3.8 Pig Eec No Dtc

Discussion in 'SN95 V6 Mustang Tech' started by g96v6-250k, Aug 15, 2012.


  1. g96v6-250k

    g96v6-250k Member

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    Why does my eec-v run such a pig rich fuel trim that the cats slowly clog, the engine vibrates, horses are missing, and fuel mileage is ****. I'm talking it cant get more than 20-22mpg highway babyed and if i wale on it, possibly as low as 8-10 mpg. When i got the car the damn thing could rip ass and still get 25-32mpg highway and there was no worry of vibration or clogged cats. Also i could damn near stay with the 5.0's and 4.6's.
    Next question is why is it that when i clear the KAM, unplug the ECT the ACT and the fan and drive it performs like it did years ago and the above concerns do not exist. Has adaptive fuel trims gone stupid? "DEAD CPU? Cam angle? Ethenol? . If its learning a injector problem or something, why does'nt it lose horses/MPG and vibrate with these sensors unplugged? Does the eec NOT learn anything with these sensor faults present? Am im tricking the eec into a leaner trim? i try not to kick its ass with no ECT,ACT & fan but i have and no difference, it wont go pig rich/vibrate. i tested both sensors and they check normal to spec and no ground out. These problems started as the car sat overnight back in 08. i could feel it the moment i left the driveway.
    anyone with eec knowledge that has any ideas? I hate stinking up the air to stop the cats from plugging up. any suggestion appreciated. Oh i must add i have found 12v to ground but have fixed them. Did the eec fry or do i still have shorts to ground? I get a paranoid feeling there is a remote rf trim control by the gmen and they want my horse dead. lol
     
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  2. wmburns

    wmburns SN Certified Technician

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    More likely your problems are more "typical". Especially since I see no evidence that the usual causes have been ruled out. For example:
    • clean the MAF
    • changed the fuel filter
    • changed the PVC value
    • spark plugs and wires
    • vacuum leaks
    • exhaust leaks
    • Excessive fuel pressure.
    • how old are the O2 sensors?
    Have any tests been done to confirm the health of the base motor? Compression test? Does the motor use oil or coolant?

    In answer to your question about how a car could run better with sensors unplugged, the answer is likely that the PCM uses default values when ever sensor input is missing.

    The post states that the motor is running "pig" rich. But what does the PCM "think"? IE, does the PCM "think" the car is running lean? Like for example what would happen when there's an exhaust leak? Look at the long term fuel trim values (LTFT). What are they at idle and under load?

    This may offer a clue which sensor is causing the immediate problem. IE, which sensor if unplugged gives the MOST improvement?
     
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  3. g96v6-250k

    g96v6-250k Member

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    maf was cleaned and volt checked at idle and reved.
    filter was done twice since vibration started.
    plugs/wires changed/checked .
    fuel pressure was jumpy between 28-30psi and i swapped the regulator which made it less jumpy. must have put 200$ of inj. cleaner in since 08. all different types
    changed the pcv valve.
    only vacuume leak that is possibly is the lower intake manifold gasket where it meets the heads, but im doubting that and i was told that will be mettered air anyway because pcv is metered on the maf. or the egr regulator. seems like more pcv vacuum pull then a 3.8 t-bird but i dont know why.
    no exhaust leaks that i can see or hear except for the possiblilty of a small crack where the 3 header meet but i dont hear anything there.
    the engine wont loose oil or coolant and oil stay clean/full for well over 5000 miles.
    i took the all 02s out and propane torched them and when hot :after about 2 minutess" they react as they should 0 to 1 volt very quick. i was told that if any go negative volts they are shot? oh they are the proper NTK.
    mounts done.
    transmission seems flawless
    the list could go on. bat/alt changed. shorts found/fixed.
    I had this car to a ford dealer and i told the mech that it vibrates and bad fuel mileage and they couldnt find anything wrong. im sure they had it on the new gen star machine but i dont know if they did a comprehensive data logging. it happen to be like 10 degrees F at the time and it seemed to be ok that morning when i took it there "sometimes its not bad". the vibration isnt the worst part, its the 18-20 mpg highway with no hard acceleration that kills me. when i got the car i swear i was seeing up to 32mpg, possibly more and no vibration. its had many thounds of miles since the problems started and no real change no matter what i do or how hard i drive it. you think i should swap 02s, injectors or muffler?? i feel like thats a shot in the dark. i rarely get a quick power surge and p0443 for the purge but only on hot days near creeks which is weird. i swapped the purge valve cylindr and no change. im feeling like the ecu is screwed as this all started when the car was sitting overnight. it used to be tuned like a ferrari but now it runs like a ugo lol. i hate ford computers. no it still **** n gits at WOT but it sucks down some fuel and rarely detonates like its confused. any ideas?
     
