[s-cars] '92 S4 won't start

[tedebearp at yahoo.com]

It runs!  Thanks to everybody who replied.

Most responses from this list and all the responses from my gearhead friends were against having the shop fix it, so I brought the car back home, where I discovered the battery was completely dead and two bolts were missing from the spark plug cover.  After charging the battery overnight and replacing the missing bolts, I tried to start the car.  I was hoping that if the splices had gotten wet, they'd have dried out.  The car cranked fine but didn't even catch a little.  I took off the upper timing cover because I wanted to check whether the splices were wet.  I found the splices were inaccessible, hidden behind some other bits including the camshaft pulley.  At that point I decided if I was going to remove parts to get to the splices, I might as well as replace the CPS, but thought it prudent to check codes before tearing everything apart.

I finally got around to checking codes with the VAGCOM today, and got the following:
00518 - Throttle Position Sensor (G69) 
            29-00 - Short to Ground
00515 - Camshaft Position (Hall) Sensor (G40) 
            30-00 - Open or Short to Plus
00513 - Engine Speed Sensor (G28) 
            03-00 - No Signal
00516 - Closed Throttle (Idle) Position Switch (F60) 
            30-00 - Open or Short to Plus

The TPS codes were a surprise.  The shop hadn't mentioned those.  I wiggled the TPS connector to verify that it was seated.  I cleared the codes, and again hoping that the splices might have dried out, tried to start the engine - and it started!  

The idle zoomed to 3-4k and stayed there even when I prodded the accelerator pedal.  Shut off engine, restarted, and idle was around 1000-1400 rpm, fluctuating.  I let the car run a little and the idle never stabilized.  I scanned codes again after turning off the engine and got:

00518 - Throttle Position Sensor (G69) 
            27-00 - Implausible Signal
00513 - Engine Speed Sensor (G28) 
            03-00 - No Signal
00516 - Closed Throttle (Idle) Position Switch (F60) 
            30-00 - Open or Short to Plus

The CPS plug has indeed disintegrated but there's a stub intact with the three metal terminals so I left it plugged into the harness, wrapped with electrical tape to keep it from disconnecting.  I'm going to have to find a replacement connector, but the CPS code is gone so I'm going to deal with the hunting idle first.

I have to do a little troubleshooting as I think the G69 and F60 are separate components, and it seems unlikely that they both failed at the same time.  However, it beats having to tear things apart to replace the CPS.  

Any thoughts on the codes above?  00513 is normal since the engine wasn't running when I scanned codes.

Sent from my iPad

> On Jan 5, 2014, at 7:43 AM, Tom Green <trgreen at comcast.net> wrote:
> 
> Teddy,
> 
> You have selected this shop based on reputation, and I see no red flags to indicate you have made a mistake.  I recommend that you review the reasons your AAN won't start in Dave Forgie's 
> email and if you agree with the shop's diagnosis, discuss with them the procedure I am sure you used to change the CPS sensor without disturbing the timing belt position on the crankshaft.  If the shop is comfortable with it, that should reduce the bill considerably.  7 years/50K miles is probably a good interval to consider timing belt service, so I suppose it depends on whether you can agree on a price for them to do the work.
> 
> This is apparently a repair shop that is new to you, so an in-person visit and discussion at the car might be useful, even if only to assure you that the tech is doing a complete troubleshooting job.  This could include if they use a VAG specific diagnostic tool, i.e., VCDS, to interrogate for diagnostic trouble codes.  On your question, if the fuses at the ECU have blown, the MIL should not light when the key is turned on and there would be no communication with the ECU.  They should check them though, and replace them if they are the original circuit breaker types that get unreliable at this advanced age.  Swapping out parts can be a valid repair method rather than spend expensive hours troubleshooting, but the CPS is not one of those.  
> 
> As far as the $1500 estimate goes, a proficient tech could do that job for half that, even at bay area labor rates.  It probably also includes genuine Audi parts at dealer list, which I doubt you are using when there are suitable aftermarket alternatives, so you may be successful in lowering the price.
> 
> You may not want to have the shop replace those suspect connectors, but it appears they are giving you good advice, and you should look for an economical source to get replacement connectors to replace yourself.  It appears that your vehicle is starting to ask for some TLC so it can continue to provide reliable service.
> 
> Tom '95 S6  
>          '95.5 S6 avant
> Knoxville, TN
> 
> 
>> On Saturday January 4, 2014, at 3:57 PM, Theodore Chen <tedebearp at yahoo.com> wrote:
>> 
>> All, thanks for the comments so far.  The shop is in SF and has gotten high ratings, which is why I took the car there instead of spending $250 to tow the car home to my garage or a local shop. That doesn't mean I might not decide to take the car after all.  
>> 
>> I just got email from the shop:
>> 
>>> The crank sensor has failed no codes, we surmise that this occurred when the hose blew and water got into the connectors, Many of the plastic parts under the hood are deteriorated due to age, heat, possible oil contamination in the past. These all can lead to breakdown of the plastics.  At this time we have no spark and no injector pulse.  When testing crank sensor, signal line is flat.
>> 
>> The part number in the quote is the replacement Bosch camshaft sensor, not crank sensor.  It sounds like they actually tested the sensor and weren't relying on codes.  When I replaced the CPS, I used a ChenYang sensor from a group purchase on this list, and spliced it into the old sensor connector.  I wonder if the splices might have gotten soaked in coolant.  While I'm sure I used heat shrink tubing and electrical tape, it's not going to be watertight against a good dousing in coolant.
>> 
>> Keep the comments coming, they're helpful.  Thanks.
>> 
>> Sent from my iPad
>> 
>>> On Jan 4, 2014, at 6:15 AM, Peter <audionly at gmail.com> wrote:
>>> 
>>> I agree with Michael. The garage has either inadvertedly damaged the cam sensor by pulling on the plug-in which is right above that hose; or somehow possibly got water in the connection; or disconnected it and forgot to plug it back in. If you can find someone with a audi scanner in the area, it does have a diagnostic port (limited) that will tell you if there is a signal from that senser. Or, you can use a blink test. I don't see any way it could be the crank sensor. The only other thing I can think of is if they didn't know what they were doing and for some reason removed the timing belt/cam gear and now the timing is off by a tooth which won't allow the car to start. I smell a fish here. I would find someone else that knows the car to do a diagnostic.
>>> 
>>> 
>>>> On Fri, Jan 3, 2014 at 9:15 PM, <tedebearp at yahoo.com> wrote:
>>>> The little rubber hose under the intake manifold popped a leak last week, about 35 miles from home.  I topped off with water and hoped to make it home.  Unfortunately, the leak got worse and not wanting to blow the head gasket or warp the head, I had the car towed to a nearby garage (otherwise it would have been $250 to tow it home).
>>>> 
>>>> The shop repaired the coolant hose.  However, they said the car won't start, though it cranks fine.  The car was running fine when I parked it, and they drove the car off the flatbed truck and into the shop last week.
>>>> 
>>>> They think it's the crank sensor and said there's no signal from it.  They speculated that coolant got everywhere and shorted out the sensor.  They said it's behind the timing belt so they'd need to take all of that off to replace the sensor.  While they're at it, they'd do a timing belt job.  Total cost is about $1500.  I said I'd think about it and get back to them.
>>>> 
>>>> Does this sound right to you guys?  I think it's the cam sensor, not the crank sensor, since they said this sensor is behind the timing belt.  I replaced the CPS when I did the timing belt at 133k miles, which was 50k miles and probably 7 years ago.
>>>> 
>>>> Is it possible that there's a shorted ECU fuse?
>>>> 
>>>> Sent from my iPad
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