High idle?

Tiny
ALYSSA STEPHENS
  • MEMBER
  • 2001 HONDA CIVIC
  • 0.7L
  • 4 CYL
  • 2WD
  • MANUAL
  • 199,000 MILES
My car typically idles at about 1,000. Car RPM's jump from roughly 500-1500 then drop down to 0. It started jolting but earlier today was fine. I was not driving my car (I had a few beers) but my brother was who has driven many manuals before. I don't think he wore my clutch out or anything crazy, he seemed to be driving it just fine. When we made it back home I toyed with it. I turned it on and let it idle in neutral. The check engine kept flashing and the tachometer would bounce for about thirty seconds then go to 0 the temperature gauge quit too, but the has and mileage was still there. When I would press the gas the rpm gauge was not registering. Turned it off and back on. Would register for a few seconds when surging (if that's the right term) and wouldn't register after 30 seconds. It has done something similar a few months ago where the car would completely shut off and would have to be turned off and back on. I took it to a shop and they replaced the ignition coil pack. I'm a girl so bear with me. I know a bit but not enough. I have replaced the spark plugs a few months back. There were used parts from a junk yard (he picked the nicest looking ones being a mechanic) put in as well by my ex which included a starter, alternator, new A/C belt, cleaned fuel injector, new map sensor, and many more I may not even be thinking of. Do you think it could be a head gasket? Maybe check the spark plugs again? Vacuum leak? Could it be a faulty sensor or fuse? I'm somewhat knowledgeable from being with someone who worked on cars and helped pull parts, but I'm not very good with diagnosing. Please help :(
Monday, April 13th, 2020 AT 5:46 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi, Alyssia,

Listen, if the check engine light is flashing, that most always indicates a misfire. Have you tried scanning the computer to see if there are any diagnostic trouble codes that can point you in the right direction? Here is a quick video showing how it is done:

https://youtu.be/YV3TRZwer8k

I realize most people don't own a scanner, but often times a parts store will do it free of charge, or they will rent / lend you the scanner to do it. This really is what needs done first.

As far as your questions above, there are many different things that can cause idle related issues and the things you described. Certainly an engine vacuum leak will do it along with the other ideas you mentioned.

In this case, I honestly recommend to have it scanned. Once you do that, let me know what you find so I can direct you.

Here are a couple links you may find of interest:

https://www.2carpros.com/articles/check-engine-light-top-ten-reasons

https://www.2carpros.com/articles/check-engine-light-is-it-safe-to-drive

Let me know what codes are stored so I help you diagnose the issue.

Take care,

Joe
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Monday, April 13th, 2020 AT 6:10 PM
Tiny
ALYSSA STEPHENS
  • MEMBER
  • 4 POSTS
Do you think it is safe to get it to the nearest Auto Zone with it jolting the way it does? Like I said I have experienced this before and I think I could handle it, just don't want to get stuck if you deem it to be a serious issue. Do you think bent valves could cause recurring misfire with the previous repairs listed? Thank you for getting back so quickly.
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Monday, April 13th, 2020 AT 6:27 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
It is so hard for me to tell simply because I'm not there to hear the vehicle and how it's running. If it is running really bad, maybe it would be better to see if you can get a scanner from them and check it at home. Honestly, I don't want it to stall when you are pulling into traffic, have you break down, or cause additional damage to the vehicle.

As far as bent valves, that usually isn't an issue unless the timing belt had broken. You have done a lot already. If, however, we determine by scanning the computer that you have a lean fuel mixture, the problem could be an engine vacuum leak. If the misfire is specific to only one cylinder, we can confirm the plug is good, getting spark, and if needed, check compression.

Let me know if you have other questions. Also, I forgot to mentioned this in the first post, but chances are the RPM's are jumping because of a misfire.

I possible, have it scanned and let me know the results. If you have additional questions, let me know. I'll try my best to help.

Take care,

Joe
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Monday, April 13th, 2020 AT 6:36 PM
Tiny
ALYSSA STEPHENS
  • MEMBER
  • 4 POSTS
It isn't running bad other than the rpm gauge and jolting as far as I know. The gas isn't registering with the rpm. I had two different brothers drive and both said it wasn't accelerating with gas. In thinking its possible bent valve since I have done a coil pack change and spark plugs. I guess I should check spark plugs tomorrow morning before I say any more though. Could be as simple as that which I can do myself.
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Monday, April 13th, 2020 AT 7:08 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Anything is possible. If you feel more comfortable checking the plugs first, that would be great. Let me know if you need help or have any questions. Also, let me know what code are pulled if you have it scanned. The nice thing would be to know exactly which cylinder is causing the misfire. Then you could pull that one and inspect it.

Regardless, I'll be here if you need anything.

Take care,
Joe
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Monday, April 13th, 2020 AT 8:36 PM
Tiny
ALYSSA STEPHENS
  • MEMBER
  • 4 POSTS
Thank you. I know before it was a cylinder 2 misfire. If it is another cylinder 2 misfire do you think bent valves are a possibility. I bought the car for cheap off of Facebook marketplace and definitely seemed to be a project car but ran. Didn't seem like a project Until we worked on it under the hood. Seems like they may have meant for it to be some type of street race car. It is straight piped with no catalytic converter. Until I got on the highway and it wouldn't go over 40 mph it seemed fine though We had it fixed for about 6 months but I do not have that connection any longer and am not savvy as he was lol. All I know is what he has done (for the most part) and what I think is possible. I will have it scanned asap just looking for options before I risk a break down. Thanks in advance.
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Monday, April 13th, 2020 AT 8:58 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If there is a concern of a bent valve, the best thing to do would be simply perform a compression test on the engine. By doing that we can determine if there is an issue with any of the cylinders (specifically cylinder 2). However, before I would go to that extent, remove the spark plug from cylinder 2 and inspect it. Is it wet? What color is it? Is it getting spark? You could have a bad plug.

If the plug is getting spark, then do the compression test. Here is a link showing how it is done:

https://www.2carpros.com/articles/how-to-test-engine-compression

You will need a compression gauge, but most parts stores will lend you one.

Here are the directions specific to your vehicle including the manufacturer's specs. The attached pic correlates with these directions.

_________________________________________________________________

2001 Honda Civic DX Sedan L4-1668cc 1.7L SOHC MFI
Component Tests and General Diagnostics
Vehicle Powertrain Management Tune-up and Engine Performance Checks Compression Check Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
Engine Compression Inspection
1. Warm up the engine to normal operating temperature (cooling fan comes on).
2. Turn the ignition switch OFF.
3. Remove the air cleaner housing.
4. Disconnect all four injector connectors.
5. Remove the four ignition coils.
6. Remove the four spark plugs.

See Pic 1

7. Attach the compression gauge to the spark plug hole.
8. Connect a tachometer.
9. Open the throttle fully, then crank the engine with the starter motor and measure the compression.
Compression Pressure:
Above 930 kPa (9.5 kgf/cm2, 135 psi)
10. Measure the compression on the remaining cylinders.
Maximum variation:
Within 200 kPa (2.0 kgf/cm2, 28 psi)
11. If the compression is not within specifications, check the following items, then re-measure the compression.
Damaged or worn valves and seats
Damaged cylinder head gasket
Damaged or worn piston rings
Damaged or worn piston and cylinder bore

__________________________________________________________

Let me know if you decide to do it. If you have other questions, let me know.

Joe
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Tuesday, April 14th, 2020 AT 9:11 AM

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