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Old 12-03-2012, 01:56 AM   #697
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So the wife was out of town this past week which meant I had a few hours to work on the car. With Jay's help, we installed the camshafts, adjusted the clearances, and installed the timing belt kit.

As most have figured out by now, I am installing an EJ207 into my car. The Version 8 Spec-C EJ207 that I bought runs on a 16-bit ECU with a DBC throttle and AVCS. My car, a 2006 WRX has a 32-bit ECU with a DBW throttle and AVCS. Unfortunately, the way in which the 32-bit USDM ECU's/motors monitor the AVCS is very different than the 16-bit JDM ECU.

The main difference lies in the way the ECU monitors the camshaft position/angle. There are some technical details here that I'll skip, but basically, the USDM sensors cannot read the JDM cams properly. The JDM sensors cannot read the USDM cams properly. You must keep the USDM sensors with the 32-bit ECU with the USDM style cam. This means I had to tear open my nice new EJ207 and pull out the JDM hardware and swap in the USDM cams and sensors (and of course use my old engine harness and ECU).

This sounds simply enough, and for the most part, it is. The USDM EJ255/257 cams are the same basic dimesions as the JDM cams and fit into the EJ207 heads without issue. The pickups on the USDM cams however do not line up with the senor holes on the EJ207 heads, at least not on the driverside cam. This requires you to open up or extend the senor hole slightly to push the senor toward the back of the head about 7mm. Additionally, the bolt holes on both the passenger side sensor and the must be modified slightly to allow you to bolt the senors down using the existing factory threaded holes.

So to summarize:

Driverside: Extend or open up the sensor hole to allow the sensor to be located 7mm further back on the cam. This centers the sensor squarely over the signal grooves on the USDM cam shaft. The depth of the sensor does not need to be changed and it should end up placing the tip of the sensor ~2mm off of the camshaft. The bolt hole on the sensor will need to be slotted/extended so that it aligns with the threaded hole on the head. A gasket solution will need to be implemented to make sure the sensor hole is properly sealed since the factory oring on the sensor will not seal in the extended hole.

Passenger side: The sensor should be centered over the signal grooves on the camshaft and requires no positional adjustment. The tip of the sensor should stand off of the camshaft ~2mm. The bolt hole on the sensor will need to be slotted/extended toward the body of the sensor so that it aligns with the threaded hole on the head. The USDM sensor is a bot loose in the hole so a thicker oring needs to be used to properly seal the sensor hole.

That's it in a nut shell. Now I've got some pictures to help show what was done.


Here is where the USDM sensor (black cylinder part) sits in the EJ207 head in relation to the USDM camshaft. The deep cut/slot in the camshaft is the location feature that the sensor uses to judge camshaft position. There are four (?) of these grooves around the camshaft's circumference. Ideally you want the sensor centered over the slot. In this current position, the sensor may detect the slot, but it may not be as strong as it should be/needs to be for the ECU to use the signal.

Here is where the sensor sits after modification to the hole. It is not centered over the slot.





Next I modified the mounting hole on the sensor so I could bolt it down using the factory threaded hole.


After: (note it's just slightly off, but enough that the bolt won't thread in without moving the sensor too much.)

To cut the hole, I used a Dremel tool with a carbide bit. To keep things clean and shaving free, Jay and I taped off the inside of the heads thoroughly. No part of the inside of the head was exposed. Jay also vacuumed up shavings while I cut the hole. We removed only small amounts of material at a time and then test fit the sensor. Measure twice, cut once. Remove as little material as possible.

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Last edited by kpluiten; 12-03-2012 at 02:18 AM.
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