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  4. wmburns

    wmburns SN Certified Technician

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    IMO, you are silly to ignore the P0443. It points to a possible wiring problem which may be the clue you are missing. Anytime a "circuit malfunction" is called out, the sensor is failing some basic circuit function test. Think short, open, ground fault, blown fuse, bad PCM, or totally wacked out sensor.

    >>
    P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction

    • VPWR circuit open
    • EVAP canister purge valve circuit shorted to GND
    • Damaged EVAP canister purge valve
    • EVAP canister purge valve circuit open
    • EVAP canister purge valve circuit shorted to VPWR
    • Damaged PCM
     
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  5. g96v6-250k

    g96v6-250k Member

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    the red wire on canister purge valve/solenoid goes to chassis ground at 100 ohms and the gry/yel to ground at 700 ohms. that red is to/from ccrm and pcm and just about every sensor i can see in the hanes manual. does this sound like broken ccrm or pcm? or possibly wires rubbed together in the harness. i can't see anything suspect in the harness near this valve. should i keep unplugging things one at a time untill this continuity goes away?
     
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  6. wmburns

    wmburns SN Certified Technician

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    What Model year car are we talking about?

    Measuring the Ohm value to ground is not going to help. You did not state if the circuit was active or not at the time. To correctly "ring out" a wire, the circuit must be inactive (no power) and go from the connector as one test point. The other test point is the PCM harness connector.

    Most ppl start out by confirming VPWR at the sensor and work from there.

    If you want more help a set of wiring diagrams is needed. Plus several detailed tests will be needed. PM if interested in getting a service manual and wiring diagrams for your car.
     
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  7. g96v6-250k

    g96v6-250k Member

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    i think i figured this one out. i took off the MAF sensor and probed its pins with a DVM and did the same with 2 other known good MAFs from a tbird and saw obvious differences. So i swapped them and i think i got it. gas mileage is up but im not sure the vibration is gone yet. ill post back with results
     
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  8. g96v6-250k

    g96v6-250k Member

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    After i changed MAF sensors "which fixed mpg and horse power" i have a code p0174- bank 2 too lean, i have never had this one before. does this sound like a bum injecter or 02 sensors? possibly bank 1 has a plugged cat? or does that not affect the ecu with how it determines whats going on. should i torch the hell out of the 02s again?
     
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  9. wmburns

    wmburns SN Certified Technician

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    The odds favor a vacuum or exhaust leak. Pay special attention to the EGR system. Is it leak free? Value cover gaskets? Oil dip stick?
     
