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post #1 of (permalink) Old 02-07-2003, 12:14 AM Thread Starter
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TiminMB MeagSquirt data

I got my MS up and running and will not have a stimulator after tomorrow. If I download data to the MS now will it remember it? If so, I would like to load it up with some data that will be close. Can you give me the data you are using on yours?
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post #2 of (permalink) Old 02-07-2003, 10:08 AM
 
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Re: TiminMB MeagSquirt data


My VE table currently looks like this:

20 38,38,38, 38,38,38, 33,33
30 38.38.47. 50.49.48.47.45
40 48.48.52. 52.52.48. 47.45
50 52.53.54. 54.54.48. 48.48
60 63.63.63. 63.63.63. 57.57
75 79.79.79. 79.78.78. 73.73
90 88.90.90. 90.90.84. 78.78
100 94.97.98.100.100.90.84.84
500,1000,1500,2000,2500,3000,3500,4000

Values along the left are MAP values in Kpa, values along the bottom are in RPM.

These numbers are based on using two 50 lb/hr injectors (or at least entering that value as I am unable to get consistent answers on that question, and in the end it doesn't really matter) and a calculated Reqfuel of 11.3/16.9. Injector open time of 1.0 ms, battery voltage correction of 0.2, PWM mode inactive by setting PWM threshold to 25.4 (I'm using 5.7 ohms in series with each injector), 2 injections per cycle, injector staging simultaneous.

If your injectors are from a 305 and you enter the flow rate as 50 lbs/hr this data will be good. I can also enter as 40 lbs/hr and scale the table down accordingly. It doesn't matter either way, it's the same opening times once the formula gets through with it. One source says 305's use 50 lb/hr (custom EFIS), another (the DIY EFI group) says green / white injectors are 40 lbs/hr. If you overestimate the size of your injectors, the VE numbers wind up being higher, that's all.

Once you load the data onto the megasquirt, it remembers it without needing power. So you can use your PC to program it at first and the laptop later to fine tune it.

Two squirts simultaneous produced the only smooth idle. Alternating squirts didn't produce happy results at idle.

I hope to have the full right up ready soon for anyone else following this project. My tuning isn't completely finished, as I could do some more fine tuning at higher rpms and map values. Nevertheless, it has never run better and I'd be surprised if any stock 258 made as much power and torque.
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post #3 of (permalink) Old 02-07-2003, 10:23 AM
 
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Re: TiminMB MeagSquirt data

Here's a VE table that a helpful fellow named Konstantin from former USSR is using on his 258. Clearly, he is using a different number for his injector capacity to get these lower VE values, but the progression is interesting. I notice he cut off his RPM at a lower value that I did. When you go outside the table, it just uses the last values. My 4.2L will performs well at RPMs just below 4000 rpm when looking for maximum accelleration. Also, I notice no tapering of his VE beyond peak torque rpm. It's interesting to see what someone else came up with. He seems to be suggesting this is the stock 4.3L table. Anyhow, it's food for thought.

His message below:

Original VE table 4.3L V6 GM

VE Table RPM Range [ 8]
[ 0] = 4
[ 1] = 8
[ 2] = 12
[ 3] = 16
[ 4] = 20
[ 5] = 24
[ 6] = 28
[ 7] = 32
VE Table Load Range (MAP) [ 8]
[ 0] = 20
[ 1] = 30
[ 2] = 40
[ 3] = 50
[ 4] = 60
[ 5] = 75
[ 6] = 90
[ 7] = 100
VE Table [ 8][ 8]
[ 0] [ 1] [ 2] [ 3] [ 4] [ 5] [ 6] [ 7]
[ 0] = 12 15 22 29 33 38 42 45
[ 1] = 14 25 32 36 40 43 46 50
[ 2] = 21 33 39 42 45 48 51 54
[ 3] = 30 39 44 46 48 51 54 57
[ 4] = 36 43 46 49 52 54 57 61
[ 5] = 44 49 52 54 56 59 61 63
[ 6] = 50 55 58 60 61 63 64 64
[ 7] = 54 57 59 61 63 63 64 65

I use for the engine AMC 258
Konstantin
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post #4 of (permalink) Old 02-09-2003, 08:31 PM Thread Starter
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Re: TiminMB MeagSquirt data

Hey Tim,

A couple more questions.

1 - What did you use for an O2 sensor? I would think a non heated would be OK because the sensor is neer the top of the exhaust manifold not to far from the engine. I should stay hot enough even at idle. Do you agree?

