Dobber1

Preface -
2007 Civic DX, AT, 385K Miles , Original Owner

Parts Replaced to Date -
Starter, Front Wheel Bearings, Front Discs & Pads, Plugs, Serpentine Belt, Air Filters, Lots of Oil & Tires

Symptoms -
Starts right up, but idles rough. Will stall taking off unless you feather the accelerator (like driving an old '74 Chevy 350).

If you start it & immediately start driving it like a MT from Low & running up through the gears, you can get going pretty easily.

It's happiest running about 80mph or any speed as long as RPMs are over 3K. Using 1st & 2nd in town, 3rd up to 55mph, then overdrive above 55. Otherwise it's herky/jerky.

If you're up to speed (any speed), you can slowly accelerate and gain mph, but if you just floor it, it just maintains the current speed with a bog or limiter effect. The transmission will backshift on a steady acceleration, but if you just stomp the pedal to the floor, it just bogs & holds your current speed. Whether it's 25 or 65, doesn't change the results.

Here's a list of the codes (at least one of these is old, because the CEL has been on for 6 months or more). The CEL used to come on for a few days then go off for a week or so, then come back on, then back off, until it just stayed on. Didn't effect performance or fuel mileage, so just ignored it. With this many miles, this car doesn't owe me a thing, except 15K more miles!

P0420 This may be the old code I used to get last time I pulled them? (Catalyst System Efficiency Below Threshold Bank1)
P0497 Evap System Low Purge Flow
P0171 (Fuel System Too Lean Bank 1
P0301, P0302, P0303, P0304 (Cylinders 1-2-3-4 Misfires)

Let me know where you think I should start throwing parts at this tired puppy.
Thanks!
Dobbs

ezone

Fuel pressure test?

Some of the symptoms coupled with the P0171 and misfires would make me want to check fuel pressure and monitor it while trying to drive and see where it goes while the symptom acts up (bogs).


If it is not dropping fuel pressure during the bog then I'd check for backpressure/exhaust restriction/clogged cat.

I might check for that first instead, depends on what I think after a test drive. Maybe remove the top O2 sensor and see if letting exhaust escape through its little hole helps reduce the bog or performs a little bit better.



Hard to just pick one thing and declare "that's it!"


Valve adjust? Sometimes tight valves can cause cold start-stall and cold rough running.

Dobber1

OK, pulled the top O2 sensor (car was still hot after 60 mile drive home). Started the car, RPMs went to 1,500 like they have been, then it idled down to a rough idling 500 RPMs before stalling within a couple seconds. Replayed this 3 times with the same results each time.

Before the last couple days, I was able to feather the accelerator to take off from a stop in low, but now I have to turn it off, then restart and take off right away coming up through the gears. Overdrive is seldom used with this method of madness as the RPMs aren't high enough in OD to keep it running.

Doesn't look like there's a fuel pressure port to hook up to on this year/model, or I'm not sure where to look? Is this a dealer only pressure check procedure?

One more observation, every now & then, there's a strong fuel smell inside the car. Like if you were to be near the vent tubes at a gas station when the transport is dropping premium fuel, which is what I've been running the last couple tanks.

Thanks again,
Dobbs

jordan1794

Wait, are you using a higher octane fuel than 87?
If so, stop now! It will do nothing to help, and if anything could add to your woes.

Running a higher octane than your car is designed for (So unless you have an Si, you should be using 87) will not help performance, and will actually make it run less efficiently.

Using GOOD gas on the other hand, is a good thing.
Google top tier gasoline.

ezone

Is this when and how (your 'bog' description) always happens?




So.....if you can keep it running above about 1500 RPM it will run ok?

There is no port, you'd have to adapt a pressure test gauge into the plastic lines' quick connect fittings.
From the engine compartment?
Raw fuel leak?
EVAP line leak?
Possible odor is related to the P0497 code?

Wait---You can smell a difference between regular and premium???


You've potentially got an awful lot going on here, and I guess I'm not real clear on exactly how this acts and under what conditions it acts up. Might decide more or different things if I could spend some quality time with it, and take a ride in it with a scanner hooked up.

Got any freeze frame data, and which code does it go with?
If you erase the codes, what code comes back first?--and what's the FF data at that time?


Is the EGR valve is stuck open?
MAF dirty?
Also, high mileage injectors might have buildup causing some restriction.
I dunno, I'm only making wildass guesses right now.

Dobber1

Oops, didn't to the "quotes" right, but answers are in the box.
Thanks for your thoughts.
Dobbs

ezone

I've seen what huffing gasoline can do to a person, I don't want it LOL

I've accidentally gotten high on gas fumes while working before, it wasn't the most pleasant buzz IMO.

Mass Air Flow sensor, it's the sensor in the top of the air filter box lid.

Is the air filter box put together correctly?
Is the rubber tube (at the rear of the lid) still in the right place, it didn't get folded under the last time someone took the box apart?
Some big air leak between the throttle body and the MAF sensor?
Breather resonance chamber didn't come apart?


I'm tempted to tell you to unplug the MAF sensor and then start the engine up and see if it runs/drives any better.

Dobber1

Ding, Ding, Ding...we have a repeat winner!
Thanks Ezone!

Unplugged it & sure enough idled/drove fine. Bought some electrical cleaner spray and hosed the MAF sensor down (saw a little hard shell insect in there also) and everything is great!

ezone

Right on, thanks for the update


How did the bug get in? Cheap air filter? Deformed gasket?

A few years back...in the span of just a few months we had several Accords come in with cheapie filters that let bugs in around the gasket (gasket was too thin) causing anything from check engine light to lack of power to not running at all. I guess a local oil change place was installing them.

Dobber1

Actually, I'm afraid I let the little bugger in when in my infinite wisdom a couple weeks ago, drove about 6 miles without the air filter in place to see if that would cure my problem.

Thanks about a thousand or so!
I owe you a couple.
Dobbs

Oh, I like it when people give updates. Kinda turns a mystery into a suspense thriller.
One more thing...I have a '78 Logan Earth Ski w/Tracker Trucks & Kryptonic Wheels (4 different colors) lifted on a couple 3/8" Risers.

ezone

Saweeeet!