Chapter 20 "Idle Speed Controls" - preview (an SD Premium video)
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- เผยแพร่เมื่อ 5 ก.พ. 2025
- This is a preview I put together of my Chapter 20 lectures available on ScannerDanner Premium. For anyone interested in joining my class at Rosedale Technical College, but cannot be there in person, I’ve created this channel for you. There is a 14-day free trial period so you will have plenty of time to review the content before making any financial commitment. On SD Premium you’ll find daily lectures that go hand-in-hand with my book (Engine Performance Diagnostics), playlists that mirror my class format, as well as exclusive case studies.
Head over to ScannerDanner Premium for more information:
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Engine Performance Diagnostics chapter 20
Topics discussed
defining minimum idle speed
IAC counts and learned values
electronic throttle control systems, and how a dirty throttle plate causes problems
why you should NEVER touch the minimum idle speed screw
differences between stepper motor and solenoid valves
solenoid type idle control valves and their associated data PIDs
Ford IAC scope testing
Four wire stepper motor scope testing
the idle flare and what it indicates about IAC functionality
Playlist
(Chapter 20) Idle Speed Problems and Testing
• (Chapter 20) Idle Spee...
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P0507 Idle Control System (RPM Too High) - vacuum leak - GM
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How to test an Idle Air Control (IAC) valve - Nissan/Infinity
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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdan... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.
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Thanks Paul. I bought it for 3 reasons.
1) you are always honest and down to earth.
2) When you teach some thing, you know what it is..
3) I think I have asked at least 100 questions to you and you have always answered it. I still owe you a lot. This is just my start.
The above qualification is must for a lecturer but now-a-days it is very hard to find some like you. What i have learned so far from ebook is infinte, I assume u will send user and password info to my email. thanks a million
I'm excited to now have the ebook and it's an honor to support you Paul. It's incredible the knowledge you have. Keep it up!
APP is the input. PCM reacts and opens the throttle. TPS informs PCM that throttle opening matches what is desired and commanded. The TPS on an ETC system is now a feedback sensor. It is completely different than before.
What a classic, always getting us thinking.
The ending of the video had me wanting more info......great stuff.
first of all thank you for your kind words and support. Next is a compliment to you. If I seem to always answer your questions it is because they are to the point and intelligent questions. You don't even know how many people i don't answer :-)
After your purchase were you redirected to the video page? If not, email me and I'll give you instructions on access
yes currently these are streaming video only. i have increased the access to 90 days. also what i can offer is a free view or two after it expires upon request. i am actually looking into other alternatives (maybe a monthly subscription to all of them?) in the future but no time frame for that yet.
3) on some there is some initial activity during key cycles
4) no, move the plate manually (make sure you unplug the connector and key is off)
5)yes
6) no, usually two TPS signals and motor controls, so at least 8 wires
(1/1) Hey Paul, just my 2 cents from a total noob you helped greatly. On my 2001 Honda Civic, I found out that clogged IAC's are actually very common when suddenly my car would stall dead stopped while driving on the interstate. I don't remember the OBD code for it but taking it out and cleaning it with brake cleaner and a toohbrush fixed it, as well as replacing its gasket and flushing the entire radiator with new antifreeze and a flushing kit. Only about 60 bucks total, where the mechanics...
Thanks a million for sharing ur knowledge with very cheap price. It should cost more and i know many in markets are selling less material then you by a tleast 400% price of yours. I am not joking, serious.
I thought below questions will be useful for other subscribers who are going to buy this webinar . I will ask questions in 4 part because of size issue. .
I've thought about the DVD but if I do one I wanted to do the whole book. I still have to complete Sections 17,18,19,21,22, & 23. I am still not 100% on doing a DVD though. I want to protect myself as much as possible. So as of now, there is no download or DVD. I hope you understand. Thanks! Let me know if you have any other questions. Oh, the ETC systems, yes, it is a pulse width modulated reverse polarity DC electric motor. No separate IAC device.
for other people reading this, my website is scannerdanner d o t c o m
Meant to say "cleaned plate" but idle issue still present. Ran all diagnostic tests, everything checked out. Only question mark was the TPS pids off at idle. So after much diagnosing replaced the TB thinking the TPS was at fault. Issue resolved, but it didn't occur to me after u replaced the TB: idle screw!
@Bri C not sure if that comment was geared towards me, but I can assure you I am far from a parts changer! Lol. This particular VW it just did not occur to me that someone had tampered with the idle screw. That happens sometimes. In my case the TPS was off because the screw was adjusted not letting the throttle valve close to spec. It occurred to me days after the vehicle was fixed that perhaps the adjuster was tampered with. Testing the old TB on my personal vehicle confirmed it.
Had a case once where an adjusted idle screw whooped my butt. 2008 VW CC. Code for idle range, erratic idle, surging, and the occasional stall. Plate was dirty, idle improved but vehicle still "searched" for idle, and code still present...
great video! as always!
