Megasquirted 300 problem

[84FordVan]

I just got my MS2 installed on my truck tonight, but I seem to be having a very weird issue. First off, my setup consists of a stock 300, stock efi intake and exhaust manifolds, stock injectors, stock Duraspark II distributor with a GM 8-pin HEI module, GM coil, Megasquirt 2 v3.57 running fuel only, letting the dist. control timing. I went through the distributor, put in new shims and advance springs, made sure everything was set the same in terms of spring tension and total amount of advance, basically I freshened up the stock dist. The mech. advance has one light spring and one heavy spring. Vacuum advance module is in good working order. I am getting the fuel map dialed in, it runs, idles alright, but only drives well if the engine RPM is over 1400 or so. Struggles to get going until the tach reads about 1400 RPM, then it takes off like I floored it. If I give the engine a little more timing at idle it seems to idle better, but when I increase engine speed in neutral it doesn't like it too much (knocks and pings), never drove it like that...didn't want to destroy it. My timing at idle is right around 12-13* WITH the vacuum line attached, if I try removing the line at idle, the engine dies. Maybe I goofed up the dist. when I was going through it? I know it's definitely an RPM related issue. I'm about ready to buy a remanufactured distributor, but don't know if that will fix anything. Anybody out there have any input as to what may be happening?

 

[80broncoman]

I just got my MS2 installed on my truck tonight, but I seem to be having a very weird issue. First off, my setup consists of a stock 300, stock efi intake and exhaust manifolds, stock injectors, stock Duraspark II distributor with a GM 8-pin HEI module, GM coil, Megasquirt 2 v3.57 running fuel only, letting the dist. control timing. I went through the distributor, put in new shims and advance springs, made sure everything was set the same in terms of spring tension and total amount of advance, basically I freshened up the stock dist. The mech. advance has one light spring and one heavy spring. Vacuum advance module is in good working order. I am getting the fuel map dialed in, it runs, idles alright, but only drives well if the engine RPM is over 1400 or so. Struggles to get going until the tach reads about 1400 RPM, then it takes off like I floored it. If I give the engine a little more timing at idle it seems to idle better, but when I increase engine speed in neutral it doesn't like it too much (knocks and pings), never drove it like that...didn't want to destroy it. My timing at idle is right around 12-13* WITH the vacuum line attached, if I try removing the line at idle, the engine dies. Maybe I goofed up the dist. when I was going through it? I know it's definitely an RPM related issue. I'm about ready to buy a remanufactured distributor, but don't know if that will fix anything. Anybody out there have any input as to what may be happening?

I'm not nearly as well versed on this as others here. from what many of the others have said the EFI head has a fast burn chamber that pretty much Requires a different spark curve from the older carbed 240-300 engines.
Obiously you have found it like timing at one RPM and doesn't at another RPM.
Keep working on it and you will find the cure.

I know you might see in my sig that I have the EFI head with a carb. My EFI head was modded so much that he Fast burn part is almost not there.

 

[E4ODnut]

I don't know anything about Duraspark. Is it expecting manifold or ported vacuum?

Have you used a timing light to confirm what your no load timing curve is? You can do this quite easily right in the driveway. Do it once with the vacuum line connected to see what the combination centrifugal and vacuum is, and do it again with the line disconnected and plugged to see what your centrifugal is.

If Duraspark works like a garden variety mechanical distributor you should be able to disconnect the vacuum line and run it on centrifugal only. If the centrifugal curve is more or less linear with idle at about 10 degrees and all in about 25 or so at about 3000 RPM the engine should run just fine for initial settings.

You are assuming that all your problems are ignition related, and they might be, but unless you are really good, or really lucky, you could have some fueling issues as well to complicate matters. If you like, do a data log and PM me with it and your .msq file and I'll see if I can see anything obvious.

 

[MustangSix]

First off, I've never seen an 8 pin module used in a fuel only application. The additional pins for PIP and SPOUT are there to interface with the computer to control timing beyond base. If those aren't connected to the MS, the module might work, but then again, I don't know how well. A 4-pin version may serve better.

Second, when you set the timing, it has to be with the vacuum disconnected. The vacuum advance module could be adding as much as 20 degrees, so its no wonder the engine dies when you unplug it. With the vacuum plugged in, as soon as you hit the throttle the vacuum falls off and the engine runs like a dog until the mechanical advance starts to catch up (around 1500, I suspect). Then it runs well to higher rpm.

