To Mod Or Not To Mod... Stalling Update

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Chris M 2

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Just about everyone has read about my stalling woes... well, there's some good news at last. Today marks one whole month stall-free. What fixed it for me? After all the multiple cleanings, treatments, and part-swapping, a new IAC appears to have done the trick. Just cleaning it didn't.



I also don't go to the Murphy USA (Wal-Mart gas station) down the road anymore. The last two stalling episodes happened the mornings after filling up there. Can't say for sure if their gas caused or contributed to the problem, but I avoid the place just in case. They are the only place I can think of around here with 10% Ethanol stickers on their pumps.



Okay, now here's the question... I bought a gen 1 Zabteck TB direct from Todd Z about a month and a half ago. I've been waiting to solve this stalling problem before I put it on. Any reason why I shouldn't go ahead and install it? One month seems pretty good to me.
 
Just remember that when you install it, it'll take a while for the computer to catch up with the new TB. When I did mine (07 V8), it took several days before it settled down and ran great. The extra air provides a more peppy engine and - if you take it easy on the pedal, it'll provide better gas mileage as well - mine added about 1.5 mpg to my average.



my 2 cents.



 
Yep, you guys are confirming what I thought. :)



I'd have already put it on, but when the stalling was happening and I was posting regularly about it, everyone said "Hold off installing any more mods until you get that stalling issue fixed."



So I appreciate the confirmation! :p
 
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Disonnect your negative battery cable while installing the TB. This will dump the computer and force it into learning mode right away. It will begin to set itself in accordance with the new throttle body immediately after the install. This will cause it to "settle in" with the new throttle body sooner.
 
When I installed my TB the motor was cold. After the install, I let the motor come to normal idle and temp, before I drove it. All was good.
 
I would like to think that you got this fixed but the thing that bothers me is the fact that it died while you were accelerating, the IAC is just not capable of causing this problem under acceleration. I wonder if a change in the weather has calmed your issue, wouldn't be the first times.
 
The reason behind this is that when you are on the gas the IAC is taken out of the picture, even if the IAC were to mysteriously slam shut while you were accelerating the amount of air that it introduces into the motor is negligible. Realistically the only thing the IAC does is create a calibrated vacum leak to make the engine rpm go up or down and when you are on the gas vacum leaks are of no concern being that almost all of the engine vacum is lost during accel anyways. Why cleaning your IAC cured your hesitation while going up a steep hill while obviouosly under moderate to heavy acceleration is beyond me becasue it just doesn't make any sense at all, maybe you cleaned your maf and a few other things at the same time along with a so called pcm reset...IDK. Heck I can take the IAC off and not have any of the problems here that people say have been cured by cleaning or replacng the IAC. I know engines and there control systems can throw you for a lop once in a while but with the amount of odd problems here that have been solved with IAC's I would have thought that i would have stumbled upon one or 2 of them in my day.
 
I1tech, I just did a web search on "Idel Air Control Motor/Valve". Here is the explaination of what it does under load, or going up hill.

------------------------------------------------------

Car Repair: Idle Air Control Motors and Valves



The Idle Air Control Motor (IAC) stabilizes idle speed during cold starts and once the engine is heated, to stabilize the idle when a load is put on the engine (i.e. when your air compressor comes on). It allows air to bypass the throttle plate, thus giving the engine more air when it needs it, such as on a cold start or when there is a load on the engine.



Diagnosis:



While your IAC is part of the Emission Sub Systems, and is, in most cases, controlled by the ECM/PCM (Electronic Control Module/Powertrain Control Module), it is usually diagnosed with a scanner.



It can be diagnosed without the scanner, but as the symptoms may be caused by other sensors and/or components, you do run the chance of a misdiagnosis.



Did you ever come to a stop or turn a corner only to have your engine stall? Chances are, your IAC is not working. The IAC controls the air flow into your engine at an idle, and if it “sticks” closed, particularly with a load on the engine, such as the air compressor running, the car may stall, as the engine is not getting enough air at an idle speed.



The IAC can also “stick” open, which causes a high idle at normal operating temperatures. If the IAC is stuck in the open position, the 14:1 (in most cars) air/fuel ratio is distorted, causes a high idle, which can result in hard automatic transmission shifts.



