Trend...P0443
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Elder User
Joined: Feb 2000
Posts: 775
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From: Temperance,MI
Trend...P0443
96 F150 5.8, had this come up about a week ago. Put the old scanner on it read it, O.E. VMV 177k on it. Pull it off take cap off nothing out of the ordinary just dirt and dust. Harness is fine nothing out of the ordinary.
Bought new one, fine for this week, this morning light came back on, scan it came up first round P0000, use other scanner that does less details P0443. pull VMV connector, battery 12.96v. at connector 12.94v. Pull EEC connector VMV to eec has continuity no high resistance, same with vpwr. Odd thing for me from reading everyone elses I do not have any trans codes coming up
. I plugged it back in fired it up drove it for 10miles, mainly light throttle try to get VMV to do its job, no light.
Any ideas? I was debating on pulling my other OBD-II 5.8 EEC out of my 92 and try it with it but can not shut overdrive off with that one so somethings diffrent in that processor.
Thank you
Curtis
Bought new one, fine for this week, this morning light came back on, scan it came up first round P0000, use other scanner that does less details P0443. pull VMV connector, battery 12.96v. at connector 12.94v. Pull EEC connector VMV to eec has continuity no high resistance, same with vpwr. Odd thing for me from reading everyone elses I do not have any trans codes coming up
. I plugged it back in fired it up drove it for 10miles, mainly light throttle try to get VMV to do its job, no light. Any ideas? I was debating on pulling my other OBD-II 5.8 EEC out of my 92 and try it with it but can not shut overdrive off with that one so somethings diffrent in that processor.
Thank you
Curtis
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
P0443 Evaporative Emission System Purge Control Valve Circuit
What are you calling a "VMV"?
Oh and if you have a 96 f150 OBDII? then you can't put the OBDI computer from your 92 in it anyway. Unless your 92 is no longer "stock"?
What are you calling a "VMV"?
Oh and if you have a 96 f150 OBDII? then you can't put the OBDI computer from your 92 in it anyway. Unless your 92 is no longer "stock"?
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
Your test show have power direct to the valve, tests good. The computer provides ground required cycle it open, you tested that circuit and its good too?
So you replaced the valve, took it for short test drive no more light? so sounds like you fixed it, unless not enough drive cycle yet.
Or am I completely miss reading your post and or missing the question in it?
No trans codes be a good thing, unless of course you're having shifting or issues of some sort with the trans? expected codes for the trans?
Oh and I was fairly confident you where talking about the purge valve, just wanted be sure!
Senior User
Joined: Jun 2011
Posts: 382
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From: Milford, CT
Why would you expect a trans code from the VMV? It's not critical by any means, and has nothing to do with the engine or transmission at all.
For anyone wondering, this is a little valve downstream of the carbon can, part of the system that catches any evaporated fuel from the tanks to prevent pressure buildup/allow air in when running. (IIRC)
Check the wire insulation (both sides) for pinholes, and the connector for corrosion, might be that the new valve is bad too.
-Mike
EDIT: This isn't pulse actuated, is it? If so, you'll need an oscilloscope or high speed graphing meter to test it usefully.
EDIT2: Also, if the new valve fixed it, what's the problem?
For anyone wondering, this is a little valve downstream of the carbon can, part of the system that catches any evaporated fuel from the tanks to prevent pressure buildup/allow air in when running. (IIRC)
Check the wire insulation (both sides) for pinholes, and the connector for corrosion, might be that the new valve is bad too.
-Mike
EDIT: This isn't pulse actuated, is it? If so, you'll need an oscilloscope or high speed graphing meter to test it usefully.
EDIT2: Also, if the new valve fixed it, what's the problem?
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Elder User
Joined: Feb 2000
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From: Temperance,MI
Last Sat night when I was on my way home from work light came on diagnosed it Sun. ordered new VMV. Monday I replaced the valve, got through until this morning on my way to work light came back. Never idles rough or any other symptoms of a issue. Today I went through and checked wiring and everything plugged eec back in and drove it for 10 miles no light came back was running 195deg. so it was up to temp.
