Engine Car Wont Rev Past 4/4.5k

Discussion in 'Fox 5.0 Mustang Tech' started by omarimoe, Jul 6, 2014.

  1. Proper plug gap for a 5.0 without NO2 or pressurized induction is .050.

    Try spraying a fine mist of water around the plug wires with the engine running in the dark. Look for spark jumping or blue glow a round the wires.

    If you are sure the spark plug wires are good, the ignition coil and TFI on the distributor are the other culprits in a high speed miss situation.

    The TFI module mounted on the distributor is usually the culprit for a high speed miss on a warm engine. If the problem does not occur when the engine is cold, the TFI module is definitely suspect. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.

    Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.

    View attachment 113973

    See Automotive Tools Specialty | Auto Mechanic & Technician Diagnostic, Testing Equipment | Thexton

    diagram courtesy of Tmoss & Stang&2Birds
  2. so while doing a last inspection today before i start buying parts this is what i found. does this look a potential cause of my high rpm breaking up issue? looks like crap to me but what the hell do i know. im going to hit them with some sandpaper and see if it helps at all. i think im also finally going to replace my old worn out wires. i would be really nice if all this car needed was a new cap and rotor.
    dizzy cap.jpg
    dizzy cap2.jpg
    dizzy cap3.jpg
  3. well i had it fixed for all of like 5 mins. i went to napa and got a cheap cap and rotor threw them on and the car was perfect for 5 mins. ran all the way up to redline seemed like it had more power and was super responsive. then it started breaking up again. i took the 5 min old cap off and this is what i found. what the hell is causing this buildup/corrosion on the cap points. there is no way a brand new cap should look like that after a 2 mile drive. dont know if the car not being super hot had anything to do with it or not it was not cold but not at op temp when i first went for the drive.
    dizzy cap4.jpg
    dizzy cap5.jpg
  4. If your plug gap is too wide and/or your wires are shot then it is going to cause issues with the cap
  5. plug gap was set at .040 2 days ago with brand new autolite 25's. im also going to order a new set of wires. i forgot to mention when i did the cap and rotor i took the tfi module off the dizzy to clean the contact points. im now beginning to think the TFI is the main source of my problem. the car had the problem i took the tfi off cleaned the contacts, put a new cap and rotor on, bumped the timing to 16* and it ran great for about a mile and a half then started acting up again. i tried to test the tfi and it all seemed to check out ok. other than a motorcraft TFI are there any other good options out there? my dealer wants $115 for the tfi and late model and American muscle have the dyna mod tfi's for $70. the one on my car isnt an original and says assembled in XXXXXX on the back (cant make it out it's all smudged).
  6. Parts update. I ordered a set of 9mm ford racing wires, a screaming demon coil, a dynamod tfi, and an msd cap and rotor. Everything should be here by Wednesday so hopefully the car will be back to normal. I figure the wires are pretty bad anyway the coil is original and the tfi is some autozone junk so why not upgrade everything. Ill be sure to post back with what I find was the issue. And thank you guys for all the pointers and help.
  7. If you are keeping the car, do not use the dynamodule, that thing is a total piece of crap. Probably last like 6 months then the heat will kill it.
    Use a ford tfi and coil. The rest of the stuff doesn't last.
  8. I've heard mixed reviews on the dynamod's but ive heard nothing but good things about the screaming demon coils. I guess we'll see what happens worst case I can always send it back and get new stuff from ford.
  9. Installed new coil and plug wires today. Still got no change but I expected that and didn't think they were really the problem anyway. Tfi should be here tomorrow hopefully that will fix the problem. If the tfi doesn't fix it what should I be looking at next? Dizzy? I cant think of anything els that would cause this. I bought the car not running and half torn apart. It has new pump, new filter, cleaned injectors, new plugs, new wires, new coil, soon to be new tfi, cleaned maf, cleaned salt and peppers, adjusted tps, new o2's, and checked for vacuum leaks.
  10. ok so i put in the new dynamod tfi today and the car is still doing the same exact thing it was before. at this point i have no idea what could possibly be causing this. new plugs, new wires, new coil, new tfi, new fuel pump, new filter, and i cleaned all the sensors. where do i go next? i recorded a vid of what the car was doing on my phone and figured maybe that would help a little so ill post it up as soon as i upload it. should i try another cap and rotor? when i swapped them out before i also cleaned the contacts on the tfi and after i put everything back together the car ran great for all of 2 miles before it started doing it again. i assumed it was the tfi but should i be looking into another cap and rotor?
  11. so i grabbed another new cap and rotor from the parts store and it seemed to help a little but the problem is still there. someone please help me and tell me what the hell is wrong with my car. i was contemplating selling the car but there's no way i can get what i was going to ask for it with it running like this, and with this current issue i dont really want to drive it. please please please someone point me in the right direction. also this is what my tfi wireing looks like under the loom. is this ok? factory?

