1970s 40, 350/TH350 on Megasquirt 1 PCB3.0 (1 Viewer)

[toyotaspeed90]

This weekend was a perfect example of why this project is taking so long.....

Father in law bought a house less than 2 miles away, helped move in. Helped rewire portions of the house and shop for essentials. Rewiring the house meant my strip/Crimp tool was left at his house so couldn't work on wiring while everyone (FIL, wife, and our 3yo son) else took a nap. Shopped yesterday and ended up with 8 new LED shop lights from Costco and ceiling insulation for the garage here. Now that's in the way and will take precedence.

So over a 3 day weekend I got 1 wire run from the fuel pump relay to the fuel pump... but not connected. I also looked at the throttle linkage, but didn't do anything with it yet.

 

[toyotaspeed90]

No photos to share....

Last night I got some wiring done and did a test fire.... there's good and bad.

TPS doesn't seem to be reading properly. Fuel pump isn't turning on via MS.

With the pump jumpered I was able to get it to run through the initial cycles, but it dies rather quickly.

It doesn't have idle control setup, nor wired. I doubt that's the problem.

A bigger concern is I got a couple small 'backfires' (more like a quick flame than a compression driven backfire). Could be simple constants set wrong. I'll try to get some screens hots but really I haven't done much.

The glove box is getting a bit cramped. Although most of the wiring is done/working, tracking a few things here/there may be more of a pain than just going with a relay board and pre-built DB37. I'm guessing I went way overzealous with the tinned 14ga wire.... in the past I've used relay boards and been wildly successful.


Injectors are 55lb units.... I set it in constants as fuel req with 48lb just in case, but may not have been the right plan.... pretty sure I'm getting too long of a spray.

 

[srgould41]

Well a short run is better than no run. At least now you know where to go next. Good work.

 

[toyotaspeed90]

Well, sort of. MS is setup to add additional fuel in 2 ways at start up - based on the warmup enrichments (increase based on coolant temp) and there's a 'start' setting where it basically dumps fuel for the first 255 cycles (though that can be changed).

The plus side of MS is everythino can be changed on the fly whether just key on or running. The downside is that everything can be changed, and injectors can be finicky.

It's interesting- MS and TBI have got to be one of the more popular combinations, yet I can't pinpoint injector settings for these most common TBI injectors (however I can easily find injector settings, and even dyno tuned maps, for a 16v 4age, 4agze, 20v 4age, etc).

So we'll see how this goes.

 

[srgould41]

Weird considering those are the most common v8 injectors. Or would that be the 40lb 305 injectors? I should have 65lb in my motor, but have not verified yet. I will start the engine buildup in a few weeks.

 

[toyotaspeed90]

Based on the part numbers on the injectors they are 55lb units.

The 40lb injectors were found on the 4.3s. Unsure about the 305. I believe the 454 has 2 different sizes of injectors.

 

[srgould41]

Here is where I pulled the data from.

TBI injector flow rates - Hot Rod Forum : Hotrodders Bulletin Board

 

[toyotaspeed90]

Poking around I'm getting some very odd results.

The ground to MS is obviously working as it works fine. However, the problem with the coolant and air temperature sensors is that the return isn't grounding within MS properly on the return line. Oddly, if I leave the wiring as is (with sensors connected to the return) and connect that to ground, both AIT and CLT work properly.

I've chased the TPS wires and they are correct.... but I can't seem to calibrate it (as time continues the value read from the TPS continues to climb, and has no bearing on TPS position or even if it's plugged in). This will be a problem.

 

[toyotaspeed90]

Here is where I pulled the data from.

TBI injector flow rates - Hot Rod Forum : Hotrodders Bulletin Board

Yup, I've come across that several times.

 

[toyotaspeed90]

So I found the problem to the CLT, AIT, and the fuel pump - the sensor return is a ground fed back to the ecu from the sensors.

There are a large number of grounds available in the DB37 connector. Generally you use 5 of them and run them to the engine for ECU grounding.

There are several more that can be used for sensor return - which is generally pin 7.