Trans has never been a issue. Back in 07 when I melted forward planetary that was but after build no issues but whole other story there.
I searched before I posed a lot of guys were having P0443 and a trans code issue at the same time with OBD-II 5.8.
Thank you
Curtis
Trans has never been a issue. Back in 07 when I melted forward planetary that was but after build no issues but whole other story there.
I searched before I posed a lot of guys were having P0443 and a trans code issue at the same time with OBD-II 5.8.
Thank you
Curtis
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 12
From: Sand Lake, MI
Might be the act of unplugging then plugging the ECC connector back in corrected a bad connection on that pin.
Just drive it see if the problem returns.
Not sure might be you have small hole, a leak in the tube running from the tank to the canister/valve, not sure these trucks OBDII systems monitor that aspect or not. Maybe someone else comment on that.
You wouldn't notice drive ability issues because of that either way, light "on" on the dash now and then be bothersome about it far as that goes.
Just drive it see if the problem returns.
Not sure might be you have small hole, a leak in the tube running from the tank to the canister/valve, not sure these trucks OBDII systems monitor that aspect or not. Maybe someone else comment on that.
You wouldn't notice drive ability issues because of that either way, light "on" on the dash now and then be bothersome about it far as that goes.
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Elder User
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From: Temperance,MI
The 92 is no longer a EEC-4 set up, I was going to put my 400 in the 92 with 96 5.8 OBD-II EEC-5 built harness for it and all even have the DLC set up under glove box like factory 
. If light comes back I will post.
. If light comes back I will post.
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Fleet Owner
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From: Kentucky
We have had a few posts in the last year, and over on FSB.com, where the issue is a recurring P0443 code. Sometimes the issues involves a transmission trouble code, can't recall which one, and a flashing O/D light. In EVERY single case a replacement Vapor Management Valve (VMV) has not resolved the issue, nor has anyone found a wiring/connector problem. In each case a replacement EEC-V resolved the issue.
In this case all of the symptoms are not present, but it appears the OP has followed a reasonable troubleshooting path. Ford did not fully implement a true fuel vapor circuit check on this vintage truck. From what I recall when I researched this issue the PCM momentarily opens the VMV (yes it is pulse width modulated) and looks for an increase in idle RPM. If you have a vacuum leak and a higher than normal idle RPM already this could be falsely triggered. Same for a sticky IAC perhaps?
In this case all of the symptoms are not present, but it appears the OP has followed a reasonable troubleshooting path. Ford did not fully implement a true fuel vapor circuit check on this vintage truck. From what I recall when I researched this issue the PCM momentarily opens the VMV (yes it is pulse width modulated) and looks for an increase in idle RPM. If you have a vacuum leak and a higher than normal idle RPM already this could be falsely triggered. Same for a sticky IAC perhaps?
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Elder User
Joined: Feb 2000
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From: Temperance,MI
Thanks for the replys, yes I reasearched too kinda weird. The truck runs like it always does, good this is the only weird issue I have ever had with it. with 177k it has VMV and a O2 replaced for sensors. I put little over 100miles on it today light never came back idles at 600ish in gear no miss no roughness nothing like eec-iv my 92 had its good and bad days. All my grounds are in good shape, connections when I bought the truck I coated them with a NYK anti corrosive anti conductive gel. Living in MI rust and corrosion go hand and hand this truck came from mid OH it was spotless when I bought it.
I will update if the light comes back on for the same issue. rla2005, has anyone that has had this issue that replaced the processor had the issue come back over time? or too recent? I hate to have the issue come back buy a reman unit and year down the road have the same issue, throwing parts at a problem without being able to have a full diagnosis just throwing money away.
Thank you
Curtis
I will update if the light comes back on for the same issue. rla2005, has anyone that has had this issue that replaced the processor had the issue come back over time? or too recent? I hate to have the issue come back buy a reman unit and year down the road have the same issue, throwing parts at a problem without being able to have a full diagnosis just throwing money away.
Thank you
Curtis
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