9thgenidiot

I've had some acceleration and idle issues for quite some time.. the issues seem to get much worse with the A/C on, and very relieved with the A/C off. The car is a 2012 Civic LX with 155k miles.

When idling in park with the A/C on, I feel very rough bursts of vibrations every 10sec or so.. feels like it might be missing (?) but I have brand new OEM plugs and OEM coils and I haven't gotten a CEL. This also happens when idling in DRIVE but stopped, such as at a red light or stop sign.. but I feel NO vibrations when accelerating or cruising. just severe hesitation.

If I turn the A/C off the bursts of vibrations seem to go away.

When accelerating with the A/C on I notice it's VERY weak. If I turn the A/C off I feel a lot of the power is back, and I can accelerate much more easily.

What I've done:

I had a tear in my air intake boot that was causing some surging-- replaced the intake boot and surging went away but the acceleration/idle issues above remained.
Removed and cleaned my MAF sensor with MAF sensor cleaner.
Installed new air filter since it needed a new filter anyway
Ordered new Denso OEM plugs and coils (4 plugs, 4 coils) and installed them to replace old ones
Reset ECU after cleaning the MAF and again after replacing plugs/coils

Nothing has helped.. car isn't showing any codes, nor has it ever. I'm thinking my throttle body may have gotten dirty when I had a tear in my intake boot.. but would this result in my issues getting worse when the A/C is on? Maybe dirty fuel injectors (would this set a code?)

Any suggestions would be huge. Thanks

Tachi

If there aren't any issues when the AC is off, under any throttle/rpm regime, then my inclination would be the compressor or an issue with the charge/oil since you mention the AC is weak as well. Possibly a clog in the system causing the compressor to work extra hard when the clutch cycles on, putting such a load on the engine that idle adjustment cannot compensate properly? That's my first guess but even a remanufactured compressor is too expensive for a guess, especially after you just spent probably $400 on the engine.

Dirty injectors wouldn't set a code, but that would cause a consistent hesitation and idle quality issues, and your car is only a few years old, unless you've been exclusively buying gas from the bottom of Costco's tanks before they get refilled they shouldn't be dirty yet. Same with the MAF, they usually get dirty only from infrequent air filter maintenance or yabos sticking K&N's in the box.

9thgenidiot

Thanks. With the A/C off there really is no problem accelerating and there are zero idle issues. However, immediately when I turn my A/C on, I feel the car rumbling in bursts while at idle (does not rumble under acceleration), and the acceleration is incredibly weak. Could there be an issue with my serpentine belt causing this? I looked at it today and saw a very tiny crack line in it but there is no squealing at all.. at 155k miles it couldn't hurt to get that replaced anyway.

Sorry if I didn't mention earlier but the A/C itself works fine. Cool air blows out perfectly, it just seems like turning it on causes unreal idle roughness and horrible acceleration.

I guess it could still be the compressor failing, or could this be a sign of just low oil in the A/C?

Good point about the injectors, the issue definitely isn't consistent. It just gets bad with the A/C. I get my gas at Hess and Sunoco mainly, sometimes Wawa (major convenience/gas chain here in NJ).

Also I was one of those yabos with a K&N filter. I did have one in but took it out as soon as I cleaned the MAF after reading horror stories and replaced it with a standard Purolator air filter from Autozone. The MAF did look a LOT better after cleaning it but cleaning it didn't provide a noticeable difference in performance.

Appreciate the assistance!

Tachi

Hmm, if the AC works fine, then it is likely not the compressor.

Experiment: At idle, turn everything on. Lights(brights), blower motor, defroster, wipers. Load the alternator as hard as you can.

If your idle goes to crap again, then I'd look into cleaning the idle air control valve. The IACV add extra air to compensate for loads at idle, and it sounds like yours is either dirty or failing.

9thgenidiot

Thanks, will try that in the morning. Should I leave the A/C off with all of those running? Or A/C on? I'll report back with findings.

Also could my problems be caused by a low battery? I've heard some stories about people who had similar issues all caused by a low/failing battery that was causing alternator issues, thus wreaking havoc on performance. Not sure if that is really relevant considering my problems.

Thanks again

Tachi

AC off, we're putting a completely different accessory load on the engine.

A low battery has no effect on the alternator. If it can get the engine started, then it's job is purely as a capacitor, a buffer between the car's electronics and the pulses coming out of the alternator. And again, your car is kinda too new to be having a dying battery already, unless you let it sit for months on end, or let it go weeks without being driven in the dead of a northern winter.

9thgenidiot

Okay thanks, makes sense. I went out this morning and at the same time ran:

Blower on max, front/rear defroster on, wipers on max, headlights and brights on, radio on, all while the A/C was off.

The car vibrated very rough again and seemed to be constantly rumbling, unlike the sporadic bursts I noticed before. This rumbling seemed to not go away until I turned off the blower motor. Once I did, the car idled smoothly.

Sounds like it could be the IACV. Maybe when the A/C was on the car was only rumbling when the compressor was working, then went away.

So the IACV could easily affect acceleration? Hopefully this is the culprit, I was really hoping it wasn't the compre$$or or alternator :/

P.S. I'm wondering why I seem to never get CELs for any issues. A friend of mine said 99% of IACV issues would generate a CEL. If my issue is the IACV, I'd imagine there'd be a light? In the past I had a tear in my air intake boot that was causing a lean +22% AFR condition and there was no CEL. I've also had a misfiring ignition coil and again, no CEL. I wonder if the CEL issue is some separate malfunction in my ECU?