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  10. g96v6-250k

    g96v6-250k Member

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    i think i got the lean bank code fixed for good on this 96 3.8, i had found and repaired a crack on the vac supply line to the egr regulator.
    it was 90 today and the engine surged for a second and this damn p0443 for evap purge came back again. this one started 1 day after i had replaced all the rubber lines from the charcoal can and to the purge s0lenoid and evap flow sensor. when it first happen it was surging badly so i rechecked my work and i had the solenoid lines reversed, so i fixed it and it stil had this code always 5 mins after the codes cleared. i figured i broke the seal inside the solenoid so i replaced it and i still get this code when its 90+ outside. like i said i never had a problem with the surge and p0443 code untill i revered the soleniod. old soleniod pops the code in 5 mins no matter what" im almost certain the flow sensor is not reversed but is it possible that leaks or is just shot? the surge leeds me to believe the flow senser/purge solenoid might be leaking vac somehow but i tried to suck on the line at the manifold vac T and it seems to hold. the surge feels like a vac leak or the solenoid opens but gets no fumes to burn. maybe its goes very lean expecting fumes but never gets any? you think my new soleniod is'nt opening when its hot outside? the flow sensor is closest to the manifold and purge solenoid is after the charcoal can correct? any ideas would be awesome and thanks again for all your help.
     
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  11. wmburns

    wmburns SN Certified Technician

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    Why guess. Test. Perform a functional test on the EVAP solenoid. You should not be able to blow through it with no power. Power via 12 volts and you should be able to blow through it.

    Then replace the EVAP flow sensor. They fail a HUGE number of times. It's a cheap sensor and is well worth the $$ just to rule it out.
     
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  12. g96v6-250k

    g96v6-250k Member

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    bro i never guess when i can test. im only asking because i have bench tested both the old valve and the new one and they are sealed with no power and wide open with power. whats is funny and has me scratching my head is i replaced the rubber hoses and the next day i rolled 199,999 miles on my way to work and thats when the code popped. i almost **** myself and blamed ford for a prefect, but when i pulled the code and it was for purge i figured it screwed something up, which i did. i fixed it that very day by replacing the valve but 2 weeks later my new valve apparently does not open on hot days. im thinking both valves work but there is something i am missing as the gas mileage seemed to have dropped a hint after this. im really doubting that i screwed up the original one by having the "to engine arrow" pointed at the coal can, but the original valve pops the code within 5 minutes of running after the codes cleared. i guess ill have to go with the new one is intermittent on hot days. i would have suspected the flow sensor if i had not reversed the valve and then had the code and surge the next drive cycle. if my car was run by windows like pc i would have formatted the rom and reinstalled the OS by now lol. i have been doing that for 15+ years now, same duration with car/truck repairs, but my car is the only one i cant seem to figure out eventually. now i think i hate all computers, not just pc. i wonder if i can mount a holley carb to this damn v6 and still get a max of 32mpg lol. is it possible i have too much manifold vacuum and this code pops? i have never heard of any engine having too much vac, but nothing would suprise me with this car. except maybe getting 35mpg again. :p.
    also it still sounds like a get a hint of pre-ignition at about 80-90 percent throttle, never at wot and i have not seen this lean bank 2 code in about 300 miles now. it accelerates a bit better without going WOT so any ideas on both issues would be awesome. it never stop running or left me sitting but it always has me wondering wtf its doing. any thoughts on remote rf manipulation? lol j/k
     
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  13. wmburns

    wmburns SN Certified Technician

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    FWIW, normally EVAP problems are difficult to trouble shoot because it takes so long for the motor to run an EVAP purge cycle. Since your car is throwing the code so quickly, this means something. I have to admit that I did not look up the DTC code until now. The P0443 circuit malfunction has special meaning. There is a signal the PCM is looking for that's not present.

    Inspect the wiring to the purge flow sensor and solenoid looking for bent/pushed pins. Is the connector clean? Does the connector make solid connection? Are there any breaks or chaffed points in the wiring harness?

    If the electrical connection to the purge solenoid is removed/connected with the key on and motor not running, can you hear the solenoid engage? If so, this means the the solenoid GY/Y wire is shorted to ground.

    Measuring the voltage on the purge flow sensor and purge solenoid RED wire with the key on. Should be 12 volts. Post.

    Remove the purge flow sensor and test the resistance of the BK/W wire back to battery negative with the key off. Should be low. Post.

