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Discussion Starter #1
hello all and yes did the search didint help much but anyways i have a fluctuating idle and miss i cant seem to find its seem fine when i first start it up but like 5 mins after its kinda warm it has an intermediate mis so bad that seem like the truck is gonna die its like some is getting warm and starting to malfunction could it be the coil that is going bad by getting warm?? fuel pump going bad??

things i have done
1 Full tune up plugs wires cap and rotor
2 checked for vacuum leaks ( None )
3 New IAC
4 New TPS
5 Fuel pressure is good
6 New FPR
 

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I actually just having this exact problem with my '90 xlt. Check the throttle head, there may be a gasket missing, i also had to reset my throttle computer. this seemed to fix the problem.
 

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same issue here. I have replaced everything I can think of (needed it anyway) and it was better for a while with the new IAC but it is going back to high idle now. If I unplug the IAC it comes back down. I am guessing a that good cleaning might help. Can you put in some kind of oil in the IAC to help it move easier?? Im out of ideas too...
 

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Discussion Starter #4
alright well the motor was rebuilt last week my mechanic told me it has something to do with the egr system but im not sure what parts to replace how would i check the egr valve my truck seriously sounds like it has a cam but i know there is not thumper cam in it.... the truck sounds like it is going to die could this be a weak fuel pump??
 

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Maybe there is a guarantee that comes with the rebuild.
 

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Discussion Starter #6
well i should have fixed the existing problem... before i had the motor rebuilt i just dont understand what else to do would the egr cause this problem?? the check engine did come on then went away..
 

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Pull codes from the computer, and see what codes are displaying. Just because the light goes away doesn't necessarily mean the problem went away. Usually it flashes intermittantly, but still has a problem. Run both scans. Motor off, and running.
 

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Yes. The system would. Check the vacuum line, and basically the entire egr system.
 

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Discussion Starter #10
alright well the egr code went away now i just have 111 and the bronco still has a stumble when truck is fully warmed up hmmm:banghead you can see the needle just bouncing back and fourth... it feels like the motor shakes
 

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Discussion Starter #13
no it has not ever stalled but last night i took out the distributor and cleaned up the dizzy and it seem to help i think.... but i have that bad stumble intermittent motor shake
 

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Charlie don't surf..
'92 Ford Bronco XLT
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might want to pull the EEC and check to see if there any burnt spots on the board..

have you checked your fuel pressure?
 

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Discussion Starter #15
alright this weird but ive seen on the fourms that if dizzy is magnatized it can cause this problem i took off the rotor and i used a butter knife and it stick to the rod that the rotor sits on is this normal???
 

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Discussion Starter #16
i took the eec out today and does not smell burn nor anything burnt up... this strange any help is much appericated
 

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First off, verify the EGR valve is clean and functioning. Then whenever you replace a TPS, you should adjust the idle so the computer has a reference point. Here is a procedure from another web site. It supposedly comes from Ford racing. I have never done this to a Ford engine, but I have on a SBC and it is about the same.

1.) Get your engine to running temperature.

2.) Un-plug IAC while the engine is running, if it stalls turn idle screw 1 entire rotation, re-start stab throttle, continue this until it idles without the IAC plugged in.

3.) Set the idle to desired level (750-MILD 900-BIG CAM) by adjusting the idle screw, always tap the throttle so it lands in its natural location.

4.) Set TPS between .96 AND .98 Volts with a multi-meter. Loosen the screws and move it around while the meter is attached. Drill out holes more if you can not reach proper adjustment. Use the 2 volt (DC) setting on your multi-meter to get most accurate idle reading. (Do this while the car is still running.)

5.) Stop engine, disconnect negative battery cable wait 20 minutes to reset computer. Turn on headlights and tap the brakes a few times to drain the remaining power. I leave the headlights in the on position the whole time to make sure all power is drained to make sure the computer resets.

6.) Re-Connect the IAC

7.) Re-Connect the negative battery cable.

8.) Start engine, and smile the pain is over! Unless of course you have a bad TPS, IAC, or EGR. LOL
 

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You know what? I see your first guess was the problem was the coil. I think you should go with your gut feeling on this, because alot of times, our gut feeling is right. Maybe it is an electrical problem, like a bad ground, or the tfi module. TFI's show their ugly heads on a hot motor, to my knowledge.
 
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