Honda crx with auto transmission idles roughly in drive or reverse. AC on makes it worse.what can cause this?
There are a lot of things that can contribute to an idle issue on your Honda. In fact, in the end it may still be there to some degree because of the nature of a 4 cylinder engine. 4 cylinder engines fire every 180? of crank shaft rotation. Because of this, the crank spends a LOT of time in rotation before the next power stroke. This creates a 'choppy' power delivery that may be most noticeable at idle. So if you have a rough idle with your 4 cylinder Honda, this might be a contributing factor to your rough idle.
The first step I take to solve a rough idle issue is to start with a good tune up. Use NGK or Nippon Denso plugs only in your Honda. Don't change the wires if they're OE (Original Equipment). Honda wires last just about forever so if you still have them on your engine, leave them be unless they show signs of external damage. If you feel you need to change the ignition wires and you want to save a couple of bucks, you might consider NGK wires as they are very good and less expensive than OE. They also come in a snappy blue color! A quality cap and rotor should also be used. I often go with Beck Arnley if I want to save a couple of bucks. Once again, OE is best for these parts. Honda's are VERY picky about the parts you use on their ignition systems. You'd be surprised at the difference between OE parts and aftermarket parts when it comes to Honda ignition systems. Trust me, I've seen plenty of issues here which is why I mention it. I've solved more than one idle issue just with a basic tune up using Honda parts. Lastly, a new air filter is a good idea to add to your list of tune up parts....heck the oil. You'd be amazed at how often I find low oil in an engine. If your Honda is low on oil the engine will have to work harder and possibly run rough as a result. I think it's also important to note here that you need to use the proper viscosity when putting oil in your Honda engine. DO NOT stray from the factory recommendations here. You may think it's a good idea to put thicker oil in your Honda engine, but the truth is that if you do that you can actually starve the top end by doing so. During start up, your engine is almost dry of oil. If you use thicker oil it will take longer for the oil to reach the top end of the engine. Because of this, the cam and valve train do not get oil for some time during start up. When this happens, the parts wear faster and eventually cause things like rough idles.
Don't change the PCV valve unless it's broken or aftermarket. If you see an aftermarket PCV valve, exchange it for an OE valve. Believe it or not, I've seen idle issues caused by aftermarket PCV valves on Honda's. The OE PCV valves last just about forever so you can easily justify the expense. I will admit however that the OE valves sometimes come apart internally and cause idle problems. If that's the case, it creates a large vacuum leak. When this happens, it effects the idle as well as fuel economy. Usually if the PCV valve fails in this manner, you'll experience a 'high' or 'hunting' idle. An easy way to find one of these faulty PCV valves is to pinch off the supply line to the PCV valve with a pair of pliers while the engine is at idle. If the idle smoothes out when you do this, replace the PCV valve with an OE unit.
Sep 28, 2016 |
Honda Cars & Trucks