95 4.3 TBI spark table info

[ironwill11]

Sorry to read about your key board ony. Not sure if my typing would be readable if my delete button did not work. Thank you for the effort.

Tried some new stuff tonight and got some interesting results.

Is it accurate to check your timing with a timing light while it is cranking?
I unplugged the bypass wire from the megasquirt so there should be no timing advance; however, I can't get it to start and run like that so I put the timing light on it while it is cranking and trying to start. If this is accurate then it means I am about 15-20 degrees retarded. The other night I took the valve cover off and distrib. cap off and rotated the flywheel twice to go through all 4 strokes. I verified that the distrib. was pointing in the right direction for when the valves were working and the timing marks were lined up. However, I don't know if that is specific enough.
Does anyone know a good way to get this timing lined up? The only way I can think requires three people. One to crank, one to hold the timing light, and one to turn the distributor.

Deciding to throw caution to the wind (being a frustrated newbie at this), I changed the spark table so it would have radically different advance seeing as it was normally reading 20 degrees I set it so 800 rpm would be the 20 degrees instead of its 1200. Well all the megasquirt did was increase the advance to 33 degrees and it started at 1200 rpm again. Thinking that the base timing is not correct, the only other issue I can see is my required fuel may be too high.

Thank makes me wonder about my injectors and try to figure out what their flow rate is.

Megasquirt is really frustrating me and I am thinking about converting the harness back to using the 7477 ecm.

Sorry for the long post, any thoughts?

[myburb]

Although there is differences between ms and extra it shouldn't be hard to get it idle. When you talk about bypass I will assume you are using a hei 7 or 8 module. With the bypass disconected set your initial to 10 advance. If everything else is correct it should run and idle. Once that is working you can proceed with setting the reference angle and that is done differently for different firmware but in extra go to fixed timing and do reference until it matches. This is from memory. I have two cars running ms and the setting can be different. I mostly fool with gm 6395 and 7427 although one of my cars has both gm and ms.

[skandolis]

are you positive the idle problem is in the tune? have you checked for vacuum leaks? a spray bottle of soapy water can save a lot of headaches. a bad diaphram in the brake booster can drive a man crazy chasing idle problems...... still seems the ms should run with the bypass disconnected, maybe have the ignition module tested, check voltage at the module........ they do some funny things if ya get one that is a little flaky or the voltage is off...... i have seen factory modules with 20-30 degrees difference to one identical to it............

i don't believe the timing light will tell you much during cranking, too much variation due to compression,starter and other stuff......

[ironwill11]

are you positive the idle problem is in the tune? have you checked for vacuum leaks? a spray bottle of soapy water can save a lot of headaches. a bad diaphram in the brake booster can drive a man crazy chasing idle problems...... still seems the ms should run with the bypass disconnected, maybe have the ignition module tested, check voltage at the module........ they do some funny things if ya get one that is a little flaky or the voltage is off...... i have seen factory modules with 20-30 degrees difference to one identical to it............

i don't believe the timing light will tell you much during cranking, too much variation due to compression,starter and other stuff......

skandolis,

I am not sure if the idle problem is in the tune. The idle used to hunt prior to megasquirt. The folks at diyautotune told me it megasquirt would help me out. The MS does try to run with the bypass disconnected. It cranks and stumbles once or twice, but can't stay running.

As far as vacuum leaks, I spent a year looking for them. I found a number of people online that had the same idle hunting as I had and replaced many parts looking for vacuum leaks to no resolve. The most damning evidence that suggests there is no vacuum leak is that when hooked up to my laptop my MAP is very constant.

I am at the very beginning of the tuning process. All my tables were generic tables created by tunerstudioMS (Very difficult software to used since all the material in the manual references a tunerstudioMS version that does not exist anymore. I have no idea how to set it to fixed advance. I know that if I increase the trigger offset the idle will come down a little (up to around 28).

I do know that as it warms up it tends to gradually increase the idle. Only once did it act like it should and start around 1200 rpms and come down to 800 rpms. Then the next day it would not start at all unless I increased the advance.

I have played around with the timing so much that I wanted to make sure I had my timing marks aligned properly but I could only do it by hand.

Will

[ironwill11]

Hello everyone,

Did not get a lot of work done due to a nasty sinus infection, but it gave me time to think.
Since there is very little information on getting started with megasquirt, I have decided to hook up the GM wiring harness.

First question: I have the two 7477 ecus. Any recommendation on another ecu that I should use for a relatively stock 95 4.3l TBI from an s-10 blazer?

Follow up question: Can anyone point me in the right direction to getting started with tuning whatever the recommended ECU might be?

All help is appreciated.

Will

[ironwill11]

Although there is differences between ms and extra it shouldn't be hard to get it idle. When you talk about bypass I will assume you are using a hei 7 or 8 module. With the bypass disconected set your initial to 10 advance. If everything else is correct it should run and idle. Once that is working you can proceed with setting the reference angle and that is done differently for different firmware but in extra go to fixed timing and do reference until it matches. This is from memory. I have two cars running ms and the setting can be different. I mostly fool with gm 6395 and 7427 although one of my cars has both gm and ms.

myburb,

Thanks for the info. I have the hei 8 module. My engine does not have degrees of advance on the timing belt cover. It only has the one slot to line up.
My biggest problem with megasquirt is that there have been numerous updates to tunerstudioMS which major changes and after searching the internet, the manual only references the older version of tunerstudioMS. For example, the tool bar is different on my version and I can not find the location to set the reference angle or fixed timing. I appreciate the info. I am at the very beginning of the tuning process and have no way of know if my timing is accurate other then pulling the valve cover and turning the engine by hand.