I haven't touched TunerStudio but with Megatune you can "calibrate" the % shown on the gauge. You click a button when your not touching pedal, then click another when pressing all the way down.

You have to remember this only calibrates the "on screen" gauge - it doesn't make a difference as to what the megasquirt uses for its fuel calculation.

IIRC megasquirt only uses TPS for enrichment (acceleration... equivalent to a carb pump shot) anyways.

Prop the pedal all the way down with your favorite implement and then look under the hood just to verify pedal all the way down really does equal throttle plate fully opened.

Hi PIerre. That has all been done. And, the dial on the gauge cluster reads correctly. It shows a full swing from no throttle to full throttle. I just do not know what the numbers mean in the datalog. It all seems a little odd to me. Why am I not seeing 100% on the log when I know I have planted the pedal to the metal? Maybe the number is voltage and not percent.

Sam

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Sorry, misinterpreted, the way I read your post you were reading a percentage directly from the datalog. Raw values in datalog are likely ADC ticks. The megasquirt converts the analog voltage into digital representation. Probably an 8 bit value, so it can be anywhere from 0 to 255. 0 being TPS all the way one direction, 127 being in middle, 255 at other end (remember, this is physical TPS shaft movment, will not correlate to % of throttle plate actually open or closed. A 90deg swing of the throttle plate from fully closed is fully open). The 23 you are seeing is a unit-less number on the scale of 0 to 255, not directly indicative of percentage or voltage.

Interesting. Then I should NOT assume there is something wrong with the TPS if the gauge is reading full swing. When the datalog is in operation, you cannot see the full gauge cluster. But I could see it light up red when I had the pedal fully depressed. I will focus my attention other places.

Peter is now thinking the problem is not EMI but that the HEI is simply not powerful enough to support the turbo. He is suggesting maybe firing the MSD box and blaster coil with the HEI module if I can find the room to mount it. It violates Dan's rule of avoiding multiple parts, and complexity, but does not require rewiring the Mega Squirt ECU. If that worked,then simplifying the system would come later.

Sam

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I don't think that assessment is likely, unless your HEI is really junk. Your car does not make enough boost or power to put the spark out, I think. If that were the case, then changing plug gaps (go bigger and see if it gets worse, or the reverse) should have a big effect.

I have an MSD 6A I could lend you to try, if you like! Was working perfectly up to 12 psi boost on the '68 Dart until I replaced with the programmable 6AL-2...

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou. I have a 6A on hand. Basic tune up comes first. I appreciate your thoughts. It is important to know that things are getting better, a little at a time. I sent a datalog to Peter, and he identified an RPM error I did not see. So the RPM count issue is not entirely dead yet. I will send him the current tune file tonight. He wants to see the fueling table.

Sam

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Correction. I had sent Peter the wrong datalog.I sent him an old one by mistake. There were no misreads in the most recent one. Here is my thinking on this entire thing at the moment:

I have had too rich a VE table almost always because of a mistaken idea about how to format a fuel table. This is from the very beginning and with every management system. Read my most recent post on Jari's fuel map post for details. This was not evident in the past with the MSD, because it simply blew threw it. The results then was poor economy, and poor performance, but no total breakdown.

Now with the HEI and its weaker spark (owing to a weaker coil) excess fueling was blowing out the spark and creating real problems. The fact that excess fuel on coast down caused serious misfires and resets with the HEI and not with the MSD kind of proves this in my mind. I feel like I have been kind of shadow boxing for three months. Hunting down ghosts by looking in the wrong closets. Another detail: the Buick GN did NOT use an HEI ignition,but a coil pack. Apparently they found the HEI insufficient for boost applications. I am sure they would not have spent the extra money if they did not think it was really needed.

As Peter says, "spark blowout creates a nasty high voltage situation, (counter-intuitive, I know)". The HEI has forced me to deal with the fuel in a way I did not have to do before. Once the fueling is corrected, and we hopefully do not see the big breakdowns, I may upgrade the ignition in some way. But for now, I am concentrating on the fuel. And the weaker HEI ignition will pin point where I still have problems with too much fuel.

