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Old 11-11-2010, 08:17 PM   #131 (permalink)
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Default Re: Is it time to pull the head off ?

Bet your plugs are reading rich.....
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Old 11-11-2010, 08:23 PM   #132 (permalink)
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Default Re: Is it time to pull the head off ?

Out of the blue here..I've lost track of everything you've done, so I might be repeating something. Is there anyone around you with an old SUN analyzer? I think those were older smog testers. (I wouldn't know, as we don't have smog regulations in Ms.) There only a few in this area back in the '80s in specialty shops. That might pinpoint your fuel status (rich or lean), and remove that from your list of problems. Frankly, from the number of posts on this problem, I think you need to consider sacrificing a chicken, beating a drum, and burning incense. ???
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Old 11-11-2010, 08:52 PM   #133 (permalink)
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Default Re: Is it time to pull the head off ?

Quote:
Originally Posted by Vigman
Bet your plugs are reading rich.....
No. I checked all 6 two days ago. They were actually reading just a hair lean, but almost normal. I've got a pic on my phone I'll upload later. The white on the insulators was more like an off white so I figure it was getting closer.
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Old 11-11-2010, 08:54 PM   #134 (permalink)
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Default Re: Is it time to pull the head off ?

Quote:
Originally Posted by rednekz
Out of the blue here..I've lost track of everything you've done, so I might be repeating something. Is there anyone around you with an old SUN analyzer? I think those were older smog testers. (I wouldn't know, as we don't have smog regulations in Ms.) There only a few in this area back in the '80s in specialty shops. That might pinpoint your fuel status (rich or lean), and remove that from your list of problems. Frankly, from the number of posts on this problem, I think you need to consider sacrificing a chicken, beating a drum, and burning incense. ???
Yeah, no doubt. Pretty sure I'm running lean, but at some point I probably need to call around and see if someone can test or figure out how to rig my own.
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Old 11-11-2010, 10:25 PM   #135 (permalink)
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Default Re: Is it time to pull the head off ?

I'm voting chicken!
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Old 11-12-2010, 08:15 AM   #136 (permalink)
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Default Re: Is it time to pull the head off ?

Well I'd hate for these cheap spark plug wires to be the cause of my issues all of this time, even though I ohmed them out. I ordered some good ones from MSA a few days ago, along with an internally resisted coil. I didn't order the coil because I suspect mine is bad, I just wanted to clean up the wiring and get rid of the ballast resistor. But I mention it because maybe I will get lucky and the new wires will help, although I seriously doubt it.

Anyhow, considering all of the resent internal test, the fact that I've ruled out vacuum leaks about two dozen times with 10 different methods (I like to exaggerate), I'm refocusing my efforts on a fuel delivery issue, or remotely possible electrical issue.

Maybe I'll see if I can make a video of a test drive. I tell you, the way this thing stumbles randomly, it feels like fuel. It's just like when you first start to run out of gas.

I wish I still had my oscilloscope. I'd look at the pulse wave of the injectors. I sold it on ebay years ago. My fluke meter does have frequency measurement, so maybe I'll look at that and see if it stays constant. I'll figure out a way I can look at the tach signal on the ECU as well. I know I've tried another 78 ECU, but perhaps there is an issue with the A11-600-000 ECU that shows up after some age and would explain why this seems to be a somewhat common issue to the 78. I doubted the ECU after I tried the 2nd one I got, but it's old too. Those old analog circuits are subject to environmental and component degradation, it's not on or off like today's digital ECU's. Would be nice if we had a test point schematic of the ECU. Seems like it's common for some 78 280 owners to abandon the FI system (like Six Alexanders car, or Propa McGanda's car). Others just richen it up, bump up the timing, and live with it.

I also went on and ordered a 3/8 T fitting for my summit fuel gauge that will be here today. I reckon I'll use some 5/16 fuel hose to put it inline and make it fit. This way I can leave the fuel gauge on the car while driving and get a look at that hot start thing too.
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Old 11-12-2010, 09:59 AM   #137 (permalink)
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Default Re: Is it time to pull the head off ?

At this point I would vote Megasquirt... ask Santa....
If it was wires you would have problems on the big end too!

I still think lighter springs to bring in the mechanical advance earlier.. ( and a chicken or maybe a baby goat!)

Mike
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Old 11-12-2010, 10:32 AM   #138 (permalink)
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Default Re: Is it time to pull the head off ?

One of the reasons I haven't looked into the lighter advance springs yet, is that the problem exist even at idle, so it's just a work around. I've got it running decent enough to drive with the work arounds in place, so I'm more interested in just finding the real problem. I do think driving it is doing some good overall, as the vac has come up some. While I hadn't planned on making this a daily driver car, I will be driving it as much as i can over the next couple of months to help smooth it out, test, and to just get more familiar with how the car runs.

As far as megasquirt, I'm sure I could handle that. I actually have a fair amount of EFI tuning experience on my race bikes, so it's not something I'm afraid of. I'd rather just get the stock EFI performing as it should though.
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Old 11-12-2010, 12:22 PM   #139 (permalink)
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Default Re: Is it time to pull the head off ?

I agree... but the effort expended is getting exponential......
AND you might come full circle to find ... it's as good as it gets ( with the age of all existing components ).

I agree more run time will help.... heck maybe a little BonAmi cleanser might even help...
But a run, flush... maybe some 20-50 high milage oil next change....

I'm stumped ( at this point ) ....

Mike
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Old 11-12-2010, 12:55 PM   #140 (permalink)
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Default Re: Is it time to pull the head off ?

Im pretty stumped too, but I've got a few ideas. I'm going to find a way to get data on what the ecu is doing. For start I'll just do some simple stuff like measuring the duty cycle on injectors, and see if anything obvious jumps out
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