2 - Where did you put the air and coolant temp sensors?
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post #5 of (permalink) Old 02-09-2003, 08:50 PM
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Re: TiminMB MeagSquirt data

1. Howell chose to go to a Heated O2 sensor,
2. If they haden't they couldn't get the engine lean enough.
3. It's one thing that helped them obtain CARB certification.
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post #6 of (permalink) Old 02-09-2003, 09:17 PM
 
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Re: TiminMB MeagSquirt data

If you are buying a new 02 sensor, the heated version would be a good idea. I had a practically unused jeep (unheated) sensor lying around so I used it. I left megasquirt at the default setting of no 02 correction until 1200 rpms. With the heated sensor, there is no reason you couldn't lower that value to correct the mixture at idle. My 02 sensor reads rich at idle. How rich, you really can't tell accurately with a narrow band sensor. The standard 02 sensor hits the reference voltage of around 0.45 volts at 14.7 to 1 air to fuel mixture and flutters back and forth when you are near that value. It's non-linear and unpredictable in reading beyond that, so in essence you can tell if its 14.7 to 1 (stoichiometric mixture, in other words chemically balanced for complete combustion to C02 and H20) rich or lean,ie just 3 known conditions. Ok, I'm wondering off topic. If you are buying a new one, you'd might as well spend a few more bucks and get the heated one and see if it works better. It will read more accurately during periods of low temperature exhaust, and will more quickly begin to give usefull info after starting a cold motor. The unheated one, however, doesn't seem to be impairing my performance either. So, take your pick. What I wanted to comment was that my mixture reads rich at idle. I adjusted my idle mixture to get the best lean idle, just like using a carb. If I set it by the unheated 02 meter at idle, and adjust it to 14.7 to 1, the motor doesn't idle as smooth as when I add in a little more fuel. Whether my 02 reading is accurate at that point or not is an important question. Or does a 4.2 with it's varying length of intake runners need a slightly rich mixture at a central source to acheive the minimum a/f ratio needed for the furthest cylinders? Multiport overcomes this dilemma.

For the temperature sensors, I'm using the ones I pulled off the 89 parts car. The CTS is a standard GM sensor with a 3/8 npt thread. I screwed it into the drivers side of the block in place of one of the old CTO switches.

For air temperature, I am using the GM open element sensor I got from the parts car. It's the one that has two exposed wires that form a little shell around the thermister. This is the type of sensor found in the air cleaner assembly, outside of the filter element. I've heard they can disentegrate, so don't put it inside the manifold. There are also GM closed element sensor, similar to the CTS sensor that can safely be placed in the manifold. I believe job of this sensor is to correct for temperature related air density changes. The ideal gas law formula, from Boyle was PV=NRT. In other words the molecular quantity of a gas is proportional to volume + pressure and inversely proportional to temperature. So the hotter a gas is, despite it's pressure, the less molecular quanity there is. So for a turbocharged engine, putting the sensor in the manifold is necessary, as the air becomes heated by the turbo compressing it, and cooled by the intercooler. That's a lot of temp changes. For a normally aspirated engine, you just need to know what temp of air is entering the throttle body. I placed mine just on the outside of my K & N open element filter. Would it have made a difference if I placed it inside the intake manifold. Possibly, as I am using a heated intake manifold. Once again, you are open to experiment. My setup however seems to be working well.

You could order the two temp sensors based on an 89 chevy caprice 305 v8 and you'd have the same two I am using.

Here's some info I've gathered from other users of Megasquirt as to the GM sensors they are using:

Coolant temperature sensor (CTS) GM #12146312
Wells SU107
GP SORENSEN TSU81
AC DELCO 213-310
NIEHOFF DR134AK;

GM intake air temperature sensor (IAT) GM #25036979
Wells SU109
GP SORENSEN 779-19001
NIEHOFF IGNITION DR-136W ;

I don't know if the above IAT sensor is the open element type or not. They both read the same values though and could be interchanged by you. The open element sensor has the advantage of responding more quickly to temp changes.
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post #7 of (permalink) Old 02-09-2003, 09:32 PM Thread Starter
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Re: TiminMB MeagSquirt data

Is this what your air temp sensor looks like?

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post #8 of (permalink) Old 02-10-2003, 09:34 AM
 
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Re: TiminMB MeagSquirt data


Mike nice photo. Send us a photo of your rig. Would like to see that J.C. 7 leaf set-up (soa)
Thanks
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post #9 of (permalink) Old 02-10-2003, 09:52 AM
 
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Re: TiminMB MeagSquirt data

No, it has two small wires sticking out of it (about 1/2"), and the two wires come together as the sensor probe. Looks kinda like a model rocket ignitor with a base that the harness plugs into.
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post #10 of (permalink) Old 02-10-2003, 10:10 AM Thread Starter
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Re: TiminMB MeagSquirt data

My Jeep is out gettig some needed welding done to it. Since I don't have a welder I had to send it to a pro to do the work. I should have it back Wednesday. I will post some photos then.
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