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idle issues

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I get a TON of questions about Honda idle problems so I've put together this article to help you should you run into a rough idle on your Honda.  Here are a couple of videos to get you started.  When watching the Honda idle video please remember that adjusting the FITV is the LAST step in the process and you need to back it off at least 1/2 turn after it bottoms out or it will not start properly when cold.  I have many of you come to me and say that you've adjusted the FITV and you still have an issue.  The FITV is not the only thing that can cause an idle issue with your Honda so be sure to follow ALL the steps first before making that adjustment.




Here is my "Idle Speech" that I posted to the forum some time ago.  I’ve added a few updates but the information is still valid and should help you if you find that you have a Honda with a rough idle problem.

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Idle Speech

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 180º 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.

Check 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.

idle issues

Quick Links




I get a TON of questions about Honda idle problems so I've put together this article to help you should you run into a rough idle on your Honda.  Here are a couple of videos to get you started.  When watching the Honda idle video please remember that adjusting the FITV is the LAST step in the process and you need to back it off at least 1/2 turn after it bottoms out or it will not start properly when cold.  I have many of you come to me and say that you've adjusted the FITV and you still have an issue.  The FITV is not the only thing that can cause an idle issue with your Honda so be sure to follow ALL the steps first before making that adjustment.




Here is my "Idle Speech" that I posted to the forum some time ago.  I’ve added a few updates but the information is still valid and should help you if you find that you have a Honda with a rough idle problem.

Advertisement


Idle Speech

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 180º 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.

Check 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.

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Next, do a good valve adjustment.  This goes a long way to smooth out the idle if done correctly.  Mess it up, and things can get a lot worse.  So make sure you're ready when attempting a valve adjustment on your Honda.  Here are some videos I've done on Honda valve adjustments you might find helpful.

 











While you have the valve cover off check the timing belt tension, if you feel a lot of slack this can cause the cam to 'chunk' as it spins causing a rough idle.  This is because the valve spring pressure pushes on the cam as it rotates past the lobes causing a brief acceleration of the cam.  A loose timing belt will aggravate this condition. If you think the belt has been on there for some time and you find that it's a little loose, consider changing it out along with the water pump and resetting the tension properly.  If it's not ready for replacement you can reset the tension to take up the slack and recheck for your idle problem.

DO NOT adjust the idle screw under any circumstances, it is set at the factory and has been sealed to prevent tampering.  If you find that the seal has been broken and you have a low or rough idle and you have done all of the above, then you might need to perform a base idle reset procedure.  There is a special procedure that needs to be followed when setting base idle on your Honda.  Usually you need to disconnect the IAC to do the adjustment.  Consult the service manual for the vehicle you're working on to find the proper procedure for setting base idle with the idle screw.  Do not just start cranking on it hoping to find the right idle speed.  This isn't 'Nam' Smokey, this is auto repair, there are rules.

Lastly, remove the Idle Control Valve and clean the screen. This can get clogged up with carbon over time and cause the flow through it to be restricted which can cause idle issues.  Not all Honda IAC's are designed this way.  This procedure normally works on older Hondas, usually older than 99. If this isn't successful you may need to replace the IAC (Idle Air Control Valve).  These wear out over time and need to be replaced.  You can sometimes clean them and they work fine, but not always.  If you clean your IAC and you're still having issues, replace the valve and recheck your idle.

If you still have a 'rough' idle after all of this THEN look to the engine mounts.  You want to be sure the engine is running correctly before you go for those.  I have so many of you come to me saying that you've replaced all the engine mounts and you still have a rough idle.  You're doing it backwards.  Start with engine performance if you have an idle issue.  If you can't solve it with correcting any engine performance issues, THEN look to the engine mounts.  The engine will still run rough on good engine mounts.  Engine mounts are NOT the silver bullet when it comes to solving idle problems so put those at the bottom of your list and look to engine performance first.

I hope this information was useful to you.  If you didn't find what you were looking for, type in a few key words into the search at the bottom of the page.  You can even type in specific check engine light codes.  In addition to the code meaning you may find articles and forum posts that pertain to that code.  If nothing comes up for your issue, sign up for our forum and ask your question there. We'll be happy to help if we can.  It's free, all you need is a valid email address.  Just be sure to respond to the conformation email to complete your registration.  If you don't see the conformation email, check your spam or bulk folder, it might have gotten stuck there.  

Stay Dirty

ETCG

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