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Discussion Starter #1
Hey Guys...
I am having some misfire issues with my 04 mustang GT... when my engine is at about 2000RPM my check engine light starts flashing and i can feel it drop a cylinder or sometimes 2. I first thought it was the coilovers since I have an ignition booster and that just killed them... but as far as i know, when a coil goes out it stops working forever. I hooked a computer up to get the error codes and it showed that I had misfires on all 8 cylinders. What rating is the stock fuel injectors? I would like to try and replace those first. Does anyone know of a cheap but good set and where to buy them? Or does anyone have any other idea of what might be wrong???
 

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Consider an injector cleaning and flow test service such as injectorrx.com. Once cleaned and tested, the injectors are "as good as new". Much cheaper than buying new injectors.

Regarding other possible sources of misfire, if the COP insulator boots have been damaged, they will continue to misfire. Autozone (Duramax) makes a set of 8 replacement COP boot insulators that are way cheaper than a single COP. This offers a why to have a "known good" reference set.
 

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Discussion Starter #3
Thanks i will look into it :)
 

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Discussion Starter #4
Which one should i try first??? one of my friends say the fuel injectors and the other says ignition coils
 

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As wmburns suggested regarding the boots, I would start with pulling the cop's one at a time and inspecting the boots. Although possible, I think it's unlikely that all 8 cop's went bad at the same time. And also, what error code are you getting? Might be helpful to know. If it does turn out that multiple cop's are bad, I've heard good things about Weapon X coils; a few guys on another forum I'm on have recently installed them and have nothing but good stuff to say. And for a set of 8, they're cheaper than oem.
 

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Discussion Starter #6
I'm thinking it was my ignition booster that is either messing up or killing my coils... I think tonight I’m going to unplug it from everything and see if it works worse or better. I'm pretty sure that the boots are ok since I just had a auto shop to a complete cleaning and tune up with new belts and spark plugs to make sure that wasn’t the problem... you would think that if the boots were bad they would be able to see and tell me... but I think that it is either the coil itself or the injectors... living up in Alaska there is alot of additives in the fuel which when I had a cerebrated Subaru it gave me alot of problems.

So I think I’m going to try unplugging the booster tonight and getting the brand of it so I can actually look it up. and then if that makes it worse I will replace the coils but if it doesn’t change anything i will replace the fuel injectors first... I found a set of 8 on American Muscle for $219, and I would rather buy new than clean these old ones.

What do you guys think about that idea???:?:
 

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Discussion Starter #7
So i took off the booster and it still dose not fix the problem... same exact problem. i think now it is the injectors... i also noticed my crank shaft pully moves up and down some. Thats not normal is it?
 

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Do you have underdrive pulleys? Sometime UD's will cause an unstable CKP signal. The usual sysmptom is random misfires.

Since you have not posted any DTC's, I don't know if the problem is random or in the same cylinder.

Did you look at the cost of the replacement boots? You asked for a cheap solution. It's hard to get much cheaper.

If the crank damper is moving around, this usually means the rubber ring between the damper and inner pulley has dried up. This can contribute to an unstable CKP signal. Why is that important? An unstable CKP signal will CAUSE ramdon misfires.
 

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Discussion Starter #9
Thanks wmburns... i will let you know if replacing the injectors fix it or not... i already bought them so i'm going to try that and try tighting up the harmonic balancer
 

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IMO, tighting the bolt is unlikely to help if the rubber ring is hard and brittle. Replace the harmonic balancer.

Follow the torque procedures when re-installing. Be sure to use a new oil seal.
 

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Discussion Starter #11
Wmburns, So just get a new rubber ring for it?? So all I would have to do to replace it is remove the belts, remove the five bolts on the pulley and the pulley itself, and then pull out that rubber ring? Or do I also have to empty the oil as well??
 
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