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Bucking / Power loss at Full Throttle

 
  #151  
Old 04-08-2019, 12:14 PM
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Don't worry about the coil resistance. You answered my question when you found the "Use with ballast resistor or resistance wire" posted on the side.

I'm interested in the camshaft response.
Do you have a lot of torque right from an idle?
 
  #152  
Old 04-12-2019, 10:33 AM
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Wanted to give it a few days of driving before I gave it a firm answer.
So far so good. It seems like the response is nice.
The throttle response is nice and crisp. The torque is hard to gauge, since the power band is so smooth. It doesn't snap be back or anything, but when I try to get on it to see, I first think "hrm, it doesn't seem super responsive", but then I look down, and I'm doing 45 in a 35. It moves.

This weekend, I'll pull out the spark tester and go through it. I still want to check grounds and make sure I'm getting a good, hot signal to the ignition. A 0.025" spark plug gap still seems small.
 
  #153  
Old 04-12-2019, 09:38 PM
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Looking forward to seeing what the spark tester shows as a comparison to the Duraspark system.
It would be nice to be able to open the plug gap to at least .035"
 
  #154  
Old 04-15-2019, 05:50 PM
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Have you looked at the fuel table to see if there is any change?
Did you get a chance to spark test the DUI this past weekend?
 
  #155  
Old 04-15-2019, 06:35 PM
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There were a couple tweaks to the fuel table, but nothing major.

I tested the spark today after I got home from work. The voltage started to fizzle at the same spot at around 30,000.
I then took another spark plug I had, gapped it to 0.025" and clamped down on it with a jumper cable and put the other and on the negative post on the battery.

The spark was a weak, little, dingy yellow spark.

I'm still not sure what the deal is. I've replaced all of the wiring, and know I have good, solid grounds.

Any ideas on how to diagnose this? I still think I'm dealing with a weak spark, but don't know why. The two ignition systems are almost completely unrelated in their wiring except for the power wire, which is solid..
 
  #156  
Old 04-15-2019, 07:04 PM
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Holy cow
what a massive cluster.

i would have guessed something with efi was wonky.
 
  #157  
Old 04-15-2019, 07:07 PM
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Yes you are dealing with weak spark.

The DUI only requires a good power lead and a well grounded engine block.
The power is being supplied through the power relay directly from the battery and you know the block has a good connection to the negative battery cable or the starter would have problems.
As long as the distributor is grounded to the block well and there isn't any engine paint in the way the DUI should be good.

If you can't find a problem I would Strongly suggest adding an MSD 6A or 6AL.
You won't believe the difference in performance.
 
  #158  
Old 04-15-2019, 07:11 PM
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Originally Posted by AbandonedBronco View Post
There were a couple tweaks to the fuel table, but nothing major.

I tested the spark today after I got home from work. The voltage started to fizzle at the same spot at around 30,000.
I then took another spark plug I had, gapped it to 0.025" and clamped down on it with a jumper cable and put the other and on the negative post on the battery.

The spark was a weak, little, dingy yellow spark.

I'm still not sure what the deal is. I've replaced all of the wiring, and know I have good, solid grounds.

Any ideas on how to diagnose this? I still think I'm dealing with a weak spark, but don't know why. The two ignition systems are almost completely unrelated in their wiring except for the power wire, which is solid..
Have you replaced the power wire? If so, where does it get power from, what's the setup? I assume it's got continuity and voltage, have you testing the circuit? I'm not sure what I'm thinking of, load test or parasitic draw? Those dont sound right, I'll go look at that sticky real quick. This One
 
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Old 04-15-2019, 07:41 PM
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The power to the ignition system comes directly from the positive battery cable by way of a 100+ amp power relay. There are no voltage drops or power losses.
 
  #160  
Old 04-15-2019, 07:51 PM
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Originally Posted by pmuller View Post
Kramercd
The power to the ignition system comes directly from the positive battery cable by way of a 100+ amp power relay. There are no voltage drops or power losses.
How about if one of the high amp legs of the relay is partially burned through either internally or externally? Add a lot of resistance wouldn't it?
 
  #161  
Old 04-15-2019, 08:23 PM
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Originally Posted by Kramercd View Post
How about if one of the high amp legs of the relay is partially burned through either internally or externally? Add a lot of resistance wouldn't it?
Sure but this is a new relay that has the same make up and contact area as a starter relay.
It is highly unlikely that a few amps from an ignition system would damage the relay to that extent.
The supply voltage from the relay has been checked with a meter and appears to be the same as battery voltage.
 
  #162  
Old 04-15-2019, 08:42 PM
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Originally Posted by pmuller View Post
Sure but this is a new relay that has the same make up and contact area as a starter relay.
It is highly unlikely that a few amps from an ignition system would damage the relay to that extent.
The supply voltage from the relay has been checked with a meter and appears to be the same as battery voltage.
Crib death straight from the manufacturer would be out of the question on account of how everything these days is made and tested so well. Point I'm trying to make is, until it's properly tested you can't rule it out. Could be the connection at/near the relay. What ever it is, it's shared between both ignition systems, unless they are both faulty in the same way.... How do THOSE grounds look? Got to be a short list of things both systems have in common. Maybe it is some of that pretty paint interfering with grounds....
 
  #163  
Old 04-15-2019, 10:39 PM
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Good point.
While doing the spark test one could certainly jumper the relay out of the equation using jumper cables as well as jumpering the distributor case to the negative battery post.
 
  #164  
Old 04-15-2019, 10:54 PM
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Originally Posted by pmuller View Post
Good point.
While doing the spark test one could certainly jumper the relay out of the equation using jumper cables as well as jumpering the distributor case to the negative battery post.
You have a better grasp on this than I do. My truck is still in pieces, not sure right off where my harness and ignition system are right now actually. Do you think you could describe for me, the path, electrically, from the key to the spark plugs?
 
  #165  
Old 04-16-2019, 09:43 AM
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Thanks for the responses and ideas. Much appreciated.

As pmuller said, the power goes from the battery to a new continuous relay, then from the relay to the ignition.
I will test the resistance through the system (from the start of the wire at the battery to the end of the wire at the ignition) to be sure, but I don't think that's the issue.

I started out just using a starter relay, but burned it out in quick order since I didn't know they can't be used continuously. While I had it out, and was waiting for the continuous one to come in the mail, I had the ignition bolted directly to the battery. I had to bolt and unbolt it every time I shut the vehicle off (which was fun). So, I've driven it around with power straight from the battery to the ignition with nothing in between.

I DO like the idea of testing it again with some jumper cables clamped to the negative battery post and then to the distributor housing, to see if maybe it isn't grounding properly.
 

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