O.K. Here are the syptoms.
Car is rough and shakey at idle,
When timed then reved, it won't stay timed no matter how tight you tighten that bolt. Its either really retarded or really advanced and irratic. When timing and following the Haynes instructions, after you set the idle and start moving Crank andgle sensor, idle will almost die or rev nice and high. This is the only problems besides the 1/2inch gap in an exhaust gasket.(stock header to pre-cat). Does anyone know if its the crank angle sensor?
Charles

 

it is NOT the CAS unless you have broken teeth inside it.
open it and check.

You have the engine codes?
If not pull them.

I think youll find the one that tells you where this problem is.

Tell me what you find.

 

Not only broken teeth,also if you have debris between the teeth(like rust etc).

 

Anytime you rev the motor with a timing light, the mark should move, once you get it back to idle, the mark should be back where it started. Make sure that your "initial set" connector is jumpered when you are checking your timing, or the ECU is going to fight your changes...

Rat

 

Well the CAS is fine, I'm not sure I know what you are talking about with "initial set", but even when you set idle, set timing and rev the engine, the idle wont come down past 1000rpm and the timing marks are nowhere to be found. When the idle gets below 100rpm to about 750, the engine just wants to die and just jump around in the mounts. What is this initial set thing? I have never used this before.
Charles

 

You need to study the FSM (Factory Service Manual). It will eliminate alot of the headaches you are currently having. I am pretty sure that the S4 and S5 cars both have an initial set connector. This connector disables the ECU from making compensating adjustments whenever the Idle/mix, and timing are adjusted. Once the adjustments are made, you pull the jumper out, and your ECU starts taking readings from where you just set it. This should mean that the ECU will always remember the initial timing, mixture, and idle speed, and always try to return to that setting even if under different loads. If you start adjusting things while the ECU is still controlling the engine, its gonna fight you the whole way.

Rat.

Remember, this DEFINATELY pertains to S4. I am not as up on the S5 motor, but fundamentally they are the same.

 

interesting.
I will have to go and find me some FSM here in a minute. I'll check it out.
Charles

 

This goes DOUBLE for an S5 engine.

Anything done without the initial set connector is a bad idea.

 

my CAS started going bad, when accelerating it would start missing RPM signal, so you watch the tacho and the thing would start going higher then kinda stutter a bit go up some more, stutter, higher, stutter etc, and it was very intemitten. i changed the CAS and haven't had the problem since

 

Thanks, I was pretty sure, but I need an S5 person to verify.

Rat

 

Where do I find the initial set stuff? I can't download anything right now, my computer is being a dick. CanI find this in the Haynes manuel?
Charles

 

The initial set wire plug is next to the leading coil. Small green plug with two pins 90 degrees from eachother.

Looks like this:

|-

Get a short piece of wire and crimp a male connector on each end. Connect the "Jumper wire" into the plug and adjust timing accordingly. This jumper wire disables the feedback from the BAC to the ECU so the idle can be adjusted properly. It may be a bit different in the S5, but that's the proper method for ther S4 cars.

Good Luck.

Jim

 

Damnit.
Now I feel stupid. Thanks for the info Jimmy.
Charles

 

I think you probably have figured it out by now, but.......the timing automaticaly advances when you get above approx 1000/1100 rpm as was mentioned before. You MUST set your timing with the rpm well below 1000. Get it at 750 and then set it on the marks. Fully expect the timing to advance when you rev the engine up. And as the man said, when you let off the throttle fully expect the timing to stay advanced for a moment after it drops down to 750. Its normal.

And the fight begins. Outside of disabling the feedback to the bac, the initial set coupler does squat for the timing. My 86-87 cars ECU's have no memory whatsoever. The initial set coupler is put in to keep the bac from changing the idle speed while you set the timing or influencing the idle speed as you set the idle.

Also sounds like you probably have air leaks or possible plug wiring problem/sparkplug problems to boot.

 

I checked for hose leaks and found none. I bought new plugs and wires, The timing with out bridging this set coupler thing does advance but after you rev and then let off the throttle it is WAY outa whack. I know about advance when you rev and everything. I have been around cars all my life, I'm just new to the rotary. Only been at it for about a year. There is so much I still have to learn.
Charles