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Down on power !!! Help !

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Old Apr 7, 2012 | 10:14 AM
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Default Down on power !!! Help !

So I finally got my setup complete, setup is in sig. I went down to New Era Performance for a tune. It was running pig rich, he even had to wear a mask. It was back firing under a load. I changed all the plugs, made a run and it still did it. I pushed all the wires on the coils and we made another run, still down on power.

When I say down on power, it was 360 rwhp. It should be well over 400 rwhp. Graph was smooth, locked in the air fuel.

Now I suspect it was a spark plug wire problem and coil mounting, I have a relocation kit. I just put the coils back on the valve cover and now it wont even run. It back fires and barely idles, no power. I checked the wiring diagram and the coils are in the correct location. I followed the wires on the 1 and 2 cyclinder to make sure I had those in the correct location, then the others just follow to the other cyclinders.


Any Ideas? All grounds are connected, could it be a bad coil?
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Old Apr 7, 2012 | 10:54 AM
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Did they have any suggestions?
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Old Apr 7, 2012 | 11:19 AM
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Ignition, its running again, backfires under load
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Old Apr 7, 2012 | 02:55 PM
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Originally Posted by SWEET98SS
So I finally got my setup complete, setup is in sig. I went down to New Era Performance for a tune. It was running pig rich, he even had to wear a mask. It was back firing under a load. I changed all the plugs, made a run and it still did it. I pushed all the wires on the coils and we made another run, still down on power.

When I say down on power, it was 360 rwhp. It should be well over 400 rwhp. Graph was smooth, locked in the air fuel.

Now I suspect it was a spark plug wire problem and coil mounting, I have a relocation kit. I just put the coils back on the valve cover and now it wont even run. It back fires and barely idles, no power. I checked the wiring diagram and the coils are in the correct location. I followed the wires on the 1 and 2 cyclinder to make sure I had those in the correct location, then the others just follow to the other cyclinders.


Any Ideas? All grounds are connected, could it be a bad coil?
I saw the thread about the silver and black look you went with over winter. I thought it said it was running better then the old cam or something like that when you 1st got it running a while ago? Why did you take it to get dynoed if it was backfiring under load?

If you painted your valve covers black, and the coils. Dont just bolt them on. Sounds like you know why, if its not running when you moved them back on the valves covers from that coil relocating thing you did. If you look, thats why the stock coil bolts are they way they are so they cut a little when GM installs them new.
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Old Apr 7, 2012 | 08:55 PM
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I actually just had a plug wire mixed up when I first got it going. I put 300 miles on it, no backfiring. When Mike put it on the dyno, that was the first time I ever heard the car backfire.

So tonight, changes the wires, still no go. I bought a new coil, switched it with a couple of them still no go. I got a check engine light so I got the codes pulled, it was for fuel injectors and fans not working. So this tells me wiring.

Well I drove it around a little more, check engine light went off, I opened it up and it ran great, tons of power, no back firing. I finished mounting everything so I will see tomorrow how it works.

Last edited by SWEET98SS; Apr 7, 2012 at 10:13 PM.
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Old Apr 8, 2012 | 11:56 AM
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Ok, so I have an update. Now I have the CEL again, it comes up with a code for injectors and cooling fans. I guess I need to find what harness is the problem. I am going to check for 12 V at the injector and also at the coils.

Anyone else have any suggestions ? It runs like crap also.
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Old Apr 9, 2012 | 07:49 PM
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So of course the CEL went out , still runs crappy. I ordered new wires and sleaves so they dont get burnt, put new plugs in, bought a ls6 coolant line. I also took all the injectors out and blew them out. It looks like there may have been some paint chips in there from when I painted the manifold and injector manifold. We will find out tomorrow if this was it. It will all be here tomorrow, so if this doesnt fix it, I dont know what it is.
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Old Apr 15, 2012 | 07:22 PM
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So the stuff in the injectors was the problem, that would explain why it ran crappy after they put the new injectors in.
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Old Apr 16, 2012 | 04:59 AM
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Can you tell me how you blew them out? At 149k I figure mine need a good cleaning, but have no idea how.

Congrats on finding the problem.
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Old Apr 16, 2012 | 05:57 AM
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I just took them off and blew air in both ends. The end where the fuel goes in has a filter. I had black paint chips all over the place, inside and outside so I figured they got swept into it somehow.
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Old Apr 16, 2012 | 06:34 AM
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chips in the rails will do it, that can hurt the motor too. lean out a cly and cause major damaged.
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Old Apr 16, 2012 | 08:08 PM
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Yup, I know. Mike watched the airfuel the whole time, it only started doing it when they put the new injectors in.
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Old Apr 16, 2012 | 11:50 PM
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thats a average of all 8 cly. If you had paint chips in the rails, its blocking only that one injector
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