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

[toyotaspeed90]

Ignore the mods that were displayed above, and if you do anything like this yourself - ignore the HEI upgrade kit. I don't understand (at all) how it's supposed to work - and for me, it didn't. Not even remotely.


Now.... on to what was actually done.

As I mentioned previously, the HEI upgrade kit from DIYAutotune was removed, and I followed this (and grounded the coil) to get signal/and the truck started enough to set base timing:
Removed C30, Removed D1 and installed a jumper, Jumper D2 (for now), remove C12, then jumper XG1 to XG2, OPTOIN to TachSelect, TSEL to OptoOut, and JS10 to IGN.


I attempted my SPR4 to 5V mod (with a 1k resistor) - which is then tired directly to the "B" pin on the HEI8 ignition control module.

The purpose of this - and how it works in a factory equipped vehicle - is when the car is cranking advanced timing is turned off. There is no 5 volt signal sent to pin "B", and as such no advancing of timing takes place. After cranking is done, or 5 seconds of cranking, 5 volts is sent to pin B and ignition advance is put into place.

Seems like no big deal - as long as the vehicle starts well, I can supply voltage full time.

For *whatever* reason, when I did this mod, I got no signal - no fuel. Unplug pin B (everything I've wired I use weather-resistant male/female crimps) and there's signal & fuel (and starts up). While running - plug that wire in, and it stays running.


So - I followed the suggestion in the MSExtra guidelines. Remove D16 (one of the 3 red LED's). Solder one side of a 1K resistor (I used a 1/4W, see below) to the resistor near it, then the other leg of that 1K resistor to the negative side of D16. After that is done, run a "jumper" wire from that same negative D16 over to your spare output pin (I used SPR4 since it's already wired). Set, in Tunerstudion, the GM HEI to "Bypass". Everything works - I can start/get signal, and timing advances after it starts.


The MSExtra guidelines indicate to use a 1/8W 1K resistor. I asked on the MSExtra forums if a 1/4W would be fine (I have lots of those, no 1/8W and nobody nearby carries 1/8W). The wattage of a resistor apparently doesn't have an impact on the circuit - generally the limitation of the wattage ends up being it's physical size. The wattage refers to it's capacity to withstand heat/power - most circuits are designed with 2-3x the necessary wattage, so bumping the wattage up is perfectly acceptable (even though I didn't get a response).

Following photo shows the mods...


(right now I have the driver-side muffler cut off trying to find a quieter option ironically, so I can't start it - once I get it filled back up with coolant I'll get some Tunerstudio screen captures).

This all means that now I can basically run ANY engine I want (as long as it has a distributor - the HEI8 allows for basically reading the inputs of any Hall/VR sensor and can be modified for use with other distributors) with little to no rewiring, just some pretty simple software changes and tuning. I know that sounds silly, but I have been seriously considering swapping engines....

 

[toyotaspeed90]

Photo....

 

[toyotaspeed90]

So an update.....

Things have been busy around here (we bought a 100 series, been doing some work with that, we got a GSD puppy, and wife is 9 months pregnant - literally past her due date as I type this) so the 40 has taken a backseat.

One of the "issues" is that the vehicle is too loud for our 4 yo son. I ordered some large mufflers - they were too large. I ended up ordering more of the same (turbo style mufflers in almost the exact same size) and some piping - at least moving the new mufflers back about 4-5" each. While that isn't much, anything helps. I also wrapped the headers (first attempt at that, I think it went OK).

Since I was in there - I recalibrated the wideband O2 when it was out.


Mind you - this is really the first true running/testing with ignition control and not using a coil neg signal.

Starts up better than before - still need some work on the warm up values. There's a possibility the TPS enrichments are a bit off, but I'm unsure.

Idles quite well when warm. In park/neutral, it revs horribly - even has mini backfires (tried pulling back and advancing timing at the base timing... from 10 to 5 to 15.... and essentially no change.. right now it's at 15).

Something got in my bean brain "just drive it, see how bad it is". Mind you, I only drove it up/down our street (which is narrow, has some steep areas, and speedbumps) and it drove wonderfully, even at the same throttle/rpm where it had issues at idle.

I'll have to see what the values are at for map/rpm when under load and maybe make some changes elsewhere, but I don't plan to be in a habit of revving in park. I feel it's good enough to start driving (conservatively, close) and tuning again.

 

[SuperBuickGuy]

backfires can be a timing or lean issue. Your comment about being noisy, add fuel, lean is louder

 

[toyotaspeed90]

it was noisy because it has over-fender headers made of thin metal, leaking collectors, at least 1 of the gaskets at the head was broken, and the mufflers were crappy "turbo sonic" from the late 70s. I wasn't saying the engine was noisy from a bad tune/timing.

