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iac ohms test

boggs1227

Explorer Addict
Joined
February 19, 2008
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City, State
Flowery Branch , Georgia, 1994 sport 2wd auto
Year, Model & Trim Level
2005 colorado 2wd 5spd
today i decided to clean the iac again to see if i just did not get it clean enough ,but before i did i looked in the haynes manual and it says that if ohms on the termials are 10k or less then there is a internal short and to replace. i tested and got 9.7/8 ....almost ten but dose this mean that yet being so close to 10k ohms it's still shot ??

has anyone dealt with the iac enough to say that 9.7/8 is still good or should the reading be more like for example 11-12k ?
 



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anyone ? ....come on now ........ :)
 












To answer your question, yes your IAC is bad, you are not only measuring the resistance of the actuator coil (actually, it's a stepper motor) but also the shunt diode across those terminals. Less than 10K and the diode or coil windings are shorted , if you check the resistance with the probes reversed and it doesn't read 7-13 ohms you have a diode that is open and you are only reading the resistance of the coil.
 






ok if i get this correctlly .....it's bad with 9.7 ohms measurered off the truck with my meter and i don't really need to replace the ect sensor....right?
 






..... thanks ........
 






...Were you able to get your problem resolved???
 






i'll let you how it turns out tommorow when the yard will be open ...considering that new it's a $ 60-70 part ...at pull apart it's $5.79 so we will see . right now when you crank it ...it would do all what i described before except in random bursts but now ....it won't idle worth a crap not even fora minute at time.you can feel the engine want to idle correctlly but it's like it can't catch it's breath with out giveing it some peddle...even then it wants to take over the throttle while the peddle is up to say 1500 rpm.let off and it wants to go back to 400-500 then downwards till it starts to sputter.take the iac off and give it some gas and it's fine and smooth .

with 203k on it and it being the stock one that came from the factory it's time for it to go belly up i guess ....it had a good life lol.
 






ok ...today i bought 3 used iac's and put the best looking one of the 3 on and at first start it acted like it did before with the eractic idle then it cleared up after 30 seconds of the engine running ....took it for a 20 mile trip and it drove great ( even the pulse in the engine had disappeared ) stopped and turned off the truck for about 20 minutes then got ready to leave to go back home and as soon as i started it ....i was right back to where i was before with bad idle ( but it did not do it as bad as before i replaced it) but yet still going down the road my pulse was back and the engine wanting to take over the gas going down the road .

so in the other thread that shaggymane posted about a similar problem being casued by the ECT sensor ...do you think this is what i'm faceing as well ?

...faulty ect sensor is out of spec and the engine does not know if it's cold or hot and is telling the iac to open and close quicklly ?? then why in the heck did i leave and it drove like a dream then after 20 minutes of being off it was right back doing what it had been ?
 






....Did you clean the new IAC before you put it in???...Did you disconnect the battery before you put it in???...It takes the computer a few starts and like 50 miles to reset it self if you didn't disconnect the battery first....You can also short out things when you swap electrical parts while the battery is still connected...

...It could possibly be the ECT...Are you getting any stored codes...And Your computer will be compensating for changes for both, good and bad parts...
 






yes before i unhooked and replaced anything i disconnected the battery.right now i just got home from another trip tonight 40 miles round trip plus the other 20 i drove earlier about 50-60 miles all together and tho it's not quite as bad it still does it .the iac i installed ...no i did not clean it but looked very clean for the most part .plus also tonight i went out and bought a new ect sensor .( one of the only 2 sensors i did not replace when i was trying to get the truck running after i bought it )

did not check for any codes but yet my cel was not on as well from any of this .we'll see tommrow morning when i replace the ect and flush the coolant system how every thing turns out .
 






well-allrightythen.......replace the ect sensor today...flushed the system,cleaned out the new used iac i bought and slapped it all back together and when i first started it acted like had been for about a minute then it cleared up .at this point now i have drove on it for about 30-40 miles today and it "seems" to be actting normal ( keeping my fingers crossed) and it has not been giveing any problems and seems ok .

i want to say it was a 2 part problem ...out of spec ect sensor and a failed iac together .the ect sensor had ford stamped on it and also had the factory orange thread sealant on it so i know no one had ever replaced it .so the iac and ect with 203k on it i think i would go belly up too .

but the true test of seeing if it's fixed is to go start the truck tommorow morning cold over night and see it it starts normally ...knowing my luck it won't so i don't really want to say it's fixed completlly and jinx myself ;)
 






...Fingers crossed and knocking on wood, I think you got her fixed...:biggthump
 






...Any update on it starting in the morning???...:popcorn:
 






ok....... it still does it ....... starting up cold it goes right to 400 rpm's and when you give it gas it takes it about 1-2 minutes of steady throttle to keep it from going down in rpm's and chugging out .it does tho not do what it did before in the seance of it just trying to go and down in rpms by it's self randomly and in a quick like fashion....still does it but not as bad as before.

so it's better than before but still screwed up .driveing it after the engine has warmed up is fine but idk it seems at 55 mph @ 1500 rpms it acts like it don't like that rpm for some reason ...not bad but of any rpm and speed that seems to be the numbers......most likelly in my head .....

