yo BIG, Did you do that self-test?
Vacuum Leak Test; On an idling engine check for vacuum leaks using a mechanic's stethoscope, or a ~3' garden hose section. Don't spray flammables on a running engine. MIESK5 NOTE; Also check: vacuum hoses; intake manifold gasket & throttle body; PCV line; vacuum reservoirs: EGR Sys Vacuum Tank & 2ndry air (coffee can); AC, heater, defroster, vent control ckt & vacuum tank (plastic ball type), under dash & lines to heat/blend/etc. doors; power brake booster; cruise control ckt, etc.... where applicable
BEWARE OF BELTS/PULLEYS, FAN AND HOT ENGINE
base idle off- 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..."
Overview & 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..."
Source: by Ryan M (Fireguy50) at
http://oldfuelinjection.com/?p=39
Idle Speed Adjustment in Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...A vehicle that won’t idle with the IAC solenoid disconnected is a pretty good indication that these procedures need to be performed. Any good tuneup manual should give you the the details for adjusting base idle and performing a relearn. In case you don’t have a manual handy, here’s the rundown: 1. Unplug the SPOUT connector, start the engine and let it reach operating temperature, then check and, if necessary, adjust base timing. 2. Shut the engine down, then stick a .050-inch feeler gauge between the throttle stop ***** and lever. 3. Disconnect the IAC solenoid connector, shift the transmission into Park, start the engine and allow it to stabilize for approximately two minutes. 4. Adjust the throttle stop ***** as necessary to obtain an idle speed of 675 rpm ±25 rpm.5. Shut the engine down once again, then disconnect the battery for a minimum of five minutes to allow the PCM’s keep-alive memory to time out. 6. Remove the feeler gauge, reconnect the SPOUT and IAC solenoid connectors, then start the engine and allow it to stabilize for two minutes. 7. Goose the throttle several times, let the engine return to idle, then make sure the base idle speed remains in spec. Readjust the TV cable, if applicable. 8. Reset radio station presets, clocks and other programmable accessories that were erased as a result of disconnecting the battery. I’ve mentioned this before, but it bears repeating: Ford has a service kit (Part No. F2PZ-9F939-A) to prevent sludge accumulation in the throttle bores of many of its 1983-92 EFI vehicles (except those with sludge-resistant coatings). The kit contains two gaskets, a spacer plate that you put between the air bypass valve and its mounting boss and installation instructions. Ford says installing the kit will eliminate the need for periodic cleanup of the throttle bore and plate, and as such, no longer covers the procedure under its 5- year/50,000-mile emissions warranty. If you prefer to go a different route, be aware that Tomco recently introduced a similar kit to the aftermarket under Part No. 8491. If you’d like more information, call Tomco at 314- 567-4520 for specific year and model coverage..." Read More
BUT DO NOT ADJUST throttle stop ***** until vac leak tests and Self Test for Codes and more are doneSource: by Bob S at
http://www.motor.com/magazine/pdfs/081999_08.pdf
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..."; miesk5 Note, Tomco makes an idle plate P/N 8491 = to Ford, P/N F2PZ9F939A; Like Ford’s service kit, Tomco’s spacer plat e (arrow) is installed between the air bypass valve and its mounting boss using two gaskets. The two holes in the plate are for bleeder screws, which provide a minimum air rate adjustment independent of the throttle opening.
Source: by Nelbur at Ford Bronco Zone Forums
