Common misfire problems?

Discussion in '94-95 5.0 - Specific' started by Photonfanatic, Apr 14, 2015.

  1. Photonfanatic

    Photonfanatic Active Member

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    What are the most common misfire causes on the 302 cars? I have a 94 GT and its got a bit of a stumble at idle. I talked to my long term mechanic friend, and he said that 99% of the time, its the same problems coming in on the same cars. He said they'll get some odd stuff in every once in awhile, but once you've fixed a few, you begin to notice a pattern. He said nowadays, he can pretty much go right to the problem a given vehicle is having, just because he's fixed that same problem on so many others already. And that its a recurring theme with most vehicles.

    Given his response, I wanted to ask this question. So what is the common misfire that most of these 94-95 5.0's get? My other one also had it. My buddies cars have had it, before they sold them. I'd be willing to bet its something that most, if not all of them suffer from until its corrected. Anyone have any idea?

    I've given it a full tune up, dizzy cap, rotor, plugs, wires, O2 sensors, air filter, fuel filter. It has maybe 5k miles on that tuneup. So what else? What are some areas I could check?
     
  2. Magic

    Magic Well-Known Member

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    Bad injector(s).
     
  3. Photonfanatic

    Photonfanatic Active Member

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    There is also a well known distributor problem, isn't there?
     
  4. JKady

    JKady Active Member

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    Yes there is. EFI Fords are known for the PIP in the distributor going bad/getting dirty etc... and causing a stumble/stall/no start. Ignition modules are also known to fail occasionally. I've got a phantom stumble/miss in my car that at this point I'm willing to throw a distributor at, they're cheap.
     
  5. CC'S95GT

    CC'S95GT Legend

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    A coil is something easily over looked. Yes they do wear out. And its a cheap upgrade too.
     
  6. Michael Plummer

    Michael Plummer Active Member

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    Personally, I think trying to pin-point the source of a misfire is very tough to do because a mis-fire can be associated with so many systems in your vehicle. One system (ignition) for an example can be tied to numerous components (spark plugs, spark plug wires, ignition coil, timing, and cap and rotor). That's 5 components for just one system and when you look at the other systems that can be responsible for a mis-fire the list of likely components can reach up to and over 25 components.

    Nothing can replace good maintenance practices along with quality OEM parts. If you have bad maintenance practices and use sub-par parts then you'll be subject to a vehicle that doesn't perform well in most cases.
     
  7. Photonfanatic

    Photonfanatic Active Member

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    Would you recommend the Accel brand coil? I was thinking of getting that one. Even though its yellow lol, might have to paint it.

    Are you aware of an improved PIP that can be put in there? Vs buying a whole distributor. Anyone got the diagram of all the dizzy guts? I know I've seen that around here somewhere. Perhaps I'll just rebuild my dizzy, minus the cap and rotor since they're still pretty close to new.

    I don't use cheapo parts, I use motorcraft or better. Also you have to be careful with OEM parts, because with some OEM parts, you could just be installing a repeat of the problem you're trying to fix. It will just take the required time to fail, however long that is. Gotta make sure its not an engineering design flaw then you're safe to use OEM. Just like the PIP he talked about, above.
     
  8. Michael Plummer

    Michael Plummer Active Member

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    Sorry but I'm a little confused here. Are you suggesting if the PIP dies in your distributor, it's best to buy an aftermarket PIP or OEM PIP? And what engineering flaw are you taking about?

    Thank you
    Michael Plummer
     
  9. Photonfanatic

    Photonfanatic Active Member

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    Well none specifically. But its well known that some parts are just prone to premature failure, and some quality aftermarket companies will capitalize on this by beefing up the part and selling it as a higher quality replacement. Notice one member said that the PIP is prone to premature failure. Well, if a reputable company like Accel is selling one that they claim eliminates the problem, I'm going to try that one before I go back with the Ford part. Take my 2001 volvo Turbo s80. Volvo had a real problem with their oil return line gaskets, for some reason. I really don't know why they couldn't get it right. But they revised it 3 times, and it still leaked. Over on the volvo forum there was a company that made a part that fixed it, ( i think their name was swedespeed) and I bought that one and never had the oil leak problem again. This type of thing is pretty well known to experienced mechanics
     
  10. JKady

    JKady Active Member

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    A pip is a pip, they get old and they die. Replacing just the pip is labor intensive (require full tear down of the distributor) and with a whole ready to drop dizzy running less than 75 bucks, I wouldn't spend the time.
     
  11. Photonfanatic

    Photonfanatic Active Member

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    Yeah but is that Ford (or motorcraft) quality or above? I've been looking at some of the youtube videos on these chinese remans, and the results aren't good.
     
