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Ask Mike V. Your Own Question
Mike V.
Mike V., Subaru Technician
Category: Subaru
Satisfied Customers: 24615
Experience:  Certified Subaru Technician, factory trained by Subaru.
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I have a 05 sti with no spark at coil pack 1 and on 4 I only

Customer Question

I have a 05 sti with no spark at coil pack 1 and on 4 I only get spark one time but when I unplug the cam sencer i get spark and it will fire up but runs rough
Submitted: 1 year ago.
Category: Subaru
Expert:  Mike V. replied 1 year ago.

Hi there,

Do you still need assistance with this?

Customer: replied 1 year ago.
Yep
Expert:  Mike V. replied 1 year ago.

Has the engine recently been replaced or any other work on the car other then what you have listed?

Customer: replied 1 year ago.
I just rebuilt it
Customer: replied 1 year ago.
All grounds are on
Expert:  Mike V. replied 1 year ago.

You need to double check your timing. Since it will run without the cam sensor plugged in, and it runs rough, you likely have a timing issue going on.

Customer: replied 1 year ago.
It's spot on I've had the cover off to many times to count all marks are where they should be
Expert:  Mike V. replied 1 year ago.

Can you shoot me a photo of the timing marks?
Especially the crank sprocket?

Customer: replied 1 year ago.
It won't let me load them but the single marks line up with the timing case and doubles line up with the pullies
Expert:  Mike V. replied 1 year ago.

Ok, some of the crank sprockets have 2 marks, make sure you are using the timing mark on the cog on the back of it for the belt. If you use the mark on the face of the crank sprocket, it will put you off a few degrees. This might be what you have going on here With the cam sensor plugged in, it's actually seeing the timing. The cam sensor is the one sends signal for fuel injector pulse and for spark. Unplugged is more of a default and the car will run. I believe this may be the issue. The cams sound like they are on the money, but if the crank is off just a bit, then it's going to make the cam timing off when it's running.

Expert:  Mike V. replied 1 year ago.

Here is a good look at what I am talking about. The line on the cog, but there is a pointer on the face.

If your woodruff key isn't at 6 o'clock when you are set up, then it's off.

Customer: replied 1 year ago.
It is on the money as well
Customer: replied 1 year ago.
Yep it's on as well
Expert:  Mike V. replied 1 year ago.

My only other thought would either be a security system type of issue or the remote possibility that maybe the IVT harness is connected to the cam sensor, like maybe you have those crossed, otherwise, I will have to open this back up for the other guys to see if anyone has an idea or has dealt with it.

Did you rebuild this or have it rebuilt at a machine shop?
I am asking because I have seen times where the cam sprocket was switched and not reading right, but in this case it would have to be from a different engine, not something you would likely do unless you did an engine swap or head/cam swap of some sort.

Customer: replied 1 year ago.
Nope I built it at the house it has the same one that came off it
Expert:  Mike V. replied 1 year ago.

Sorry, I am going to have to open it back up for the other experts. Please don't reply to me or it will lock it to me.

We have a few other Subaru guys on here that are good and may have seen this.

Sorry I couldn't help!