The bad revving is probably because there's been very little to no tuning done just sitting and revving in park - as that's not usually needed. Driving it puts a load on the engine and will change the VE needed based on map reading/rpm - which the same rpm would have a different map reading when revving in park. The 'backfires' weren't an issue when it was fuel only, so it's probably a timing issue.

 

[toyotaspeed90]

Haven't had much time lately to dedicate towards the 40 (septic issues, and I'm literally digging 1/4 our yard up, newborn, puppy, work)....

Took it on a short trip to the store - it ran horribly. Realized almost as I got there it was out of fuel.


Pro-tip - autotuning your VE maps when out of fuel really screws with the VE values. Thankfully the program I use stores previous tunes and does a check to see what the last tune vs what's in the system (and you can choose which to save). Will get gas in it, adjust timing, and retry.

I'm having a coolant leak issue. It's ridiculous. T-stat housing is adjustable and, granted I made the mistake, has a propreitary O-ring that was nicked. It's sealed back up (RTV) but now the hose is leaking. Tried about 4 times to reposition the hose and clamp back down (even now with T-bolt clamps) and it's still dripping. It's always the unbelievably stupid crap that happens on this vehicle.

I could have just taken gas and driven it home, but it was just easier to get the 100 and tow-bar it home....

 

[toyotaspeed90]

Playing with the 40 this weekend and it isn't looking good. I'm on the verge of yanking the 350 (and MS) and throwing in the 4.3L with complete harness and a new pump in.

Megasquirt isn't the problem - it's doing exactly what it should. It's tuning as expected. If I lean the curves out, the engine leans out, if I add fuel, it definitly adds fuel.

The wideband is doing it's thing - it's registering AFR's and working in tandem with Tunerstudio trying to tune it.

Ignition seems to possibly be a bit off, but making changes in the swing of almost 20* has almost no effect. I have a few last ditch efforts:

Going to see if the 4.3 has the same ignition module and if it does, swap them. Though the one I have worked fine and is a genuine GM (out of a suburban).

Next will be to play with ignition timing a bit more - although I checked TDC for just about everything and I had the engine torn down, I'm not convinced the pointer I just added is actually accurate. I'll set TDC on number 1 and get as close to zero as I can - then make the adjustment electronically.

In doing this I will also check to make sure that ignition advance is working properly.

If none of that solves the issues - it'll be out with the 350. It didn't run right on the carb/mech dizzy, didn't run right on a rebuilt carb, didn't run right on MS/mech dizzy, and now it's struggling with the MS/electronic dizzy.

I have checked firing order who knows how many times. Coil is new, new plugs and wires, distributor is new, sensors seem to work as expected, engine is resealed (intake, timing, oil pan, TB/adapter, exhaust, wrapped the headers, new mufflers). Things are starting to just point at the engine having problems.

 

[SuperBuickGuy]

Ignition seems to possibly be a bit off, but making changes in the swing of almost 20* has almost no effect. I have a few last ditch efforts:

.

Not saying this is your problem but when timing isn't sensitive to changes, that's a huge indicator that you have a vacuum leak somewhere (such as manifold gaskets failing to properly seal and that leak being in the lifter valley - ask me sometime how I managed to melt down a blown, 400 sbc).

 

[toyotaspeed90]

Not saying this is your problem but when timing isn't sensitive to changes, that's a huge indicator that you have a vacuum leak somewhere (such as manifold gaskets failing to properly seal and that leak being in the lifter valley - ask me sometime how I managed to melt down a blown, 400 sbc).

I agree.

The engine I bought from a friend ~5 years ago. It came from a running/driving truck that seemed fine. However I've had constant running issues with it. As the story goes it has a cam and "had a bunch of work done to it" - back in the late 80s.

When I resealed the engine - tearing it apart I found that the PO had used massive amounts of orange RTV/permatex on the intake ports (with a gasket), not just around the water jackets. This kind of makes me think the heads have been cut too much and are sitting too low for a proper lower seal to the intake manifold (which now has new gaskets, I did a very light block sand to both intake/heads to ensure they were flat/clean, and only rtv'd at the front/back and water jackets).

Map reading in MS does what you would expect, though.

