[V8] no start sometimes

[Dave Saad]

Yes they can be tested!

If you can get them off the car, all you need is an ohm meter and a  
hot air gun.  By the way, you could probably pull codes to get the  
same info.  The ECU probably knows why it is unhappy, but anyway to  
test, remove the sensors and gently hold one in a vice.  Connect an  
ohm meter to the two signal wires and you should read about 1000 ohms.
As you heat the sensor tip up with the hot air, you will see a gradual  
rise in resistance, then it will begin a sharp increase, then it will  
open up.  As it cools, it will eventually go back to 1K ohm.  Don't  
get crazy with the hot air either or you may just accelerate the  
already common fail mode for this sensor.  My bet is that you have 4  
intermittent sensors.  Audi/VW seem particularly clueless in the  
design of this part as it is a problem on other newer motors as well.

I agree with a previous post (Steve?) that using starting fluid should  
not fix an open sensor, but how about this WAG: maybe the starting  
fluid ignites from compression - like a diesel, and the increase in  
RPM allows the ECU to use the cam position sensor for timing reference?
Then the motor could magically begin to run.

I should probably drink more coffee before tossing WAGs around - but  
it is kinda fun.

Dave

btw, WAG = wild assed guess.

On Aug 9, 2009, at 8:48 PM, <george.fallot at verizon.net> <george.fallot at verizon.net 
 > wrote:

> If the sensor is bad does that stop the voltage to the pump? I have  
> trouble
> thinking that both sensors are bad. I hate to throw more money at it  
> without
> knowing it will help. Can these sensors be tested?
> Thanks, George
> ----- Original Message -----
> From: "Roger Woodbury" <rmwoodbury at roadrunner.com>
> To: <v8 at audifans.com>
> Sent: Sunday, August 09, 2009 8:14 PM
> Subject: Re: [V8] no start sometimes
>
>
>> I'm betting on the crank position sensor.  The used one that you  
>> installed
>> may well have the intermittent fault that is a sign of it dying.   
>> My guess
>> is that a new sensor could well solve your problem.
>>
>>
>>
>> As you said the car has around or less than 100k, it seems to me to  
>> be a
> bit
>> early to give up.  I well understand the frustration, but if this one
>> problem can be solved, it may well reinvent your case of V8itis that
> infects
>> us all.
>>
>>
>>
>> I am eying the '93 V8 that is on eBay right now..black with black and
> "only"
>> 139k or so..but alas:  NO.  No more cars until the kitchen, barn  
>> and house
>> are built, and at the rate we're going it will be two years.
>>
>>
>>
>> Sigh.
>>
>>
>>
>> Roger
>>
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