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My 96 (or maybe 97) Honda Civic does some strange things. They are all connected.

It will frequently refuse to start. It's not a battery/alternator issue, as it's trying to crank. It just ... refuses. It'll eventually start. Then the fun begins.

Once it's started, it'll sometimes begin revving the engine. Not that I can hear it revving, but my RPM's will jump between 0 and 8000. Sometimes it doesn't die when it hits 0 ... but if it stays there for more than a split second, it will turn off.

Sometimes it runs great. Then, out of the blue, I'll just lose the ability to accelerate. I still have electrical power, mind you. Just not any acceleration, no matter how hard/far I push down on the gas petal. I've been on a highway going 70, lose acceleration, and coasted down to 0 mph. I waited on the side of the road for a few seconds, regained acceleration, and drove until I reached work. The car never shut off.

Right now, you're thinking its a spark plug issue. And I agree... mostly. So I changed the spark plugs. The car worked great! None of these issues came back around ... for about 2-3 months. Then they began back up. So I changed the spark plugs again (and the wires). It lasted about a week before the symptoms began again. I just checked my spark plugs a few minutes ago and they all 4 look identical. There's some black on the very bottom of them, but its identical across all 4.

Any ideas? I'm flabbergasted. Thanks in advance!

  • any codes? i'd think it would be more of an electrical issue and the spark plug change has little correlation with your symptoms. when you say it doesn't crank do you mean it doesn't crank at all or it cranks slow or it cranks and doesn't start? – Ben Sep 12 '17 at 16:48
  • It cranks (as if it's trying to turn over), but doesn't start. Changing the spark plugs fixes the problem temporarily. As in - all the symptoms go away. When they return, they return at basically the same time. – tcrudisi Sep 12 '17 at 21:11
  • Sorry, but that's still not very clear. So it cranks slow? Or it cranks once and then nothing? I'm still doubtful of the correlation between the spark plugs and all these symptoms. Spark plugs going bad/being fouled wouldn't inhibit cranking speed by themselves. Nor would they explain the tach going to 8000RPM or your lack of power without misfiring. Is there fuel leaking into the cylinders? What kind of ambient and in cabin temperatures are you seeing when these problems occur? – Ben Sep 12 '17 at 21:46
  • I took the car to get the check engine code figured out. The response: all 4 spark plugs are misfiring. The guy at the auto parts store suggested I replace the distributor cap and button. I went ahead and bought both parts but I've failed horribly at figuring out how to replace the button. I know there's supposed to be a screw, but for the life of me I can't see it. I've even had my wife crank the car a couple of dozen times to see if the screw will appear when rotated a different way ... no luck. So I'll reply in a couple of days and say if these two things have fixed it. – tcrudisi Sep 13 '17 at 1:12
  • Have her bump the key briefly you'll see it eventually. I forget if it's under the tab or 180° around. It'll be on the flat side. – Ben Sep 13 '17 at 1:22
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Maybe it could be the fuel injectors or the fuel pump that has gone bad or is clogged, are all 4 cylinders getting good compression? It could be a valvetrain problem but with the spark plug situation I highly believe it to be the fuel system if it's getting spark.

Edit: did you check out your fuel filter? Not enough fuel means not enough power!!!!

  • I just replaced the fuel filter but it's still doing the same thing. I now think it's most likely either the fuel pump or fuel injectors. Any suggestions on how to determine which one is failing? – tcrudisi Oct 6 '17 at 13:55
  • You can take the physical injector out and see if it’s squirting fuel or if it’s clogged if that helps – sjfklsdafjks Oct 6 '17 at 14:07
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It could also be a vacuum leak. If you get unmetered air into the engine, it can be detected by a lean air-fuel ratio at the lambda sensor, which means the closed loop control will respond by injecting more fuel, hence the revving.

Also, a vacuum leak can definitely cause the condition of being hard to start. Too much air for the amount of fuel that is usual when starting the engine can mean there is no combustion (gasoline being combustible only at certain air-fuel ratios). No combustion, thus no start.

Because the vacuum lines are rubber, they can very well be failing on a car that is as old as 20 years old.

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There's two possible things that come to mind about that Idle Bobble you're experienced, that I didn't see mentioned...

Idle Air Control (IAC)

Here's a Replacement Video from YouTube Here's a Cleaning Video from YouTube

The other thing is seemingly Honda-Specific. It's called a Fast Idle Thermo Valve.

Here's a Honda-Tech Forum Post about cleaning the FITV

The FITV can cause hunting/surging Idle, aka Idle Bobble. As far as I know it's specific to Honda. The IAC can also cause this issue.

Here is a link to a Forum post with some basic diag to determine between the IAC vs FITV

This is also one of those times where I would recommend a Motor Treatment/Detergent be introduced into the Intake/Top-End. Something like SeaFoam Motor Treatment. I URGE you to read the instructions carefully, as inducing fluid through vacuum can cause harm if you put in too much. Just given the age of the engine, I feel that it could benefit from this treatment.

I am not sure if this is the answer, but the IAC nor the FITV was mentioned, so I figured I'd throw it out there.

Obligatory clean and tighten your battery terminals, grounds, and check all fluids etc.

I hope this helps.

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I'm taking a different approach to this. First, there may be multiple problems here.

First, if replacing the spark plugs temporarily solves the problem, and the car was randomly misfiring on all cylinders, then I can think of only two possible scenarios that fit that description.

  1. Either the tips of the plugs are getting fouled
  2. Or there is high resistance in the secondary circuit causing the spark to look for another path to ground causing carbon trails to form inside the spark plug boot, along the porcelain to the block.

There are a number of possible reasons for #1.

  1. Engine running too rich: This could be due to a stuck open thermostat, a defective ECT ( Engine Coolant Temp ) Sensor, a defective oxygen sensor stuck lean, the engine burning allot of oil, and less likely a defective fuel pressure regulator or fuel pump.
  2. Burning excess oil could itself foul the plugs and cause misfires, even without causing the the engine to run rich

The primary reason for #2 would be the engine running extremely lean. This could be due to either a vacuum leak, insufficient fuel pressure, or a dirty MAF sensor.

On the other hand, I can't think of any reason why fouled plugs or plugs with carbon trails would cause that crazy revving behavior and intermittent loss of power, or how that behavior could be solved by replacing said plugs. In fact, that behavior sounds allot like a defective camshaft position sensor. A defective CPS could also causing misfiring.

However, the bigger point is that it's unlikely you'll be able to properly diagnose this yourself, without a scan tool, potentially an oscilloscope and allot more knowledge than you have. My recommendation would be to take this to a competent mechanic, and in general that means one who has an oscilloscope and knows how to use it.

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That era civic had problems with the relay board that powers the fuel pump. Often worse in hot weather, it can intermittently lose power to fuel.

Lots of sites have tips to diagnose and/or replace. Good place to start because it's pretty easy to test and a fairly inexpensive part.

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