If Your're Familliar With The Rbs, Confirm Or Deny.

[sonicz]

My timing was jumping around by big numbers in just few seconds. I figured it was my CAS, so I made a WTB thread and ordered another unit from a SAU member. http://www.skylinesaustralia.com/forums/topic/424325-wtb-rb25det-cas/ The new unit arrived today, although the timing is a bit more stable than with my CAS, its still jumping around.

Do I have my hands on 2 faulty CAS or is could it be something else? I need a definite yes or no answer if this is normal behaviour for a R33 GTST-t Series 1.

I have used the same diagnostic gear on other skylines, but only series 2 rb25s, and they seemed to hold 15 just fine. Anyone have a S1 R33 willing to let me hook up the nissan consult to it?

Edited May 2, 2013 by sonicz

[89CAL]

Does it hunt when it returs to idle? Looks like it is from the timing. It seems to hold 15 pretty well once it settles down

The Revs dont look like its hunting to bad if it is, but the timing seems a bit like it might be. What happens if you rev it and hold it at a certain RPM does the timing stay pretty stable?

[GTSBoy]

I'd be looking for a bad connection in the CAS wiring. That looks like noise more than jitter. You tend to get jitter (caused by dud CAS) at high RPM, not idle.

[Kane_R32]

*you're

[sonicz]

Does it hunt when it returs to idle? Looks like it is from the timing. It seems to hold 15 pretty well once it settles down The Revs dont look like its hunting to bad if it is, but the timing seems a bit like it might be. What happens if you rev it and hold it at a certain RPM does the timing stay pretty stable?

No it seems to idle just fine, no more "hunting" than any other RB25 i've seen, even less in fact.

It looked like it holds 15 for those few seconds, but that was just a lucky streak. If I left it for a bit longer it would have been back to its old ways

At the higher RPM it seems to hold the timing ok, certainly better down low where the problems are.

I'll try get a friend to record the laptop whilst I actually go for a drive.

[sonicz]

I'd be looking for a bad connection in the CAS wiring. That looks like noise more than jitter. You tend to get jitter (caused by dud CAS) at high RPM, not idle.

Its a possibility. But I couldn't "look" for that to save my life. I wouldn't know where to start, and it doesn't sound like a good idea to just take it to an auto electrification who been working on commodores for the past 40 years and pay them by the hour to check something they have no clue about?

Anyone tuner in syd familiar with the car and wiring and these types of "tuning" issues that would have a look at it without wanting an arm and a leg?

With the new CAS i got today, the car definitely has much much more grunt down low. So it has made a difference. But I really want to find another s1, check that the timing is stable, and put that cas in my car to check if it ok. Free pizza, any topings in syd to anyone who lets me do that

[MBS206]

You guys are reading a gauge, that is giving you the timing BTDC, based on a sensor...

If sensor is physically flogged the timing will move around when you have a timing light on it. The gauge will stay stable though (What you're looking at). The issue is something is making the ECU move the timing around. The CAS only tells the ECU where the engine is physically up to.

[Risking]

Flogged out star drive inside the exhaust cam.

Poor quality sensor

Poor quality wiring

Damaged shielding

We put a scope on the two cam sensor outputs and compare them to known good traces to determine if its a fluctuating signal.

You can determine anything with the ignition timing trace on "consult"

[Don Dada]

Cant see the vid here at work but is the car up to temp when checking the timing?

Because the car has more grunt doesnt necessarily mean the cas is working better. It could mean you have advanced the timing some when putting in the new one, so you need a timing light to set it back to 15*

Ignitor could be a possible cause also on the S1

[GTSBoy]

Now, that's not entirely true. The ECU calculates the engine speed from the stream of pulses it receives from the CAS. The CAS doesn't calculate rpm and send that number to the ECU, it just sends pulses. So if the ECU is trying to work out the engine position (which of course is what it is supposed to do) but the nice steady stream of rpm pulses is all messed up (which is what happens when the CAS or drive is flogged) then the ECU has a hard time knowing exactly where the engine is. It has a stab at getting the timing right, but the timing point is of course calculated with respect to the rpm and it can all get very untidy.

