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Discussion Starter #1
1992 Bronco 5.0 with e40d
My truck starts and drives like a champ. The only concern I have is when idle I feel a very slight shake like something isn't quite perfect. The engine has 139k on it. I've replaced the cap, rotor, plugs, passed emissions etc. I do have a cracked drivers side exhaust manifold though which should get replaced next week. Could that be the cause or could it be something else?
 

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A few things you could try...

- Clean the throttle body
- Clean the idle air control valve
- Maybe time for a new fuel filter?
- Run some fuel injector cleaner through the system

It's most likely one of these things...
 

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1992 Bronco 5.0 with e40d
My truck starts and drives like a champ. The only concern I have is when idle I feel a very slight shake like something isn't quite perfect. The engine has 139k on it. I've replaced the cap, rotor, plugs, passed emissions etc. I do have a cracked drivers side exhaust manifold though which should get replaced next week. Could that be the cause or could it be something else?
I seen no mention of plug wires....
 

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I'd think the exhaust manifold could cause for it to run a little rough, but like the other guys mentioned you didn't mention the spark plug wires.

While waiting to replace the exhaust manifold, it couldn't hurt to test those wires.

Every 50,000 miles (80,000 Km) or 60 months, the resistance of the wires should be checked with an ohmmeter. Wires with excessive resistance will cause misfiring, and may make the engine difficult to start in damp weather.

To check resistance, an ohmmeter should be used on each wire to test resistance between the end connectors. Remove and install/replace the wires in order, one-by-one.

Resistance on these wires must not exceed 5,000(ohms) per foot. To properly measure this, remove the wires from the plugs, and remove the distributor cap. Measure the resistance through the distributor cap at that end. Do not pierce any ignition wire for any reason. Measure only from the two ends. - AutoZone Repair Guides
If any of your wires test questionable.... replace your wires.
 

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I don't see that you "pulled codes" from the computer to find out what elec./electronic faults might be indicated for initial diagnosis.......it could be any of the above including a vaccum leak some where in the emissions system.......

There are no codes for FPR = fuel pressure regulator because it's a vaccum issue so unless you've been participating in "submarine activities" where mud was involved fouling the system I don't think a dirty fuel filter would have that affect.


Good Luck ~ :thumbup
 

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Discussion Starter #11
Running Fuel Injector Cleaner through the system to start. Will explore the other options if that doesn't work. I'll let you all know. Thanks
 

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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 and 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 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:

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.


See if that helps!


Good Luck ~ :thumbup
 
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