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Misfire /breakup and high rpm with stand alone AEM infinity


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  • 9 months later...

Okay - I am in the same boat here and I’m glad you posted .

A while back I had a misfire issue that was very hard to diagnose . It was the spark plug wires were leaking and cross firing . These were genuine GM wires that weren’t very old . It took forever to figure out . Put a new set Magnacore on there and fixed it

Now I have put a bigger motor in and have a high compression build I am having issues again. #6 is fouling for no apparent reason . 
I swapped everything possible , coils, wires, plugs, injectors -  nothing helps .
225 cylinder pressure , good leak down test, good coolant pressure test . 
Getting ready to install a zx dizzy and wires to check to see how things go . I think these smart coils trigger to easy . #6 coil sits right above my starter . Maybe proximity is going to be the issue . If not I have a hardware problem - like piston ring ?

 

Edited by madkaw
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Don't think you have a engine internal problem Stephen. Other than possibly a slightly leaking oil seal on #6. But I don't think that is the main issue. Funny, I was just thinking about coils on your FB thread. Seems you had a lot of problems with those COP's.  

 

Going single coil with dizzy should be a good way to check to see if its' anything related to the coils. 

 

And yes, D585 coils are sensitive to EMI and electrical noise from large ground loops. . It can trigger Auto Discharge. One of the big things is that the Main ground for the GM Coils ( Not the Trigger ground ) MUST be grounded to the cylinder head. Grounding elsewhere creates a larger ground Loop and thus more EMI. Might be a good idea to double check the ground wires on all of the coils. Especially #6. 

 

Also had a couple of thoughts on the injector drivers in your FB thread. 

 

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7 minutes ago, Chickenman said:

Don't think you have a engine internal problem Stephen. Other than possibly a slightly leaking oil seal on #6. But I don't think that is the main issue. Funny, I was just thinking about coils on your FB thread. Seems you had a lot of problems with those COP's.  

 

Going single coil with dizzy should be a good way to check to see if its' anything related to the coils. 

 

And yes, D585 coils are sensitive to EMI and electrical noise from large ground loops. . It can trigger Auto Discharge. One of the big things is that the Main ground for the GM Coils ( Not the Trigger ground ) MUST be grounded to the cylinder head. Grounding elsewhere creates a larger ground Loop and thus more EMI. Might be a good idea to double check the ground wires on all of the coils. Especially #6. 

 

Also had a couple of thoughts on the injector drivers in your FB thread. 

 

I started a thread #6 fouling. I swapped to a zx dizzy and nothing changed

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  • 9 months later...
On 12/29/2018 at 10:09 AM, tioga said:

Never check the back three with a light. Yes load made a difference. Less throttle higher I could rev. This made it impossible to check timing at high rpm and see if it was moving around because it wouldn’t do it. 

I keep rereading this thread because I am sure I am experiencing the same thing. At around 6700 rpm my engine starts to get louder and not smooth and looses power. This shouldn't be happening with this motor. I will get fouling of 5&6 . It will clear off during normal driving . Can't see anything during datalogging . Looks like you went different coils? looks like Audi COPs?

I guess I need to go this route to be sure . There doesn't seem to be any other reason this could be happening. 

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