Tachi

Sometimes the IACV generates a CEL. I'm not sure how it is on the recent Hondas but on my 96 Accord its a solenoid that is run on pwm to adjust airflow. The ECU is still fairly dumb, it looks to see if values are within parameters and if they are then no CEL. My Uncle's late model Tundra idles rough with the AC on and it doesn't toss a CEL.

Take off the IACV and clean it up if it looks dirty. Short of that, the dealer might have a procedure to test the IACV, I'm not sure. Your engine is a bit more complex than the ones I'm researching for my own benefit.

DCFIVER

Have the AC system checked. Sounds like a low charge.

9thgenidiot

Okay, so I got the A/C system checked while getting my tires rotated and all was good. The compressor showed no signs of failure, was blowing cool air just fine, but still caused a rough idle when activated.

I'm going back tomorrow for a diagnosis but I'm leaning now towards a worn alternator. I had some new issues tonight:

- Leaving the supermarket tonight I was accelerating onto the highway and was getting almost no response while pressing the gas.. no matter how hard I pressed on the gas, the car accelerated at a very slow, steady pace. But all of a sudden my car surged and accelerated rapidly while holding the pedal down.. very delayed response.

- At night, with my car/headlights facing the wall, every time my A/C kicks in my headlights dim for a second, then go bright again. This also happens every time I turn the blower on, the lights go dim real quick and increase slowly in brightness again.

So now instead of IACV I'm thinking alternator. The battery could be worn too, but since I have no issues starting the car and only have issues while driving, alternator stands out.

Could a bad alternator cause: (1) rough, rumbling idle, (2) horrible acceleration / occasional bucking, (3) acceleration is much better with A/C system OFF, (4) potentially no CEL when failing to this degree?

Thanks

DCFIVER

Yes.

9thgenidiot

Thanks, I tested my alternator (results of the test: https://honda-tech.com/tech-misc-15/...r-bad-3256878/) and it seemed to be working normally.. but I'll retest tomorrow to be safe since I've gotten mixed replies.

Tonight on the Torque app I noticed something called "EGR ERROR" kept bouncing from 0% to 99.22% constantly while I was idling. Could this be a sign of a problem with my EGR valve? I wonder if that could be what's causing my issues, since every other thing I have troubleshooted has come back seemingly normal.

This is what I'm seeing in Torque:

Tachi

If the EGR valve is opening at idle then that is a problem; it's only supposed to open under throttle load, and at idle it will cause a vacuum leak, while at the same time not giving the engine much extra oxygen to work with so it could very well cause your problem. What that's displaying is either the ECU attempting to reconcile an EGR valve that's stuck open, or its directing the EGR valve open by itself which is a problem.

9thgenidiot

Thanks, if the EGR was opening at idle creating a vacuum leak, would there be a lean condition / positive fuel trim numbers? At idle I'm seeing 0% to -6% total fuel trim on average, but would expect to see +20% or so with a vacuum leak (unless this scenario would be different involving the EGR). Not too savvy but that's just my 1st grade understanding.

So it sounds possible that either the EGR valve is sticking open at idle or the ECU itself could be malfunctioning? The car is in the shop as we speak for an 'official' diagnosis so hopefully I'll have some updates in a few hours.

9thgenidiot

Just got out of Honda, their official diagnosis was a collapsing front-right engine mount that was causing my issues. They gave an estimate of $350 to replace it.

Apparently my EGR valve has no problems and the idle + hesitation are caused by the engine mount collapsing. The rough idle I understand but I haven't seen many mentions of engine mounts causing performance issues.

DCFIVER

A broken mount wont cause hesitation issues. However, your description of the problem may be the culprit. Perhaps "hesitation" wasnt the right wording??




As for the EGR error,I suspect the Torque App may be the issue. Only way to know for sure is to use another scan tool....

9thgenidiot

Yeah I didn't think so.. I'm wondering if they missed it here. I can't argue with the engine mount being bad in general, I agree it needs to be replaced. But I just don't feel like it's causing my acceleration problems.

By hesitation I just mean it takes a lot longer to accelerate and get up to speed. From a stop/red light, when the light goes green I hit the gas. But it takes so much longer than usual to get up to speed, and sometimes I feel like I need to floor the pedal to pick up any speed since I'm just slowly accelerating. Most of the "pull" is gone when I accelerate, and it's 10x worse with the A/C turned on.

Torque could easily be the culprit with the EGR meter too.. it's a shame how it's not really more descriptive than "EGR ERR" so I'm just gonna take its output with a grain of salt.

Thanks!

flamingdragon

Not sure if you have found a solution yet, but have you checked for any corrosion on the wires? I had a similar issue before in my VX and checked the wires connecting to the ECU and noticed corrosion at the contacts.

9thgenidiot

Hmm I'll check that today, gotta look up where the ECU is lol. Haven't thought of that

I'm still waiting for Honda to receive the engine mount to fix the idle problems (where do they order these things from, the moon?). But I still haven't been able to resolve the slow acceleration issue.

My acceleration is better with no A/C on but still laggy. Sometimes it feels like the car has trouble shifting and gets stuck in between shifts, and makes kind of a loud rev-like noise until I either press harder on the gas or let off.

I've been recently (once a day) smelling a rotten egg smell inside my car.. lasts maybe 10 seconds and only happens about once a day. Not sure if this could be a sign that my cat converter is failing. I have read it could be an issue with exhaust back pressure causing both the rotten egg smell and acceleration issues.

Not having a CEL has been the death of me!! Respect to any mechanics who worked on cars prior to 1996/OBD-II!!

9thgen (2012) Civic LX coupe, 161k miles