Crazy Idle,help!!

[Gawthle]

Ugh. picked up a nice 87 foxbody for 2 grand. everything worked perfect, nice body work etc. lots of little things wrong but all easy fixes.

anyway, it's idling all over the place now (3 weeks later). i can't find any rhyme or reason. idles high when its cold, and hot. when i get off the freeway and when im just stop and go around the streets. sometimes itll idle around 900, other times, 1500, sometime up to 2000 and theres nothin i can do to get it down (i turned the idler screw all the way done, and nothin)

the temp gauage wasnt working, so i figured the computer didnt know when the car was warmin up and wasnt adjusting properly. a mechanic told me to replace the idle control somethin, but that didnt fix anything.

i dunno anything about EFI, i usually just work on blown carb cars. so throw out any ideas you got...even if it's "are you sure there's enough gas in the tank?"


HEELLLPPP ! ! ! !!

 

[wickedstangs]

Idle Air Bypass

IAB TESTING

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.

 

[wickedstangs]

Get yourself a code reader from Kragen or Autozone like 34-40 dollars and post your codes, I can give you a hand.

 

[beejay31000]

it might not be that tho. remember mine was bad and my idle never changed. it was at 950 all the time, no matter what. when we fixed it it started idling high around 1500 before droping down to 1000

 

[wickedstangs]

Idle Hunting

Another possibility could be the O2 Sensor. Idle hunting is an indication of a properly functioning idle air control system trying to compensate for varying fuel/air mixtures.

Proper fuel/air mixture is required at all phases of operation. The Idle Air Control (IAC) Valve attempts to compensate for a low RPM by opening wider, increasing the air flow and in turn increasing the fuel injection time. When the mixture burns completely, the RPM will increase and the IAC will close. Idle hunting is due to the rapid opening and closing of the valve. So a careful check of all the engine operating systems needs to be done to insure they are working properly.

Remember IAC is another name for IAB which is what Mustangs Have.

 

[beejay31000]

emilio....your knowledge amazes me

 

[Gawthle]

i replaced the IAB already. didnt test it, just replaced it instead, lol.

i will go ahead and get a code reader today and post them up after work this evening. thanks guys !

 

[wickedstangs]

Gawthle were do you live? I have a code reader, I will help you check out your car.

 

[Gawthle]

im in newport beach/pomona area, so not that far;but i just bought a code reader. its just been raining so much, i didnt wanna get drenched. so im gonna do it today, and see what i get

 

[beejay31000]

good luck

 

[Gawthle]

Ok guys....i got a ton of codes and i looked up what they all mean and i'm so lost. here's what it told me:

21
67
82
51
21
94
44
82
12
21
94
44
13

so what do i need to repair, fix, and replace?

oh and the base timing is 29 degrees
HELP! ! !

 

[orange395w]

The base timing is not *29 unless you in fact did remove the spout when you checked it. You said that you replaced the IAC, but you never said wether it fixed your problem. That is an awful lot of codes. I would recommend diconnecting the battery for 20 minutes and rechecking the codes after hooking it back up. Some of them may go away and narrow things down a bit. I would check and clean the mass air meter with electronic cleaner if your idle is still an issue.

 

[wickedstangs]

Ok guys....i got a ton of codes and i looked up what they all mean and i'm so lost. here's what it told me:

21-ECT out of self test range 0.3 to 3.7 volts.
67-Neutral safety circuit failure. / A/C circuit was on during KOER Self-Test.
82-Air management 1 circuit failure (AM1/TAB)
51-ECT sensor signal is greater than the Self-Test maximum of 4.6 volts
21
94-Thermactor Air Injection system inoperative (left side).
44-Thermactor Air Injection system inoperative (Right side).
82
12-Cannot control RPM during ER Self-Test high RPM check.
21
94
44
13-Cannot control RPM during ER Self-Test low RPM check

so what do i need to repair, fix, and replace?

oh and the base timing is 29 degrees
HELP! ! !

Just like orange said you need to set your base timing to 10degrees with the spout removed.

How did you do the test? KOEO or KOER?
2 Digit Self-test Codes
Abbreviations:
KOEO = Key On Engine Off
CM = Continues Memory
KOER = Key On Engine Running

 

[wickedstangs]

1st Step

Setting the Timing
Look closely inside the distributor, inside the cap base, you will see the number 1 molded into the cap and into the base. These obviously indicate the number one piston in the compression cycle. In the second picture you can see how I recommend marking the distributor base. First I highlight the “1,” then after I get the engine timing set perfect at 10° I mark that position with a short fat line that lines up with both edges of the rotor. Then I remove the distributor and mark a longer skinny line that shows where the rotor should be pointed before the distributor is dropped into the block. All these marks may seem like overkill, but it is my web site and these are the best ways to do the job. You’ll thank me later when it saves time on distributor work if the need arises in the future.

