Help Request: AVCS Related Problem

[waltm]

Just thought I'd chime in here.

 

I had a similar situation as yz123mx, bought car from auction with two spun bearing. Replace most of the components in the oiling system when the engine was rebuilt but cleaned out the pulleys (or at least I thought they were clean).

 

Logs looked the same as yz123mx's above. Verified wiring to OCV was fine (current draw in log), cleaned and verified operation of valves and swapped OCV from left to right side to see if issue would follow valve or stay on same cam, verified oil flow to right side OCV. No change in logs so replaced intake pulley. Now both side are working fine.

 

Thanks Underdog and everyone else who commented in this thread as it was very helpful to get to the root cause of this.

 

Still have some issues to sort out but at least this one is fixed.

[Underdog]

Glad to hear it. Replacing the intake cam sprocket has become standard procedure on any blown motor rebuilds in my shop. With the right bit (mentioned earlier in this thread) you can disassemble/clean/rebuild the intake cam sprocket to save some money, but there is definitely a risk vs. cost saving that needs to be considered if you are paying someone to do the work.

[nismo4life11]

Bringing this back yet again... I have an 04 foz XT and have been having AVCS issues with it but cant find help anywhere on them (a google search has lead me here). So here is the back round I have a completely random idle and mid range minor misfire (sometimes shows up on my AP under cylinder roughness sometimes doesnt). I've had a leak down and compression test the results came back fine. Car is stage 2 OTS map on my v3 AP (mods include dw200 pump, STI top mount, STI bpv, cobb SF intake, injen 3" catted dp, 3" N1 WRX cat back). So far I've replaced the fuel filters, fuel pump (dw200), fuel injectors, spark plugs, coil packs, maf, alternator, battery, AVCS Oil control valves, did a grounding kit, .5v alternator mod. When I did the new AVCS oil control valves it has helped the most the misfire seems much less frequent now. But on my AP under WOT I've noticed that AVCS in left seems sluggish (up to 4-5 degrees off between left/right side with some misfires). At idle the right side will stay at a solid 0 while with each misfire the left side will be jumping around from 0-3. Also on my AP I have been watching the OCV duty cycle at idle both stay at 9.4 but while cruising the left side will consistently stay about 1% higher than the right side so if the right side is at 46.3 the left side will be about 47.1ish. I'm pretty much at wits end with it and I feel like the AVCS left cam might be clogged/sticking but not a normal on/off sticking that most people experience (when I replaced the OCV on both sides the left one definitely looked way more gummed up). Does this sound about right? I'm considering replacing the left side AVCS cam gear to see if it finally fixes it once and for all but wanted some other opinions.

[rmoore5]

This seems to be a good place for this.

 

After losing a rod bearing I disassembled the VVT sprockets to clean out the debris.

 

Afterwards I had a P0018 code after running awhile. It turned out the variable cam timing sprocket on bank 2 had bound up on the cam.

 

I noticed when I assembled the sprocket to the cam it didn't slide easily on to the cam. The 2 bores of the sprocket can be assembled non-concentric.

 

I removed the cam and disassembled the sprocket, reassembling using an old cam to assure the concentricity. So far so good.

[1-3-2-4]

This is what you start with:

 

http://img716.imageshack.us/img716/6933/img8003c.jpg

 

1. Remove sprocket from AVCS mechanism. This uses a T30 tamper-resistant Torx Plus bit.

 

http://img27.imageshack.us/img27/415/img8005cc.jpg

 

2. Gently pry the sealing flange away from the casing.

 

http://img705.imageshack.us/img705/8906/img8006c.jpg

 

3. Now you can disassemble the mechanism by popping out the middle section. There are six spring-loaded seals that will come apart, but they are easy to reinstall.

 

http://img691.imageshack.us/img691/5746/img8007c.jpg

 

http://img708.imageshack.us/img708/5531/img8009c.jpg

 

http://img695.imageshack.us/img695/180/img8010c.jpg

 

The piece on the right is what bolts to the camshaft. Notice how it has a spring loaded plunger that locks into the sprocket carrier? When I pressed it a few times look what came out (no, not the nickel ):

 

http://img684.imageshack.us/img684/9746/img8011c.jpg

 

Hopefully this means I was right and the sprocket was getting stuck in the position where the plunger engages (0* would make sense). This would also corroborate with the cold start/reset ECU evidence where the high oil pressure of a cold start was able to unlock the sprocket, but the next time it went to zero, it wouldn't recover.

 

 

I wished I knew about the Torx bit size I ended up buying the company 23 one oh well.. but it seems easy to clean what about that gasket did you use anything when closing it back up to make sure it's sealed?

[rmoore5]

Sorry it is a t-30. I probably should edit above.

 

I did find some crap inside my sprockets.

 

 

Got mine at PEP BOYS. Sorry a little late, be sure to reassemble the pieces concentric. They will bind on the camshaft otherwise.

[biggreen96]

Hi guys, so taking my intake sprocket off(belt method, vicegrip'd nice and tight) I noticed the center of the sprocket rotated when I put my impact to it. Is that a bad sign? Could I have sheared that plunger?

 

I haven't gotten it apart to look yet, the 5 point gets here in a day or so from amazon.

[rmoore5]

Hi guys, so taking my intake sprocket off(belt method, vicegrip'd nice and tight) I noticed the center of the sprocket rotated when I put my impact to it. Is that a bad sign? Could I have sheared that plunger?

 

I haven't gotten it apart to look yet, the 5 point gets here in a day or so from amazon.

 

The plunger is not straight sided, it has an angle on it. The impact may have overcome the plunger.

[biggreen96]

Got it apart last night, plunger looked just fine. Passenger side was clean, driver side had sediment packed into corners. Glad I cleaned that one up.