My daily driver of 5 years has me completely stumped - 87 S4 non-turbo, 69k miles on a rebuild with air-pump bypassed & valves open

I drive it 70mile a day, but after coming home one Friday and then trying to go back to work the following week it decided to not start. Which has happened before, and the only way to get it going again is to push-start it (doesn't make since to me if starter is doing the same thing) or wait an hour or so (waiting sometimes doesn't even work, only push-starting).

-The starter is turning it no problem.
-There is spark (tested by taking wires off of the spark plugs one-by-one, sticking screwdriver into wire, placing/securing safely near metal/ground, and having some crank it over to see a spark then jump from the screwdriver to ground)
-AFM appears to be working just fine (i can even hear injectors go when key's in 'On' position and I push the AFM flap)
-Reset the ECU via disconnecting battery for min
-Plugs are fairly new, and i checked them for abnormalities
-Re-did my grounds about a year ago per some of Aron Cakes website
-Checked my relays and fuses
-TPS is reading good ~1.0v (always able to see voltage via ApexiNEO)
-Confirmed that my throttle body is mechanically working

I can't even get it to fire with Ether/starting-fluid, and at this point I started to think that maybe there's something wrong with the CAS/timing (like she's not sparking at the right times and so gas nor starter-fluid can produce firing)

Please advise :/

 

If you have spark, the cas works.

Take out the cas, key to "on" and turn it.
You should hear the injectors fire (pushing the maf flapper does nothing!)
Re-align timing marks and put cas back in.

No start means either no spark, fuel, timing or compression
Check in that order and you will find the problem!

 

The Ecu does not reset when you disconnect and reconnect the battery.

 

Sounds like classic flooding usually due to leaky injectors or low compression. Next time it doesn't start, follow the de-flood procedure. Pull the EGI fuse, crank for 5~10 seconds, put fuse back in and try starting normally.

 

Thank you for the responses, I will be able to give an update later today hopefully - depending on when I get off of work.

sorry just confirming: So I'll be able to hear the injectors fire/squirt when I spin the CAS?
What was the squirting-like sound I heard when I did push in the flap of the AFM with keys in 'On' position? Could it have been the BAC I was hearing?

I thought it was, oops :P - thanks for clarifying

RXSpeed16:
Thanks for the advice there too, learn somethin new every day

 

The fuel pump turns on w/key to on and the AFM flapper door opened.

 

Well, I did as Furb suggested in that order and she still doesn't want to run, even with some starter fluid (no firing). I could however here the sparkplugs going when I had the CAS out and turning it w/ key-On. (I removed the CAS, lined up the pully timing marks, lined up the CAS's 2-toothed gear properly, re-installed the CAS, and yet again adjusted/ensured the CAS was lined up properly before bolting it all back up. no go...)

I'm thinking that my CAS may be going bad then, it may be somewhat working, but maybe it's not keeping the timing as needed. I did try searching to find out how to test the CAS, but couldn't find exactly how (more than likely with an ohm meter, but which pins). I just realized as I was typing this that I could have just checked my Haynes for the testing procedure, duh... lol

But, could it even be a possibility that the CAS is infact going out?

Otherwise I think I may need to get something to test the fuel pressure, and then test the injectors - but then again this still wouldn't explain why it doesn't even try to fire with starter fluid :/

 

in my experience the symptom of a bad CAS is the same as a flooded engine, but you wont smell fuel. what happens is that the ECU needs to see power from the battery and an RPM signal from the CAS to fire the injectors.

so bad CAS = no rpm signal = no spark AND no fuel.

id suggest the simple way to test the CAS is to hook up a timing light and crank it, if you have spark the CAS is fine, and with FC's if its got an RPM signal its probably flooded

 

Like i said before, if you have spark, the cas works..

Check if the fuel pump works by jumping the yellow connector on the right strut tower.

But to me it sounds like its flooded like ^ says

 

+1 for flooded engine due to leaky injectors, all too common in these cars.

PS: i've never heard of a failed CAS before....

 

Well, i actually had a faulty CAS once..

 

i had one with a bad pin on the connector. i was actually able to fix it.

however it did stop running, we were 10 blocks from the shop, and i am way to lazy to walk back and tow it, and i'm not going to push it. so i spit on the CAS connector, and that would work well enough to get it to run for a block or so.

that CAS connector was gross by the time we got back....

 

Thanks a ton for the reply's everyone!

Now I just gotta find a decent amount of daytime to hammer down on this thing - dam work has me tied down :/