Before you install the distributor make sure the engine is at TDC for cylinder one, and you have mounted the TFI to the side of the distributor. Drop the distributor so the rotor is aligned with that 1 molded into the cap. Note that the actually positioning of the distributor to the block is not important; we are aligning the rotor inside the distributor with that 1. Make sure there is enough room to rotate the distributor in the block 1/8th turn. You will need to rotate it to set the base timing of 10° before TDC

HOW TO CHECK AND SET TIMING

1. Insure the key is OFF position
2. Place transmission in PARK or NEUTRAL, A/C and heater in OFF position.
3. Connect timing light.
4. Disconnect the single wire in-line SPOUT connector or remove the shorting bar from the double wire SPOUT connector. Examples of the SPOUT connector:
SPOUT connector on our EFI harness:

SPOUT connector on Remote TFI vehicles may be on the inner fender:

5. Start the engine. To set timing correctly a remote starter should not be used. Use the ignition key only to start the vehicle. Attaching a remote starter might disable or initiate the start mode timing after the vehicle is started.
6. Read the timing from the engine dampener on the crank.

7. If the timing does not read 10° before TDC continue to step 8, if timing matches 10° before TDC skip to step 10.
8. Shut engine OFF, and loosen distributor enough so you can twist it with your hand. Do not loosen it to the point where the engine rotation moves the distributor.
9. Re-start engine and twist distributor to a point where 10 can be read aligned with the timing pointer.
10. Shut engine OFF, reconnect SPOUT connector, and insure the distributor hold down bolt is tight.
11. Re-start engine.
12. Check timing advance to verify distributor is advancing beyond the initial setting. (This confirms Computer control)
13. Shut off engine and remove test instruments.

YOUR SPOUT IS GOING TO LOOK SOMETHING LIKE THIS

 

[beejay31000]

wow, thats a lot of good info...reminds me of the things we had to do to get my car running right.

Gawthle they know what they are saying, i had about the same number of codes, and since we spent about a half days work i havent had a single check engine light

 

[Gawthle]

The base timing is not *29 unless you in fact did remove the spout when you checked it. You said that you replaced the IAC, but you never said wether it fixed your problem. That is an awful lot of codes. I would recommend diconnecting the battery for 20 minutes and rechecking the codes after hooking it back up. Some of them may go away and narrow things down a bit. I would check and clean the mass air meter with electronic cleaner if your idle is still an issue.

well the code reader i purchased told me to set up the car in a specific way, which i did, and then to time the car and it said, and i quote "to find the base timing..." "the base timing should fall between 27 and 33 degrees". i thought that was rediculously high cuz i run my other 302s at 10.

Just like orange said you need to set your base timing to 10degrees with the spout removed.

How did you do the test? KOEO or KOER?
2 Digit Self-test Codes
Abbreviations:
KOEO = Key On Engine Off
CM = Continues Memory
KOER = Key On Engine Running

i did everything the manual said to do. i did key on, engine off which gave me those codes and then the continues memory. then i did key on, motor on, then it had me erase the continues memory codes, and then it had me disconnect the PCV valve, run the car, do a WOT test and a power steering test, and it gave me some codes from that too...

 

[wickedstangs]

i did everything the manual said to do. i did key on, engine off which gave me those codes and then the continues memory. then i did key on, motor on, then it had me erase the continues memory codes, and then it had me disconnect the PCV valve, run the car, do a WOT test and a power steering test, and it gave me some codes from that too...

Now do what I or Orange say. Don't worry about power steering test that is for 94 and up mustang. Make sure to set you timing to 10degrees with the spout off., Next clear all your codes. Our next step is to fix the KOEO codes first. Go and do that and tell what your codes are YES again. Want you to get useto doing it.

 

[Gawthle]

Now do what I or Orange say. Don't worry about power steering test that is for 94 and up mustang. Make sure to set you timing to 10degrees with the spout off., Next clear all your codes. Our next step is to fix the KOEO codes first. Go and do that and tell what your codes are YES again. Want you to get useto doing it.

the timing is at 10 on the dot.

moving on

i already cleared all my codes, and double checked all the codes and they were the same. i dont mind doing things a few times to double check things

i think i forgot to mention earlier, when you start the car, hot or cold, you have to hold the throttle to the floor, i know its EFI, but i think it works cuz i'm letting more air through the throttle body? if you try cranking it without stepping on the gas, it will never fire.....

 

[Gawthle]

I would check and clean the mass air meter with electronic cleaner if your idle is still an issue.

and does my model even have an air mass meter? where it at?

 

[beejay31000]

The '86-'87 Mustang 5.0 port fuel-injected engines used SD fuel control, with a return-style fuel flow system. Note the lack of a MAF sensor on the air inlet.