[urq] No start situation - suddenly - not any more!

Fri Apr 9 12:05:58 PDT 2010

Good news!

It works! The bad news is I have no idea why. As you know I have tested and checked everything (including flywheel pin and teeth) and nothing seemed to be wrong or out of spec other than the coil. Tomorrow I was going to borrow a known good coil and try it. I have even ordered a new one which I will get next week.

Anyway whilst, at a low point last night I rang one of my oldest friends, Alan Bishop, who is an old school mechanic and the only person I know with a real "ear" for engines and a "nose" for sniffing out gremlins. He was working last night and so couldnt pop round but this evening he called in. I went through how everything should work, everything I had checked, the readings, what I suspected etc (he has no experience or love of Audis - steam engines are his passion). He said "try and start it and let's have a listen". So I plugged it all back together and turned the key. Yes, you guessed it, it worked. I've tried it 5 or 6 times since - no problem. The only thing now is that I have no idea what the problem really was. I have however checked all the sensors and wiring, found the coil to be out of spec and really know my way around it now. The last thing that might have had a bearing was that I removed and cleaned all the earth straps. Could it have been that simple? I know one or two of you mentioned the earth straps but I have to be honest and say that I doubted you because of the sudden-ness of the problem. I'm not doubting you now. Fingers crossed that this was the cause. If it was, it can go to the top of the diagnostic process list and save others much time and heartache.

My heartfelt thanks to all of you who helped me, sustained me and kept me going through there last couple of days. I love this list. It has helped me more over the years than my own club has (qOC in UK) and I hope I have helped others a little at times too. It really is a great community.

Thanks again and I'll keep you posted if I discover the real reason for the no start but just now it looks like it could have been the earth straps. And the legend of Alan Bishop grows - he just had to be in the garage to fix it this time. My good lady was impressed! She suggested I ask him round first next time and save myself (and you all) a lot of time and effort!

All the best

Keith 

p.s. I'm still going to fit the new coil!  I need a beer.

> From: urq at pacbell.net
> To: urq at audifans.com
> Date: Fri, 9 Apr 2010 10:29:21 -0700
> Subject: Re: [urq] No start - situation
> 
> Yes, no problem. Your other post was larger than the 25K character limit so
> I had to approve it for it to be posted. It probably would have been
> preferable to let the interested parties follow the link to Phil's site . in
> fact I'm going to add a link to it on the yahoo group, but no post from a
> member is thrown away by the server, only queued up for me to disposition. 
> 
> 
> 
> The problem is that the resistance measurement does not guarantee
> functionality, or malfunction for that matter. It is primarily intended to
> find short and open circuits. Fortunately the test you ran on the Hall
> sender is a functional test, so you know that is OK. Since things seem to
> be working, the next step would be to check the flywheel teeth and reference
> pin to make sure they are good . if that all looks OK you may want to try
> replacing (or perhaps exchanging) the reference and speed sensors . or swap
> in another ECU if you can get one to try . 
> 
> 
> 
> Steve Buchholz
> 
> 
> 
> 
> 
> From: Keith Lloyd [mailto:spotatashleys at hotmail.com] 
> Sent: Friday, April 09, 2010 7:36 AM
> To: urq at pacbell.net; urq at audifans.com
> Subject: RE: [urq] No start - situation
> 
> 
> 
> Hi Steve
> my posting below seemed to get on the list ahead of my epic one which I
> wrote first and which contains my test results.
> I can confirm that the ECU is receiving battery voltage 12.4v when ignition
> is switched on. The battery is brand new yesterday and fully charged.
> Re: The timing sensors - I will admit to being a little confused by Phil Ps
> text- they have the correct resistance according to the initial tests but
> Phil says "if bad, proceed" which suggested to me that if they were in spec,
> you accept as good and move on to test the next component. But at the end of
> the section, it says, "if the sensor passes the test, replace the sensor" I
> don't get it.
> Could be that I've read and tried so much I can't see the wood for the trees
> now.
> Just going to check the earth straps around the engine bay now and double
> check.#
> Thanks again
> Keith 
> 
> > From: urq at pacbell.net
> > To: urq at audifans.com
> > Date: Fri, 9 Apr 2010 07:19:19 -0700
> > Subject: Re: [urq] No start - situation
> > 
> > No. The ignition side of things is an output and would not affect the
> basic
> > inputs you describe. 
> > 
> > If you believe the timing sensors are working properly you may want to
> > verify that the grounding at the intake manifold is good. I'd even try
> > keeping a charger attached to the battery to ensure that the battery
> voltage
> > is OK. How have you tested the sensors? Have you verified that the ECU
> > itself is getting power?
> > 
> > Steve Buchholz
> > 
> > -----Original Message-----
> > From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
> > Of Keith Lloyd
> > Sent: Friday, April 09, 2010 6:06 AM
> > To: Audifans List List
> > Subject: [urq] No start - situation
> > 
> > 
> > Another question - I'm sorry about this - If, for fuel to be delivered the
> > ECU needs to receive syncronous signals from TDC sensor, RPM sensor and
> hall
> > sender - would the fact that the ignition output unit and/or the coil
> aren't
> > working mean the ECU wouldn't receive these signals? Isn't the function of
> > the ignition output unit downstream of the hall sender because if it is I
> > have still not explained why the fuel isn't pumping because my tests
> suggest
> > the RPM, TDC and hall senders are working fine.
> > 
> > I'll be glad when this is sorted..........as will you all, no doubt!
> > 
> > Thanks
> > 
> > Keith
> > 
> > 
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