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Thread: 95 T-bird 4.6 lx suddenly running like crap, help!?

  1. #1
    Join Date
    Aug 2010
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    VA
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    95 T-bird 4.6 lx suddenly running like crap, help!?

    Been reading this site for ages, but finally have an issue I cant figure out on my own.

    I've got a 95 T-bird LX 4.6. I had some time on my hands lately, so I have been working on the car. I replaced the front strut mounts which have needed replacing for a while now. I cleaned & re-oiled my KN cone filter, and a couple days later I check my MAF, and sure enough, it was covered with junk. I cleaned it with a q-tip and some electronics cleaner. So far so good....
    About 2 days after that, I drove to the gym. I come out of the gym, start up the car, and its rumbling a LOT louder than usual and my butt is shaking in the seat. I drive it home, and it seems to drive ok, although the whole car seems to shake/rumble, and that worries me..... I decided to floor it for a sec and see what happens, seems ok/normal till about 3000k rpms, then it takes off like a bullet and gets loud as all hell. Again, its the shaking that worries me....If you get out and look at the car when it's idling, the front bumper is vibrating, which i dont think it did before...
    I tried unplugging the MAF and driving it a bit, and it ran much worse.

    Not real sure what to check next, and friend i've talked to seem as stumped as I am. Whats a good way to check for exhaust/gasket leaks, because when I stick my hand down there, I dont feel any leaks, at least where I can shove my hand in.....
    There are no engine codes at this time, I cleared them when I cleaned my MAF (was reading lean bank 2 prior), and I havent put enough miles on it to reset the sensors yet. Any help would be greatly appreciated.

  2. #2
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    Aug 2010
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    VA
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    Also, this may or may not be related.......

    A couple weeks prior to this I had the rear brakes replaced, as they were original at I just hit 90k. :P I also asked them to check the belt, and they said it looked a-ok. I get it home and the next day I hear a weird rattle when i start it up, i look under the hood and after a few mins find a thing that looks like an EGR valve, but when i look up the part number, its not for my car....strange....
    It was just sitting in there, not attached to anything. So i get it out and look around, everything seems ok, no hose leaks, nothing unplugged etc.
    Start the car up again, the rattle is back. When i hit the gas, the rattle speeds up, and slows down etc when i let off the gas. I had to be somewhere so I just drove with it. After about 10 mins, the rattle is gone. Never came back all day.
    Next morning, go out, start it up, rattle's back......... Thru trial and error, it only seems to rattle when the car is totally cold, and even then its 50/50.

    Not sure if its related to what else is going on, but wanted to throw this in there in case it was. Its possible this noise is my aftermarket exhaust rattling, but I cant prove it yet.

  3. #3
    Join Date
    Aug 2005
    Location
    Paoli Indiana
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    4,549
    Try new spark plug wires! soundsl like it is missing? when it comes to 4.6's they are very very VERY finicky about plug wires! I had to throw away a $120 set of aftermarket wires in favor of MOTORCRAFT which is the ONLY wire that works right on a 4.6! believe me i know! ive had two vehicles with 4.6s and they both gave me trouble until i ran MOTORCRAFT wires they are the only ones that connect to the coils properly! I hade same stinkin problem with my z-71 chased a miss around forever and finaly replaced the fairly new autozone plug wires with AC-Delco wires and bam my miss went away! somtimes cheaping out on plug wires is not the ticket.

  4. #4
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    define its louder, is the exhaust louder? is the rattle from the engine bay or under the car?

    does it sound like the catalytic converter broke up and is causing a restriction hence the shaking?

    check the coil packs for cracks as well if you have a bad coil it will cause it to start missing on more then one cylinder causing a bad shake
    Last edited by TwoToneThunder; 08-16-2010 at 10:25 PM.

  5. #5
    Join Date
    Aug 2010
    Location
    VA
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    Update

    The exhaust is louder IN the car than it was, outside it just sounds a whole lot deeper. Noticed today that acceleration is lacking, really have to floor it to get it moving. Im not sure what a t-bird sounds like when its missing, but i dont believe it is.......slow rythmic rumble, same as before, just deeper and louder.
    Confirmed that cold start rattle is the aftermarket exhaust, its shaking and vibrating, and rattles a little when its cold.

    I tried to think about it logically at work today, and this all *seemed* to happen shortly after I cleaned the MAF, so I found a site with a no-questions asked return policy and overnighted it. I should have it tomorrow. I'll swap it out and see how she goes. If that doesnt fix it, i'll try swapping plugs & wires.
    Coil pack seems A-ok, no cracks etc, although one of the wires on the harness is abraided a bit, but when I grab it with the car on, it doesnt shock the piss outta me, so I guess its ok for the moment.

    How can you tell if the cat's are clogged? Im still feelin plenty of output from the exhaust, and I've been told clogged cat's stink like eggs.... Only got 90k miles on this car.

    I'll keep you posted.

