been covered, I'm sure i'll find it shortly after I write this. Just thought i would post and possibly get a lucky with a good answer. thanks, -Mike
07-15-2008, 04:23 PM
...fairly certain the plugs are different, I'd ohm them out to see if they're compatible though.
07-15-2008, 04:29 PM
The 7M resistor pack is 3 seperate circuits vs a single for the 5M.
07-15-2008, 04:53 PM
wait, the 7m has THREE BANKS??? I thought it had two. It is also confusing that the 5m's are wired at the injectors like a two bank system and then when they reach the resistor pack become a single??? This may be a problem for me as I have always been running my megasquirt as an alternating injection system so injectors only work half as hard to prevent overheating........ I could always just run megasquirt on simu injection, but then it defeats the purpose of of the twin fused banks the megasquirt utilizes... Any suggestions?? I know this is also a long shot, but does anyone know of a reisitor pack from any other twin bank car set up for six injectors of appropriate resistance. (runs away from computer, lol) I have heard of people just using 10ohm individual resistors inline with each injector, but doesn't the resistor pack hold the circutry of the "peak then hold" injector power supply features??
07-15-2008, 05:16 PM
Had you seen this setup?
They also have a board that drives up to 8 low impedence P&H injectors with individual control that you can setup which ever way you want. The board takes logic level switching to control the injectors.
Just another option if you are running MS.
07-15-2008, 05:24 PM
Wait my bad, the 5M is a 2 circuit setup (which is stupid). 7Ms are 3 circuit setup, matched cylinders are pair (1-6, 2-5, 3-4). The injector drivers should be built into the ECU. The resistor pack is simply a power resistor with aluminum heatsink case.
07-15-2008, 05:44 PM
if the 5m is a two circuit system, how can there only be 3 wires on the injector resistor?? this means one 12v source then two resisted lines out to what seems like two banks?? I am confused again, lol. I think the 5m's are indeed one bank, but for some wierd reason are wired up the harness at two. Ya, all the peak&hold circuitry would be on the ecu side, I'm thinking of just using individual resistors along each injector, using the resistor calculator on a megasquirt page here:
For those wondering why I am not using meagasquirt's PWM current limit feature for resisting low-imp injectors, is because i believe mine has become corrupt or completely failed, as setting my current limit from 100% to 0% results in the same output!!! FTW MATE?? I don't have time to dig into the megasquirt and scope out what the problem is, I just want to fix this for the rest of the summer/fall and get back on the road!
07-15-2008, 05:54 PM
if the 5m is a two circuit system, how can there only be 3 wires on the injector resistor??
Common ground with 2 source wires, 3 wires total.
07-15-2008, 06:37 PM
Oh, ok, I was under the impression that the resistor was inline resisting the main power supply, not the grounded return. I need to go back to pre-standalone supra school, I seem to be forgetting alot the stock efi system. Well, I ohm'ed the 5m resister pack and got around 2.5-2.6 ohms through each line to their shared ground. Does anyone know of the spec on any of the three circuits of the 7m resistor pack??? I assume it should be different, as in less, as each 7m pack has only 2 injectors to resist insted of three, but... I'm not sure. I am thinking of using the 5m resistor in reverse, but don't know if that will work, as in supplying +12 constant onto the single plug (ground in old system) and then tying both banks into each perspective prong on the double plug for the constant 12 v source wires to the injectors. I don't know if this will work though. If not, then I will have to intercept the grounding lines for the two banks (going to megasquirt as megasquirt grounds the injectors to open them, and the injectors always have a constant 12v souce) and tie them into the two prong connector, then taking the one prong connector and splitting it off to the two injector bank lines again going to megasquirt (making it only truely a one bank system in either case). Any comments/ concerns?? I have a feeling im going to be limited to a one bank setup no matter what i do, but a one bank is just as stupid as a two bank on an inline six anyways! lol, megasquirt right now only has the option of twin bank setup (i.e. hapy v-8 boys) unless you switch over to the dramaticly complicated sequential injector firing setup, which I have not even looked into.
07-17-2008, 02:55 AM
Just thought I would throw this out there, has anyone used individual resistors for the 440cc injectors?? Anyone hear of or know of a good size and type of resistor to use possibly from another friend/website/forum. It seems there are way too many varrying resistor sizes for the 7mgte when I search online, anyone know for a fact a good size to use?? Any info is appreciated. -Mike
07-17-2008, 09:50 AM
actually. the resistor is going the positive of the battery and the drivers in the ms are grounding the injectors. so 1 +12feed to the resisitor ten it splits power 2 each of the 2 injector banks. then the ms grounds each bank alternatly to fire the injectors.
07-17-2008, 12:20 PM
as megasquirt grounds the injectors to open them, and the injectors always have a constant 12v souce
Yes, as I said, but my question is as the resistor pack on the stock efi system is used at the grounding point of the injectors, i.e, the ground for the teo banks end up at the two prong on the resistor pack, each bank is then resisted, and they share a common ground to be grounded to complete the circuit. So the only way I can kep an alternating injection setup, is if i use the resistor in reverse (as I believe you are saying), giving the constant (while running and cranking) 12v feed (which is actually two seperate +12v fused lines on the megasquirt with the relay board), tying them together, running them to the one prong on the connector, then when the line splits in the resistor pack, the two lines then meet the internal resistors, both lines are now resisted, and the resisted 12v source can go to the two bank wired injectors, and megasquirt can still ground them in an alternating pattern, just that now the 12v source in a single feed. Is this what we are getting at?? lol, the only problem is I don't know it the resistor pack will work in reverse, bit I will try. By the way William, how bout them Venoms?? lol, saw your post on supra forums:ugh: -Mike
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