Hello,

I recently purchased a 1985 Targa and have been having a great time tuning it up. The car was very lightly driven for the last 10 years. It has 93,000 miles on it. I recently noticed that the idle is a bit rough especially during a cold start. The exhaust also smells as if the car is running slightly rich and contains a fair amount of water for 1-2 minutes after starting (white steam and drips out the tailpipe). I don't remember this happening prior to doing the tune up. The work I've done as part of this tuneup includes:

- Valve adjustment
- Spark Plug change (Bosch WR7DC+)
- Ignition Wire Change (Clewett Engineering High Performance Ignition Wires - 8mm)
- Cap and Rotor Change (Bosch)
- Oil Change
- Air Filter Change

I've done preliminary checks for vacuum leaks. I've pulled the oil cap off mile running and observed a dip in RPM. I've also checked to make sure I'm getting spark/combustion in each cylinder (measured exhaust temperature on each cylinder with IR thermometer).

I just added some Liqui Moly Fuel Injection cleaner to the fuel to see if perhaps I'm having an issue with a clogged/dirty fuel injector.

I've read a lot about the Cylinder Head Temperature (CHT) sensor and did some preliminary testing. With the engine could I read ~1130 ohms. I believe this should be closer to 3000-3500 ohms. This would mean that the sensor is incorrectly reporting a temperature that is higher than reality. With the engine hot, the resistance dropped as it should. The car also idles fine when warm.

Curious to see if anyone has had similar issues with CHT readings that indicate a warmer temperature at idle? I suppose the next step would be replacing the CHT, but am curious to know if there are other things I should try.

Thanks for any advice you can offer.

 

Well water And steam is a byproduct of combustion so i would not sweat that. If you have the single wire cht i would replace it regardless with the updated two wire one.

 

+1 Great upgrade to any 3.2 Carrera.

 

Do either of you know the part number for the upgraded CHT with 2-wires? Or does the factory part number supercede the old part?

 

930-606-915-00

That should be the two-wire CHT sensor.

 

Thank you Bruce!

 

How's your air meter?! Caused me a great deal of havoc w/ rough idle and stalling, till replaced...

 

 

So your problem is resolved? "Normal" is a tricky word w/ these old cars, due to age, lack of computers, etc. You did have a decent amount of work in there and who knows if the mechanic did something in error to knock off the mixture. I'd say if your problem is resolved, don't worry about it!

 

 

I would still get a two wire sensor if you get the chance.

I had to eventually adjust my mixture to get my car to stop hunting when cold. I would say it is not normal to do it after basic maintenance but it would be normal to have to do it at least at some point in it's 30 years of existence. If you're going to do it have the right equipment on hand and follow all the steps. You can also check to see if the cap is still on the mixture screw, it might serve as an indication if someone has messed with the mixture in the past. Either for the better or for the worse.

Another point: adding fuel injector cleaner will not definitively tell you if you have injector problems.

 

Just a question ,after all this work you have done you did not change the fuel filter??

Ivan

 

ok, so you 100% sure it's not your air meter, which obviously deals w/ the mixture?

 

 

Here's mine! https://rennlist.com/forums/911-foru...d-startup.html