Ford Mustang Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
So I've got the P1443 code in my 96 GT. Instead of just doing the replace and check method, I actually want to narrow it down.

Here is what I've done so far:

Disconnected the sensor and checked resistance values. When I blow through the sensor the values change (after all its just a temperature sensor, so the air coming over the sensor either cools or heats it up, thus showing change in resistance).

Disconnected the solenoid and connected it straight to the battery. When connected to the battery it activates and allows air to flow through it. Disconnected it totally blocks air and can hold pressure for over 30 secs (test I saw in repair manual).

When I check voltage at the solenoid connector I get just a little less than the battery voltage....around 12V. This is done with key on. But when I connect the solenoid it doesn't energize, it still stays in the closed position. Is there a current limiter in the ECU that prevents this?

Also I hooked up a vacuum gauge between the canister and the solenoid and ran the engine. It showed 0 vac the whole time, so the solenoid never opened.

Any thoughts? Thanks in advance.
 

·
Registered
Joined
·
6,859 Posts
When I check voltage at the solenoid connector I get just a little less than the battery voltage....around 12V. This is done with key on. But when I connect the solenoid it doesn't energize, it still stays in the closed position. Is there a current limiter in the ECU that prevents this?
Bad solenoid. For the 96-99 MY, the EVAP solenoid is an open/close type valve. Application of voltage it shoud change states. If it doesn't, it's bad.
 

·
Registered
Joined
·
6,859 Posts
Sorry didn't read/understand what you were saying. I think I now know what you are asking.

Like most devices on modern cars, the solenoid is a "GROUND START" device. The PCM activates the device by grounding the circuit to complete the circuit.

That also means there is +12 volts at the device all of the time. So seeing 12 volts at the device only means that the key is on.

So your functional test of the solenoid indicated it's good.

Therefore, you problem is either the flow sensor (which breaks a lot because gas vapors are hard on everything), a problem in the EVAP lines (break or clog), or in the charcoal canister.

My vote, replace the purge flow sensor. Cheap enough just to rule it out.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
I don't know why but I thought I tested the voltage at the plug. In other words both probes of the multimeter in the connector. But I went back and checked it again today and it wasn't. I probably just confused myself.

They lines are original. The one that looks the worst is the one from the canister to the solenoid. Probably replace all of them since they are pretty cheap.

When do these solenoids activate? When you first start the car or is it random times picked by the computer?
 

·
Registered
Joined
·
6,859 Posts
When do these solenoids activate? When you first start the car or is it random times picked by the computer?
The solenoid opens during an EVAP purge cycle. The PCM decides depening upon a ton of factors. However, most of the time an EVAP purge is run after a COLD SOAK when the motor has been running for a few minutes and stable.

Another trigger is a gas tank re-fill.

When trying to figure this out, might as well consider it random.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #7
So you could probably test it by letting the motor get up to normal temp? I think I read somewhere about getting it up to normal and then reving the engine a little over 1500.
 

·
Registered
Joined
·
6,859 Posts
WHY?

The functional test of the solenoid is golden. There's no magic involved. The solenoid should block air with no power. With power applied, it should pass air. Unless I misunderstand, the tests done prove it's good.

So if the the DTC continues, the problem is elsewhere. My vote will continue to be the purge sensor until there is a known good one.

If the intent is to force the PCM to perform an EVAP purge, research "drive cycles" and run the car through a drive cycle as that will speed up the time between purges.

Most of the rest of us perform a repair, reset the DTC codes and drive it to see if the code comes back.
 

·
Registered
Joined
·
1 Posts
is there any diagrams out there that will show where these parts are on the vehicle? i also have a p1443 code on my 1998 base mustang and i would like to get a diagram on where these parts are listed so i can look them over.:bigthumbsup
 

·
Registered
Joined
·
6,859 Posts
For the 98 and older MY Mustangs, follow the EVAP vapor line from the throttle body towards the fire wall. The purge flow sensor and solenoid are in-line with the the EVAP line usually along the firewall.

The EVAP vapor line will then pass through the right hand fender well onto the charcoal canister.

If you have looked and still can't find it, consider getting a Chilton's manual or a Ford Service manual on DVD. If interested in getting a Ford DVD for yourself, I maybe able to help. PM if interested.

Note, the 99-04 MY Mustang does have a different EVAP system. The location of the charcoal canister is behind the left rear tire. There aren't any active EVAP components in the engine bay.
 
1 - 10 of 10 Posts
Top