  12. Michael Plummer

    Michael Plummer Active Member

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    Q) Well none specifically. But its well known that some parts are just prone to premature failure, and some quality aftermarket companies will capitalize on this by beefing up the part and selling it as a higher quality replacement. Notice one member said that the PIP is prone to premature failure. Well, if a reputable company like Accel is selling one that they claim eliminates the problem, I'm going to try that one before I go back with the Ford part.
    A) I'll agree the PIP is prone to premature failure. As far as aftermarket companies producing parts that outlast OEM I would serious doubt that. The aftermarket doesn't have the resources (money and time) to engineer and test parts on an OEM level and that's a fact.

    Now what never seems to be a part of the discussion is why does it fail? Heat is a huge factor when it comes to electronic failure. Did Ford know about the PIP premature failing issue? I believe so but there was no way to relocate the PIP. Ford relocated the TFI module on 94/95 cars due to heat related issues but to replace a component inside the distributor wasn't going to happen. Plus around that time Ford was already developing vehicles without distributors, so why spend resources on a fix?

    So when it comes to electronic part selection, I'm going to select OEM electronics over aftermarket all day, every day because the quality is better.

    Q) Take my 2001 volvo Turbo s80. Volvo had a real problem with their oil return line gaskets, for some reason. I really don't know why they couldn't get it right. But they revised it 3 times, and it still leaked. Over on the volvo forum there was a company that made a part that fixed it, ( i think their name was swedespeed) and I bought that one and never had the oil leak problem again. This type of thing is pretty well known to experienced mechanics.
    A) Well, I'm not an experienced mechanic but I do know my way around some vehicles, I've worked on a few Championship race teams and had the pleasure of working with Ford on a few Mustang projects. In your example above, it looks like Volvo tried to find a fix but they failed in your example above or they were leaning in another direction and it wasn't worth the resources to continue looking for a fix. Now you have to ask yourself, if Swedespeed had a product that was sub-par would they redesign it 3x times?

    In closing, are you trying to get ideas on what could be causing your issue or are you looking for a fix? This site has a few experienced members that will help including myself with your issue. But you also stated you had an experienced mechanic friend so that should be an option as well.
     
  13. ttocs

    ttocs Legend

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    I had the problem of my spark plug wires would pop off just enough that they would sometimes work, sometimes not. They all looked normal but a light tug on them and it would pop right off. I got new cables and installed a loom as well and its been solid since then.
     
  14. CC'S95GT

    CC'S95GT Legend

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    Accel is a quality brand. I opted for a summit brand 42,000 volt vs the 45,000 versions because I didn't think my stock motor would benefit from anymore volts thus saving a dime or 2 in the process.
    My car was missing in the upper RPM ranges and after running some tests on the coil found in the Haynes manual I determined it was faulty.
     
  15. Photonfanatic

    Photonfanatic Active Member

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    I'm not trying to start a flame war, but as an engineering student I can tell you that's not even close to being true. You're referring to engineering in a perfect world. In a perfect world, the engineers at Ford wouldn't have to put up with bean counters. They wouldn't be subject to time constraints. They wouldn't have a budget. Etc, etc. Some aftermarket parts far exceed OEM quality, and that's a fact. Take my bilstein shocks for example. Superior in every way to the stock ford ones. Or my michelin tires. Or hell even upgraded lightweight racing wheels. I could say my Moog HD balljoints are superior to OEM because they have a grease zerk, which will afford them a longer lifespan. My Alpine brand radio far exceeds the Mach 460's capabilities and replaced it due to the fact that the Mach 460 one died on me. Now is this always the case? No freakin' way. I can go down to autozone and get parts that would fail WAY before motorcraft brand parts ever would. It all varies from part to part, and from company to company.

    I can't speak for that particular part, because thus far I haven't even been able to find one made by accel or anyone else for that matter. Then again I haven't looked all that hard. It might actually be cheaper and easier just to buy a new dizzy rather than tear that one down and try to rebuild it. I don't know yet, haven't got that far. But I can tell you that it would indeed be possible to build a heat resistant PIP, which would exceed OEM quality standards.


    I think you might have misread that. What I basically said was volvo tried 3x and still couldn't get it right. Apparently they stopped even trying, because they never did make one that worked as far as I know. Swedespeed came out with a gasket to address the problem, since there were lots of people trying to deal with the issue. Their gasket fixed the problem that volvo seemed unable to. They are a big aftermarket volvo parts seller, or at least they were. This was all back in 2006 and I haven't looked at any of that since I sold the car, so I don't even know if they're still around.


