Printable Version of Topic
Click here to view this topic in its original format
914World.com _ 914World Garage _ Cylinder Head Temperature Sensor
Posted by: JawjaPorsche Nov 12 2018, 04:05 PM
My 73 1.7 FI engine starts normally. The AAR works great then my engine really runs rough until the engine warms up: usually three miles of driving. Especially bad in cold weather. A friend who also has a 914 suggested I disconnect the Cylinder Head Temperature Sensor to see if that would help and maybe isolate the problem.
Was wondering what to expect if I disconnect it. Needless to say, your input would be greatly appreciated.
Thank you in advance.
Posted by: BeatNavy Nov 12 2018, 04:21 PM
QUOTE(JawjaPorsche @ Nov 12 2018, 06:05 PM) 
My 73 1.7 FI engine starts normally. The AAR works great then my engine really runs rough until the engine warms up: usually three miles of driving. Especially bad in cold weather. A friend who also has a 914 suggested I disconnect the Cylinder Head Temperature Sensor to see if that would help and maybe isolate the problem.
Was wondering what to expect if I disconnect it. Needless to say, your input would be greatly appreciated.
Thank you in advance.
No, your engine will flood almost immediately with CHT disconnected. It may not even start. He's probably talking about (or may be thinking about) disconnecting the T1 (ambient air sensor). Disconnecting that will richen the mixture a little through the whole warm-up range. That's probably a useful test, but it's not a great long term fix.
Better option is to get a CHT spacer from 914LTD. That will slow down the CHT warm up and give you a richer mixture longer while your engine warms up.
Posted by: JawjaPorsche Nov 12 2018, 04:31 PM
QUOTE(BeatNavy @ Nov 12 2018, 06:21 PM)
QUOTE(JawjaPorsche @ Nov 12 2018, 06:05 PM)
My 73 1.7 FI engine starts normally. The AAR works great then my engine really runs rough until the engine warms up: usually three miles of driving. Especially bad in cold weather. A friend who also has a 914 suggested I disconnect the Cylinder Head Temperature Sensor to see if that would help and maybe isolate the problem.
Was wondering what to expect if I disconnect it. Needless to say, your input would be greatly appreciated.
Thank you in advance.
No, your engine will flood almost immediately with CHT disconnected. It may not even start. He's probably talking about (or may be thinking about) disconnecting the T1 (ambient air sensor). Disconnecting that will richen the mixture a little through the whole warm-up range. That's probably a useful test, but it's not a great long term fix.
Better option is to get a CHT spacer from 914LTD. That will slow down the CHT warm up and give you a richer mixture longer while your engine warms up.
What a cool idea! I will check out the CHT spacer! Thanks!
Posted by: TheCabinetmaker Nov 12 2018, 07:06 PM
It won't run with it disconnected. Sounds more like an aar symptom.
Posted by: pilothyer Nov 12 2018, 08:47 PM
QUOTE(TheCabinetmaker @ Nov 12 2018, 07:06 PM)
It won't run with it disconnected. Sounds more like an aar symptom.
Posted by: JawjaPorsche Nov 13 2018, 04:08 AM
QUOTE(TheCabinetmaker @ Nov 12 2018, 09:06 PM)
It won't run with it disconnected. Sounds more like an aar symptom.
I have an extra AAR so I will swap it out to see if that helps. Thank you for your input.
Posted by: jim_hoyland Nov 13 2018, 06:55 PM
The AAR is easily bench tested... 
Posted by: Jamie Nov 13 2018, 07:23 PM
QUOTE(jim_hoyland @ Nov 13 2018, 04:55 PM)
The AAR is easily bench tested...
Testing by what method Jim? I suspect this part might be a factor in my continuing idle searching problem.
Posted by: jim_hoyland Nov 14 2018, 06:45 AM
QUOTE(Jamie @ Nov 13 2018, 05:23 PM)
QUOTE(jim_hoyland @ Nov 13 2018, 04:55 PM)
The AAR is easily bench tested...
Testing by what method Jim? I suspect this part might be a factor in my continuing idle searching problem.
Remove the AAR from the car.
At ambient temp, or lower, the orifice will be open or partially open; the window shade inside is the moving part that regulates the air flow.
Then attach a 12 volt source to the AAR's spade connectors, and note the time.
A working AAR's window shade ( inside the AAR ) will being to close. Mine closes in 1 1/2 minutes.
Thats it.
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)