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Need help with my sons car

Discussion in 'Road Side Pub' started by toomanytoys, Dec 7, 2019.

  1. toomanytoys

    toomanytoys Active Member Established Member

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    I know it’s not a mustang but it is a ford product (2003 mercury sable 3.0 dohc) and I can’t seem to get it running right. I am hoping the members here can help-

    Here’s the problem- the car stumbles when you first step on the gas like pulling away from a traffic light. Sometimes it even gives off a lean miss pop through the intake. When driving with light throttle the car runs fine. If you hit the pedal hard like when getting on the expressway the car falls on it’s face. Back off the pedal and hit it again and sometimes it responds

    I found some minor vacuum leaks and repaired them. I changed the pcv, fuel filter and the fpdm. I verified fuel pressure at 38-42psi at idle. The car has no codes pending or showing. The stft is at -1.6 on both banks but the ltft is between 10.2 and 11

    What else could it be? The car has 62k on it and I bought it new so I know it’s history. Clogged injector? Fuel pressure sensor?
    I need to get this old girl running right
     
  2. slo984now

    slo984now AKA 01yellerCobra Established Member

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    You need to check the fuel pressure while driving. There isn't much of a load on it at idle. It sounds similar to a car I worked on years ago. It would randomly fall on its face until one day it didn't start anymore. A new fuel pump fixed everything.
     
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  3. 03cobra#694

    03cobra#694 Want to play a game? Staff Member Super Moderator

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    I'm moving this to RS so you get more views.
     
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  4. Crimson2v

    Crimson2v Well-Known Member Established Member

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    Looks like it’s running lean, just not lean enough to throw a cel. Definitely check the fuel pressure while driving as mentioned earlier. I would also check the rubber hose from the pcv to the intake those are known for breaking and collapsing. Check the intake tube after the maf make sure it’s not broken anywhere. Double check all the vacuum tubes. If those are all ok, the intake gaskets may be compromised. Check your MAF too, see if it’s dirty.
     
    Last edited: Dec 8, 2019
  5. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Chilton Library

    Here is a link into manual if you don’t already have.

    On board diagnosis.

    Should be a chart by description with out code

    Have you used an older vacuum gauge.
    Clogged exhaust will do this and run. Until it’s fully done
     
  6. toomanytoys

    toomanytoys Active Member Established Member

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    All the vacuum hoses were changed. The one under the intake was broken which was one of the leaks so when I swapped it out I did the pcv as well. The maf has been cleaned and shows smooth transfer on the scanner. The fuel pressure only moves slightly during driving. I’m reading around 40 at idle in gear and it only rises to 43 while driving regardless of throttle rate
     
  7. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    What type of scanner are you using?

    Mine is a Bosch from orielys

    It also does engine running test.

    Which is different and may give a code that isn’t setting cel
     
  8. Coiled03

    Coiled03 Well-Known Member Premium Member Established Member

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    Pretty sure the fuel pressure should be a lot higher than that under load. Someone correct me if I'm wrong.
     
  9. toomanytoys

    toomanytoys Active Member Established Member

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    That’s what I was thinking too. I’m so used to having boosted cars I can’t remember what the rise should be on a n/a car. The pressure just seems to sit there. Maybe try a different fpdm? Doesn’t a member here mod fpdms?

    The scanner I’m using is a actron. Shows live engine data as well as codes active, stored and pending
     
  10. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    Fuel pressure 35-70 says reference chart.

    Your scanner should be able to do a

    Koer tests

    Also

    What is timing doing during the fall?

    Reading about system.

    This has knock sensors.
     
  11. hotcobra03

    hotcobra03 Well-Known Member Established Member

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  12. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    I would also do a compression test

    Hate throwing out money on something missed on basic engine checks before
     
  13. Crimson2v

    Crimson2v Well-Known Member Established Member

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    Can you check mode 6 on your scanner? If so check for misfire data. What’s the condition of the plugs and wires? Are they original? How about the coil pack?
     
