[V8] 1990 Audi v8 Coolant temp sensor

[bkrussow at comcast.net]

Here is a bit more accurate infor on the location of the sensors on the V8. 
http://www.audiworld.com/forums/audi-5000-200-v8-discussion-27/audi-v8-3-6-coolant-sensor-location-2748264/ 
  
Is your temp gauge reading low? If it's reading is normal 87" C. then I would look more at the O2 sensor not sending the correct information to the ECU. In other words it maybe running in "Closed Loop", The ECU thinks the engine is cold even though it is warmed up so it increases fuel. Can you pull the codes? 
  
Bob 
  
  

----- Original Message -----

From: "Dave Saad" <dsaadme at me.com> 
To: "V8List Fans" <v8 at audifans.com> 
Sent: Wednesday, June 3, 2015 8:40:47 AM 
Subject: Re: [V8] 1990 Audi v8 Coolant temp sensor 

What color is the sensor you bought?  There are two. Going from memory here one is black and is for the ECU, the other is white and is for the gauge. The white one is easily visible at the front of the the drivers side cylinder head, top. The other is at the rear of the passenger side head, on the back. It will take a little work to expose it, but not that big a deal. Be careful with wires and connectors though they are getting brittle. 
I think you will have to remove the engine top cover and air filter box, spark plug cover and wires, maybe the distributor cap and distributor. All pretty easy stuff. 

If you continue to have problems, have a look at the canister purge valve behind the coolant tank. These leak vacuum and cause all sorts of strange running problems. If you have a K&N air filter you may also have oil on the MAF sensor. That will cause trouble. 
You could also pull all the spark plugs and inspect. You can blink out any ECU codes too. 

Dave 


> On Jun 3, 2015, at 6:51 AM, Ed Kellock <ekellock at gmail.com> wrote: 
> 
> How recently was the oxygen sensor changed? The ecu doesn't read its input 
> until the engine has run for a short time from a cold start. 
> 
> Ed 
> On Jun 2, 2015 11:26 PM, "chris brown" <sacheldog at hotmail.com> wrote: 
> 
>> Hello long time since iv'e chimed in. Iv'e got a 1990 v8 and i bought a 
>> coolant temp sensor a couple months ago because my engine is running rich 
>> and i was told this could be one of the easy fixes for that.   I dont know 
>> where on the engine to find this thing i looked around a little but i 
>> figure ot be easier just to ask here.   Is it a pain in the neck. 
>> Engine runs fine with a cold start and after about a minute and a half as 
>> it warms, idle gets rough and starts to hesitate and run rich. 
>> thanks  guys 
>> Chris 1990 v8 
>> 
>> 
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