Engine Misfire at Idle
01-11-2014, 03:11 PM
#11
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https://www.s2ki.com/s2000/topic/106...ashing-MIL/CEL
Are you sure your plugs are in check? This is a great thread to read.
Are you sure your plugs are in check? This is a great thread to read.
01-11-2014, 05:25 PM
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The compression test is the first thing that I would do. This will give you the piece of mind that the engine is healthy and allow you to focus on the smaller and cheaper things that can cause a misfire. Use the compression tester that you bought and post the numbers here on your thread. The pressure in each cylinder should be above 200, with no more than a 10 (or 15) percent difference between each reading. The compression test should be done with the engine is hot, at wide open throttle, and with the fuel pump fuse disconnected. Once you determine that the engine is in good shape, I would than inspect the spark plugs and swap coils (which you already did). OEM spark plugs do not need to be gapped, actually gapping the plugs can cause them to fracture and break. This is the part number 98079-571BH SPARK PLUG (PFR7G-11S) (NGK). Its best to stay OEM on a stock car.
After the spark plugs, coils, and compression test all checks out; I would than swap the injectors with another s2000 by finding a local s2000 owner or post on your regional s2ki forum to find someone willing to help. They take about 10 minutes to pull. Disconnect the fuel rail, 3 bolts and 2 screws, and pull it up towards yourself. Some of the injectors may come right out when you pull the fuel rail or be stuck on the intake manifold. It is a very easy job. If the car runs smooth, no popping exhaust, no shakes at idle, or engine codes, than you have successfully found the problem. There are three ways you can clean the injectors. First you can use an on-car method by running products such as SeaFoam through the gas tank. Secondly, you can use an off-car method by sending the injectors to get flow tested and ultrasonic cleaned by a local shop. Thirdly, you can watch YouTube videos and create your own rig to shoot carb cleaner through the injectors using a hose, air compression, and switch to activate the injectors.
If the car stopped misfiring but still not running as smooth as you wanted; you can than do a valve adjustment. To get the valve cover off you have to pull the pcv valve which may be needing a cleaning. Do that now. While you are in the engine bay, also clean the throttle body and map sensor which can also cause an engine misfire. You can also check for cracked retainers when the valve cover is off. I heard (Do not quote me), that cracked retainers do not have any symptoms. Those are the major components of parts that will cause a misfire. If your problem still persists I would than look at more uncommon but possible solutions. Low fuel pressure, a clogged fuel filter, chewed or problem coil pack wires, the connections for the injectors, etc.
You can also find someone who has a scanner to get a fuel trim reading and post it on the forums to get experienced members to help. Goodluck, and keep updated.
P.S. If the CEL is blinking at idle, after you swap injectors it maybe a good idea to reset the ECU prior to firing up the car. You can do so by:
After the spark plugs, coils, and compression test all checks out; I would than swap the injectors with another s2000 by finding a local s2000 owner or post on your regional s2ki forum to find someone willing to help. They take about 10 minutes to pull. Disconnect the fuel rail, 3 bolts and 2 screws, and pull it up towards yourself. Some of the injectors may come right out when you pull the fuel rail or be stuck on the intake manifold. It is a very easy job. If the car runs smooth, no popping exhaust, no shakes at idle, or engine codes, than you have successfully found the problem. There are three ways you can clean the injectors. First you can use an on-car method by running products such as SeaFoam through the gas tank. Secondly, you can use an off-car method by sending the injectors to get flow tested and ultrasonic cleaned by a local shop. Thirdly, you can watch YouTube videos and create your own rig to shoot carb cleaner through the injectors using a hose, air compression, and switch to activate the injectors.
If the car stopped misfiring but still not running as smooth as you wanted; you can than do a valve adjustment. To get the valve cover off you have to pull the pcv valve which may be needing a cleaning. Do that now. While you are in the engine bay, also clean the throttle body and map sensor which can also cause an engine misfire. You can also check for cracked retainers when the valve cover is off. I heard (Do not quote me), that cracked retainers do not have any symptoms. Those are the major components of parts that will cause a misfire. If your problem still persists I would than look at more uncommon but possible solutions. Low fuel pressure, a clogged fuel filter, chewed or problem coil pack wires, the connections for the injectors, etc.
You can also find someone who has a scanner to get a fuel trim reading and post it on the forums to get experienced members to help. Goodluck, and keep updated.
P.S. If the CEL is blinking at idle, after you swap injectors it maybe a good idea to reset the ECU prior to firing up the car. You can do so by:
1. Disconnecting the negative battery cable for 10 minutes
2. Pulling the fuse for the ECU.
2. Pulling the fuse for the ECU.
01-13-2014, 05:19 AM
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Gotpepsi you've given some good advice. But I'd have to point out.. the oem plugs are best not to be messed with, but I've pulled them out of the box that were way out of spec. Though it may not be a good idea to regap, it's always a good idea to check the gap.
I'd also just check the plugs during your comp test, you'll have them out anyways.
There are way more effective injector cleaners than seafoam. Personally I wouldn't take a chance with any cleaner. I'd take them out and clean them myself or send them off.
I'd also just check the plugs during your comp test, you'll have them out anyways.
There are way more effective injector cleaners than seafoam. Personally I wouldn't take a chance with any cleaner. I'd take them out and clean them myself or send them off.
01-13-2014, 03:03 PM
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I had a similar problem. The CEL would flash only at idle. Pulling the codes showed misfires on all 4 cylinders. I changed the spark plugs, to no avail. I doubted that it was a bad coil since i was getting misfires on all cylinders. Next step was the compression test, where I found that #2 was way down on compression. I started to think the head gasket might have blown between the #2 and #3 cylinders, so I figured I'd try changing that and see what I found along the way. What I found was an intact head gasket, but worn valve guides. I later read that a CEL flashing only at idle and showing misfire is commonly indicative of worn valve guides. I'm now in the process of reinstalling the head after replacing the entire valvetrain.