Hey ScannerDanner,
Excellent videos, they have helped me understand so much better then traditional research. I was wondering if you do any videos or have any information on a chevy TBI idle surging up and down right from start up? I have seen so many people with this issue online but no one has any good information on it.
Will
ContagiousFX - Cranking at closed throttle and no minimum idle air flow will quickly cause a flooded engine. WOT during cranking (no fuel) clears the flooded condition.
(2/2) ... Only about 60 bucks total, where the mechanics wanted at least 400$ just to replace the IAC for a new one, and nothing more!!! Mind you, I think I was lucky I got away with it by just cleaning the IAC, because it hasn't given any problems since then 6 years ago, but if you have to replace it, I would go for a non OEM part just to try it out because the IAC from the dealer was so expensive. What do you think?
Hi Paul i have a Toyota truck with a hig idle speed i have smoked the vehicle and there are no leaks the idle speed is normal when cold and when hot its at 1200RPM
Its an old toyota system 1997 i think it has that wax type of iac system
where in you book can i find help
Part 3
7) can we use IAC functional testing(Solenoid or stepper type) for cold and hot engine testing for drive by wire as well.
8) which manual will give us the position count or desired angle of tp on idle. Only manufacture manual will give?.
Paul, one last Q, Drive by wire have TPS signal along with Motor control. will this TPS signal mirror APP signal?. What I did not understand is, APP signal should tell PCM how much Throttle should be opened and in my view, PCM should just PWM signal to motor control to open throttle accordingly, why PCM is sending TPS signal to DBW actuator in addition to motor control. Am I missing some basics.
Hi scannerDanner. Your videos are amazingly helpful. Where do I go to buy your ebook?
If the system will let you do that. I know some cars must be in gear for that to work. Just keep your fingers clear of that plate!
I've never hurt one by doing it manually. Of course no matter how you do it you have to do an idle relearn when your done. This is different on every car
Part 2
3) Does drive by wire also extend and retract when we cycle the key?.
4) Drive by wire is pulse width modulated type. Can I use my test light to open the throttle plate for cleaning in vehicle even though it is pulse width signal type.?.
5) Can i forcefully open the throttle plate after disconnecting Drive by wire physically from the car to clean?
6) Drive by wire will always have three wires Dc motor(+,- and % open signal feedback) unlike 4 or 6 wire stepper motor, am i right ?
Part 1
1) Can stepper motor or drive by wire mechanical problem be reflected in wave form while scoping computer control or we only know the computer is just controlling and mechanical problem will not be reflected, ?.. i assume this question
will apply for fuel injectors as well, i may be wrong.
2) in 4 wire stepper motor for a coil, we have + and -, does computer send control to both + and -?. I see that + signal and - are inverting each other..
LOL!!! @ 13:17, I had that EXACT problem come into the shop today, only difference was it was for a 96 Oldsmobile instead of a 95 Chevrolet.
Paul, I like to buy this section alone. Is there a way i can buy DVD and would like to pay more because i like this as reference.. pls advise. I assume ur current deal is to buy once and that will expire in a month or 2.. i like to permanently own this, do u have any deal on this. I own ur ebook as well.
Hi great video!!Can someone help me with the meaning of idle S/D? TMPRNG?
can this causes the reduced engine power light to light up ?
Is the Ford IMRC valve the same function as the IAC? Just asking because I don't see an IAC pid on my verus, for my Ford truck 5.4L.
no, totally separate. IMRC is the intake manifold runner control. IAC is idle air control
Do you cover this on gm vehicles? I’ve got a 2000 gmc Sierra 5.3 and I’ve been having idle issues but they’re intermittent and super random
Yes, I actually have a few case studies right here on YT as well. You'll find them in my chapter 20 Idle Speed Controls playlist th-cam.com/play/PLAFYVCyenqcrqC1WhVE1LTzQSn4mbMjdu.html
The reason there are two TPS signals is for safety and accuracy
Great explanation there! I have a theoretic question- I am just wondering if we want higher RPM for whatever reason(for example 1100 opposed to ECU desiring 800) and we adjust 1100 at closed IAC-> ECU will keep that closed IAC position running at 1100 RPM - it will fail to achieve the desired 800 beacause of the very closed IAC which has no room for closing anymore , is our goal achieved resulting in higher RPM and just one ERROR CODE ( Idle speed incorrect-higher than ECU desires).
don't ever adjust the min idle air control screw ,it is a factory setting and it is essential to proper IAC operation .and depending on the year will probably set the light and create more drivability problems.
Obviously this is on non-ETC models.
If you have a "no start"/"hard start" issue,with this type of system, verify the complaint but then crank again and start pressing on the accelerator while cranking. Continue cranking until you get to WOT. A WOT the computer will shut off the fuel (clear a flooded condition) and the engine will likely start.
That is not true my friend. The "protective" coating that Ford used was to help keep the throttle body from building carbon deposits, that would restrict minimum airflow around the throttle plate. (It didn't work!)