The distributor will work with manifold vac. Set your base timing with the line unplugged, probably 6-8 degrees will do, to start. Plug the vacuum line in and see where timing goes. I suspect it will be 20-25 degrees. See if it will start and run ok with that. It should be ok, but may ping a little at light load. If so, you need to see if the vacuum unit can be limited. Some have an adjustment in the canister that can be turned with an allen key or a screwdriver.

Frankly, though, with the system you have, you could more easily go completely to the MS controlling ignition. Just lock down the advance plate and plug the 8-pin module into the Megasquirt. trigger the coil from the MS unit and develop a timing map that suits the engine.

 

[80broncoman]

Very good point abouth the vacume aadvance. on my lower compression (pump gas) veihicles. I have usually hooked the vacc advance to venturi(some call it ported vacume) vacume and then mess with the mech advance to get the final timing where I want it to be.
This lets me set the base and then, as the Rpm comes up+ with throttle= more timing.

 

[E4ODnut]

I agree with Jack. Why not let MS control ignition as well? I think that in another post I asked you why you would use the Duraspark and your response was basically "that it works". Fair enough, but it would appear now that for whatever reason, it might not be working.

Having said all that, before abandoning Duraspark, why not try find out why it's not working first? You might then be able to get it to work after all. Determining what your actual timing curve is now is quite important for trouble shooting.

I've got over 150,000 KM on my stock 300 since switching over to MS so I may be able to help.

 

[84FordVan]

Thanks for the advice everyone. Could it be possible that the 8-pin module may be throwing off the timing? I am aware that the module is supposed to be connected to a computer for timing control, but maybe the module has a "curve" of it's own so to speak. Would be a good reason I'm having timing issues. I know it's a Ford thing, but I have heard the TFI has a built in kind of a default curve so if you unplug the spout connector it reverts to that. From what I understand it's an RPM based curve, maybe the 8-pin is similar? The local parts store has 4-pin HEI modules, might try going that route first before I attempt trying to make a timing map.

 

[84FordVan]

Good news: got a 4-pin HEI module today, wired it in and the truck runs beautifully, idles better, likes advance now, even has some get-up-and-go Still needs fine tuning, but seems to run excellent. My suspicions were right, I guess the 8-pin module does have a timing curve built into the module. Before when I would run the throttle up and check timing with a timing light, I would see as much as 55* advance. Definitely not right, since the distributor was incapable of anything more than 30* at that time. Nice to have this problem figured out, the truck was undriveable yesterday. Thanks again for all the input!

 

[E4ODnut]

I can't comment on the GM HEI modules because I've never had cause to study them. With the Ford TFI, when you unplug the SParkOUTput connector, the module defaults to firing the spark on the Profile Ignition Pickup signal which is normally set at to occur at 10 degrees BTDC. There is no curve, it is base timing only. The SPOUT signal is generated by the EECIV, or whatever ECU you are using, such as MS, and is really just the delay time from PIP to SPOUT. It's what's known as "next cylinder" strategy, also used by the Ford EDIS system. EDIS is distributor-less, waste spark, but both systems are really quite good and very dependable.

 

[84FordVan]

Here's a little about my truck:

-Stock 300 carbed motor with EFI pistons/head/manifolds, roughly 8:1 CR (~145 PSI cranking)
-Stock Duraspark dizzy w/GM 4-pin
-Megasquirt 2 V3.57 running extra code
-Innovate MTX-L Wideband O2
-1990 F-150 shortbox, 4x4, C6 auto, 4:11 axle ratio, 31/10.50R15 tires, truck weighs around 4,250lbs

I would like to know how to upload a copy of my MSQ file and a couple datalogs that you guys can look at, need some input on if I'm doing anything wrong in terms of settings for the MS2. Starts a little hard, I do know that my cranking pulsewidths were a touch high, just decreased that a little further tonight. Seems to run pretty good, warmup settings are close, getting the PWM idle settings figured out. Timing is set about perfect now that I got the ignition problem figured out. Haven't checked my mileage yet, but I'm sure I'm up from the 10MPG I was getting with the mass air ecu I had on the truck before.

 

[E4ODnut]

I'm curious as to how you know your timing is set about perfect. Getting part load timing dialed in can be quite time consuming and will depend a lot on what your fuel mix is. Unless you are doing it on a dyno there is a fair amount of educated guess work involved. Do you know exactly what your actual 3 dimensional spark map is at all speeds and loads?

Are you using Tuner Studio for your tuning software and data log analysis?

You might not be able to post attachments on this forum, I know I can't. If you like, PM me and I'll give you my e-mail address so you can send the files them to me and I can give you an opinion based on what's working for me.