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Never ending P0443 and P1443


cstarbard

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Hey guys,

On my 96 2.3, I've been having super persistent Evap system codes P0443 and P1443 and I'm hoping you guys can help me fix this issue since I've tried a lot of things. Here's what I've done so far:

I have had both codes off and on for as long as I've had the truck, so about a year. Today I scanned it and I only had P0433. I checked the wires to the Evap purge valve and it was clear the wires were damaged because there was an obvious cut in the insulation on one wire, and if I probed the wires with a multimeter, KOEO, I got readings from 0 volts to 12.6, depending on how I moved the connector around. I fixed those wires with spare Ford wiring bits I have, and now the connector reads 12.6 ish V consistently. The P0443 did not come back after a 30 minute drive or so, but now I have a code for P1443.

I checked the wires on the thermistor connector for kicks, of which there are 3. I used the black wire with white stripe as ground, then switched the multimeter's lead between the red wire and the black and green wire. One way gave me 12.6 or so V, the other way got me 5V. As with the purge valve connector, moving the connector could fluctuate the readings from 0 to 5 or 0 to 12.6 depending on which wire was being probed, so as with the purge valve connector I replaced the wires and now the connector consistently reads 12.6 or 7.5 ish V, depending on which wire I probe with the lead.

I found it odd that one way got me 12.6 and that one way got 5-7. I was guessing that there are two power wires for some kind of switch, in which case I would have expected about 12.6 on both. Should the lower reading be higher? Can anyone provide me a wiring diagram?

I have several Evap purge valves and several thermistors (all from junkyard 2.3 trucks), no combination of those will shut the light off so far. In the past, whenever I have cleared the Evap code/s or had the battery disconnected working on the truck, the code/s came back almost immediately- is there a chance I have fixed the code and the light will go off later? I'm doubtful

Other things I've done: I swapped the gas cap, no difference. I replaced the vapor line all the way from the engine bay to the fuel tank vapor filter thing, I know its not clogged or damaged because its new line. I inspected the valve on the tank and it is undamaged, seems to work

What else should I look at? I feel like I'm running out of things to check

I know I could replace the evap valve and the thermistor, but it's like $70-100 to do both and I don't really want to waste the money if they are in fact fine and I have a wiring problem. I also would think that if they were bad one of the many spares I got from a junkyard would have worked, but I guess I wouldn't be surprised if they didn't either
 
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cstarbard

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I also replaced the lines that connect the evap purge valve and thermistor to each other and to the carbon canister, and have also replaced the line that goes up to the intake manifold
 

cstarbard

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So for kicks I just tested all the purge valves I have, and they actually all do work.

I wired them to a spare battery I have, and put a tube on one fitting of the valve so I could try to blow through them when they were opened with power. I heard them all click when energized, can blow through all of them with no resistance at all when they have power to them, when power is disconnected I can't blow through them at all.

Hoping someone knows of a way to test thermistor or can make sense of the voltage readings I got from it.
 

cstarbard

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More updates:

P0443 has not returned. P1443 still will not leave.

I read that a new thermistor should read to the tune of 1.65V while the thermistor is capped off (can't suck air through it) and should read ~3.57 while allowed to pull air through it.

I probed my black/green stripe wire at thermistor with a multimeter. The thermistor read 1.53 V capped off, and 2.8V open.

I tried it with a brand new thermistor borrowed from my brother's truck (97 3.0- same part) and it read 1.65V closed and 5.12V open. Even though this is basically ideal reading, the new thermistor did NOT shut off my CEL/ clear the P1443

Any thoughts anyone? I'm pretty lost. Going to get a vacuum tester and see if I'm pulling correct vaccuum through system, doubtful thats the issue
 

tomw

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Have you checked the integrity of the filler neck fittings & hoses? I have not dug into what is going on exactly, did do a search for 'ford p01443' and got indications that were not totally specific. I have read that some vintage filler neck tubes/hoses/etc deteriorate and cause evaporative emissions control problems.
The checks that are run depend on: vapor pressure of the fuel, volume of fuel in the tank, and ambient temperature. I think. The test closes the valve and lets pressure build, and if it does not build assumes a leak. The words of the 'code' indicated flow was greater than something and should not be blah blah blah. Again, did not decode them mentally.
Have you looked at your filler neck parts?
tom
tom
 

cstarbard

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Tom thanks for the response.

Yes, the codes are pretty non specific lol. I appreciate the info about the evaporative system function. I had gathered some of that from reading elsewhere.

I actually was just looking at the fuel filler neck and it's ok. Some checks in the rubber, but no cracks and no leaks of gas from it during fill up etc.

What is interesting is that whenever I disconnect the battery or clear the P1443, it always comes back immediately. Like, in seconds of startup. I thought it might have something to do with it being ridiculously hot now, i.e., vapor pressure in tank relatively high/constantly present. After doing everything I've described previously, I cleared the code again, and I have not seen it in days. Even just filled the tank- still no code, I'm wondering if I might have actually solved the issue, and the computer hadn't run a test of the system and recognized it was fixed, and now that I've cleared the code the ecu it ran its check and everything checked out?

We will have to see. Once I'm 100% certain it's gone I'll update this thread.

The only things I did to rectify the issue (assuming it is fixed) are everything I've discussed here. Also, I found a great, more detailed writeup for this issue:

http://asavage.dyndns.org/ftp/Aerostar/OBD-P1443/FR_EPS.htm

The only parts he does not cover are what I did, fixing broken wires at connectors for purge valve and thermistor.
 

cstarbard

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I also noticed that since doing all this to the evap system my mpgs went up 1-2 mpg, got my best mileage yet owning the truck. Hoping that is an indication I've solved the issue
 

cstarbard

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It do like it be
So after 2-3 days, I have no more P1443 or P0443!

If you have these persistent codes like I did, try everything I outlined doing in my above posts and it should go away. If it does not at first, clear it and see if it returns.

Also be sure to check your carbon canister, the breather vents on mine (two caps at top) were plugged up with a million dead ants, other bugs, and mouse debris.
 

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