What are some symptoms of a bad idle air control sensor?
Idle air control valves open to allow more air to "leak" into the intake, raising the engine rpms, or close when not needed. When your AC compressor kicks in or power steering is activated as you suddenly turn the steering wheel, the sudden drag on the drive belt will bog down the engine. These systems send a signal to the engine computer telling it they are active and it then signals the IAC valve to open, which increases the engine speed. Without this occurring, the engine could struggle, or die. The IAC valve can cause weird idle issues, mess with throttle functionality or cause the car to die. Sometimes they fail, get stuck or just get all carboned up. Sometimes people have success at cleaning them, but generally it is best to replace them when bad. Idle issues and even problems with the IAC valve may not be due to the IAC valve being bad itself. An idle issue does not mean the IAC valve is bad. It is best to pay close attention to how the vehicle is acting, and then communicate that clearly and as completely as possible to your mechanic. Intermittent problems can be very hard to diagnose. Details will help. Knowing more about the vehicle in question and its symptoms (in detail) will also help in understanding more about what it is doing.
How do I fix my car having a rough idle after replacing the alternator?
You're right to assume that something else going on. Because it is!Personally I'd check to see if the alternator is providing the right amount of voltage. it's not impossible to get the wrong part installed. and when I say that, I don't necessarily mean you chose the wrong part, but during the assembly line a part they grabbed while assembling the alternator could have been or of spec or something. Check the grounds. A lot of the time, over years of use a little sand blasting or sand papering of the hookups does help. while running the engine, disconnect the battery. A poorly performing battery can drag the entire system down. check to make sure your AC ain't causin' problems too. make sure the clutch is spinning or not spinning when not being used. double check the water pump to see if it was messed up. lastly check all your ignition wiring too. depending on the model year and brand, it might be chatty with obd2. if it's carbureted, obviously you won't get any feedback. if it is obd2, there might be information in there that can give you an idea of what's going on. so get a reader and check. also with modern fi engines, they'll run rough after a battery removal for a while. make sure your fuel economy hasn't been affected, if it has, it's a clear indication that something is wrong.
What problems go along with a bad catalytic converter?
A clogged catalytic convertor causes the symptoms of a loss of power when accelerating or going up a hill. This is an often overlooked cause of loss of power, can cause check engine fault codes and lights, and mechanics will often change a few parts unnecessarily , especially if it is only partially plugged. A couple ways I check for plugged cats when a low power complaint is a symptom, and other obvious basic maintenance items have been checked for service is to have someone hold the rpm at about 1800 to 2000 steady. Then check for a good push of exhaust with my hand from behind the tailpipe. A plugged or partially plugged cat typically leaves a hot sickly feeling exhaust flow from the tailpipe. Compare to a known good working car nearby, known to be performing properly and with the same amount of cylinders. That slow , hot sickly flow at 2000 rpm compared to the hard push blowing your hand away of a not clogged cat is a dead giveaway, and I have NEVER misdiagnosed a plugged cat , or made false diagnosis with this method. Another way is watching a vacuum gauge connected to the intake manifold. When revving up, if the exhaust is plugged the gauge reading will climb then begin to slowly drop as the exhaust pressure builds up. Further testing will be needed to verify which part of the exhaust is plugged. Diagnostic by codes is unreliable and until now I had not heard of it. A code p420 only refers to catalyst efficiency. And can be set by faulty o2 sensors. Removing the exhaust and testing for engine power returning to normal works. But the hot sickly flow has been most accurate with my experience, in several cases where shops had missed it, were stumped and called me to come check. They are always embarrassed for missing the simplicity, but need not, as cars and their complicated electronics and even age old problems can lead to loss of power without any immediately obvious cause.
Why does my car idle at a really low RPM while stopped, and start shaking?
You may have a misfire, a vacuum leak, or a clogged/faulty idle air control valve. It could be a couple other things, too, but those are the most common and first things you should explore. This is because:If you have a misfire, one of your cylinders is not working and while that may be less noticeable at higher speeds when the engine is spinning really fast and the throttle is wide open, at lower speeds the difference is more apparent.If there is no misfire (and no codes / check engine light), the problem is most likely air related. This could mean a vacuum leak from a hose or the intake manifold itself. Or, commonly, it could be that your Idle Air Control Valve is clogged or not working well. The engine monitors via sensors how much air is coming in vs engine speed and uses that to control fuel injection and ignition timing.If it's a vacuum leak, the engine is getting more air than it thinks it is and that is causing a 'lean' fuel/air ratio.If the IAC valve (and its passages around the throttle plate) are clogged up, the engine thinks it's getting more air than it really is at idle with the throttle plate closed (foot off the gas), resulting in a 'rich' fuel/air ratio.All of these scenarios will probably cause some sort of engine code and checking them should be your first step. Note that an oxygen sensor code will be indicitave of one of the above 'air' situations because it detects how rich or lean the ratio is.
