Yo
Bronco_4life,
Welcome!
I know how you feel about your 88.
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
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.
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19 @
Post Code(s) here according to:
KOEO & KOER
A helper can assist you by counting the codes. Some use their smart phones to record them.
BEWARE OF FAN, BELTS, PULLEYS, HOT HOSES, IGNITION HIGH TENSION WIRES, AND ENGINE COMPONENTS
Or ask local mom and dad parts stores if they will test it for you. The majority of parts chain stores tests just OBDII vehicles now.
Or purchase a coder reader such as;
"Innova ODB-1 and we generally recommend getting the extension cord with it, so you can work the ignition key in the cab while watching/holding the reader. It will save the codes but knowing when to go through the cycles and ensuring you get it right the first time can save time and hassle, especially if you're working on it by yourself, as most of us do." by BikerPepe`.
See my Vacuum leak test in post #11 incl some jowens126 HVAC Control Panel pics/info @
https://www.fullsizebronco.com/forum/21-noobie-bronco-tech-questions-flame-free-zone/206824-help-dtc-codes-idle.html
Some parts stores will loan you a gauge with refundable deposit.
The vacuum gauge should read between 15 and 22 in-Hg depending upon the engine condition and the altitude at which the test is performed. SUBTRACT ONE INCH FROM THE SPECIFIED READING FOR EVERY 1,000 FEET OF ELEVATION ABOVE SEA LEVEL.
The reading should be quite steady. .
When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.
When vacuum leaks are indicated, search out and correct the condition. Excess air leaking into the system will upset the fuel mixture and cause conditions such as rough idle, missing on acceleration, or burned valves.
If the leak exists in an accessory unit, such as the power brake, the unit will not function correctly. Or Air Conditioning when in MAX mode may switch to Defrost.
Air filter, is it relatively clean?
Air inlet atop radiator support to filter box and to throttle body; look for obstruction; damaged tubing, openings in tubing, loose fit at throttle body or if equipped, at MAF sensor.
Fuel quality; Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.
Electrical connectors; inspect for corrosion, etc at coil, firewall, ICM on distributor, PCM, etc. especially those with broken locking tabs.
Try unplugging the Idle Air Control (IAC) Valve.
IAC Location pics & Cleaning by Bobby (blue) @
http://www.supermotors.net/registry/3982/17193-2
Testing..
"First let me say this little thing has many names. But they all talk about the same item under the hood. Here all the names I've had the torture of learning throughout the years:
•Idle Air Bypass •Idle Air Control •Idle Speed Control •Throttle Bypass Air •Idle Bypass •Inlet Air Controller
•Inlet Air Bypass •Intake Air Bypass •Intake Air Control.
This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection.
The IAB can pass and still need repair, or it can fail and not need replacing. The plunger and internal spring can get clogged with dirt and oil. This will slow down the air flow and not allow the IAB to function properly. Remove the IAB and clean it. There are 2 halves to the IAB, and you can not buy just one half, but you can take it apart to clean it. But if the internal solenoid is faulty the IAB needs to be replaced." By Ryan M.
...
This is by Nelbur; "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.
It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. ... ...
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."
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..."
Buy a Motorcraft IAC in event it needs to be replaced.
See the 88s Dealer Brochure @
https://www.broncoiicorral.com/articles/1988-ford-bronco-ii-brochure/
GL!
Al