    View: http://youtu.be/GF0-3-jeYls?list=UUayMcTRpcToIHfHaRNZME7Q
  12. Wiring shown in your picture:
    It's a little hard to tell, but it looks like someone peeled the outer cover off the TFI wiring harness. It looks like the shield wire that covers the aluminum foil shielding is flapping in the breeze. That could be a problem, since the wiring may be picking up electrical interference from the spark plug wiring. Fix this first because it's cheap, relatively easy to do and needs to be done anyway. It may fix your problem.

    I would spiral wrap the TFI wiring with a strip of aluminum foil. Then lay the shield wire over it and wrap it up with the best quality electrical tape you can find. There should only be about 1/2"-3//4" of the wire that isn't covered by the aluminum foil shield when you get finished. The shield wire is grounded back by the computer under the passenger side kick panel. Make sure it is screwed to the body at that point. Then cover the whole mess with some black wire loom and tape up the ends real good.

    After you have taken care of the wiring problem, here are some other things to think about:
    What's the status of the distributor and PIP sensor? Are the new? The PIP sensor is the other culprit in high speed miss when the engine is warm.
    #32 jrichker, Jul 17, 2014
    Last edited: Jul 17, 2014
  13. the whole dizzy is original or at least old. every time i check/fix something i find a problem but when i fix it my problem doesnt go away, very frustrating. i pulled the upper off today looking for a possible vacuum leak after i fixed the tfi wiring and found the injector harness ground not attached and neither was the body ground. so i figured while im in here i might as well check the injectors. i pulled them and 3 o rings are all ripped up and 2 pintle caps are cracked. the car is a nightmare. before this breaking up issue it never had a problem now i cant seem to stop finding problems. the PO of this car must have just thrown it back together to the point that it would start and run and called it good.
  14. You have become a victim of the previous owners efforts, or lack thereof...

    Be patient and thorough, and you will find and fix all the problems.

    The purpose of the pintle caps is to hold the O ring in place. They keep the O ring from sliding off the injector and down into the intake manifold. Properly installed, they have no effect on performance.

    Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $3-$4 per kit.. The following are listed at the Borg-Warner site ( http://www.borg-warner.com ) as being resellers of Borg-Warner parts:

    http://www.partsplus.com/ or http://www.autovalue.com/ or http://www.pepboys.com/ or http://www.federatedautoparts.com/

    Most of the links above have store locators for find a store in your area.

    Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber.

    The pintle caps fit either injectors with a pin sticking out the injector end or 4 with more tiny holes in the injector end
    The pintle caps hold the O ring in place and keep it from sliding off and into the manifold. If the correct pintle caps are used, they do not have any effect on the injector spray pattern or engine performance.

    Heating the pintle caps in boiling water makes it much easier to install them.
  15. Pintle caps and orings are cheap, but I order online at Advanced Auto using coupon codes and pickup my parts at the store. Can usually save 30 - 40 %.
  16. Take your time and while you have the intake off go through all the wiring, vacuum hoses, seals, etc. and replace everything suspect. I would also replace the thermostat while you are at it. Clean all of the electrical connections with some sandpaper or a small wire brush- CNC also sells a spray youcan use on electrical parts. Put some dielectric grease- the kind you put on the back of the TFI in the connectors. The salt and pepper connectors are a problem area- make sure the pins are clean tight and greased. Check all the grounds- there is another one behind the battery that is a 2ndary ground for the EEC.

    I would get some diagrams of how things are supposed to be hooked up and follow that.
  17. If I ever buy another 5.0, the first thing I am doing is all at once fuel pump/ filter. PIP TFI coil rotor plugs and wires and injector o-rings. all cheap and easy stuff that will give you absolute headaches trying to troubleshoot
  18. so im not sure if i did this removing the old caps or if it was like this but i just noticed that one of my injectors is missing/has a broken needle. do i now need to hit up the junkyard for a replacement or will it fire the same? otherwise i got all new caps and o rings.
    injector needle.jpg
  19. I ran into this very problem years ago on a customer car. Turned out it had the wrong dist. rotor in it. The distance from the end of the rotor to the points on the dist. cap was to great and caused the spark to scatter at higher rpm. I do not know if that is your problem, but the rotor tip should be very close to the contacts of the dist. cap when it swings by. Should be a real easy check .
  20. How would I go about checking that? If I put the cap on to check the distance of the rotor from the cap points I will be covering up the only access point to visually or physically measure how far apart they are? I have gotten 2 new caps and rotors and the problem never went away. Im going to get all new vacuum hose, reseal the intake and install the new injector o rings. If this doesn't help I will rent a small puller and change out the pip sensor in the dizzy. If none of that works ill drentch the car in gasoline, set it on fire and make some smores (not really but im stumped). Could a bad tps cause this? I swaped the original one with a junkyard replacement and set the voltage but never checked it for dead spots.