[urq] need IAT

[urq]

Thanks Alan!

That 13-33 ohm value at room temperature value is given in the IST
Maintenance & adjustments document (which can be viewed from Martin Pajak's
site).  

In the thread I see a graph someone did which showed a range from 18 to 25
ohms over a range of -15degC to 100degC ... I must say that if the nominal
value at room temp (~25degC) is larger than the total range measured from
below freezing to boiling of water that there may have been something wrong
with the part that was tested.  

Did a bit of searching and found a company (www.thermistor.com) that makes a
PTC thermistor with a value of 27 ohms @ 25degC.  The resistance changes
0.7% per degC, which means that over a range of 100degC you would get a
change of 70%, or 18.9 ohms, still pretty small.  As I recall the thermistor
in our IAT is quite tiny, this part is 0.41" long.

The thing is ... Tom, if you read in the hundreds of ohms at the MAC-02
connector pins you definitely have a problem with your IAT sensor.

Steve Buchholz

-----Original Message-----
From: Alan Pemberton
Sent: Sunday, May 15, 2011 11:38 AM
Subject: Re: [urq] need IAT

Hi Steve

There was a good thread on this subject on the UK quattroforum list (started

by Phil Payne) at

http://www.quattroforum.com/forum/wr-specific/24562-inlet-air-temperature-se
nder.html

which. on the third page, includes resistance - temperature characteristics.

Alan
85 urq


----- Original Message ----- 
From: "urq"
Sent: Sunday, May 15, 2011 8:06 AM
Subject: Re: [urq] need IAT


> There are other causes besides the IAT proper which can cause 4K RPM cut 
> out
> on the WX/MAC-02 ...
>
> In the days when my ury and I were much younger I had this problem too.
> This was in the days before I was aware of audifans and the urq community
> here ... so I wrote a letter to VW & Porsche magazine, where Ned Ritchie 
> was
> a columnist.  He gave a list of possible causes for the issue, which can
> still be found on IA's website ...
>
> http://www.intendedacceleration.com/tip_2.html
>
> The funny thing is that when I checked the link I did not see the 
> situation
> which was causing my problem ... the timing on the dizzy was slightly off.
> Do a bit more research at Martin Pajak's and Scott Mockry's sites to see 
> if
> you can get more guidance there.
>
> http://www.quattro.ca/
> http://www.sjmautotechnik.com/trouble_shooting/urq.html
>
> I *think* Robert Houk's site has been archived somewhere ... if you can 
> find
> that you might gain some insight into the possible causes there ...
>
> The good news is that if it is the IAT there is a pretty good chance it is
> repairable.  I believe I have a spare urq wiring harness in the garage (if

> I
> can find it!) ... I can take measurements of resistance over temperature 
> and
> see if I can find a thermistor which has the same characteristics.  I 
> doubt
> that the housing will go bad, and the thermistor is soldered in ... so 
> once
> we have a P/N for a replacement thermistor anyone can repair their IAT ...
>
> Steve Buchholz
>
> -----Original Message-----
> From: Thomas Pollock
> Sent: Saturday, May 14, 2011 7:02 AM
> Subject: [urq] need IAT
>
> I lost the recent post discussing IAT prices and sources. I have the 
> dreaded
> 4k
> cutout again. Resolder fixed it temporarily but I think I burnt it pretty
> bad
> and just want to replace it. Any help ?
>
> thanks,
>
> tom.
> _______________________________________________