If your IAC is the type with a vacuum line attached to it or very near it, check the vacuum line for cracks and dry-rot. This will also cause stalling.



IAC Motors and Control Valves:



There are different types of IAC Motors and Control Valves. Some cannot be cleaned, but if you have the type with a plunger and a spring (mostly used on Fords), these can be cleaned, and 90 percent of the time, they will continue to work properly. Though the different types may be shaped closely on the outside, they are different on the inside. Most will have a valve that attracts carbon (the black powdery stuff that builds up on certain engine parts).



If the internal solenoid is dirty or in disrepair, you will have to buy a new IAC – this cannot be cleaned.



Removing and cleaning or replacing the IAC:



You will find the IAC located near the throttle body. Most of them look like the one pictured. Usually, you will have a plugin from the wiring harness to the IAC and two screws to take it off. Some systems use vacuum hoses, and you will also have to remove those.



Once you have removed the plugin and the two screws, carefully remove the IAC from the engine. If there is a gasket, do not lose or tear it. You will need it again. Your engine will not run properly without the gasket in place, as it will create an air leak.



Insert the plastic spray straw on the can of carb cleaner (it comes taped to the side of the can), and holding the IAC with the valve pointing down, spray the valve with carb cleaner. Be sure to do this over a bucket, as you do not want these chemicals in the ground! Wipe it clean – if carbon and oil remain on the valve repeat. Do not tip the IAC up so carb cleaner runs into the electronic part of the valve.



Make sure the gasket is not torn and is placed even on the IAC, and replace. Insert the two bolts and plug it in. Do not put too much torque on the bolts, as you can break them. You just need them hand tight (use a screwdriver instead of a socket if you’re not sure, it is easy to over-torque bolts when using a socket and ratchet).



If the IAC seems like it is still stuck, bang on it with the handle of a screwdriver. Do not bang on or near the plug, you will crack the plastic plugin. If this still does not get you<
 
The load that they are talking about in that post is at IDLE ONLY OR VERY SLOW/CRAWL speeds...THERE IS NO NEED FOR IDLE CONTROL WHEN YOUR FOOT IS PHYSICALLY PRESSING THE SLIM PEDAL ON THE RIGHT SIDE OF THE DRIVERS FLOOR.
 
I understand you point, but that is not the way it reads to me because it also says "when your air compressor comes on".



The Idle Air Control Motor (IAC) stabilizes idle speed during cold starts and once the engine is heated, to stabilize the idle when a load is put on the engine (i.e. when your air compressor comes on). It allows air to bypass the throttle plate, thus giving the engine more air when it needs it, such as on a cold start or when there is a load on the engine.



I read under load as just that. Whenever there is extra load on the engine, as well as at idle. I am not a mechanic, but that is the way it reads to me.

 
I am at a loss as how to explain this to you so that you will understand it. Idle is when the vehicle is not moving and your foot is off the gas. The IAC controls engine idle speed. When you press on the accelerator pedal you are no longer at idle. If the engine needs more power becasue of additional load while off idle you press on the gas don't you?? If not how do you get your vehicle to move or maintain speed?



 
I definately understand what idle is, and the purpose for the IAC. But, what I am reading is that in addition to the idle function and cold starts is that it opens up under a load as well. I am probably misinterpreting what the article is intending for load. Is there a way of testing it to see if the IAC opens other than at idle or cold starts?
 
If you have a scan tool you can watch the commanded Iac percentage pid on it and on later model Fords even watch the milliamps that the Iac is requiring to move it's pintle(this is very good info to have).The Iac will open up a certain amount while you are on the gas in order to prevent the engine from just stalling if you take your foot off the gas suddenly, works on the same principle as a dashpot on a carbuerator. I think you understand what they mean buy load, it's just additional work that the engine is asked to perform, but it's a load at idle from an accessory that they are talking about here not a load from a big hill you are tyring to climb or a car you are trying to pass, becasue afterall you compensate for that load by pressing the go pedal and allowing more air to flow past the throttle plate.
 

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