i did do a code test.....maybe you can make better seance of it better than i can ......took a video of it so you can see.....
http://www.youtube.com/watch?v=Ma8P4QEymfw

what do ya think it can be ....i'm pulling my hair out over this one :eek:
 












ok .... i just got back from going to town about a 45 minute trip overall with the engine running the whole time with no stopping and starting ,and it drove ok and no throttleing by the engine.got home shut it off and restarted it 10 minutes later and it did ok ....reved up to 1k then slowlly back down to 600/700 rpms like it should .....i don't know this thing is starting to p-ss me off lol ....good one minute then crappy the second .

tell ya what ..... i'm going to goto advanced auto today and let them pull some codes and i'll get back to you and let you know what they tell me .

btw: as for the egr system . i have replaced all of it except the egr solinoid sensor.the valve and the dpfe sensor are brand new ( with one years worth of use on them )
 






...I will be looking forward to see what they say the code is...:popcorn:
 






just got off the phone with auto zone and advanced auto and they do offer free code reading but not for obd1 systems only obd2 ....man i swear....

this should be in a sticky as a warning for anyone that needs codes read that does not own a ob1 code reader that you can not get the codes read for free at those places( i know i have read in many posts that "you can get your truck scanned free" and it being a 91 -94)......96' is the latest that they will go back to .
 



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With the OBD system we have, all you need is to jumper 2 pins (a paperclip will work) and you read the codes by counting how many times the CEL flashes.http://www.explorerforum.com/forums/showthread.php?t=160035
http://www.fordfuelinjection.com/?p=13
To check for codes without buying a code reader is simple. If your EEC is wired correctly, the engine light works, and there are not any electrical faults in the vehicle you can get the codes out of your EEC.
Good reference here: http://www.extreme-check-engine-light-codes.com/Ford%20OBD1%20Decoder.htm

1. Turn key to OFF.
2. Get a length of wire that can connect the STI to the negative battery terminal or body ground.
3. Ground the Self-Test Input.
4. Get some paper and a pen.
5. Get comfortable in the drivers seat.
6. Try to keep your self from getting distracted from here on.
7. Turn key to RUN.
8. You will hear some relays engage and the fuel pumps prime the system. This is the EEC beginning the test.
9. When the fuel pumps stop be ready to count!

If you are a lost soul that does not have a working engine light, or did not install a light into your dash don’t fret. You can still get the codes. You still need that wire to ground out the STI. Now you will need one of the following tools; digital volt meter, analog volt meter, test light, or you can hook up any other 12 volt light that does not draw more than 0.5 watts max.

1. Turn key to OFF.
2. Get a length of wire that can connect the STI to the negative battery terminal or body ground.
3. Ground the Self-Test Input.
4. Attach one side of the test device to the Self-Test Output (STO).
5. Attach the other lead to the positive side of the battery.
a) If you are using a digital voltmeter you’ll want to use the continuity setting.
b) If you are using an analog voltmeter you’ll be counting the meter make sweeps.
c) If you are using a cheep light you’ll count like the rest of us.
6. Get some paper and a pen.
7. Get comfortable in the drivers seat.
8. Try to keep your self from getting distracted from here on.
9. Turn key to RUN.
10. You will hear some relays engage and the fuel pumps prime the system. This is the EEC beginning the test.
11. When the fuel pumps stop be ready to count!

How To Count “Check Engine” Light Blinks

When the “Check Engine” light blinks during the test you will get several different blinks, the separation time between blinks is used to indicate what information is being displayed.

Turn key to RUN. You will hear some relays engage and the fuel pumps prime the system. This is the EEC beginning the test. The fuel pumps will stop and the EEC will now begin giving codes.
You may catch a brief flickering of the light. This is a rapid code read that is used by the code readers you can purchase. Do not worry all those rapid flashes you just say flicker buy will now be given at a slower pace of ½, 2, & 4 second pauses.
First digit of first KOEO code (1/2 second between blinks)
2 second pause
Second digit of first KOEO code (1/2 second between blinks)
4 second pause
Next KOEO code
Once all KOEO codes are read the EEC will repeat them
6 second pause
Single Separator Blink (this indicates the change from KOEO codes to CM codes)
6 second pause
Codes from Continues Memory (uses same 1/2, 2, and 4 second timing as KOEO codes and also repeats them) If nothing has been recorded by the EEC since last battery disconnect you will see:

Blink - 2 sec - blink - 4 sec - blink - 2 sec - blink - 6 sec - blink - 6 sec - blink - 2 sec - blink - 4 sec - blink - 2 sec – blink

This translates into 11-11 current condition (KOEO) and 11-11 in the continues memory (CM); or SYSTEMPASS

This may seem hard to count; recommendation is to record codes with slashes, and to lump them all together. Sort them out into numerical codes later. Here is an example of this:

This would give you codes; 41, 83, 14 & 18. If you miss some of the codes or feel you are counting wrong continue to count the remaining codes for practice and to compare to the next code test. When finished simply turn the key to OFF wait 15 seconds then back to RUN. The codes will be presented again.
 






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