Every fuel injection system has a "minimum idle speed" (airflow past the closed throttle plate). Some will actually have a hole drilled into the middle of the plate. On this design, dirty throttle bodies are a non issue.
Hi sir, sorry my poor English but can you explain about the PCV systrem. For me it works like a bypass valve it breathes before the thottle plate and realease the blowby gases after the thottle plate. Greeting from Guatemala
No preoblem, the PCV system will pull crankcase vapors and re-introduce them into the intake to be burned. In general the valve itself provides a regulated, controlled amount of flow and the air inlet for the system is behind the MAF sensor so it is also accounted for in the fuel delivery strategies.
Nevermind that, a stupid question. 4pin means Stepper Motor-> 2coils fed with current flow in order to rotate a screw and control the depth of its exact position in 256steps. I guess that is kind of slow control compared to the duty cycle IAC
2) Will a 4pin IAC
hold its position(20-100%) or close(0-20%) when we unplug its 5volt power
7) yep
8) TPS voltage, no problem. TPS %, good luck
So I swapped the TB onto my own personal vehicle, and messed with the screw... Boom! Issue resolved. I was like man, 2012 and ppl still mess with idle screws?!?!?
Thanks Paul, Before I buy i have 2 q.
1) So even i pay around 100 dollar, will I get a chance to own a DVD copy. If your are not interested i will go and head and buy from ur site for 21 dollar.
2) I was told Drive by wire so far have not use stepper motor is that true rather they use pulse width Dc motor , pls advise.
I think a throttle body re-alignment could've cured that my friend, symptoms are usually a hunting or surging rpm.
1) stepper motor - most likely not
2) yes
I have a new respect for 2-wire IAC's. How in the heck don't they burn themselves out in a week with that kind of PWM duty cycle? That's just an insane design. Why can't it be something simple like variable voltage, nooo gotta do it the hard way with PWM cycle from hell that only a scope can measure.
Nvm, i see your site listed in the description :p
thank you! contact me and let's get you set up with that free video lecture sample now. make sure you keep an eye on your spam folder for my emails and add me to your contact list.
have to disagree with you ! Older Ford products that use an Idle Air Control (IAC) non-stepper actuator do NOT allow any air past the throttle plate. In fact there is a coating sprayed on the throttle bore behind the plate so that it seals without locking in the bore.
Understanding this is important because a common "no start"/"start and stalls" condition is caused by the owner cranking without stepping on the accelerator. This will eventually flood the engine. Clean only the IAC !
Mine jives along with all he is saying here, yet he claims it is a vacuum leak. I checked, there is no leak.
Checked fuel trims at idle and 2500RPM on my Ford Focus. Results STFT way over 20% at idle gets better (less) at 2500. LTFT was stuck at 25% Both O2 sensors passed switching test and I/M readiness passed, but then code P0171 came back and idles rough and then dies. Also, one O2 sensor says max amplitude failed, and even though it goes into CL quickly, an OL-FAULT is showing up. Not a code, just what my rudimentary AL519 Autel shows me. Also of note, scanner shows both O2 sensors passing switching test. I bought an IAC but DID NOT install it, can return. I need the $80 back. Also of note, my Downstream O2 sensor the waveform does not look regular up/down sawtooth like US sensor, and seems to cut out at times while watching live data.
Any ideas welcomed. I feel it is the IAC because the idle hangs high at times, before coming down. I feel IAC is full of crud. Turning on AC keeps idle up enough it does not die and is very drivable, no power loss. My throttle body is clean inside.
Lazy O2 sensor AND IAC problem?
Why are you talking, like that? Like other people are seeing your post on this old ass video. Talk to me bro and stop this condescending approach. You want help, this isn't how to get it from me.
How did you check for the vacuum leak? Did you know PCV valves can stick open and be a vacuum leak?
Your car was known for PCV valve issues. It's below the intake manifold. Got to get underneath to see it. (From memory). Pinch or block it off and see what your trims do.
How does it run under load?
(The rest of your replies to me, need to be under this thread and you need to be patient. I have 400k other people asking me questions too)
not all vehicles have clear flood mode ford, gm has it not Toyota and hondas
I don't really want to start a argument here, but 4 out of 4 retired Ford engineers disagree with you. Most non-ETC Ford's will have a hole in the throttle plate for minimum idle air flow. No air flows around the plates at closed throttle by design.
There really is no reason to have a position count/voltage for closed throttle. OBD checks it for range. The rest of the software "adapts" to closed throttle.
TBH I am looking forward to affordable, FAST-charging electric-motor propelled cars.
Me too man. Toyota is working on a solid state battery with 900 mile range and 10 minute charge times
A throttle body cleaning or at least an inspection should be part of any tune up procedure....what, an extra 20 seconds to do the job, so what.
check your spam folder. i sent you two emails....stupid spam blockers.
"Parts changer" lol