Need some pinout clarification/ideas

[cheappower82]

I'm narrowing down the pins I need for the PnP fuel-only Megasquirt install. Looks good so far, but I'm still having minor issues with a few pins.

This is what I've determined so far:

MS DB37..............TSRM ECU pinout
Pins 7-11 & 15.......just about any ground pin E01-02, E1, etc
Pin 20..................will be run externally to a air temp sensor
Pin 21..................THW
Pin 22...................VTA
Pin 23...................Ox
Pin 24....................run externally to tach or neg. coil wire?
Pin 28....................B+ (main relay)
Pin 30....................won't be used - spark
Pin 32+33...............No.10 - bank 1 injectors
Pin 34+35...............No.20 - bank 2 injectors
Pin 37....................fuel pump relay - shouldn't need this

Pin 21 is coolant
Pin 22 is TPS variable signal
Pin 23 is O2
Pin 24 is ign trigger
Pin 28 is 12v switched+ power

What I'm doing here is using the ECU for everything but fuel. I have extracted the injector bank pins from the ECU PCB and will be wired to the MS. Everything else will be shared with the ECU.

What I'm not so sure about is the tach-in from the neg side of the coil and possibly the fuel pump relay. I haven't dug too deep into the TSRM yet, but I'll try again later. I'm going to start soldering now.

D

[cheappower82]

This is what I've got so far:

http://www.pbase.com/celicaxx/image/77241282/large.jpg
http://www.pbase.com/celicaxx/image/77241285/large.jpg

[cheappower82]

Started the install; made a few stupid mistakes. For some odd reason I ran 5Vref from the ecu to the megasquirt; basically backfeeding voltage into MS.

anyway, clipped that wire and finally got MS to come alive on megatune. tried a few things on getting trigger for MS: tapped into neg side of coil, didn't work. then tied into IGt on the ecu, nothing. also tried IGf, same results.

Got frustrated, so I put the stock ecu back in and the car wouldn't start. WTF, mate? Blown ECU fuse (15A). Maybe the trigger issues will work if I actually had power to the ECU :sadsmilie I'll try again tomorrow

BTW, temp sensor from the afm works (seems to be accurate). No need for easytherm to calculate stock coolant sensor either. both seem to be accurate

[935motorsports]

Jumping in...


Yes the factory air temp actually works, if one was to use the AFM. The values are not far off from typical GM values.

I'm not much into MS. If the MS is doing fuel only, all it needs is RPM really right? Or does it actually have to read the distributor?

Since you still have the AFM, you won't need MS to control the fuel pump. The AFM will activate the fuel pump when it gets some air going through it.

[cheappower82]

Yeah, I'm starting to think this fuel only install is a bad idea. I'm thinking the AFM needs to stay in place to give the stock ecu data to make a usable ignition map. I'll press on, but I'm not getting the results I was looking for.

Theoretically, I should be able to pull the trigger from the factory tach signal: can't seem to get a clean signal. I haven't tried any pull-up resistors yet, so that's my next option

[walkerhiboost]

Why are you wanting to go fuel only?

[cheappower82]

Wishful thoughts.....I was looking for an easy way to get cs members started on a clean megasquirt install. Fuel only is really easy to configure in megatune as long as your inputs (wiring) are dead on.

So far my problem is tach input. When I get a clean signal on the OEM equipment (via the unmodified route), I'll be satisfied.

Locally we've encountered many issues with Toyota ignition: 7M, 6M, 3S, and others just aren't surrendering easily in relevance to working in harmony with MS. I'm hoping others will have better luck.

There's always the EDIS route, but I'd really like to see someone make use of the 24/2 dual wheel VR option.

[rwhite]

I don't know if the Ignition Tach signal is labeled IGt, but I was using this signal for data acquisition on a Zeitronix wbO2 and it was really noisy and I was even causing the car to miss fire from time to time and the data was showing rpm signals from normal up to 280000. I swapped out the coil/igniter with a spare one I had and all of a sudden the signal was clean. I thought it was an ECU problem before I changed the igniter. Is the IGf signal the command signal from the ECU?

[cheappower82]

The TSRM doesn't distinguish the difference in IGf and IGt. I've tried both with no luck

[935motorsports]

So it does read the signal, it is just erratic?

Would a shielded wire help?

[cheappower82]

I'm getting no tach signal in Megatune. I'll break out the multimeter next time

[rwhite]

On the zeitronix wideband, it does read the IGt wire at the ECU as rpm and it is stable now that I changed igniters.