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08' mark lt hesitation and light rough idle

 
Old 11-16-2015, 08:44 PM
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Default 08' mark lt hesitation and light rough idle

OK so here goes. my mark lt 5.4l 3v has a slight hesitation shaking in a way when shifting into 2nd gear as it accelerates and feels weak. def engine not tranny or anything else. looking to get the "experts" heres advice on a possible solve for this issue. below are the specifics.


as stated, it feels weak and like it has hesitation as rpm's build and upshift to the following gear. sometimes (rarely) it does not thus the reason I know somethings up with it. periodically, it will have a stutter at idle like a mis, but not always. I do have the dreaded tick that is somewhat loud inside the vehicle and has become more apparent as time has past from the outside as well. not to drive up that road as its been beaten to death, but the tick does increase as I accelerate so I would imagine its not cam phasers.


no engine light, even used a good scan tool to find no issues have shown.


here is what I have replaced within the last year:


spark plugs
accel coils
spectre air filter and gotts mod
fuel filter
passenger side cat and manifold
belts
several oil changes obviously
edge tuner (tested with and without)


o2 sensors read correctly, haven't checked flow rate of injectors as I don't have the equipment, but I have ran cleaner through the system(drip effect and through tank) to show no difference. checked all vacuum lines and are good, cleaned maf for oil residue.


also, a few times now long apart I have been driving and it starts missing like its running off 4 cylinders, shaking hardly accelerating at all. not sure if that is related.


that pretty much sums it up. PLEASE HELP. I have rebuilt this truck from light front end damage and it is all new including frame so I don't know where to go unless it could be a jumping timing issue. thanks in advance.
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Old 11-16-2015, 08:58 PM
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What brand of plugs? Have you removed and cleaned the throttle body? When was the last transmission service done? Have you inspected the FPDM? I know some of these may not be the exact cure but all things to consider.
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Old 11-16-2015, 09:06 PM
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I believe the plugs were motorcraft or autolite. Bought at advance auto for like $120 ugh. have not touched tb yet or tranny but it is def engine not tranny as you can feel it even at idle as it hesitates. in all fairness when I first got it I got a couple jerks from the tranny like the tc was sticking and I put in docs red stuff and it actually worked all gone. What is a FPDM? thanks
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Old 11-16-2015, 09:35 PM
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FPDM is the fuel pump driver module. It is located on a cross member next to your spare tire. They corrode and cause all kinds of issues. Its easy to check it. Drop the spare tire and remove it with 2 bolts. Autolite plugs are a big no no.
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Old 11-16-2015, 09:44 PM
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after checking the plugs are motorcraft SP-515 and I did check into fpdm (google). dark here now but I will get into tomorrow evening to see condition. I can say when I changed the frame last year it looked ok from what I remember
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Old 11-16-2015, 10:04 PM
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Good on the SP515's! You have the stock air box by chance? Hard to tell if there are no codes.
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Old 11-16-2015, 10:24 PM
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Yes just spectre filter and gotts mod.
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Old 11-17-2015, 05:17 AM
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Check the foam gasket around the air box... clean the throttle body...need to take it off to clean it properly with TB cleaner...clean the MAF sensor with MAF cleaner too
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Old 11-17-2015, 07:16 AM
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Originally Posted by black mark lt View Post
...but I have ran cleaner through the system...
Which cleaner?
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Old 11-17-2015, 04:13 PM
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Default Checked the fuel replay or what ever its called

so I just dropped the spare tire and check the module. def looks like crap. 2 small minor cracks on each side where water could and probably did get in and if I shake it it sounds like there is a bunch of rot inside it too, needless to say I ordered one anyhow. rockauto $56. once it comes in I will install and I will clean the TB as well. thanks I will post updates as I find
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