  6. #6
    Join Date
    Aug 2010
    Location
    VA
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    Boredom leads to wrenching on the car at 11pm

    Lol, I think i might be tone deaf, which explains why i never made it in the music industry..... Dentist appt in the morning gives me an excuse to go in a few hours late to work tomorrow, so Im out with a flashlight at 11pm messing with my ride... And I could have sworn it was not missing, and I did a drop cylinder test a few days ago....I guess its a lot quieter around here at night, because I'll be dammed.......Cylinder#8 aint firing, coil is sparking, but its dimmer that usual....turns out thats the one with the abraided cable, go figure. Also heard a very faint ticking, and after sticking my ear to everything under the hood that wasnt spinning, i've narrowed it down to either the fuel pressure regulator, or a more likely culprit, #3 sparkplug thats immediately below it, the regulator literally sits right on it. Im hoping its just a side effect of #8 misfiring, but #3 fires 2nd and #8 fires last, so im not 100% on hope. :P
    So bright and early tomorrow putting new cables on the driver side coil pack and taking it for a spin.....

    Still got the new MAF sensor coming tomorrow just in case....
    If the new cables fix my problem, maybe i celebrate by throwing on a 76mm MAF and keeping the new one in case i break the old one

  7. #7
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    Aug 2010
    Location
    VA
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    New Cables, slight improvement....

    Ok, got all new cables in, and it does seem a little better....
    But its not fixed yet. Guess im going to swap out the plugs next.
    MAF isnt here yet, apparently "overnight delivery" means 48 hours. :P

  8. #8
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    Aug 2010
    Location
    VA
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    New MAF in place

    Shiny new MAF is in now. Reset the computer. Runs better, but I'll be damned the thing is still running rough....

    Had 30 minutes to spare so I tried to yank a couple plugs, no dice, the 2 f--kers I tried have seized. Going to give em a PB Blaster bath when I get home today.

    Also going to borrow a IR Heat Sensor, as a buddy told me about an easy way to check if your cat's are clogged. Basically if the exhaust comming OUT of the cat isnt much hotter than the air going into the cat, its clogged. Seems a hell of a lot easier than drilling it or shoe-horning a sensor into the O2 sensor hole. Magna-flow makes a nice looking cat system, thats direct fit....
    I guess if its clogged, I get a shiny new one....
    Last edited by Wildyeti; 08-20-2010 at 02:09 PM.

  9. #9
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    You swapped the wires before the plugs ??

    Im guessing you didnt even do a resistance check on the wires .. Are you sure they are in the right order ?

    Oh well .. its just a 4.6 ... zzzzzzzzzzzzzzzzzzzzzzzzzzz

    - Dan

  10. #10
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    Aug 2010
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    VA
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    Plugs & Wires

    Ya, couple wires were worn, so they needed a change. It's also a hell of a lot quicker than pullin plugs!

    Plugs are commin out this weekend tho.

    LOL, and hell yes they wired up right.

  11. #11
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    Plugs alone can make the difference. I had a 94 4.6 Tbird with a stumble / slight miss not long ago .. turned out to be the plugs, worth taking a look at.


    - Dan

  12. #12
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    Aug 2010
    Location
    VA
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    Update

    Ok, plugs and cables have all been swapped, and it has really made a difference. I checked the throttle body, and it was spotless, and I have reset the drive computer. What baffles me is the car is still running a bit crappy...
    It seems to shake a bit at certain RPM ranges....If i push harder or softer on the gas pedal, I can make it stop. All of the old plugs looked normal, no crap on them or damage etc.... I found out the oil was low, so it might have been burning a bit of it.
    To summarize it all at this point:
    Plugs and cables are confirmed good. Coils seem fine.
    New MAF, throttlebody is clean, CAI is clean.
    Battery unplugged and drive computer reset.
    No error codes.

    All of that made a big difference, but why is it stull running rough at certain RPM's? Im planning to swap out the fuel filter, and the CAT's (original) are rusty as all hell. I did a temp check on the CAT after ragging it out for a bit, and the intake (between headers and cat) was about 400 degree's. The cat itself was 400 degrees, and the outlet (between cat and muffler) was 200 degrees. Im not sure if that tells me anything.....could the cats be clogged?
    Does any of this sound like a transmission or exhaust leak issue?
    Does it sound like the O2 sensors or Fuel pump?
    There is a ticking sound (sometimes) when I start it up totally cold, used to last a couple mins, after I topped off the oil it now only lasts a few seconds before it stops. Is that lifter/cam rattle?

    There doesnt seem to be any vaccume leaks, and if i put my foot to the floor the car forgets its having issues and takes off FAST!

    Any ideas on what to check/replace next?
    Last edited by Wildyeti; 08-25-2010 at 04:29 PM.

  13. #13
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    Did you use motorcraft wires?

  14. #14
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    Channahon Il
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    i dont see where you changed the MAF transfer function in the eec tuning? just checking to see if i missed something. change the maf = change the tune.

    clean and reinstall the original maf and see where your at.

    swap the coil pack you took off with the one you didnt change.

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