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914World.com _ 914World Garage _ Car is running too lean
Posted by: Daiberl Aug 23 2012, 09:44 PM
I finally had time to check my LE out and why the car is running hot. The spark plug shows that the car runs lean, adjustment knob at ECU is full rich already. MPS checked and leaks 3.5 down from 10in so based on pbanders fine. No vacuum leaks, flaps at oil cooler are open, timing fine.
What can cause the car to run too lean? Would a wrong CHT cause this, I changed the CHT when I dropped the engine last time and didn't drive the car on longer trips.
Posted by: Dustin Aug 24 2012, 01:15 AM
The knob on the ecu only adjusts mixture when the TPS is in the idle circuit.
check your fuel pressure?
Posted by: Bartlett 914 Aug 24 2012, 07:41 AM
I finally had time to check my LE out and why the car is running hot. The spark plug shows that the car runs lean, adjustment knob at ECU is full rich already. MPS checked and leaks 3.5 down from 10in so based on pbanders fine. No vacuum leaks, flaps at oil cooler are open, timing fine.
What can cause the car to run too lean? Would a wrong CHT cause this, I changed the CHT when I dropped the engine last time and didn't drive the car on longer trips.
The knob only affects the idle. The CHT is critical and could be a source of the problem. Adding resistance will richen the mixture.
Posted by: Jeff Bowlsby Aug 24 2012, 09:05 AM
TS1 can also be unplugged to give a slight richness enhancement
Posted by: Daiberl Aug 24 2012, 11:45 AM
TS1 can also be unplugged to give a slight richness enhancement
I assume TS1 is temperature sensor 1? Which one is it?
Posted by: Jeff Bowlsby Aug 24 2012, 01:31 PM
TS1 is the Air temp on the air plenum
Posted by: Daiberl Aug 27 2012, 10:19 AM
Ok, finally I had some time yesterday to check the car again, I unplugged TS1 and I rechecked timing and vacuum lines. Car is still running very hot and after 15 minutes my oil temp gauge was showing high oil temp again. Any other ideas???
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Posted by: Jeff Bowlsby Aug 27 2012, 10:40 AM
Thats a normal oil temp reading for the stock guage Juergen, I wouldnt worry about that. To really test it you'll need to get an accurate temp guage or pyrometer to know the exact temp values.
ANd to check for mixture, an exhuast gas analyzer. Maybe a shop can do that for you?
Posted by: JRust Aug 27 2012, 12:48 PM
Yeah I wouldn't sweat your temps there. I would buy one of those diptick temp gages to get an accurate read. I think you are fine there. Mine will go past the P on the temp gage in really hot weather on the highway. If that is as high as it goes don't worry about it. If you take it out & it is past the P approaching the red. Then you need to change something 
.
Posted by: Daiberl Aug 27 2012, 07:01 PM
Ok, then I will give it another try and will report back how high the temperature is going. I plan to do an oil change before, currently I'm on non-synthetic but plan to switch, maybe that also helps to keep the temperatures down.
Posted by: 914itis Aug 27 2012, 08:18 PM
Ok, finally I had some time yesterday to check the car again, I unplugged TS1 and I rechecked timing and vacuum lines. Car is still running very hot and after 15 minutes my oil temp gauge was showing high oil temp again. Any other ideas???
My oil temp reads the same sometimes in above 90 degree temps. but it takes more than 15 minutes to get there; at least an hour of highway driving.
Posted by: Dave_Darling Aug 27 2012, 09:03 PM
Is the cooling system complete? Do you have the flaps inside the cooling tin? Any debris in the fan? Any mouse nests under the tin?
--DD
Posted by: Daiberl Aug 27 2012, 09:44 PM
Is the cooling system complete? Do you have the flaps inside the cooling tin? Any debris in the fan? Any mouse nests under the tin?
--DD
Engine was rebuild, no mouse nests or debris, flaps are installed and in the open position at the moment to make sure the thermostat is not the issue.
Posted by: PancakePorsche Aug 29 2012, 03:30 AM
I raised my fuel pressure to 32 psi and 2 steps colder plugs. The new junk they call gasoline has a lot to do with the problem. ECU is not calibrated for the alcohol now present. As others mentioned, you need to trick the ECU to increase delivery. If the stripe on plug ground electrode is 50 percent or more away from tip use colder plugs.
Posted by: Racer Chris Aug 29 2012, 07:41 AM
Oil temp isn't a good indicator of fuel mixture anyway.
Posted by: Bleyseng Aug 29 2012, 09:12 AM
I finally had time to check my LE out and why the car is running hot. The spark plug shows that the car runs lean, adjustment knob at ECU is full rich already. MPS checked and leaks 3.5 down from 10in so based on pbanders fine. No vacuum leaks, flaps at oil cooler are open, timing fine.
What can cause the car to run too lean? Would a wrong CHT cause this, I changed the CHT when I dropped the engine last time and didn't drive the car on longer trips.
What plugs are you running?
Oil gauge reading is normal so how are you determining that you are running lean?
What MPS, ECU do you have?
Is the MPS a OEM unit or rebuilt?
I am in town mostly for the next 3 weeks so maybe a can help you.
Posted by: TJB/914 Aug 29 2012, 09:51 AM
George Hussey @ AA just fixed my slightly lean engine issue with a part I bought from him 10-years ago. I found it in my junk drawer and installed it a few days ago and corrected all lean issues. Check out my post with George on 914-Club site and read what happened. I suspected a lean engine idle at low RPM's & lived with it but after installing a "wehrle" part #039.971.762a that adds 270 ohms to the head temp sensor it increased the duration of injecting with a alightly richer mixture for more power & better idle when fully hot.
Guys, I felt the engine smooth out and run better than ever on my 2.0 liter F.I. Raby # 9550 camshaft with Raby LE-180 heads. Amazing tech advise from George. I understand AA sells them, don't know how much $$ but it worked for me.
Tom
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