That's why I alluded to other possible issues (could also be a head gasket between a couple cylinders causing issues as well)

 

[SuperBuickGuy]

after I blew up the blown 406, I found that someone had machined the intake incorrectly. When you deck a block and/or heads, the heads move a bit closer together and the space for the gasket at the walls on either end of the cam reduces. You have to machine the ends, then, if the distance isn't close enough, machine the intake gasket surface.... I dunno how they did it but it was bowed from front to back (much like that jerks at Jim Green's Performance does) along the intake surface. You'd think that would be hard to do on a mill, but they pulled it off on a Buick block and the same thing happened by someone else on the blower manifold.

even taking away stupid machinists with crappy machines - if you get backfires with the butterflies closed, it is possible to push the manifold gasket out enough to cause a vacuum leak....

 

[toyotaspeed90]

I ordered a set of (reasonably priced) thickest intake manifold gaskets I could find - a set of Felpro race gaskets.... just to hopefully get more material between the heads and the intake. Hoping I can disconnect as little as possible to do the job. We'll see about that.

That, and checking the things above are my last ditch effort. I'm already *mostly* done pulling the 4.3 out of the Van. Internet says it only comes out the bottom. Me and my sawzall will see about that too.

 

[SuperBuickGuy]

use an angle gauge to check the angle to the head and also for the intake. use a straight edge and a flashlight to check that the mating surfaces are flat.

Also when you get the intake off, sometimes you can see where the issue was because oil will be across the entire surface of the gasket.... good luck sir!

 

[toyotaspeed90]

Ehh, I'm not sure it's worth it to go so far as check angles. It's going to be a quick stab-in of thicker gaskets and if it works, awesome - if it doesn't, slotting the 4.3L to go in.

Mentioned previously, I have a 4.3L CPI vortec V6 that has less than 4k miles, has a new spider injector, and just about everything on it has been replaced. The only thing I think I would steal from the 350 would be the flowkooler water pump, if it will work with the serpentine belt system. It would be somewhat perfect for our FJ40 needs - some of the issues in the past have largely been due to the PO placing the 350 too far forward for a mechanical fan, the V6 being shorter allowing a mechanical fan (if needed) and requiring less cooling overall. Power would be similar (probably lower, but oh well) and gas mileage would be much better.

I have a full harness and computer (I drove the van home, short of having a bad battery, there were zero issues with it) - however I'm thinking there isn't any reason I couldn't run it on Megasquirt. Yeah, it might have some odd calculations being a 272 with 1 injector, but at the end of the day - it uses the same ignition control module as what I have in the 350 - so maybe rewire the injector and make some software changes, and a fuel pump change is all that I would need to do to make it run. I'll take some measurements to see about exhaust and some of the other plumbing.


@SuperBuickGuy - any want/need for a 2WD 4L60E/TC? Has new solenoids in it - I know I'm slotted to buy the softtop/doors from you, but would trade straight across if you could use it (currently asking $150 for the trans)

 

[SuperBuickGuy]

sure - bring it, come get the top

 

[toyotaspeed90]

I'm actually eyeing a trailer in Woodinville, just waiting to see if the sellers respond. Hoping it's a real ad....

 

[SuperBuickGuy]

Let me know, I'm up to my elbows in building a trailer... mostly because I gave up trying to find one that someone didn't want 10% more then new money for...

 

[toyotaspeed90]

It's a tent trailer, the ad seems legitimate but not getting any responses from the seller. They have an address listed phone, and email - I tried email and phone.



As for the engine - I just rummaged around....

I have a spare connector for the injector. TPS is the same as the 350. I can swap the coolant temp sensor. Air temp sensor doesn't matter. 02 sensor is universal fit (mening - I'll need a spot for stock or aftermarket). Coil and ignition control module are the same as the 350. Map sensor for the MS is on the MS.

This all means if I go the 4.3 route - once the engine is bolted in I can test fire with Megasquirt without doing anything to the stock harness. 8f it doesn't work, no harm no foul, I'll figure out the stock ecu.

The 2 drawbacks of this ECU are:
1) it uses a buffered reading (from a separate unit) for VSS (Vehicle speed sensor)
2) this is an A/T ecu

Both issues could affect the performance of the engine. So if i can go MS which is already there, then I can skip those issues altogether.

 

[toyotaspeed90]

Putting this here as a note to myself....

95 vortec CPI motors have an "Intake tuning valve" - which is an open or closed valve that allows additional airflow around 2700 rpm.

Sounds like TVIS, and I believe that would be an easy workaround with MS to control...

 

[74fj40]

Does it allow additional air or does it mimic short vs long intake runners dependant on engine RPM?

 

[toyotaspeed90]

I haven't pulled it apart, supposedly if you pull the intake top half off you can see it. I'm guessing it's a simple butterfly valve that opens/closes to allow additional air in.

I have no reason to crack open the intake manifold, so for now I'm not going to.

After looking at this, I identified the wrong connector for the injector. That's good to know.....