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24

You are right in the thinking of using less gas and that's exactly what the purpose was to have the start/stop feature. The main goal of doing it (at least here in the States) is for zero fuel consumption/zero emissions while the engine is stopped. This provides for better overall fuel consumption numbers to meet what the EPA has mandated for companies to ...


20

The oil problem You can run any engine speed you want as long as you keep the oil pressure up. Because of the impossibility of getting a roller bearing down a crankshaft, engine bearings are "plain bearings" with polished steel floating above babbitt (a soft metal). The oil pressure makes the bearings "float", so the dynamic forces of pistons being ...


12

The somewhat longer answer is that the device that makes what you're asking possible is the torque converter. This device is a pair of curved blades setup as an impeller, and a turbine. The following cutaway pictures illustrate this setup: Here is a torque converter split in half for a better view: The way this works is explained really well by a You-Tube ...


10

The engine does not rotate smoothly. The crank shaft is actually constantly speeding up and slowing down. This is most easily seen in a single cylinder engine. The power stroke is the only time the engine is under power. The other three phases are completely unpowered. This means that the engine needs to store enough power in something to get it through the ...


9

I work for a fleet delivery service. Due to safety regulations all vehicles must be shut off at every delivery point. This equals up to 150 stops a day. The starter motors fail with regularity. In most cases 3 times or more a year. Ignition switches about twice a year, and fly wheels every 2 years. While you won't see this type of abuse,stuff will wear out. ...


8

It sounds like there is an issue with something in the vehicle after it goes from open loop (before sensors are used to run the car) to closed loop (where the vehicle starts using inputs from the O2s, MAF, and other sensors). This switch over usually occurs about two minutes from a cold start-up. I would start by cleaning the MAF with electronics cleaner (...


8

The engine needs a minimum rpm to idle smoothly - a v8 can idle smoothly about 500to 600rpm but a 1 litre 3 cylinder needs around 700 to 900rpm... It is not the companies that really decided to do the start/stop, if you do some research the various governments have implemented legislation over the years that required drivers to turn off the engine when ...


6

More than likely, you have an air leak If you haven't cleaned out and rebuilt a bunch of 4 carburetor banks in your life there is a good chance you have accidentally created an air leak in the system. Unmetered air will create the symptoms you describe. The giveaway on most lean conditions is the falling idle. It idles high and is getting enough fuel but ...


5

The throttle body at this age of vehicle has a real possibility of being 'dirty'. Take off the large hose connecting the throttle body to the air cleaner at the throttle body. If the visible throttle body parts are heavily coated with cruud, then clean the throttle plate and throttle body with a tooth brush and throttle body cleaner fluid. Operate the ...


5

When the valve is 'closed', it won't completely block the airflow, otherwise, as you note, the engine would choke and stop. Therefore, even if it's stuck in the closed position, some air will still get through. This should result in a slow idle - but of course if the ECU thinks more air is getting in, it will be putting more fuel in, resulting in rough ...


5

In most electronic fuel injected vehicles, there is more air getting through than what the IAC provides. This can happen with either holes directly in the throttle plates or by having them partially open (very small percentage). This is still metered air (air the computer is aware of), but it is air getting into the system. Newer vehicles with "drive-by-...


5

The P1506 code is an idle air control overspeed error. From autocodes.com: The P1506 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up. Disconnect the car battery, remove the valve, clean, re-install valve, and drive the vehicle for about 5 minutes with the headlights and A/C ON ...


5

As long as the vehicle is well maintained.. turning the engine off, or leaving it running would not really make any difference to engine wear and tear. Well unless this was being done 50 times a day etc. I'm considering delivery drivers here who will do just that, and more. In these cases battery, starter and ring gear issues can become more of an issue as ...


5

From physical point of view, lowering the RPM means that you need to store the energy required to keep the engine running (and overcome friction) with a smaller angular speed. And the kinetic energy is proportional to speed squared. If you want to go from 600 RPM to 100 RPM, you will have (among other things) to make the flywheel 36 times heavier. Of course,...