    Disconnect the EVAP solenoid electrical connector and reset the DTC codes. Drive the car for a few days and post what ever code the PCM throws.



    >>
    P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction

    • VPWR circuit open
    • EVAP canister purge valve circuit shorted to GND
    • Damaged EVAP canister purge valve
    • EVAP canister purge valve circuit open
    • EVAP canister purge valve circuit shorted to VPWR
    • Damaged PCM
     
    #13
  14. g96v6-250k

    g96v6-250k Member

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    i can clear this code and with my old/original valve hooked up, this code returns in 5 minutes or less of driving but never surges the motor when it does. the replacement valve only pops the code on hot days and has a surge at the same time. you said it takes a long time to cycle purge but my car seems to try to purge within 2-5 minutes of driving from a cold start. both valves have clean as new pins and the harness plug looks great.

    the ford part number is different on both.
    the original valve from this V6 mustang is E4ZF-9c915-AA/B0205B.
    the replacement valve is from a 96 f250 351w with part number E5TF-9c915-AA/18.

    possibly the problem? the truck did not have any DTC for purge.
    maybe this replacement one isnt the right part and thats why i get a surge and DTC only on hot days only?
    both valve do open when i apply 12v to them from a bench test bat, then close/seal with no power. i will try to find a different valve and if that wont work ill probe some wires i guess.
    weird eh? they appear to be fuly functional and exactly the same aside from the part number.
     

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  15. g96v6-250k

    g96v6-250k Member

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    the difference in parts must be it. i did some research and it seems different pcm try to pulse these purge valves at different intervals/amounts and frequencies. i think this one for the f250 is not capable of doing the same type of pulses and the pcm sees this. you think this pcm tries to purge quickly and more frequently when its know ambient temps are higher? i think the replacemnt valve wont keep up with the rate the pcm wants to purge.
     
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  16. wmburns

    wmburns SN Certified Technician

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    The force is weak on this one. Keeps wanting to make up complicated answers before the simple stuff has been ruled out.

    What you need is a Ford service manual so that you can read for yourself how the EVAP purge cycle is suppose to work. If interested in getting a copy for yourself, I maybe able to help. PM if interested.

    OBTW, are you positive there aren't any leaks in the vapor system between the purge solenoid and the gas tank?
     
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  17. g96v6-250k

    g96v6-250k Member

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    tested ground wires for PFS and solenoid valve back to pcm connector and all good. triple checked the tank and hoses and they hold pressure. tired a 3rd valve and PFS and still only have the code when temps above 80 but not below. looked at all valves resistance and all are at 64 ohms. have since tried a different PCM,MAF, coil pack and CKP sensor. something odd is my IAC valve started to make a hum when key goes on.
    what im not sure about is the red power wire from ccrm for PFS Pruge valve and may others, it goes to ground at 600 ohms until I unplug ccrm.
    have read the coal can can just go bad but I don't think so.
    all the issues with this car started after bat+ was shorting to chassis. blown ccrm resistors, diodes, or relays?
     
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  18. g96v6-250k

    g96v6-250k Member

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    found half of the problem with random p1443 code. I hooked up a test bulb to purge valve circuit and hung it near my stereo. about 5 minutes after leaving the driveway rolling at 40mph steady throttle test light was pulsing steady, out of nowhere, the light stopped pulsing for about 5 seconds and wham! instantly the CEL goes on. had the dmm on the + side of circuit and it stayed hot at 13.7v, so somehow the damn pcm or wire lost ground for it... any ideas why? could it be lost tps signal or other?

    another weird one. today I stopped at a store for a minutes and shut off eng. got back in and hit the street, instantly noticed the test light was not coming on at all. I drove about 5 miles and no power to purge valve and no CEL. pulled over on side of road and killed the engine and waited 1 minute. started it back up, pulled off and power is back at purge valve..... any ideas?
     
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