You guys are reading a gauge, that is giving you the timing BTDC, based on a sensor... If sensor is physically flogged the timing will move around when you have a timing light on it. The gauge will stay stable though (What you're looking at). The issue is something is making the ECU move the timing around. The CAS only tells the ECU where the engine is physically up to.

[sonicz]

Flogged out star drive inside the exhaust cam.

Poor quality sensor

Poor quality wiring

Damaged shielding

We put a scope on the two cam sensor outputs and compare them to known good traces to determine if its a fluctuating signal.

You can determine anything with the ignition timing trace on "consult"

1.So a new cam gear? How does a star drive flog out anyway...and how do I check it.

2.Highly possible the 2nd CAS is faulty too. The fact that it performs better than mine tells me it has a lot do with the cas.

3.So New wiring harness?

4.Damaged Shielding to what?

Don dada, yea the car is up to temp. I've got the CAS adjusted roughly the same, and it still has the issues whether its advanced or retarded.

Here is a vid of my orginal CAS again

Notice its a lot more erratic than the new cas.

If there is a fault with one CAS it seems likely another identically manufactured cas of the same age and condition can develop a similar problem.

Edited May 2, 2013 by sonicz

[GTSBoy]

The CAS to ECU wiring is shielded to keep out electrical noise. A shield is a braided wire mesh around the outside of the signal carrying cores, earthed at one or both ends to act as a Faraday cage and stop RF getting in.

[sonicz]

So no one is willing to let me hook up their series 1 to consult or better yet try their cas??

I don't want to have to buy another cas, this time a $500 new brand new one.

I may as well buy another r33 at the rate fixing this car is costing me...

Edited May 3, 2013 by sonicz

[Ben C34]

seriously?

[sonicz]

seriously?

? Whats wrong with that? Its just a cas.

I've seen people even lend stuff for free to clear defects here on sau.

You can charge me to rent it out if you want, hourly daily, by the minute etc. I only need a few minutes.

Also the nissan consult thing is easy. Its just a plug that dangles from your foot area. I'll read your fault codes for free eh?

Edited May 3, 2013 by sonicz

[ZILR]

Have you got an aftermarket cam gear fitted

[sonicz]

No, But I'm not sure when the timing belt was done last time. Could it be loose?

I'll get a flash light and take some pics tomorrow down the hole. I don't even know how a cam gear wears out ffs.

Ill try video the car while driving as well.

[Ben C34]

Ok , why do you think you actually have a problem? The ecu alters the timing to maintain idle. Unplug the tps and see what happens. Thats what you have to do when timing the car. How did you set tge base timing when you swapped the cas?

[Hanaldo]

No, But I'm not sure when the timing belt was done last time. Could it be loose?

I'll get a flash light and take some pics tomorrow down the hole. I don't even know how a cam gear wears out ffs.

Ill try video the car while driving as well.

It's not the cam gear that is worn out, the cas doesn't connect to the cam gear at all. It passes straight through the middle of it and into the camshaft. It's possibly the drive in the camshaft that is flogged out, not anything to do with the cam gear. Can happen when people don't fit the CAS properly, eg. not putting the spacers in between the CAS and the mount, causing the CAS to sit further in than it should and damaging things.

[Risking]

Your best off giving it to someone to look at for you who knows what causes the issues your having.

30mins and the problem should be located.

5mins pulling the CAS out and physically looking at the drive peg

15mins putting a scope on the two signal wires

5 mins checking the shielding

And 5 mins of fart arsing around tidying up.

It might take more than 30mins to fix the problem but locating it is not hard.

I've got several Sensors at the workshop your welcome to try them but chances are it won't be the problem.