Hey if I have a 87 TII that uses low impedance injectors when I install my megasquirt can I use high impedance injectors?

 

Sure. That's the preferred actually. High-impedance is easier for the MS to drive.

Ken

 

do I need to change anything or will it just work?

 

Just change the injectors out, and make sure that the injector PWM settings in the MS are set to 100% and 25.5 so that they don't actually engage.

Ken

 

what about if I am using low imp injectors? I really like them and I wanna keep using them

I don't see anywhere in the wiring that utilizes the injector resistor pack anyways...

 

It's much easier to use a resistor pack or resistors (wire them in yourself) than it is to tune the PWM parameters. Often the PWM flyback causes noise that makes it difficult to run the engine properly as well.

Worst case if you really want to run low impedance injectors directly, I recommend getting Jean's (www.jbperf.com) Peak and Hold driver board.

Ken

 

I only have an NA so I'm not worried about making crazy power or boost/timing issues. I really want to use my low imp injectors because I'm poor and I had them cleaned and balanced by a friend of mine.

So right now I have them wired up directly and your saying that it wont work unless I get the jeans daughter board? What about the stock resistor pack for S4? Can I somehow utilize that instead?

I have MS2 vb3 with the 2nd VR circuit setup installed and my MS2 is already assembled.

 

I drive the low-imp injectors in my 7 without any noise issues. You just have to make sure that your CAS wires are shielded and that everything is well-grounded. I've heard of people cutting out the injector driver ground trace from the PCB and running a separate wire (or completely relocating the driver) to avoid noise, but I haven't had that problem personally. Noise-wise, you're more likely to have problems with the 2nd VR circuit (Ground pin 14!!!) than with the injectors

As far as the injectors are concerned, low-imp injectors tend to have a shorter, more repeatable opening time, and therefore for the same pulsewidth and fuel pressure can deliver more fuel, more precisely. So if you're planning on running enough boost to get close to the limit of the stock injectors, running them low-imp will give you a little more margin of safety since they'll spend less time opening, more time spraying.

 

I have excellent shielded cable for my CAS and everything is very well grounded

I don't plan on running any boost... for at least a year or two, who knows I may get board with this build and want to go E85 turbo 6pt streetport but I doubt it

 

Just remember, well-grounded doesn't necessarily mean properly grounded. All the grounds from the MS should bolt to the same spot, as close as feasible to where the battery ground is bolted (the battery ground is generally on the end of the long bolt that holds the top of the starter motor, through the transmission and engine rear iron. I have the MS ground bolted to a hole in the top of the rear aluminum rotor housing, under the UIM). I also run a thick (4 ga IIRC) wire from the alternator housing to the same spot as the MS ground, this seemed to calm down a little of the alternator noise that would on occasion affect the TPS sensor and CAS. Also, the shielded cable should only be grounded on one end, otherwise the shielding does nothing, and gives the potential for a ground loop.

 

I typically stick with the stock ground locations and have not had a problem.

Ken

 

ditto, measured them and everything, all came out great

now if megatune wouldn't stop crashing and locking up and freezing my PC all the time we would be in business...

 

Use TunerStudio; the newer code's inis are incompatible with MegaTune for one thing. However, that's odd that you're having crash problems with MT - it's a pretty stable piece of software, just hasn't been updated and maintained and probably won't be.

http://www.efianalytics.com/TunerStudio/

 

what about .vex files? I don't want to have to manually type in the AFR, VE, split table and ignition tables.

I'm following aaroncakes' guide but some windows differ on his site regarding programing the MS2.

my laptop is a piece of **** so that may not help, or all the minimizing and maximizing of MT.

 

TS imports vex files with no issues... All you need is an up-to-date Java install - which is very likely already on your machine.

 

thanks for all the support, gonna be driving this sucker today! (i hope)