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so i have a 96 bronco with a 302 133k. for the past month or so it starts hard only after it sits for about an hour or so. if i start it in the morning its fine. shut it off and start it back up its fine. only after it sits for a while it cranks for a long time like 6-7 sec or it will spit and sputter at about 300rpm till it idles ok. you can also feel a real slight low rpm miss on light acceleration. i have already replaced MAF, IAC, TPS, FPR, cleaned intake and throttle body, brand new oem injectors, egr valve and sensor, no vacuum leaks, has great fuel pressure, 2 months ago did coil, plugs wires cap and rotor there might be more i did that i forget. What else could it be? i am completely stumped any help would be great thanks
 

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Could be a weak spot in your starter, but that doesnt explain it catching at low rpms and sitting low for a bit. Try cleaning your starter coil and see if it helps.
 

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That's a lot of parts & money thrown at a problem without "pulling fault codes" from the vehicle computer for an initial diagnosis, your first line of defense when problems arise where you might have uncovered the issue much easier $$$$$.....for How To....www.fordfuelinjection.com has it all there for FREE.

Remember new parts out of the box can be bad, a slight miss could still be a vaccum leak somewhere in the emissions system, spark plug wires too close together creating cross over arcing (miss), ignition module begining to fail either TFI direct distributor mounted or remote location mounted module....both of which can be tested FREE including ignition coils at the local auto store but several times for passing grade otherwise then replace.

FPR ..there are no fault codes for this, it's a vaccum issue so you need to test for psi using a fuel pressure guage, IIRC 37psi engine off cranking, 40psi engine running with vaccum line disconnected.

Test the right side of the "starter relay" along with that cable going down to the starter motor for voltage issues, mounted on the passenger inside fender....check and clean ALL wires and cables that converge on the starter relay including it's 2 thick studs...and that the single ignition wire is securely on the small threaded stud.

Put an 850CCA battery on your wish list and the BKO will thank you everyday, check test the alternator is putting out enough voltage to run the system with your current battery.

This may give you some additional insight:

There is a Ford Racing Performance Parts "idle setting procedure" Instruction Sheet (Techline (800) FORD788) steps 1-9 on How To adjust idle by disconnecting the IAC using the throttle body idle stop screw, drilling out the mounting screw holes on a newer "plug & play" TPS so you can adjust it for voltage setting.

In the past the ideal (TPS) setting was thought to be .93-.97 volts or just under 1 volt but recently posted information regarding this appears the setting should be between .55v-.75 volts.

Posted by FSB member Jermil01 recently:
Wanted to update this thread based on some TPS adjustment information I got from one of my tuning sites. This goes against the conventional wisdom of setting the TPS closer to .95 range. Thoughts??

Regarding any ECU controlled function (and idling conditions in particular), before any strategy based adjustment can be made by a computer controlled system, it must first run somewhat normally in a default and OL mode.

To do this with a FORD you must first follow a few rules.

You must keep the TPS input above the deadband area and below the "tip in" area. On a FORD this equates to below approximately 0.9V and above 0.45. Anything above 0.90V the ECU thinks the throttle is starting to open. This brings into affect possible dashpot and fuel cut strategies which can turn one grey real fast. Below approx 0.40-0.45V the system suspects an incorrect input and substitutes a default figure.

So first off, the TPS should be set to around 0.55-0.75V. You can also disconnect the IAC then disconnect the battery for 15-20 minutes, reconnect and the computer should default back to factory settings.


Let us know what you find out...


Good Luck ~ :thumbup
 
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