Here is a diagram:

Wired mine to pin 7 - and with testing, I had continuity to ground at pins 1, 2, 8 and so on... but not 7.

Pull the connector and check continuity at the ECU... since these pins tie together, checked using pin 1 to pin 2, pin 1 to pin 7... and there's continuity.

The connector is bad or I made it bad when building it. As a temporary solution I jumpered pins 7 and 8 at the connector... CLT, AIT and fuel pump all work properly.

TPS is still problematic.

After fixing that, verified I had the flyback circuit so then adjusted the injector settings (then stupidly realized I was telling the system there were 8 injectors.... which means I was getting 1/4 the expected fuel). Fixes that and it will fire right up and idle. No, I haven't done any driving.

Sorry for the phone pics of a laptop screen - very old laptop that shuts down once power is lost, can't connect my phone to (to get screen captures), and it doesn't have wifi.....

 

[srgould41]

Woohoo

 

[Mace]

Megasquirt is a huge pita and huge fun simultaneously

 

[toyotaspeed90]

Megasquirt is a huge pita and huge fun simultaneously

Yup, especially boards older than V3... there's a reason I didn't want V2.2 even though they can handle TBI easily....

Had a v2.2 in an mr2 that had many issues... none in a v3 install...

 

[toyotaspeed90]

So I decided the best route is to trust that it already mostly works and don't need to also install a relay board.

Ordered a new DB37 connector, with a high quality metal hood, and a set of the diy auto tune 23" wires bundles.

Not so intelligently I ordered an MS3x wire bundle so the labels are all wrong... oh well, it will be wrapped anyways. On the plus side they are the proper size and I can solder into the db37 properly without damaging the pins.

Took a page out of my own book.... when I swapped a 1991 MR2 5sfe into a 1986 MR2 (4age was stock) I tried using a 'wiring guide' someone wrote up for a similar swap but it was relentlessly useless for me. I ended up creating Excel spreadsheets that labeled each side (body side and new engine side) of what wire colors were where and what they did. The end result was simply taking pigtails for the body side and wiring it to the engine - making the new ecu and harness plug into the body.

So I made a quick Excel spreadsheet for the MS plug, what MS3x wires would go where, and what color wire was on the truck side.

I know it's not tough, especially since there's under 20 wires - but it makes things go easier and faster.

Next is to solder in the shielded wires (ignition) then toss in the truck.

As a tip - DIYAuototune says the soldered connections need good "flow". When you solder, you actually want to heat the item up and allow the solder to flow/melt through the connection... improper soldering is touching the solder to the iron tip to melt, then trying to get the solder off the tip into the connection.

The green wire pictured isn't a very good solder (color is good, but too much solder) but the black wires are well soldered.

 

[toyotaspeed90]

Some progress, setbacks, and progress.

The new DB37 harness was wired to the truck/engine. To allow simple removal (if needed) for diagnostic purposes, and for a simole solution to combine the 20ga wire with the 14ga wire I installes the new harness with a spade connector kit. Each wire has a male or female end with the engine side having the opposite.

After that was rewired, I was having problems with injector power - I've decided I don't like where the fuse panel is.... thinking about moving it elsewhere.

Got it to run, but was having problems with both the GPS and the air temp/coolant temps reading accurately. Same problem with the old connector - no ground at pin 7.

A continuity test between the return wire and pin 7 (unplugged from MS) showed good connection. Pulled the board out of the case and checked for continuity between a test ground point and the return wire (soldered to pin 7) and there wasn't continuity, but there was resistance.

Something was wrong - upon inspection I determined there was a poor solder at the board on pin 7. Resolderee that and went over all the other pins I could reach and retested.

All was well, truck started and idles very well, even allowed rpm increase without too much fuss.

TPS was still problematic. No matter what I did I got off readings - even if completely disconnected.

I tested the circuits per the megamanual and it essentially tested good. TPS worked with the stim.

A suggestion at the forum asked to check resistance between the chip pin 26 and the db37 pin 22. That's where thing got odd....

