My linkyo Steven,
WELCOME!
Here is Ford's High Idle & Dieseling Troubleshooting Chart
Have you tried using a vacuum gauge yet?
Vacuum Gauge Diagnosis - BEST!; Normal engine; Steady gauge 18"-20" at all speeds..." READ MUCH MORE
Source: by Craig U at
http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
Some vacuum lines/ or component may be bad under dash; or @ firewall for diveter valve, check valve or vac storage tank for the HVAC system.
re; "...the idle ***** is all the way out..."
This is an indication of a BAD attempt by a previous owner or shop at trying to adj the idle.
To adjust;
Transmission is in PARK (A/T) or NEUTRAL (M/T).
Parking brake is APPLIED (automatic brake release is DISCONNECTED where applicable).
Wheels blocked.
Cooling system is filled to proper level. Engine is at operating temperature.
All accessories (heater, radio, lights, etc.) OFF.
Throttle lever is resting ON the throttle plate stop *****.
Ignition timing is set to specification.
With engine OFF install specified feeler gauge between throttle plate stop ***** and throttle lever. Automatic transmission .030 inches, manual transmission .030 inches.
Unplug SPOUT line and verify that ignition timing is 10°+/- 2°BTDC.
Disconnect idle speed control-air bypass solenoid.
With transmission in NEUTRAL (M/T) or PARK (A/T): Allow engine to idle for 2 minutes.
Check/adjust idle rpm: Turn the throttle plate stop ***** to 780 +50 rpm C-6 automatic transmission, 730 +50 rpm E4OD automatic transmission, 730 +50 rpm manual transmission. NOTE:
If you must turn the throttle stop ***** IN, turn engine OFF and make estimated adjustment. START engine and repeat Steps 4, 5, and 6 before continuing.
Remove feeler gauge from throttle plate stop ***** and throttle lever pad.
Reconnect SPOUT line.
Turn engine OFF and reconnect idle speed control-air bypass solenoid, verify the throttle is not stuck in the bore and linkage not preventing throttle from closing.
START engine and stabilize for 2 minutes then goose engine and let it return to idle, lightly depress and release the accelerator. Let engine idle, if problem exists, see Diagnosis by Symptom (Diagnostic Routines.) NOTE: A condition may occur where the engine rpm will oscillate. This can be caused by the throttle plates being open enough to allow purge flow. To verify this condition, disconnect the carbon canister purge line and plug it. If purge is present, the throttle plates must be closed until the purge flow induced idle oscillations stop.
On Automatic Overdrive Transmission (AOD) applications check TV pressure adjustment, See my site
The idle ***** specs are also shown in this TSB's Chart (left side, bottom panel);
Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."
Source: by Ford via Steve83 (Steve, That dirty old truck) at SuperMotors.net
Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others, Modification; "...I have spent some time this week trying to set up an air bypass around the IAC valve by cutting away some of the gasket between the IAC in and out air holes, rather than pay big bucks for Fords spacer kit. I cut away the center of the original IAC gasket from the outside of each hole to the outside of the other hole, giving about 1/2" gap for the air to pass through. I noticed an immediate improvement in the engines starting behavior, but it would still die occasionally. For most of my trucks life it has been dying when it was started hot. It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. It would never die when cold as the IAC would keep the idle speed up, and it never died at stop lights. Now it's worst situation seems to be when it has been shut down for a half hour or so, and restarted. I wonder if the heat soak is fooling the ETC into thinking the engine is warmer than it really is. I decided that more improvement could be had if I had a thicker gasket, because the original IAC gasket was very thin (0.018"). I had some 0.030" gasket material so I made my own with the same 1/2" cut out. This gave enough bypass to noticeably raise the idle speed and almost eliminate the dying. After maybe 50 starts in the last few days, it only died twice. After so many years of catching it with the accelerator it is darned hard to leave my foot off it. It is clear to me that by trial and error one can tune the air bypass without the need for the expensive Ford kit. I may combine the two gaskets for more bypass, but the idle is about as fast as I would want now, especially for driving in snow..."
Source: by Nelbur at Ford Bronco Zone Forums
DTC 15; "...is for Keep Alive Memory Test failure, usually it occurs after the battery or computer has been disconnected, because the continuous power to the EEC was interrupted. After clearing codes and retesting, this code should go away. If it does not, check for "hot at all times" power at pin 1 of the EEC connector, there should be 12v there key on or off. Check for good ground on pins 40 and 60. You can use a test light to verify good power and ground here, with the connector disconnected. A good terminal to pin fit is also essential for a good connection. It is possible that an internal computer fault could exist, first check for a bad solder joint where pin 1 connects to the main circuit board inside the EEC, resolder as necessary. If the fault remains after good power, ground, and connections are present, then replace EEC. To test itself, the computer runs memory tests and compares the results to saved values called checksums. If the results don't match the checksums, the computer is programmed to set a code 15. It's not common for memory chips to fail, but it does happen..."
Source: by Brian
DTC 67; "..One poss is that the NSS (or also called the MLPS) was ok...or connector was/is bad/corroded; or AC was left on, or transmission was in gear during the Self Test..." read more
Source: by miesk5 at fordfzone.com
DTC 67 Neutral Drive Switch (NDS) Circuit Open; "...In some cases all of us at one time or another have had to "jiggle' the column shifter to get the vehicle to start because over time things losen up from DD useage.....in the Haynes Manual transmission section and www.broncolinks.com there's a diagram referring to "Point A" which is the column shift linkage and the transmission tab. A sure way to correct the "jiggling" is to go underneath the BKO on the drivers side and LOSEN the "nut" on column shift linkage and tranny tab JUST ENOUGH to click the tranny tab all the way back until it stops then 2 clicks forward and tighten the "nut".....now the column shift linkage and transmission are in sync when you go thru the grears, assuming the steering column is in resonable condition this should help correct that problem.......TOO MANY TIMES THE NSS IS DEEMED THE CULPRIT for none start when it isn't so this is a simple check to make sure. There is also another PRNDDL adjustment, but you need to remove the black plastic collar on the steering wheel, this is usually done when an actuator breaks and using pliers drive the rod downward with key on to start.....there is usually a white cable that wraps around and attached to a small mm ***** IIRC that when lossened a bit it allows you to adjust the "needle" that registers on each letter of the PRNDDL..be careful because it's attached with a very fine wire loop and easily broken. The "upper ignition actuator" is another culprit because they're made of cheap *** metal.....and a PITA job to do..."
Source: by JKossarides ("The Bronco", Jean)
Consider Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993; & Ford Fuel Injection and Electronic Engine Control: How to Understand, Service, and Modify All Ford-Lincoln-Mercury Cars and Light Trucks, 1980 to 1987 by Charles Probst
avail @ BARNES & NOBLE, AMAZON, E BAY, ETC.