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  14. toomanytoys

    toomanytoys Active Member Established Member

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    That’s where the pressures are at. Timing is between 17* and 21* and varies constantly. Plugs and wires are fresh and coil is a year old. When the car coughs if I keep my foot in it I will get a misfire code. Cylinder is random. I don’t think I’ll be able to do a compression test as the upper intake has to come off to reach the rear plugs. They are under the plenum. All of the o ring seals between the upper and lower are new as well. The vacuum leak on this car was so bad I could unplug the iac and the car kept on running and never missed a beat. When I shut the car off it would hiss through the leak for about 3 seconds. All of that is fixed now but the stumble which I have been chasing now for quite a while is still present
     
  15. toomanytoys

    toomanytoys Active Member Established Member

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    Could it be the car is idling too low? Maybe out of range of a sensor? Scanner is showing 625-650 hot and in gear. In park it will rise to 725 and then drop back down
     
  16. kevinatfms

    kevinatfms Ex-Ford/Kia/Hyundai Tech Premium Member Established Member

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    A couple things to check:

    1. EGR vacuum port. Use a vacuum pump and pump the EGR up and see if it stumbles at idle. If it stumbles you have good flow. If it doesnt the port could be clogged. This also depends on if its a plastic or aluminum intake(they changed sometime in the 99/00 era). The plastic ones usually dont clog as carbon build up isnt bad on plastic. If its the aluminum intake they were terrible at gumming up. If it has the original aluminum DPFE sensor it needs to be replaced also. They were notorious for causing stumbles and there was a TSB to replace them on 99% of Ford cars that came in with stumbles. Some set CELs while others would torment owners/techs.

    2. Intake gaskets. I know you said you replaced them but alot of times guys pinch them when putting the intake back on. Id double check using carb cleaner and see if the STFT changes when you spray around the intake base.

    3. The plastic intake. I had a plastic intake one time split at the back. Didnt make any sucking noise or anything but enough of a leak to cause a lean condition. Carb cleaner by a co worker found that one.

    4. Pull the ignition coil off and look for "white lightning". Small cracks can develop on the coil which will arc to the bracket. Usually on the sides or under the lip of the coil itself.

    5. Compression test cylinders 4/5/6. I had a run of Taurus and Escapes with the 3.0L DOHC engine that seemed to like to burn exhaust valves on those cylinders. Replaced at least 50 or so in a two year period. If the compression test comes up good, plug an air hose to the cylinder and rotate the crank. You should hear air whoosh out of the intake and exhaust but stop when you have closed each valve. If you get to the exhaust side and it doesnt fully seat then you know burned exhaust valve.
    It was also always the "front" cylinder head for some reason. I dont think i ever replaced a rear cylinder head ever.
     
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  17. toomanytoys

    toomanytoys Active Member Established Member

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    This car has the plastic intake. I actually replaced the dpfe and the hoses due to a melted port and hose with no idea as to why it melted down. I start with some of these. Thanks
     
  18. Crimson2v

    Crimson2v Well-Known Member Established Member

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    can you get a mechanical vacuum gauge reading on the engine. Idle, acceleration? I wonder if your cat is plugged.
     
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  19. toomanytoys

    toomanytoys Active Member Established Member

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    I’ll get that reading later. Would explain the melted emissions hose and dpfe right?
     
  20. hotcobra03

    hotcobra03 Well-Known Member Established Member

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    I had these issues on my cobra and don’t have cats.
    But did get codes for it

    I replaced it with used parts being we have good junk yards to pick from

    But 62k. I’m thinking it’s something stupid that’s been over looked

    Were plugs changed? Brand.

    The scanner. You have a model #
    Like to see what it can do

    No codes show.

    Have you done something to make a code to confirm scanner is reacting

    Something I do is like unplug something when it’s running

    Iac /map/coil/injector/tps

    A code should read for what you did
     

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