I got no readings at first, until I kept probing and found that on the board, resistance was there, and at the output pin, if I applied pressure with the probe - there was resistance.

In order to check that pin on the board I had to loosen the MAP sensor and bend it out of the way.

Again, I found a poor solder. Fixed that and went over all pins under the map - checked over the rest of the board, reassembled the map and tested.

I was able to immediately calibrate the GPS. I don't like the values the GM unit puts out (registers nearly 100% throttle around 1/3 actual throttle but that's based on the potentiometer value output, not MS).

Truck started, idled, and revved freely (after changing back to TPS based acceleration).

On order, and hopefully arriving soon, is an LC2 wideband. I'll be able to tune easily and get close to where I want it to be.

 

[toyotaspeed90]

Will try and get some photos here soon.

I've learned that MS has changed drastically - and it's time for me to stop using Megatune. Ordered a new serial (FTDI chipset) to USB to use on a worthwhile laptop.

Downloaded Tuner Studio and am going to purchase the Ultra package.

Tuner Studio will allow me to have the laptop connected and self tune based on my suggested AFR targets in conjunction with the LC2 wideband.

Since part of this all is to help maintain engine temperatures I will be tuning based on AFR targets in correlation to engine operating temperatures.

This means if I'm driving steady at 40mph and see the temps climb more than I like, but AFR is at say 15.5, I'll drop it to 14.5 and see if the slightly richer system will reduce temps.

 

[toyotaspeed90]

I thought others might be interested to see the overall cost. Understand some of this is vague because a lot of pieces I price I already had sitting around.

The benefit is I can run any engine on this setup from 4 to 12 cylinders (yes modification would be needed, but ability is still there).

I can also tune on the fly, even while driving - and will be able to auto tune while driving (no interaction while driving needed) and log data.

Some of these costs are also just generic/needed costs for any EFI conversion, some specific to a SBC, and not necessarily Megasquirt specific.

TBI bits:
TBI from online scrapyard: $60
TBI adapter: $45
Air filter spacer: $10
TBI rebuild kit: $20
Total: $135

Peripherals:
Air temp sensor: $10
Narrowband sensor (no longer needed): $30
Coolant temp sensor: $10
New coolant neck: $25
Fuel pump: $100
Fuel pump plumbing/connectors: $100
Total: $275

Megasquirt/tuning specific:
ECU kit: $220
Extra DB37/hood/wiring: $45
Wiring relays (estimate): $40
Serial/USB adapter: $20
LC2 wideband and controller: $150
Tuner Studio and log viewer license: $130
Iron and solder: $30
Total: $635

Grand total comes to $1,045.

(As a side note - Tuner Studio upgrade and wideband are not necessary - math/patience combined with a narrowband can get you pretty close...and I was successful on all past MR2s that way. That's an additional $280, over 1/4 the cost, for my convenience)

 

[toyotaspeed90]

Potential future plans (the possibilities are running wild right now)... but after tuning (and when I get the usb adapter and decent weather I will go over that).

I *might* consider building a Raspberry Pi, incorporate touch screen, and a GPS board.

This would allow tunerstudio to be run (at the very least for engine monitoring - unsure yet if that supports other features or even if the PI can control tuning), have any/all music loaded on the Micro SD card (with the motorcycle stereo I have acting purely as a mini amplifier), and have GPS.... I think that would run in the $200-250 to build and setup....

I could also wire that the PI is powered up whenever I want when the vehicle is off and not in the garage, and if stolen - can track through GPS....

 

[Mace]

Jeabus MS has changed since I played with it..

 

[toyotaspeed90]

Jeabus MS has changed since I played with it..

Tell me about it....

Long way from the MS1 v2.2 I bought from Glens Garage in 2004 for an MR2... where it took 2 months to arrive in the mail and the number of people successfully running it was numbered. I was the 'outsider' then using Megatune.

Although it's been pieced out over the years.... I even have a MS1 v1 kit (bought it from a friend when I killed the injector drivers in the 2.2) where it got shipped with all components, unlabeled, in a sandwich bag.

Long way from that....