    Back on topic, yeah I'd like to determine the cause as well as fix it. I tested the coil and it was in spec from the positive, to the negative terminals, in terms of resistance. But from both of those, to the coil wire terminal, it said open loop. Aka infinite resistance. Yet the car would still run, so I'm not real sure what the deal was with that. I had another coil laying around that was within spec all the way around, so I put that on the car instead.

    Didn't make much difference, I still have a slight misfire and the car still seems somewhat sluggish and lacks a little throttle response.
     
  16. Photonfanatic

    Photonfanatic Active Member

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    I'll check this out, I only had the problem once on a different car but it could always be happening again. What type of loom are you referring to, and could you please post a pic?
     
  17. ttocs

    ttocs Legend

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    I found this universal kit worked pretty well. The only down side is to get the wires to fit perfectly you basically need to make your own plug wires. You are in luck though as I have decided to swap mine out just for stupid cosmetic reasons to satisfy my wiring ADD and will be putting the new wires on hopefully this afternoon and could sell the set I have on it now made to fit this loom.
     
  18. Michael Plummer

    Michael Plummer Active Member

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    Q) I'm not trying to start a flame war, but as an engineering student I can tell you that's not even close to being true. You're referring to engineering in a perfect world. In a perfect world, the engineers at Ford wouldn't have to put up with bean counters. They wouldn't be subject to time constraints. They wouldn't have a budget. Etc, etc.
    A) First of all, good luck with your schooling. I'm with you, I'm not in the mood for a flame war either. But as an Electronic Engineer myself and someone who has worked with Ford Engineers, I do have some insight on the subject. I apologize for not be able to get my point across as I'm a terrible writer. The parts I was referring to was OEM electrical and electronic parts that Ford has their name on.

    Q) Some aftermarket parts far exceed OEM quality, and that's a fact. Take my bilstein shocks for example. Superior in every way to the stock ford ones. Or my michelin tires. Or hell even upgraded lightweight racing wheels. I could say my Moog HD balljoints are superior to OEM because they have a grease zerk, which will afford them a longer lifespan. My Alpine brand radio far exceeds the Mach 460's capabilities and replaced it due to the fact that the Mach 460 one died on me.
    A) Lots of the parts (tires, shocks, struts, springs) you listed above are not made by Ford. Granted Ford will have design specs for these components but they do have to take into consideration price, longevity, performance, etc. like you mentioned above. While expensive aftermarket companies like Bilstein, Michelin, etc. will shift their focus to performance solely. Not fair to compare performance parts vs. stock parts. Another advantage besides focusing on performance, the aftermarket will always produce a part after the fact (meaning producing something after they had a chance to find the flaws in the OEM piece), while the OEM is usually the first to bring something to market. Believe it or not the GT40 tubular intake was the shit back in the day and is still one of the prettiest intakes ever made for our cars. But I'll agree with........You get what you pay for.

    Q) Now is this always the case? No freakin' way. I can go down to autozone and get parts that would fail WAY before motorcraft brand parts ever would. It all varies from part to part, and from company to company.
    A) Agreed. And the reason why the aftermarket will have cheaper options in their lineup. Which brings us back to "You get what you pay for".

    Q) I can't speak for that particular part, because thus far I haven't even been able to find one made by accel or anyone else for that matter. Then again I haven't looked all that hard. It might actually be cheaper and easier just to buy a new dizzy rather than tear that one down and try to rebuild it. I don't know yet, haven't got that far.
    A) If you had the equipment to do the job correctly, it would be easier to just replace the PIP. But if you don't then it may be easier to just buy a used distributor.

    Q) But I can tell you that it would indeed be possible to build a heat resistant PIP, which would exceed OEM quality standards.
    A) Agreed but no one has done it, I wonder why?
     
  19. Michael Plummer

    Michael Plummer Active Member

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    A couple of questions.
    1) Is the misfire at idle or during cruise?
    2) Is it possible to get a smoke test? Best way to locate unmetered air that may be entering the engine.
    3) What brand of spark plugs and heat range.
    4) Brand of MAF meter
    5) Brand of injectors
    6) Stk. ignition system (I'm not talking about the coil)
     
  20. JKady

    JKady Active Member

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    I don't agree with the pip being easier to swap than the whole distributor, you have to fully break down the distributor to replace it, that's not easier than pop the cap off, pull the old dizzy out and slam a new one in. The reason there isn't some super duty PIP on the market is lack of demand at this point. Its something you really only replace a couple times over the life of a car, almost all the ones I've replaced have been OE in 1995 and older vehicles.

    I also feel that the assumption that because it comes out of a Motorcraft box it's a better part isn't always correct. Small electronics parts often come out of one factory in several boxes, and I've installed brand new parts from just about everyone that were bad out of the box, Motorcraft included.