jwwrox

I bought a 2006 Honda Civic LX in June this year, and for a few months now I have noticed poor gas mileage (not more than 27mpg, even when almost all the miles are on the interstate). This bad gas mileage seems to correlate with the driving issues I have.

When I start my car, it idles around 1,300 or so, but sometimes when I am stopped at a light, it idles around 8,000. Sometimes, the car seems to be shaking excessively and the engine is making (unhealthy) noises. What is most noticeable is when I am driving and the car seems to rev really high before it changes gears, and then when I let off the gas pedal the engine doesn't rev down, it just stays. At this point, if I tap on the gas pedal, the rpm drops down anywhere from 300-1000, as if the engine is "stuck" at a certain rpm. Also, when I brake and give my car gas, it sometimes seems as if there is a "lag" between when I hit the pedal and when my car responds, and then when it does respond, there is a brief "jerk" as the car catches up with my foot on the pedal.

I'm definitely not really car-savvy, but my air filter has been recently changed, and all my fluids are good (although some things may be in need of a change). When this started, I went to my mechanic and he said that there was nothing wrong with my car, but my gas mileage is really poor when I don't drive on the interstate (25mpg or so). Also, my car has 70,000 miles and a clean Carfax, so it should really be getting better mileage than that. What could the problem be?

ezone

If "your mechanic" is old school, you may need to update him. Most average mechanics aren't going to have scan equipment to do really in-depth analysis for these cars unless they specialize in Honda/Acura, and have spent some serious coin for factory scantools.

Check Engine Light on? What codes?
1300 RPM cold sounds about right, as does 800-900 RPM warm. This engine has "throttle by wire", all electric. All controlled by the computer. Proper scan tool is needed to see what is going on.

No clue on your noises unless I can hear them myself.

Ask your Honda dealer about these:
Recall 05-061 addressed the accelerator pedal bracket. Was it done?
Honda bulletin 10-073 addresses an intermittent idle vibration when at a stop, with electrical loads on. (New software for the PCM.)
Has the water pump recall been done?
Wheel speed sensor recall?
Need sunvisors?
Lots of stuff you should see a dealer about.

Wait a sec....
I can run your VIN# to check for recalls that haven't been completed if you post it. I have access.

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Now.....Your complaint about the way it runs and shifts, coupled with the fact the air filter has been replaced....leads me to think that maybe the MAF sensor got contaminated. Bug, dirt, oil from a drenched K&N, something along those lines.

Cheap air filters that don't quite fit and seal inside the air box cause this quite frequently. I see it a lot on cars that were recently at a JippyLube and got the filter replaced.

Make sure the lid of the box is clamped down completely, and the rubber tube at the back of it didn't get folded under the tube. Air leaks cause problems.

I suppose all these complaints started soon after the air filter got changed?

Your MAF sensor is on the lid for the air filter box, the only thing with a wire on it. If you pull it out, it will look something like this:

Look into the slots on the bottom of it with a flashlight. See anything besides fine wires? A small bug, perhaps? Tap it out. Gently clean with keyboard duster/air or a spray can of brake cleaner. Maybe a q-tip, but be extremely gentle, the wires are very delicate.

jwwrox

Actually, these problems started before I got my filter changed, which prompted me to go get it checked out. I think that they started soon after I really "revved up" my car for the first time, letting it get to around 5,500 rpm or so, not dangerous levels by any means. The next day, I noticed a change in the way that the car drove and changes in the noises that the engine made.

My VIN is 1HGFA16556L075544

ezone

You didn't say whether or not the check engine light is on. If it runs as bad as you say it does, it ought to be on.

Revving the engine up isn't supposed to hurt anything (as long as it had oil in it). It has a rev limiter, so you really shouldn't be able to hurt it as long as everything is normal.

I'm a dealer tech, so I usually lean toward taking it to someone intimately familiar with the cars and has whatever tools are necessary at his disposal, instead of someone that works on everything under the sun (I have done that too, 10 years).
You have to get someone there that knows WTF they are doing though. Most shops (dealer and independent both) depend on flunkies to do the majority of the work, and only a small percentage of techs that know what they are doing (a lot of our work is fixing what the rookies screw up) and really take the time to care about a customer. (Guess which one I am.)
Ask for the top rocket scientist/troubleshooter.
Take him for a quick test drive, because SHOWING what the problem is is FAR more effective than trying to explain anything through 3 or more people (ever play "telephone"?) Be quick about the test drive. No more than 10 minutes if at all possible: MY time, literally, is money.

Hopefully your tech won't be a punk kid fresh out of community college (green).
Hopefully your tech won't be a parts replacer.
Hopefully your tech can fix more than a sandwich.

You probably wouldn't want me working on it, I look like a homeless longhaired biker.
Looks can be deceiving.


VIN info
Delivery date 03/31/2006 (No 5/60 Powertrain warranty now, out by time.)
Selling dealer: Nalley Honda
Current owner: Ques******
Emission type: KA

Recall info:
Rear bearing/speed sensor: Done.
Tensioner pivot bolt: Done.

Warranty extensions apply to:
Cracked block (8 years/unlimited mileage)
Sunvisors split (7 years/100,000 miles)

MindBomber

I second ezone, it would be very surprising if given the symptoms you've described the CEL is not on or at least a code stored in the ecu. If your mechanic has not checked for codes as of yet, then that he absolutely should be at this stage, it will go a very long way towards providing the information needed to diagnose the issue.

jwwrox

Nope, my CEL is not on, and no other lights are either. I am not sure that my codes have been checked, however. Maybe I should change the transmission fluid (and the engine coolant and the brake fluid) and see if the problem magically vanishes. I probably would have gone to the dealership already, but I live over an hour away so it's very inconvenient if I'm not sure about the nature of the problem.

Maybe it's just in my head, but I think that the rpm should go down on its own and not require a tap on the pedal to go back to normal. When it does go down after I tap the gas, the car isn't changing gears or anything, by the way, so it's a very peculiar problem.

ezone

If you are posting here then you probably have a concern that needs addressed, whether it is legitimate or not. This is why you have to SHOW THEM what you mean. Most normal people don't complain about stuff that isn't real (smoking crack). And based only on the descriptions you have given, I would want you to show me so I understand what the problem is.

CSB: Right now, I am writing this from a hospital room. My girlfriends mother is here because she lost consciousness and they suspect heart problems or something...but they want to witness what happens first hand. They don't want to send her home unless they know she has been fixed......or maybe they are just collecting rent on the room for a few days. They are taking her for a monitor and stress tests in the morning.

A quick test drive with a good tech will either verify your concern, or he should be able to tell you it's normal and you need professional help of another type (LOL) and send you on your way.

Many real problems don't leave codes. "No code diagnosis" will completely baffle all but the smart ones. Many so-called mechanics can only read codes and throw parts. If that doesn't fix it, then they are completely lost and you lose. Like I said before, ask for the rocket scientist.
Even without any CEL or codes, there is a wealth of information available from the computers in the car, but it takes the proper tools, and a smart tech with a lot of experience to be able to use that handy information. Experience can also lead them right to some obscure fixes too.

Randomly changing fluids is an absolutely pointless waste of money, just like firing the parts cannon at it.
Unless you justify it by saying "it needed all that stuff anyway".

Handy pic of a parts cannon:

Jack Smith

I really like this post.its my first time here and i will keep in touch for next updates.