1985 open or closed loop
Thread Starter
Racer
Joined: Jan 2007
Posts: 252
Likes: 5
From: bethlehem PA
1985 open or closed loop
ok if i understand, openloop is when your motor is not up to opp temp.
my 85 runs better in open loop. how can i keep the computer in open loop after the motor is at running temp. i have a 540 lift cam 239 dur, tpi sys ported,and ported dart iron heads. a chip from Ed Wright at fastchip. once warm idle is up and down and not as responsive. all imput appreciated
my 85 runs better in open loop. how can i keep the computer in open loop after the motor is at running temp. i have a 540 lift cam 239 dur, tpi sys ported,and ported dart iron heads. a chip from Ed Wright at fastchip. once warm idle is up and down and not as responsive. all imput appreciated
Race Director
Joined: Jun 2004
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From: WI
Yes that is correct. Turning off closed loop is very simple if you have tuning equipment. In my experience with tuning it sounds like something still needs to be adjusted. Using closed loop will pay for itself in better MPG. Ask your tuner to either turn off closed loop or continue to develop the tune so it works better.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
You can also read your coolant temp sensor at 100 degrees indicated on the gauge. Then buy yourself a resistor of the same value. make an adapter plug to plug into your coolant temp sensor connector, and fool the computer into thinking that the car never warms up.
Thread Starter
Racer
Joined: Jan 2007
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From: bethlehem PA
thanks to all
Pro
Joined: Jun 2001
Posts: 520
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From: Elverson PA
My 85 always seems to run strongest cold too. I don't have an aftermarket chip, but I think it likes running a little richer like it does in open loop. On a side note, the car goes back to open loop at WOT so it wouldn't have an effect on performance there.
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its just a matter of tuning...why risk the engines longivity by running too rich too cold? Tune it correctly and it should run the same CL or OL.
Poor running when its dependent on the sensors says TUNE. The fact that it stays in CL says you are close...if it were horribly out of spec it would cycle into LHM or OL on its own.
If you don't see codes after 8 seconds of CL..its not that bad. Simple tune adjustments, possibly even something as simple as a new O2 or cleaning the many electrical connections for sensor data to travel thru. THAT matters...Dirty connections in OL don;t matter since the ECM is running off the Cal-Pak using pre-set values for everything.
Poor running when its dependent on the sensors says TUNE. The fact that it stays in CL says you are close...if it were horribly out of spec it would cycle into LHM or OL on its own.
If you don't see codes after 8 seconds of CL..its not that bad. Simple tune adjustments, possibly even something as simple as a new O2 or cleaning the many electrical connections for sensor data to travel thru. THAT matters...Dirty connections in OL don;t matter since the ECM is running off the Cal-Pak using pre-set values for everything.
Race Director
Joined: Jun 2004
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From: WI
I wouldn't ever do that but if it works for you then okay. There are many parts in the tune that work off temp. Start up for one example. It will not start well in different temps if the ecu always thinks coolant temp is 100°. Timing, and fuel for others, plus will the fan even run? The resistance of the two sensors may be different. It's a good way to damage your engine if that's what you want.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Well, there will be some R&D for him on that resistor, but for the fast fix, I suggested it.
I got the idea that it was going to be an occasional thing.
As to the fan not coming on when hot, that is a distinct probability.
my 86 fan comes on cold when the A/C is on. so after he does his run, he can turn on the A/C
He will have to install the resistor and hook it to a switch to switch back and forth between temp regulated and "power when cold" so he doesn't have to keep opening the hood
in a panic.
I got the idea that it was going to be an occasional thing.
As to the fan not coming on when hot, that is a distinct probability.
my 86 fan comes on cold when the A/C is on. so after he does his run, he can turn on the A/C
He will have to install the resistor and hook it to a switch to switch back and forth between temp regulated and "power when cold" so he doesn't have to keep opening the hood
in a panic.
Last edited by coupeguy2001; Oct 13, 2012 at 10:57 AM.
Melting Slicks
Joined: Dec 2009
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Nickpe, did you upgrade the fuel injectors? With that cam & heads, your moving alot more air through your engine. If you can scan it, look for the injector duty cycle, it might be maxed out. If it is running lean then your leaving power on the table.
Thread Starter
Racer
Joined: Jan 2007
Posts: 252
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From: bethlehem PA
Ex-x-fire has a good point on the injector cycle. the motor was dyno at flywheel at 479 HP. with a holly 800CFM carb I think ill find i need larger inj.
due to the 24lbs inj. being maxed out.
Aardwolf is right on the side affect to the resistor.
u guys are grest!!! GIVE ME MORE!!!! THANKS TO ALL, PEACE
Last edited by nickpe; Oct 17, 2012 at 10:12 PM. Reason: added carb info