Cas Problem

[jrocket]

Hey all.

Just wondering what you guys think. I was cleaning the valve that controls the idle of the car (R33 GTS-t) last night becuase it was starting to hunt while idling. As expected the AAC valve was choked up with crap. I cleaned this all up and put back on car and warmed it up n tweaked the idle. While reving the engine slowly i noticed this weird scrapping noise comming from the exhaust cam area. It sounded a bit like metal scraping etc. I think the engine used to do this when i first had it. I changed the timing belt not long ago and had the lifter covers off. The cams both looked fine etc and oil pressure is still good.

When i increase the revs slightly i get this weird knocking/ticking noise. If i increase the revs it seems to stop and only return when i ease off on the revs again.

I did the old screw driver trick and listened to various parts on the lifter covers and the engine. I think i have pinpointed the problem to the CAS sensor. While reving the car and listening to it, you can hear alot of noise comming from it. I am fairly sure the bearings are buggered in it.

Has anyone else had this problem and what have they done? I would like to replace it but i am not sure if getting a second hand one would be a good idea. And a new one looks to be round $450. (ouch). Is it possible to disasemble and replace the bearings without too much hassle?

I dunno how much longer i can use the car with this dodgy sensor? Also the car has done "135,000kms" Is it know for the CAS to fail around this kms?

Any info would be great guys.

[**RB2530**]

If you take the black cover off the CAS (I think for S2) you should see the actual chopper disc itself. Make sure that when it rotates it is not making contact with the optical sensor that it runs in...

I have seen one instance where a CAS was installed without the spacers that go between the CAS and the bracket on the engine...These spacers are brass from memory and are fitted into the rubber grommet that fits around the CAS. If the spacers are not used, the coupling on the end of the CAS shaft bottoms out where it goes inside the CAM gear. This will have the effect of pushing the CAS shaft through the CAS bearing and cause the chopper wheel to scrape on the optical sensor..

[jrocket]

Hmm ok i will investigate this tonight. I am fairly sure all the parts are there tho. I took care to keep all parts together when doing the timing belt on the car.

[FALLIN]

could be water pump (dry bearing)

[jrocket]

could be water pump (dry bearing)

Water Pump also replaced when timing belt done. I replaced timing belt, water pump, tension pulley, idler pulley, cam oil seals, crank oil seal.

Only thing i can think of is the CAS is buggered. Sounds buggered tho.

[jrocket]

Hmm i took the CAS sensor off last night and had a look at it. When i turn it over by hand it seems to feel smooth and has no sign of bearing failure. I tried to disasemble it to see what it looks like inside but it seemed to hard to remove the pin holding the fitting on the shaft on. So i just left it in tact. I think i might just try and find a cheap second hand one to put on it.

[jrocket]

Hmm well put the CAS back on the car last night. Previously a had been to a tuner to hav my car dynoed. My car has a modified ECU in it and was found to be runner very rich. This tuner tweaked the CAS to help a bit by advancing the timing slightly. The car seemed to go ok etc. Previously the car used to backfire and pop between gears as you would expect from a car running rich. After this CAS adjustment the pops etc seemed to stop. Car still running strong too. I marked this position of the CAS before removing it. When replacing the CAS last night i thought i might back the timing off a bit to make the sensor sit around the middle position of its adjustment range. This had been mentioned in other threads as being the standard spot.

I took the car for a spin and now it just seems to want to back fire n pop again like previously. I am thinking i might just set the CAS back to the position the tuner put it at and see how it goes. This tuner only increased the timing to a little over center position in the advance direction.

After the dyno run the A/F was still rich as hell even with the advance in timing(like 10+:1 ratio). I was told this was due to ECU probably having some crazy fuel/ignition map and would need to be remapped etc to fix.

I hope to get the computer retuned and the car sorted out later this year.

I will put the CAS back to where the tuner set it later on tonight (marked this position before removal). My question is, would it hurt to bump the timing up a little more. Currently about 3mm offset from the middle position. Maybe do 1 mm more.

I know this prob bit dodgy without a dyno to check it on etc. Car had been performing very well with no evidence of pinging.

What do you guys think. Am i cruising for a F!#k up?

[Godzilla32]

I'd be getting a timing light for starters, then setting it to manufacterers specs. See how that goes. Its very inaccurate moving it and going on measurement. The only way you can be sure you are making accurate adjustments is by checking the balancer marks with a timing light. In theory the ECU will read the knock sensors signal and just retard timing if it detects too much knock anyway.

You can't just go picking and choosing your base ignition timing. Get it tuned properly with correct mapping rather than mucking around with base timing.