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Old 12-01-2010, 02:37 AM   #1
67AfroMaro
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Default Took car to the dyno... Need help troubleshooting

So I took the car into the dyno today... very disappointing. We made 3 pulls and couldn't get the car to RPM over 6400. It would climb, make instant boost and then hit a wall at around 6200RPM and bounce between 6200 - 6400 RPM and 20 - 22 pounds of boost. On 6 cylinders he car climbed hard on HP, stopped making power and flat lined at 710.

After looking at a lot of things we figured out #5 and #8 are both dead holes. We ohmed the wires, changed the plugs and I even swapped #8 & #7 on the cap (fire the cyl out of order) to see if the dead hole would follow... no such luck. I am assuming it is not spark related but is fuel related.

I ohmed the injector wires from the BS3 side of the harness to the injector side of the harness and they checked out OK. I'm thinking either the BS3 is not firing these injectors (but I just got it back from a checkout) or maybe the injectors are clogged.

What tests should I run to see if the injectors are delivering fuel?
What other things should I look at?
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Old 12-01-2010, 03:00 AM   #2
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Default Re: Took car to the dyno... Need help troubleshooting

I didn't realize you swapped 7/8 wires and fired the cylinder out of order, what good would that do?
The first thing you need to look at is the valve lash. If a valve is held open you won't make any compression
Second thing is to check on those cylinders is compression with a compression tester.
You need to ensure that you have compression, because if you don't everything else might be fine.
It's possible to be an injector, and a simple swap of injector 6 and 8 would tell you if you get heat in that hole.
You need to re torque the heads, or not (do your own research on that subject) I have re torqued with cometics and have had great luck.

Then if you have air, and compression and fuel its ignition.

Have you reset the BS3 crank reference angle back to the 50* its supposed to be?
I don't know what adverse effects it would have being where it is, but i am just thinking anything is possible.

I wouldn't get too down on yourself, car looks impressive trying to jump off the dyno and is going to make amazing power if its already at 700+ on 6cylinders
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Old 12-01-2010, 08:36 AM   #3
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Default Re: Took car to the dyno... Need help troubleshooting

7/8 swap was a mistake... swapped the wires at the plug but then put them back on the cap in the original position when testing o see if wire was bad... either way the dead hole didn't move to #7 so that shows the ignition was firing off the #8 all the way down to the number 7 cyl.

Checked lash and it is good.
I would think bad compression would have filled up my crankcase overflow and still would have given me something for combustion on the two cyl.
All BS3 parameters were re-checked yesterday before the dyno session and then the crank trigger, distributor and regulator were all marked with a marker so that I could quickly check if anything moved. Nothing moved.

Given what I've looked at... it has to be fuel... however, I'm open for more ideas other than what was tried last night in case I'm missing something.
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Old 12-01-2010, 10:11 AM   #4
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Default Re: Took car to the dyno... Need help troubleshooting

On the BS3 can you make it fire bank to bank or batch instead of sequential?
If so try that first and if still nothing, swap the injectors wired on the dead cylinders.
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Old 12-01-2010, 12:12 PM   #5
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Default Re: Took car to the dyno... Need help troubleshooting

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On the BS3 can you make it fire bank to bank or batch instead of sequential?
If so try that first and if still nothing, swap the injectors wired on the dead cylinders.
I'm not sure if there is a toggle. The SEFI option is literally typed into a blank box.
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Old 12-01-2010, 10:47 AM   #6
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Default Re: Took car to the dyno... Need help troubleshooting

Do you have acess to a labscope ? or a Snap-On MODIS I can walk you through diagnosing or rulling out a injector driver.
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Old 12-01-2010, 11:40 AM   #7
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Default Re: Took car to the dyno... Need help troubleshooting

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Originally Posted by Collinsautomotive View Post
Do you have acess to a labscope ? or a Snap-On MODIS I can walk you through diagnosing or rulling out a injector driver.
I left a message with my buddy last night to borrow his graphing multimeter.
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Old 12-01-2010, 11:52 AM   #8
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Default Re: Took car to the dyno... Need help troubleshooting

Subscribing. What's the gap on your spark plugs?
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Old 12-01-2010, 11:55 AM   #9
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Default Re: Took car to the dyno... Need help troubleshooting

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Originally Posted by NOS-Nelson View Post
Subscribing. What's the gap on your spark plugs?
22
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Old 12-01-2010, 11:58 AM   #10
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Default Re: Took car to the dyno... Need help troubleshooting

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Originally Posted by 67AfroMaro View Post
22
Tighten it to .018.
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Old 12-01-2010, 11:54 AM   #11
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Default Re: Took car to the dyno... Need help troubleshooting

Also pop the cap off and look at those two posts for any discoloring.
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Old 12-01-2010, 12:13 PM   #12
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Default Re: Took car to the dyno... Need help troubleshooting

Just looked under the cap... normal wear... will tighten gap.
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5.02 @ 147 on 26x8.5's (Vid)
4.79 @ 151 on 275's (Vid)


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Old 12-01-2010, 12:18 PM   #13
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Default Re: Took car to the dyno... Need help troubleshooting

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Just looked under the cap... normal wear... will tighten gap.
OK. I'd try swapping the injectors to see if it moves the problem cylinder or not. Did you verify the timing with the 30 test timing feature?
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Old 12-01-2010, 12:19 PM   #14
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Default Re: Took car to the dyno... Need help troubleshooting

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Originally Posted by NOS-Nelson View Post
OK. I'd try swapping the injectors to see if it moves the problem cylinder or not. Did you verify the timing with the 30 test timing feature?
Yes, tried timing at 20, 25 and 30 and the box sets it correctly against my light.
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5.02 @ 147 on 26x8.5's (Vid)
4.79 @ 151 on 275's (Vid)


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Old 12-01-2010, 12:33 PM   #15
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Default Re: Took car to the dyno... Need help troubleshooting

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Yes, tried timing at 20, 25 and 30 and the box sets it correctly against my light.
All you need to do is check it at 30. If it matches then your crank trigger is exactly where your crank angle reference value is. What do you have for the reference?
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