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Discussion Starter #1
hello all. Here is the issue when I start up the Bronco she starts fine and idles fine for about the first 2 or 3 mins, then it starts to idle rough shaking pretty bad. Then when I excelerator it there is a flutter noise coming from underneath the valve cover or thats where is sounds like it is coming from. I just replaced the plugs, wires, tps, ignition coil, oil and filter and I have not pulled any codes yet, just looking for ideas of what it might be and if anyone else has had a similar problem?
 

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I just had a similar problem, is your truck harder to start or does it feel like it's missing?
 

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Discussion Starter #3
It starts fine, it feels like its missing every now and again. The RPMs dont jump at all either.
 

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If you accelerate gently does it make a difference as opposed to if you accelerate hard? My truck would be fine until I got past about half throttle. I think a local parts store would pull codes for you for free. A random misfire code is a p030x. The last number 1-8 tells which cylinder is misfiring and if you get a 0 then it means the misfire keeps moving around. Hope this helps!
 

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yo lumbee1388,
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded

A helper is good to assist in reading Codes; best is to take a cell fone vid and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc.
3.Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
4.Check the Powertrain Control Module (PCM), sensors and actuators for physical damage; IAC, TPS I see was replaced, etc.5.Check the engine coolant for proper level and mixture.
6.Check the transmission fluid level and quality. See E4OD Fluid Condition Check Below)
7.Make all necessary repairs before continuing
8. Check headlights

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)

Then turn off engine and wait 10 seconds.

Do KOEO test First

Post Code(s) here according to:
KOEO
&
KOER

The Self-Test is divided into three specialized tests: Key On Engine Off Self-Test, Engine Running Self-Test, and Continuous Self-Test. The Self-Test is not a conclusive test by itself, but is used as a part of the functional Quick-Test diagnostic procedure. The PCM stores the Self-Test program in permanent memory. When activated, Self-Test checks the EEC system by testing memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

The Key On Engine Off and Engine Running Self-Tests are functional tests which only detect faults present at the time of the Self-Test. Continuous Self-Test is performed during normal vehicle operation and stores any fault information in Keep Alive Memory (KAM) for retrieval at a later time.

Key On Engine Off Self-Test
At this time, a test of the EEC system is conducted with power applied and engine at rest.
To detect errors during Key On Engine Off Self-Test, the fault must be present at the time of testing.

Continuous Memory DTCs are issued as a result of information stored during Continuous Self-Test, while the vehicle was in normal operation. These DTCs are displayed only during Key On Engine Off Self-Test and after the separator pulse. Intermittent faults that have not occurred in the last 80 warm-up cycles (40 cycles on some applications) are erased from Continuous Memory and will not produce a Continuous Memory DTC.Note: The separator pulse and Continuous Memory DTCs follow Key On Engine Off DTCs ONLY.

Engine Running Self-Test
At this time, a test of the EEC system is conducted with the engine running. The sensors are checked under actual operating conditions and at normal operating temperatures. The actuators are exercised and checked for expected results.

Is this happening? If the CEL does not light up at all when starting it; then suspect that bulb is burnt-out or loose, socket was damaged by PO or shop, etc. or someone removed it, which does happen, unfortunately.
... the Check Engine Light (CEL) comes on when the electronic engine control system is not working properly. The check engine warning indicator comes on briefly when the ignition switch lock cylinder is turned to ON, and should turn off when the engine starts. If the check engine warning indicator does not come on when the ignition switch lock cylinder is turned to ON or if it comes on while the vehicle is moving, the system is malfunctioning
 

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Might be a wild guess, but could it be a fuel problem? When was the last time you changed the fuel filter?
 

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If you accelerate gently does it make a difference as opposed to if you accelerate hard? My truck would be fine until I got past about half throttle. I think a local parts store would pull codes for you for free. A random misfire code is a p030x. The last number 1-8 tells which cylinder is misfiring and if you get a 0 then it means the misfire keeps moving around. Hope this helps!
Only the '96 is OBD2 so he won't get any of the Pxxx codes you're talking about. You'd be hard pressed to find anyone that will pull OBD1 codes for free anymore. No chain parts stores that I know of carry the equipment anymore.
 

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Discussion Starter #8
Tonight when I get home I will pull codes and see what comes up, as far as the fuel filter goes I changed it about a year and half ago. And it sat for about a year until I rebuilt the trans in it.
 

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Another wild guess here but, I had a similar problem a few months ago. Had no codes the only way I figured it out was popping the hood in the dark one night I could see one of my plug boots was arching. It had a VERY small tear in the rubber. I know you said yours are new but its worth a look.
 

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Pollux, good point- I overlooked that.
Lumbee, if you changed the fuel filter and then let it sit, maybe there's varnish/bad fuel and you're having a carbon problem?
 
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