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new motor, running like crap


rangerboy1986

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my old motor was running great until i sunk the truck in a mud hole and hydrolocked it.. i pulled the motor out and dropped in a used one out of a 1987 ranger/B2.. i never heard it run but the guy said it ran good, no overheating ticks or knocks.. only problem was a broken distributor cap and the injector harness was diffferent between the 90 motor and the 87..
I swapped on the old distributor cap and injector harness from the 90 motor.. well i got it started and it seemed to run pretty good. sounded like it hadnt been started in a few years. Well, i bought new plugs for it and i swapped out 1 of the old plugs for a new plug and it seemed to run the same.(i was sick and working all day in 90 degree weather so i could only do 1 plug that day).. I went out the next day and swapped the other 5 plugs for new ones and it runs like crap :dunno: .. sounds like its misfiring or the plug wires are hooked up wrong. i looked online and the wires seem to be right, plugs are gapped right.. I took the TPS off the old motor and put it on the new one and it sounded like it smoothed out a little but not much of a difference..
Well i put on new wires and it still runs the same..crappy.. when it starts it acts like its gonna cut off, if you get on the throttle real hard it bogs down like its gonna cut off then picks up, if you try to climb up a hill it chugs and acts like it wont make it.. and the tach needle flunctuates like crazy during idle and driving.. it had nothing but manifolds so i put a flowmaster on it hoping some backpressure would help and it did nothing. i have no idea what this could be... :icon_confused:
My other ranger with a 2.3 got new plugs once and i cracked the ceramic on one of them and it ran just like this until i took out the cracked plug and replaced it for a good one.. so im stumped.. i dont think its a blown headgasket and i pray it isnt.. but i have no idea at this point.. it starts easy but runs rough. i need ideas on what it could be and what to do..
 
Last edited:


RonD

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With engine warm cup your hand over the throttle plate, or air plenum at air filter with engine idling, if idle goes up or smooths out then you have a vacuum leak, your hand restricting the air coming in balances the mix.

Unplug the IAC(idle air control) while engine is idling, engine should die or almost die, if nothing changes clean IAC and recheck, if same results get a new IAC.

Check new wire for injectors.
If injectors have been sitting a long time they may be stuck and varnishy, run some Seafoam in the tank.
V6 injectors fire 3 at the same time, usually it is in banks, 1, 2, 3(left side) then 4, 5, 6(right side), the 2.9l does 1, 2, 4, then 3, 5, 6, which can cause a rougher idle if one injector isn't firing.
With key on one wire on each injector should have 12v, second wire is grounded by the computer to make it fire.
With engine idling use a small hose as a stethoscope and listen to each injector, you should hear a click each time it opens and closes.

If you can check the fuel pressure do it, 32psi-42psi is spec.
Check fuel regulators vacuum line, remove it and check for gas or gas smell, if there is gas in that line then fuel regulators diaphragm has a leak which lowers pressure but also allows raw fuel to flood the engine.

You should have a MAP sensor not a MAF, the MAP is a small sensor located on the firewall, follow it's vacuum line to find it, these are hard to test but check the vacuum line, needs to be "mud free", lol, and no cracks.
This sensor tells the computer the air flow in the intake, if it's not working right mixture won't be right.

Tach jumping could mean a distributor problem, if you have one to swap do it
 
Last edited:

jhammel85

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Did you ever check timing? It might even have the distributor off a tooth. Try rotating all wires clockwise or counter clockwise and see if that helps.
 

adsm08

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Check time, it may have gotten messed up when the dis got hit.
 

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