4

Most likely case is a bad throttle position sensor or a bad air sensor (some cars use mass air flow, some use manifold pressure). This is typically not something that can be seen in codes, but must be identified by comparing sensor data and graphs. Other possibilities could be a vacuum leak, but that would probably throw a code/check engine light. Of ...


4

In all probability it is the TPS. They have been reported to have a nasty habit of malfunctioning when the battery is jumped. Particularly in the 2000 Dodge Ram for some reason. Not sure why.


4

Most likely a stuck A/C VSV (Vacuum Switching Valve). It's supposed to activate to increase the idle when the A/C compressor starts. When it fails you'll have crazy low RPM idle when running the A/C. Normally the A/C VSV is pretty easy to locate for pulling out and testing. Factory repair manual will have the test procedure (normally just apply the ...


4

From some information I have gotten from several Mustang forums 3.8L come in two varieties. An externally balanced and an internally balanced variety was available. Model year 2000 was change year. 1994 thru 2000 were externally balanced. 2000 1/2 and up are internally balanced. What all this means is if you use the wrong flexplate the motor will shake as ...


4

I don't know of any vehicle (as equipped from the factory) that increases the idle speed to compensate for a large draw on the battery. If the alternator starts bogging the engine down then the computer should compensate to maintain the set idle speed but not make it increase. It's easy to find out if the alternator will put out enough current at idle to ...


4

Most modern engines should increase RPM's when the load on the electrical system increases, as the Engine Management system should monitor voltage and identify it being drawn low, so increasing RPM to increase output from the alternator. Even many older engines would do this.


4

I think you need to do a throttle position sensor recalibration (reset). (NOTE: I will post several different adjustment versions. I believe the top one is what you need (for a K8 engine), but will include another four depending on your engine.) To do this for your vehicle you need to follow the steps below, depending on whether it is a stick/auto and ...


4

Mechanically, it's a bit of a throwback to carburettor equipped bikes - my motorbike, for example, can be a little bit unforgiving when it's cold and it's not nice to go to pull away and have the engine splutter. In fact, an inexperienced rider could easily fall off because of it! And, as you've highlighted, a badly set up bike might have issues idling. ...


4

The oil level is not going to decrease due to it sitting for six months unless a seal went bad. It would appear to me you have an oil leak somewhere. This doesn't mean you are going to have low oil tomorrow morning, but it does indicate you need to keep an eye on the oil situation. What you can do is to check the ground where you normally park your vehicle ...


4

Your CPS code won't explain the hunting idle; the symptoms point to a lean air-fuel mixture: it doesn't stutter at low idle with the engine cold because the fuel management is designed to enrich the AFR while the engine is warming up (aka cold-start enrichment) turning the AC on helps because it induces an additional load on the engine, which makes it ...


4

When the throttle body becomes a little worn, it is possible for the butterfly valve to close too much for a steady idle engine speed. The ECM then tries to compensate by opening the IAC more than it is designed to under normal conditions. This can cause stalling and unsteady idle. There will be a screw on the throttle body that allows adjustment of ...


4

These are common symptoms of an split air hose allowing unmetered air into the engine intake. Check all air related hoses for cracks. Hoses include the main air intake, crank case ventilation system and vacuum hoses.


4

The manual you linked to explains what they're used for. The AACV is the main idle speed control while the FICD is used to supply additional air to the engine when the AC is turned on. AACV (Page EC-GA-117) This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air ...


4

This is a great question, and the answer lies here: Why doesn't the engine stall out when you come to a stop with an automatic transmission? And more information here: How does a torque converter work. With a manual transmission, you push in the clutch to disengage the transmission. With an automatic, that job is handled by the torque converter.


4

Check that your alternator belt is tight and in good condition. Also check that your battery is fully charged and in good health. There is a real possibility that the fault is being cause by the headlight switch, wiring or bulbs. Do the revs dip when you switch on the rear heated screen? I personally had a headlight loom catch fire on my old Mk1 Cabby ...


4

Cars don't like to sit. There is an inside joke among mechanics, they call degradation due to sitting "lot rot". The biggest impact to a sitting car is the rotors. They rust. Rotors rust even sitting overnight in a humid or rainy environment but when you drive the car in the morning the rust is cleaned off with the first few pedal applies. When the car ...


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