I started a thread on here a while back that has some pictures and more description of my troubles. You can find it HERE
I would definitely start with a compression test and go from there. Checking the valve lash is a good next step, and you can check retainers while you're in there. I think someone else already noted, though, that cracked retainers will not give you a CEL or necessarily give you any clue that they are cracked until the valve drops into the cylinder. I'm hoping your issue is something simple, as mine has cost be about $1800 so far, but I figured I'd bring it up as worn valve guides never came into the discussion on the monster misfire thread, and your story sounds similar to mine. Good luck! Go do a compression test and come back and post the numbers.
I started a thread on here a while back that has some pictures and more description of my troubles. You can find it HERE
I would definitely start with a compression test and go from there. Checking the valve lash is a good next step, and you can check retainers while you're in there. I think someone else already noted, though, that cracked retainers will not give you a CEL or necessarily give you any clue that they are cracked until the valve drops into the cylinder. I'm hoping your issue is something simple, as mine has cost be about $1800 so far, but I figured I'd bring it up as worn valve guides never came into the discussion on the monster misfire thread, and your story sounds similar to mine. Good luck! Go do a compression test and come back and post the numbers.
01-18-2014, 05:37 PM
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I had a similar problem. The CEL would flash only at idle. Pulling the codes showed misfires on all 4 cylinders. I changed the spark plugs, to no avail. I doubted that it was a bad coil since i was getting misfires on all cylinders. Next step was the compression test, where I found that #2 was way down on compression. I started to think the head gasket might have blown between the #2 and #3 cylinders, so I figured I'd try changing that and see what I found along the way. What I found was an intact head gasket, but worn valve guides. I later read that a CEL flashing only at idle and showing misfire is commonly indicative of worn valve guides. I'm now in the process of reinstalling the head after replacing the entire valvetrain.
I started a thread on here a while back that has some pictures and more description of my troubles. You can find it HERE
I would definitely start with a compression test and go from there. Checking the valve lash is a good next step, and you can check retainers while you're in there. I think someone else already noted, though, that cracked retainers will not give you a CEL or necessarily give you any clue that they are cracked until the valve drops into the cylinder. I'm hoping your issue is something simple, as mine has cost be about $1800 so far, but I figured I'd bring it up as worn valve guides never came into the discussion on the monster misfire thread, and your story sounds similar to mine. Good luck! Go do a compression test and come back and post the numbers.
I started a thread on here a while back that has some pictures and more description of my troubles. You can find it HERE
I would definitely start with a compression test and go from there. Checking the valve lash is a good next step, and you can check retainers while you're in there. I think someone else already noted, though, that cracked retainers will not give you a CEL or necessarily give you any clue that they are cracked until the valve drops into the cylinder. I'm hoping your issue is something simple, as mine has cost be about $1800 so far, but I figured I'd bring it up as worn valve guides never came into the discussion on the monster misfire thread, and your story sounds similar to mine. Good luck! Go do a compression test and come back and post the numbers.
The fuel injectors already came in, so I figured it couldn't hurt to put them in, and the car does run a little better, but the problem was obviously in the engine itself.
I guess my next step is to put a capful of oil in and see if the compression goes up, and take it in for a leakdown test. But based on the very low compression, does anyone know what the problem may be? If the bottom end is fine, how much would a head rebuild cost, or just replacing a couple of valves.
01-19-2014, 01:08 AM
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Low compression can be due to burnt or bent valves not sealing properly or a blown piston ring. I can't give you a direct estimate on a head rebuilt but I'm positive it's cheaper than the bottom end. Even cheaper if you can remove the head yourself and save labor. Look on the force induction forum on s2ki. There are write ups for the head removal. I also have a PDF version of the helms manual if thatll help you remove the head
01-19-2014, 04:46 AM
#18
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I didn't see if you checked the valve clearance.
If you didn't, that is you next step. If you do have a burnt valve, you will want to find the underlying cause.
If you didn't, that is you next step. If you do have a burnt valve, you will want to find the underlying cause.
01-26-2015, 03:53 PM
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Just wanted to update this thread in case anyone had similar problems as mine in the future.
I've driven around with the misfire for about a year with the same symptoms, but last week I made a 16 hour round trip to visit @jordanksartell to get my head replaced. He showed me the head after he pulled it from my car, and one of the cylinder 1 valves were burned to a crisp and started to develop some cracks. I'm sure that is what was causing the 90 compression.
After he replaced the head, the car idled smoother than ever and I can definitely notice an increase in power. I still don't know what initially caused the misfire and burnt valve to begin with as I bought the car like this, but I am guessing it was due to tight valves. Jordan is very knowledgeable when it comes to these cars (or cars in general), and I learned a lot throughout the process. I would definitely recommend the drive to see him if anyone is having troubles with their S2000.
I've driven around with the misfire for about a year with the same symptoms, but last week I made a 16 hour round trip to visit @jordanksartell to get my head replaced. He showed me the head after he pulled it from my car, and one of the cylinder 1 valves were burned to a crisp and started to develop some cracks. I'm sure that is what was causing the 90 compression.
After he replaced the head, the car idled smoother than ever and I can definitely notice an increase in power. I still don't know what initially caused the misfire and burnt valve to begin with as I bought the car like this, but I am guessing it was due to tight valves. Jordan is very knowledgeable when it comes to these cars (or cars in general), and I learned a lot throughout the process. I would definitely recommend the drive to see him if anyone is having troubles with their S2000.
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