Can a faulty speed sensor cause other problems in your vehicle?
Speed sensor is only for speedometer in old car's .The ECT electronic controlled transmission is integrated with VSC vehicle speed sensor ……sp 1 and sp 2. Malfunction of speed sensor can trigger engine check light ,vsc light ,abnormal gear change.If engaged in high gears can burn clutch linings.The trouble indicating codes can be p0500.
Is it bad to buy a car with over 100k mileage?
I am attaching a picture of the first car I owned. A 2004 Hyundai Sonata V6 that I bought in 2010 and I had it for around 18 months. It had 104,000 Miles on it when I got it for $4500 and it had 130,000 Miles on it when I sold it to a dealer for about $3700, when it was going to need a timing belt change soon.I ensured that the car was in good condition when I got it, the only money that I had to spend on it was for oil changes. Insurance was $65 or so per month. It was the top of the line model. Pretty powerful, handled reasonably well, leather seats, good AC and everything in the car worked. I have never owned a car since that was a better bargain or cost me lower per mile to drive. I even spotted it on the road a year or so later and it still seemed to be going good.Hitting 100,000 Miles is one of the most significant events in the history of a car with respect to depreciation. However, much like how a new car depreciates quite a bit the moment it is driven off the lot, the reason for such depreciation is more psychological than rational. There is no reason to believe a car with 101,000 is any less reliable than a car with 97,000 miles but they usually have a considerable price difference. This usually means, if you are careful about the vehicle you pick and ensure that the car in question has been maintained well throughout its life, a car that has just crossed 100,000 miles is among the best bargains you can find.Most cars that have been made in the last 15–20 years are very reliable machines. Even the brands not conventionally well known for making long lasting vehicles, like American, Korean car makers etc have made tremendous improvements in overall vehicle reliability and often offer much better deals than a Honda or a Toyota which depreciate slower due to their reputation for reliability.If you are in the market for a really cheap but still reasonably reliable car, cars with 100,000+ miles on them are an excellent place to start looking. The only caveats would be to ensure the particular vehicle you are considering is in good condition and you are fully aware of potential maintenance work or consumables that may fail in the near future and set aside enough money to be able to afford having such work done.
What are the effects of driving a car with a misfiring cylinder?
OK. I am a gear head who loves working on cars and has done so since the 1960’s.If a cylinder is misfiring because of an ignition problem you will, in the short term, just experience a loss of power increase your fuel consumption. In the longer term, continuing to drive it that way could destroy a coil and cost you more money.If, however, the misfire is caused by an injector problem, you could seriously damage your engine. Running that cylinder too lean will cause it to overheat and potentially damage the valve or the piston. If it is running excessively rich the unburned fuel could be washing the lubrication off of the cylinder walls leading to severe wear. In either case, repairing the damage will be expensive.NEVER drive a car that has a problem. NEVER drive a car in which the Check Engine light is on. If the Check Engine light begins to flash, SHUT OFF THE ENGINE, NOW! A problem that to you seems small, if not repaired, can cause a lot of damage that will be very expensive to fix.Read your car’s manual. Do exactly what it recommends. Find a mechanic you trust. Doing preventive maintenance will cost you a lot less than repairing the damage caused by neglecting to keep your car serviced.
Why is my car shaking and the check engine light flashing?
A shaking vehicle AND flashing MIL ("check engine light") sound like the vehicle is misfiring on at least one cylinder. As @Anna Nguyen, @Brendan Sinclair, @Antoun Nabhan and others have said, it could be an ignition related problem. It could also be fuel-related. If one or more fuel injectors are clogged or dead, that would also cause a misfire in the affected cylinder(s). These are relatively cheap/easy things to check and fix.Other causes (which could be more complicated and more expensive) to fix include contaminated fuel, a bent intake or exhaust valve, a broken valve spring, a damaged piston/connecting rod, and on and on.I recommend getting a scan tool and checking the codes which are causing the MIL to light/flash and I also strongly recommend NOT driving the vehicle until the problem is fixed. If you continue to drive the vehicle as is, you will exacerbate the problem. Dumping unburned fuel into the exhaust due to a misfire will overheat and kill your catalytic converter. A more serious problem like a bent valve can eventually cause you to crater your engine (i.e.: completely destroy the engine).