Avant1522

Alright where to begine. This might be alittle choppy so please bear with me. My 2002 S8 engine code AYS was having a few issues ill start from the top

-Randomly wouldnt start: Occasionally it would crank and crank and crank but not start. If I went away for a few hours to scream in a pillow like a little girl and then came back it would start no problem. -_- sounds alot like my girlfriend NEWAY next problem

-Related to the above problem,it would randomly start very hard, and then turn over and slowly sputter to life coughing out unburned fuel (my cats have been gutted FYI), and then run fine (Usually) which takes us to oour next issue

-Stalling: Sometimes when it sputtered to life, or even sometimes when it started normal, as soon as I put it in drive and/or reverse it would just die. then one of the two about problems would follow.

All of this I could deal with, I assumed it had to do with my failing chain tensioner which I had recently purchased and was waiting for some good weather to install. Car ran mint when it was running.

12 hours till D-DAY

The night before "D-DAY", as ill call it, my car was running great, rosted a few Civics just for $hit$ and giggles,but nothing to strenuous, and I was runnning on a fresh oil from two days before. Drove probably 4 hours that sunday night (05/12)and not once had any of the above issues.

****D-DAY****

So monday morning pretty much when like this....
Turned the Key, crank crank crank hard then started, but shuddering horribly, flashing CEL sputtering, the works.

attempting to remain calm i turned it off walked in side GENTLY closed the front door, got the suberban keys and left her alone to go to work.

__________

The following weekend I changed the tensioner and spark plugs because i had them out to manuely turn over the engine (you may assume I lined up all my chain marks properly). Slapped it back together. and went to start it. Started right up YEY!!!!........ wait a minute... -__- Chain slap gone, but its still running horribly. I should note that the lower tensioner pad was completely gone and cut into the metal on the tentioner. (no clue how it was running before)but pulled out all the peices and ran through with a magnet to try to get any left over metal. Vag-com says cylinder 1 and 4 are missing (probably every time judgeing by how fast it is counting at idle) and 8 is having occational misses. work was done on bank 1 with Cylinders 1-4.

here is where I am.
Checked cam Sensor, knock sensor, switche all coil packs spark plugs and injectors from one bank to the other. Do these cars how Power output stage? i cant find it anywhere but I did find a delete kit for it on line. seems weird to have a delete kit for something not there lol. anyway im getting mad I cant figure this out. Im avoiding doing a compression test but I think thats whats next -_-, also going to run through the car with a multimeter to see if somehing is amiss that Vag-com hasnt noticed.

Any help or advise is greatly appriciated, this is my only car and I really want it back on the Rd, my parents suburban just doesnt handle the same and dont get me started on highway acceleration.

Thanks in advance.
sorry i wrote a novel I will probably be adding to is as i get more info.

silverd2

The POS's are built into each individual coil in a 40V motor...No ignition control module like older 32V motors. Coils (and POS's) get their signal directly from the ECM...I'd check that for water intrusion and any corrosion on connections, fresh air plenum, passenger's side under plastic cover (E box).

If you are doubly sure all valve timing is correct (belt and chains), then YES do a compression check.

P.S. Too late now, but I can't believe you drove for even a minute with a cam adjuster pad broken off. When this same thing happened to mine (same pad), there was a loud chain dragging sound (not the start up rattle...completely different cause)...I parked it immediately until I replaced the pad...a year later the entire adjuster, when the start up rattle continued while idling (not a pad sound, worn to the point of not holding pressure).

Serlock

Saw this thread and wanted to ask about cam tensioners....my S8 40V has this noise in the morning after night, for about 1 second after starting a car. Little rattling, not loud but i can hear it for 1 second. When starting hot i dont hear it. Should i get worried?

silverd2

Not yet...they can do that for years before actually becoming a problem. The sound is NOT a slack chain...it is the adjuster itself bobbing up and down a little till oil pressure stabilizes it. I didn't change mine until it made that noise constantly (embarrassing) at hot idle.

People call the start up noise "normal" ...I'll call it "common". It does indicate wear in the adjuster, but just the beginnings of it.

If a pad breaks off, you will have a loud chain dragging noise that wasn't there before. If this is left unrepaired, the results could be catastrophic. The chain is much harder material than the adjuster and immediately starts eating into the adjuster piston.

This was mine after just about 7 miles of driving (half pad broken off)...all low rpm >>>

Avant1522

My car only made chain sound on start up and only for a split sec. Nothing else out of the ordinary. Im not that stupid. anyway getting blow back out of the intake so obviously bent valves. time to rebuild the head.

silverd2

Bent valves...broken timing belt in the past? ..or do you think a timing chain jumped time? Was the adjuster eaten away bad enough for timing to jump?

Avant1522

Chain was still pleanty tight i dont know how it could have jumped but i heard sometimes the belt will jump when they get bad. just seems weird only 2 cylinders had valve damage. unless maybe im missing something. going to check belt timing tomorrow,, but all seems to point to bent valves. only getting 30 psi compression on Cylinder 1+4

silverd2

As I'm sure you know, only contact with pistons is gonna bend valves in these engines.

Did you buy the car in this condition...hard starting, etc ...?

Also as I'm sure you know, to change the cam adjuster correctly, lining up timing is a must. Did the large holes on the belt pulleys point inward toward each other (dead level) when you set TDC at cylinder #5 ?

By the way: If timing was just off on bank #1, then cylinders 1 and 4 fire in that order (1-5-4-8-6-3-2)...so if there was a past "event" those 2 could have taken the brunt of contact 1st, before the engine died. At extremely low engine speed or hand turning piston/valve contact won't bend the valves, as the contact is absorbed by the lifters.

P.S. Critically bad valve carbon build-up could cause compression loss too...BUT this would be extremely rare in this engine design, unless extremely high mileage, crappy gas and no air filter.

Avant1522

I did not buy the car like this, it started shortly after. first thing I started to notice was the chain slap. Because I didnt pull out the exhaust cam, I only lined up the marks on the cams. (maybe this was my mistake) Im going to check the belt timing today. maybe its just a matter of correcting the timing slightly.

Avant1522

if there was any valve contact it happened that morning when I started it and it went bad.