Does the ECM activate the cowl hood door on the HO 1984 TA?
12-27-2013, 08:59 AM
#1
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Car: 1984 Trans Am Recaro Edition
Engine: 355 L98 Vortec 226/234 custom cam
Transmission: TKO-600
Axle/Gears: On borrowed time...
Does the ECM activate the cowl hood door on the HO 1984 TA?
Curious minds want to know
12-27-2013, 09:11 AM
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Car: Yes
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Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
AFAIK no. I seem to recall it being a switch on the throttle, a vacuum solenoid, and a vacuum motor, with the vacuum source coming from the same vacuum reservoir as the HVAC.
12-27-2013, 09:22 AM
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Car: 1984 Trans Am Recaro Edition
Engine: 355 L98 Vortec 226/234 custom cam
Transmission: TKO-600
Axle/Gears: On borrowed time...
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
So it gets a signal from the throttle linkage on the E4ME? That would make sense. With the hood open, The wire that comes off the induction goes down towards the firewall then gets mixed with other wires near the ECM module (I think).
Pretty cool to see it work when you fiddle with the throttle linkage on the carb.
I wonder if it's possible to rig something like a light with an orange glow so you actually see something happen when you get in the gas.
Pretty cool to see it work when you fiddle with the throttle linkage on the carb.
I wonder if it's possible to rig something like a light with an orange glow so you actually see something happen when you get in the gas.
12-27-2013, 10:24 AM
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Car: Yes
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Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
I would think so... just hang a LED w a pullup resistor across the solenoid coil.
12-27-2013, 10:31 AM
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Car: 1984 Trans Am Recaro Edition
Engine: 355 L98 Vortec 226/234 custom cam
Transmission: TKO-600
Axle/Gears: On borrowed time...
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
Hmmmm. I thinks I have a new winter project!!!
12-27-2013, 10:35 AM
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Car: 1989 IROC-Z / T-Top -1987 GTA
Engine: 305 (LO3) _350 (L98)
Transmission: 700R4 _ 700R4
Axle/Gears: 2.73 L.S. - ???
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
you could just use a switch like the brake light switch, so when you open the throttle, it comes on
12-29-2013, 08:05 AM
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01-14-2014, 11:44 PM
#8
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
The hood louver is NOT controlled by the ECM on carbureted cars. A series of switches and sensors open and close it. First power is run to an oil pressure switch, then to a cold feed(engine metal temperature) switch on the back of the left cylinder head, and finally to a vacuum sensor next to the brake booster.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
01-15-2014, 07:45 AM
#9
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
The hood louver is NOT controlled by the ECM on carbureted cars. A series of switches and sensors open and close it. First power is run to an oil pressure switch, then to a cold feed(engine metal temperature) switch on the back of the left cylinder head, and finally to a vacuum sensor next to the brake booster.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
Disregard EVERYTHING else you have read on the cowl flap operation,.... this is EXACTLY the information you were asking for !!
In basic terms; the 2 electrical switches "allow" the cowl flap to work & the engine vacuum "makes" the flap work.
01-15-2014, 10:24 AM
#10
Re: Does the ECM activate the cowl hood door on the HO 1984 TA?
The hood louver is NOT controlled by the ECM on carbureted cars. A series of switches and sensors open and close it. First power is run to an oil pressure switch, then to a cold feed(engine metal temperature) switch on the back of the left cylinder head, and finally to a vacuum sensor next to the brake booster.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
Once there is oil pressure, the engine warms up, and there is a low vacuum situation(3/4-full throttle) the hood louver electric solenoid is energized and the flapper door opens.
You can test the system by warming up the engine and then removing the vacuum hose from the vacuum sensor near the brake booster. You should hear the door open. The solenoid isn't designed for continuous duty so do not leave it energized for too long or it will burn up the internal windings.
You are correct on this one. I swear I remembered reading that grounding the test terminal on the ALDL would activate the solenoid, but after I checked the factory service manual, it doesn't.
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