After i put in the U7 chip and connected my MS to the PC, I cannot get it to recognize it in megatune. I checked the voltage and the settings on megatune. Anything else I may need to specifically look at? Maybe i shorted it out while handling it? or would this be caused by too low of a charge on my 9v batt? It has about 7 volts on it now.

I tried reflashing the firmware but the program cannot connect.

 

First thing to do is replace the 9v battery. The stimulator is brutal on batteries, 20 minute runtime before it kicks is not uncommon.

-Mike

 

7V is way too low.

Do yourself a favour and get a little 12V power supply, or a 12V gel cell battery. The 9V is only useful for emergency stimulation.

 

What Aaron said...

 

ok I remover the jumpers for the VR and still nothing.. I got fresh batteries(didnt get power supply cuz it was late at night) Put fresh Batteries and still nothing.. so then i noticed my MS1 chip was not seated correctly.. I removed it and reseated it and everything works fine.. Now this make me wonder about it coming loose.. Should I bend the pins in a way that they help keep it snug in there? everything seems to be working now, but i will see once i put the jumpers back on.

 

Put the jumpers back on and VIOLA!! i got rpm reading now.. !! So i did notice that when i flip the board to do the jumpers i might have made the chip slip out.. but all seems well now.. I got it to lock into place !!

 

I've yet to see a properly seated processor be anywhere loose enough to fall out. Perhaps it was not fully seated initially? They're normally somewhat a PITA to get out without damage if you're not careful. That said, you could glue a suitable piece of non-conductive high density foam to the inside of the cover to secure the chip. Black foam often means conductive foam and is plenty enough to load down the crystal circuit enough to stop it if the conductive foam contacts the wrong pins. Also be careful with using black rubber line to the MAP sensor, same reason.

-Mike, PhD from the Univ. of Hard Knocks & Misdirection

 

Yeah it was not properly seated, now it seems good and sturdy, just gotta go get my 47k resistor for r4 and I should be in business, then i have to build a whole harness for it.. what gauge wire do you recommend?

 

well after looking around seems most are made of 20 and 14 Ga so i will do that.. 14 for positive and grounds I guess and the 20 ga for all the other stuff. Unless someone chimes in and recommends otherwise. oh yeah and 3M heat shrink tubing all around.

 

Good calls. If it's a wire for a sensor, 20g is more than sufficient. 14g for power stuff (injector, etc.) is a great idea and highly recommended; the less voltage drop the better! Make sure your sensors ground to the same place the MS grounds to to avoid a ground offset problem. Use shielded cabling for critical inputs such as the VR input. Only ground one end of any shield of a shielded cable, preferably at the MS end. If any of your sensor wires need to go over a high current or high voltage conductor, cross it at right angles, avoid paralleling them if at all possible. Plan ahead, commit your wiring plan to paper first and review it step-by-step to make sure it follows general good practice guidelines. The OEMs make millions of reliable consumer vehicles using these same general principles, so can we! Hasty planning and improper/careless wiring is the #1 enemy of any standalone ECU system. Sorry to sound so terse, just trying to get my thoughts down to the keyboard.

-Mike

 

this is all going into my 75 Repu, it has a painless wiring harness which i removed due to some welding needed on the inner area bellow the windshield, so I will make sure i route all that stuff separately when i put the body wiring back in.. where can i get this shielded wire? I will make a run to the electronics store in Los Angeles tommorow to grab some in case they don't have it in Radioshack.

I really Appreciate your advice, and i will keep it all in mind.. Also if it helps any I will be using LED lights all around and indash as well to minimize the strain on the electrical system. The battery on the repu is in the bed but i will route that to a power block in the cab with fuses via 4ga and distribute to the accesories from there.

 

you should use 2 or ought gauge for your main battery cable.

 

Your local home improvement store (Home Depot, etc.) should have some fine stranded 16/4 and/or 18/6 plenum rated teflon jacketed shielded cable typically used for old school intercoms, 70v audio systems, thermostats, etc.

 

Since these are signal wires would it be fine to use some shielded audio cables ? I have tons if that in the garage from the sound systems i've built.

 

Yes, those should work fine. Be certain that you only ground one end of the shield, at the MS. Be certain that the other end is not grounded or connected to anything. Also be aware that the audio cable's insulating layers may (or may not!) have a fairly low temp rating.

-Mike

 

alright, well i went with some 16 gauge instead, 14 was way too fat, but it looks good.. I made the harness .. but I dont know if i need pin 37, is that for a fuel pump relay? if so my other harness has that in it already, i left that out and 30,31 and 36