jaybquick--Jason@JHM

My 2001.5 Audi S4 will not start, it has the mods in m sig. This is a complicated and long story so please bear with me. I will explain how it built up to a no start in chronological order. FYI, I was an ASE certified master tech for years but only worked on American and Japanese cars, so when in doubt I covered the basics. Also I have NO catalytic converters.

1. It started to lack power but idled perfectly. It made full boost but low power and NO misfiring.
2. It then set the check engine light, I got a code for bank one cam sensor out of sync.
3. I then data logged the heck out of it and found that everything was ok except for the lack of timing advance. At the most it hit was only 6 degrees advance most of the time it was at zero. I have many logs upon request. NO misfires showed up either.
4. The code for the bank one cam sensor kept coming back so I changed the cam sensor and verified a proper power and ground with the help of my bently.
5. Code remained after changing the sensor, then I got an intermittent crank sensor out of sync.
6. It sat for a week while I moved.
7. I finally started it again and it hardly idled and ran. Pulled codes and got codes for both cams.
8. It sat again for another week. Then it started idled like crap then died.
9. Now if I clear codes and then crank it only these 2 codes come up. 16730 - Camshaft Position Sensor (G163): Implausible Signal &16725 - Camshaft Position Sensor (G40): Implausible Signal
10. I verified this again and again, I could smell fuel out the exhaust when I was trying to start it, so it is not a fuel pump.
11. I went ahead and changed the crank sensor and the other cam sensor, still the same codes and no start.
12. Next I disassembled the cam covers and removed the valve covers to confirm the t-belt was still lined up and that the chain joining the 2 cams was ok too. All checked out ok.
13. Now I am thinking I have a computer problem. What do you think?
14. However for the heck of it I thought I would do a leak down test even though the engine should be warm when performing it and the fact I ad excess fuel in the cylinders doesn't help either. Here are my leak down results.
Cyl # 1 = 17% leakage, Cyl # 2 = 18% leakage, Cyl # 3 = 33% leakage, Cyl # 4 = 21% leakage, Cyl # 5 = 68% leakage, Cyl # 6 = 8% leakage. I know these numbers are bad but when the engine still ran it had no blowby and no smoke out the exhaust, it also had no misfires while logging or misfire codes. I am thinking it is this bad because of cylinder wash down from the no start. IT SHOULD START WITH THES NUMBERS.

15. So everyone please give me some ideas of what to check next. Also where can I take or send my ECM to get tested? Does anyone live in the California Bay Area that can let me plug my ECM into their car to see if it starts?
The bottom line to me is why the heck would I get cam out of sync codes if everything is lined up. It makes me lean towards an ecm.

PLEASE HELP!!!!!!!!!!!!!!!!!!!!!

Pop3

I hope someone will try your ecu to see if its ok. How about ecu ground or engine grounding points?

RKA

1. When you pulled the valve covers and verified the cams were lined up...how did you verifiy the crank was lined up? If you didn't, I would double check that. There is an access hole underneath the engine where you can insert a crank lock tool while you check the cams.

2. Trace the wiring harnesses going to the cam sensors. Make sure there aren't any shorts, crimps, cuts, etc.

When was the last time the timing belt and tensioner were changed, and how many miles (total) are on the car right now?

jaybquick--Jason@JHM

1. Well I changed the Timing Belt 5k miles ago with all new belt, WP, tensioner, and idler pulleys. I made my own markd before dissasembly. They are all still lined up. It ran fine after I did the t-belt that is why I doubted that the cams jumped.

2. Harness looks good, verified power voltages as per my bentley and ground checked out fine.

91,000 miles on the car now.

jaybquick--Jason@JHM

Those checked out ok, I just want to check my ECU to get some confirmation since it has an APR chip setup and all

nyet

i'd locate a stock ECU and see if that starts it up

RKA

go back in and verify that the cams are where they should be. They leave no room for error, whereas (apparently) there is room for error if you are marking all the appropriate parts. Jason @ Streetwerk put up a post a few months ago about seeing DIY TB jobs rolling through his shop where the timing was off (much to the chagrin of the owners who did the work).

And while you're in there, check that tensioner to make sure it's still good. It's rare that relatively new one will fail, but not unheard of.

jaybquick--Jason@JHM

I changed the t-belt for maintenance so I marked it just like I did when I was a ech for 5 years. it ran perfect for several thousand miles after so I did install it properly. All marks still line up so the t-belt alignment is fine. I already considered this. thanks though.

jaybquick--Jason@JHM

The problem is that it is half apart now, so the other option would be easier. To plug my ECM into another car. I don't want to put it back together just to find out I have to take it apart again. Either way if someone had a stock ECM I can try or a car I can plug mine into I would appreciate it and I am willing to pay $$$$$$

RKA

The sensor picks up something on the cams (don't know what) and returns a signal back to the ECU. If the "thing" on the cams is no longer present, damaged, etc., that could result in the implausible signal error.