Power loss at 3k RPM?

Discussion in '94-95 5.0 - Specific' started by B.mad, May 25, 2014.

  1. B.mad

    B.mad Well-Known Member Preferred Vendor

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    Sorry if its a long post

    Ok so ive been having some problems with power at higher RPM, it seems like when i hit a bump the power at higher RPM's seems to surge (1,2,2.5 =power; 3+=no power; 3,3.5=power sometimes, 3.5+= no power). Also i noticed that if i hang in 1st gear so a while, i.e accelerate to 3k, hang in at 3-3.5k, then accelerate to about 5k with all the power i can want, shift into 2nd and loss the power. My car was (not sure now) throwing codes (176,181,186,189), and throws them at either higher RPM (3k+) or at highway speeds(55 MPH+). And after revving at idle at around 3k RPM when it goes back down, it hangs at about 1000-1100 for a sec and drops down to about 500 then back up to about 750ish (thats where it idles). Usually takes a little longer to start during cold starts, warm starts are alot more quicker. The only aftermarket "high performance mods" ive done are CAI, O/R H pipe, and magnapack catback.

    Ive changed out my O2 sensors(NTK), changed spark plugs (NGK Platinums gapped at approx .054"), spark plug wires (Ford Racing 9mm), and changed my fuel filter and ive fixed an exhaust leak (still have one but barely, shouldnt make a difference). And the Dist. Rotor was changed recently (not by me). Ive cleaned out the TB (stupid i know, but i didnt know) and removed, unplugged the IAC and cleaned it as well (car was off when i unplugged the IAC). There appears to be no leaks of any sort (vacuum, fuel, air) as i can see, hoses are not cracked, with the exception of the PCV (couldnt really see it), but i dont have any oil consumption issues. I disconnected the MAF, and it idled fine, however when i rev it, the car died once the RPM went down. I do have a squeaky pulley and a rattly AC, but i doubt this will make me have these issues. I dont want to try the IAC because i dont want to screw up my idling. I saw the timing marks and they match up so it shouldnt be a timing issue. I havent checked the fuel pressure or fuel pump. Could it be the lack of back pressure due to the o/r mid pipe? Could it be a bad coil? or distributor? fuel pump? injectors? has anyone had this issue before? I am not a mechanic and i do not have any experience with these type of things. could really use your help.



    https://www.youtube.com/watch?v=HcIY39I_7fY&feature=youtu.be
     
  2. CC'S95GT

    CC'S95GT Legend

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    Mine was breaking up over 4000rpm's and I traced it to the coil. But it could be the platinium plugs too. The 5.0 don't usually like them much.
     
  3. B.mad

    B.mad Well-Known Member Preferred Vendor

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    but would the plugs really cause this?
     
  4. CC'S95GT

    CC'S95GT Legend

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    I've only used the copper plugs but others on here have tried the platimiums before with poor results.
    When did the miss begin and how long after you switched to platimiums?
     
  5. familytruckster

    familytruckster New Member

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    By which codes you are getting, I'd say MAF is bad.
     
  6. B.mad

    B.mad Well-Known Member Preferred Vendor

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    actually it was acting like that before the platinums, and maybe after a day it started missing like it did in the video.
     
  7. B.mad

    B.mad Well-Known Member Preferred Vendor

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    and you sir are correct. I ended up disconnecting it and drove it down the street with massive gains in power and no missing.
     
  8. familytruckster

    familytruckster New Member

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    Isn't is fun troubleshooting when everything except the bad part is throwing codes?

    Went through all that BS on my BMW, then a buddy told me.... If it's always lean, it's the MAF. (once you've eliminated everything else) Sure enough, tossed a used MAF on and it was fine.

    Same thing with my GTS. Ran like crap cold, lots of pinging under load with 10* base timing, 93 octane, everything tuneup related was done and checked out. Swapped the MAF, and now 87 octane and no pinging.
     
  9. B.mad

    B.mad Well-Known Member Preferred Vendor

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    yaa. good thing i didnt start replacing the pump or coil, plugs and wires were due anyways but if i replaced other things it would of really set me back. but thats a really good tip, i will definitely keep that in mind !