I can hear this high-pitched noise in the first part, then what sounds like a chirping bearing in the second. But those are just guesses, so you'll need to narrow it down. You can buy a mechanic's stethoscope, or you can do the cheap route and use a long cardboard tube - the one from a roll of paper towels will work. Stick one end up to your ear and hold your hand over it and your ear so you can't hear anything else but what's at the end of the tube.
Move the other end around the engine bay until the sound gets louder, and you'll be able to narrow down where the noise is coming from.
I really don't knowYou're gonna have to do better than that, I heard all kinds of noises.
Is the throttle body stock?
That is a home made restrictor plate, a way to reduce the Idle Air flow. It is likely they do not know how to do a base idle reset, or the IAC was stuck open.
You are right again. I've removed the "home made restrictor plate" but rpm start with 2000 . I wonder how can i base idle reset ( i've been searching almost 2 hours but can't find anything except "there is not a stop screw on 94-95 mustang") . Shall I need to replace throttle position sensor and Idle air control valve, if i can't reset?
OK, now you have gone through the list and eliminated most of the possible problems. Now your mechanical and electronic problems are fixed, you can set the base idle speed.
Setting the base idle speed:
First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. If you have a wild cam, you may have to raise this figure 100-150 RPM or so. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s. This figure will increase if you have a wild cam, and may end up between 800-950 RPM
Remember that changing the mechanical idle speed adjustment changes the TPS setting too.
This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.
Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. A wild cam may make it necessary to increase the 600 RPM figure to 700 RPM or possibly a little more to get a stable idle speed.
Changing the mechanical adjustment changes the TPS, so you will need to set it.
When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads. A wild cam may make this figure somewhat higher.
An engine that whose idle speed cannot be set at 600 RPM with the IAC disconnected has mechanical problems. Vacuum leaks are the #1 suspect in this case. A vacuum gauge will help pinpoint both vacuum leaks and improperly adjusted valves. A sticking valve or one adjusted too tight will cause low vacuum and a 5"-8" sweep every time the bad cylinder comes up on compression stroke. An extreme cam can make the 600 RPM set point difficult to set. Contact your cam supplier or manufacturer to get information on idle speed and quality [/INDENT]
Recommended procedure for cleaning the IAC/IAB:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damages some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. Reassemble and reinstall to check it out.
Gunk Dip type carb & parts soaker:
Thanks to Tmoss & Stang&2birds (Mustang FAQ - Wiring & Engine Info) and Ford Fuel Injection) for diagrams
Now for some fixes courtesy of those who have made suggestions that worked for them.There were a lot of good ideas, but I only have a limited amount of space. These are some of the highlights...
Idle bypass plates - they work for some, don't for many. The idle bypass plate fits between the IAC and the throttle body and allows a screwdriver adjustment of the idle air. A side benefit is that it adjusts the idle air without changing the mechanical settings. This keeps you from having to re-set the TPS voltage settings every time you make an adjustment. Here is a link to mustangs unlimited. "Idle Adjustment Plate". http://www.mustangsunlimited.com/it...y=&catkey=74-01 or from your local Ford dealer, use #f2pe-9f939-aa as the part number for the idle air adjuster
From dwhiskie and Hissin50: I mounted my aftermarket IAC upside down, no more surge.
Ranchero5.0’s comments on engines with other than stock cams:
A little dragon slaying lore here:99% of the time on a cammed car opening up the divider between the ports on the IAC with a dremel so the motor idles at 1000rpm with the IAC unhooked, the throttle plate shut and the TPS at .98vdc fixes all surge related problems. Found about to do that on my '93 with a very mild cam and good induction it didn't like idling below 900rpm. The IAC can't react quick enough to a lopey cam induced RPM fluctuation so instead of dampening the surge it increases it. Every E cammed car I've ever worked on needed this to keep a stable idle. Similar to Fords idle bypass plate without the cobbled look. Just dremel out a little at a time till it idles around 1k. In my experience the stock puter doesn't like to idle a cammed car down low.If that doesn't do it check the 12vdc to the heater on the O2's. One smack of wiring on headers wipes out the fusible link hidden in the wiring on the engine side of the firewall where the main puter harness goes through. This will cause the o2's to slowly go out of tolerance and the puter flips out. check this if the car's running really rich a idle too. Ranchero got nailed when first installed and the '93's done it too. I actually ended up soldering on a stereo inline fusible link and installing a 20a fuse to make the repair quicker.For an elaboration on the o2's. The two white wires on the o2 sensor are for a the o2 heater. Without them working ,especially on long tubes the o2's cool off at idle and slow cruise and stop working correctly and the puter flips out. Use a paper clip or two and check for 12dvc between the two wires. No voltage, no heaters. Ford actually made a change and put the fusible link on the outside of the harness in the early 90'sMore to come as I get time...Jamie
Blackfiveoh's approach to the same problem was solved by trimming the gasket between the two ports inside the IAC. Same effect and a easy way to test the results to see if it works for your car.
From Snake1
If you have R12 in your A/C you might want to check the charge on your A/C.
Low Charge = hunting idle Only possible if the hunting idle only happens when the A/C is on.
unplug your compressor and see if it makes a difference. It did with my 88 GT and it went to a steady 650 RPM.
jrichker's notes: This is one that will get you if you aren't careful, and it will do it with R134 too. Watch the A/C clutch while the car is in neutral and idling. If it cycles on and off, frequently, you are either low on refrigerant or have a misadjusted low pressure cut out switch. The cutout switch is supposed to shut off the compressor electrical power at pressures below 18 PSI. If it is set too high, then the compressor will cycle on and off continually, causing an idle surge.
From ArtMan with a supercharged 5.0
One other cause of a surging idle that may have already been addressed (I didn't read every post of the past 5 pages) is one that afflicts supercharger owners.After installing your Vortech you may find that the engine won't idle correctly. If you are able to rule out the other causes noted above, you should verify the crankcase is vented properly. This doesn't effect all sc owners the same, but be assured its an annoying problem.The nipple at the oil filler can suck in air at idle. If this happens air is ingested into the combustion chamber that is not metered by the MAF. An erratic or sticky high idle results. When Vortech first sold their kits they had you run a hose to the filter "area". Now they include bosses so you may run a hose from that nipple to the intake elbow that fastens to the compressor. Since I own an older kit I had to order the updated elbow special.But it cured my surging idle instantaneously and the car runs like silk (even with my cam)
From garystocker:
I had an idle of 1500rpm. And an occasional surge. Stayed that way until I disconnected the throttle cable! Idled right down!!
I pulled the cable backwards out throught he maze of vacuum lines and rerouted it in a nice sweeping way...Perfect idle. No surge. No 1500rpm. Bliss!
the idle screw is located on top of the throttle body-
I included the post about base idle reset-the while surging idle thread I stole it from is a really good source for future issues etc.
sorry RaggerGT but i really don't understand "priming"That’s the fuel pump priming
Is it normal that sound?Sorry-it’s the fuel pump turning on and pumping fuel through the lines for the start up
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