I had new speaker and amp installed and now car won't start! Can this be caused by bad installation?
Oh these are always fun. Though I can't give you a diagnosis over email, I can tell you it is 100% possible to kill a car with a stereo installation. Your amplifier needs a signal to turn on or it will stay on always and kill your battery. Stereo install guys turn on the car and stab a test light into random wires looking for one powered only when the car is turned on. Unfortunately they have been known to splice into a CAN data bus. The CAN network in charge of communication for your security and locking could be disabled keeping your key from being authorized. Or the CAN network for your chassis systems can be shut down that deals with communication for your engine, transmission, and typically traction control. A CAN network is typically a 5 volt system but it suplies power in micro amps as it is only used for communication and not supplying a load such as switching a relay, lighting a bulb, or spinning a motor. Splicing into these to supply the relay to turn on the amp effectively grounds the circuit and does not allow for the digital signal to propogate. Sometimes it easier and they just blew a fuse while poking around with a test light, or shorted a harness by running a screw through it while mounting components. Had a lowjack installer put a screw through a floorboard and into a fuel tank once, cause a check engine light due to an emissions test, luckily it didn't burn down the car first. I have fixed at least a dozen of these problems on Benz's in the shop after a car got towed in from the stereo shop.
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 bad car battery cause engine misfire?
So everyone on hear that says a weak battery cannot cause a misfire is wrong especially with a Subaru!!! I recently ran into this exact same problem with my 2013 Subaru Impreza 2.0L. My car began to have a rough idle anytime I was sitting at a stop light. Then the CEL came on for a misfire in the cylinder and the dealership wanted me to do $1000 worth of work replacing the coil packs and spark plugs. I specifically asked them if a weak battery would cause the problem and they said no as well. I knew my battery was weak because I couldn't leave my car radio on for 5 min with out the battery dying. All battery tests I did said the battery was fine. Today I finally got sick of having to worry about it not starting from leaving the door open or the radio on while it wasn't running. Sure enough my check engine light turned off and now my car has greatly improved performance! Also my car now idles like it is supposed to. I'm thinking my fuel pump was not getting enough power which caused the misfiring. Either way the problem is fixed and I suggest looking into the battery first!
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.
What causes a car to randomly cut off while driving?
It is almost always an electrical problem. Take the car to a mechanic and have them check the diagnostic computer.If it’s not electrical it’s a fuel problem. Either way, the computer should know.Do it now. This sort of error can be very dangerous. The brakes and steering don’t stop “working,” it’s just that there is no power assist, and you only have manual control. GET IT FIXED!
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.
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).