Last night I installed the new rotor, cap and stock wires. I started it, just to make sure I installed things right, but I will test drive it, and report back in a few days. They are predicting bad weather here for a few days now. Depending on that result, I may decide to retire this thread, and move to tuning, and debugging with another focus. While all the filtering and shielding has been a big plus, I kind of think I am onto the real culprit now. We will see. It is interesting to go back and read my older threads, and either cry or laugh (depending on the mood) at how wrong I sometimes was. Humbling in light of my current understanding.

Sam

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Too much fuel really screws up tuning efforts. You and I saw that before in your car, I've seen it on my cars, and on GunPilot's car (in a BIG BAD way).

Lou

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Home of Slant6-powered fun machines since 1988

Lou,

Did you ever put this problem to rest? Haven't heard much on you progress since discovering the fried distributor cap, so I was wondering how things are progressing.

Scott.

Not sure which problem you're talking about. My car is running fine. No ign issues after replacing the dist cap. It does idle just *slightly* rough when hot, which I still have figured out. No more overrich for me - ancient history...

Lou

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Home of Slant6-powered fun machines since 1988

Woops sorry,

That message was meant for Sam Powell.

Scott.

Not yet.Thanks for asking. I have been driving it a lot, but obviously not hard. I have been super busy with other things, and just letting this percolate through my brain.

It seems changing back to stock resistor plugs improved the basic low rpm torque, thus improving drivability. So I will keep those. But it did not fix the basic problem. Under boost at 3200 RPM the miss is still there. If I sneak past 3200 and keep it out of boost, it will rev past 3200 without a miss, so it seems the problem is not strictly rpm related, which suggest either fuel, or spark not strong enough.

I have played with the fuel a little by taking 10% out of those cells,but it still missed last time I drove it. Lou is sending me his MSD 6a to try, just to see if that will produce a strong enough spark under boost.

The thing that is confusing is that when you run a data log it looks like there are RPM read errors, but I kind of think the initial miss comes first, and then creates serious EMI which causes RPM misreads, then things do fall apart. I am confident I will figure this out, but am just under no pressure to to so because it is such a nice driver right now. I drive it pretty much every day the weather is nice.

I am putting replacement windows in my house, and have joined the local concert band, and am just slammed time wise. It will come though. The windows are all in now, but 4 of them still need interior trim, and exterior caulking, trim, and new siding around them. So there you go.

Sam

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Car quit running recently, kind of out of the blue. I had been running a test to see if unhooking the alternator would cure its miss problem. It did not. So, when I hooked the alt back up, it would not start. Watching the tach on the laptop showed 3K RPM at crank. Clearly impossible. There is still stray signals coming from somewhere, but not the alternator, we know that now. So I increased the tach reject filter percent from 20 to 50 and it fired right up. There is much noise on the VR pick up line, even though it is shielded. The next project is to get the DIY trigger wheel and mount a pickup to supply the RPM signal. That is ordered.

Peter thinks the tach reject filter is THE cause of the miss, but it will not run without it. Stay tuned. No puns intended.

I should have mentioned I bought and installed Lou's MSD, and that now provides a strong spark.

Sam

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Its beginning to look like there are grounding issues for anyone upgrading to MS II through the relay box. This is an issue that has surfaced with other users as well. The sensors need to be grounded to the main board first and not directly to the block. When the ECU is unplugged, the sensors should have no ground connection. When using the relay board, this is absolutely NOT the case.

Peter is working on this issue now.

To be continued.

Also, maybe related, and maybe not, it seems there is noise coming from the starter that is confusing the rpm count. I have to put the filter high to get it to start, but it will run with a low setting.

Sam

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I have to clarify that. If you ground the sensors to block as I did, there is a problem. If you run the sensor grounds back to the Relay box, then there are no ground issues. I must do that now. Another issue is the HEI is currently grounded to the block, so I will try to get it grounded through the ECU instead of the block directly. I do not understand the entire ground path thing, but am just following instructions here. I also put some chokes on the starter feeds, both the main battery cable and the solenoid feed to see if that will help with the starter motor interference noise.

Right now the radiator is out of the car to install the trigger wheel, so cannot test either of these changes yet. I will fabricate the pickup mount before putting it back in.
Sam

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