I have a Honda civic Hybrid 2008. There is a loss of power when accelerating. A friend thinks (without looking at it) that I need to change my spark plugs. They were changed 32,000 miles ago. When should I change them?

 

What does your IMA battery gauge do? The hybrid uses battery assistance when accelerating so if your battery has reduced capacity this can limit how much extra power you get.

Also dirty CVT transmission fluid can prevent the CVT from sliding into the correct ratio (gear) quickly enough, which can cause sluggishness.

 

HCH2 spark plugs should be replaced every 100K with the very expensive Honda spec (NGK and DENSO) Iridium plugs. The are about $25 each at the dealership, $14 each at parts stores and about $10 each online. There are 8; 4 front/4 rear. If you cheaped out and bought the crappers, you may need to replace them.

If you have any sensation of a slight hesitation or missing, I had that happen on an '06 HCH2. It turned out to be a single coil, but it never threw a code.

It's unlikely they are contributing to low power unless your CEL is flashing indicating active misfire.

CanadaJimmy is on the right track on both counts:

1) if you every see 2 bars on the battery gauge, you're almost certainly in a negative recalibration, which robs you of power due to forced charging and nearly disabled assist - bad battery.
2) If you're not replacing your CVT fluid every 15K miles, you may be experiencing forward starter clutch slip. The engine revs abnormally high when this happens. LOW fluid can also cause this.

Personally, just because HCH2 batteries are so crappy, I'd put my money on #1.

Additionally, there are the usual things like dirty air filter (really dirty), dragging brakes, and a clogged/restricted cat (usually throws P0420 or P0421 codes).

 

This morning, the IMA battery level gauge was at 4 cells. I drove 5 miles, it was at 6 cells on arrival. When I start to accelerate, the Assist gauges goes up. After a while accelerating, the Assist gauge is at zero. When I stop accelerating or brake, the Charge gauge goes up. When I use cruise control, the Charge gauge is small.
Last time the CVT fluid was replaced, it was 4 years ago or 64,000 miles.
So do you confirm that I should replace the CVT fluid?

 

What you're looking for is rapid gauge movement at the rate of 1 bar per second. A negative recalibration is as follows:

Car terminates all assist and beings forced charging even during light acceleration.
Gauge "marches" down to 2 bars at 1 bar/second.
Car force charges the battery most of the time. performance during this time is terrible.
It will continue forced charging most of the time until either the car hits 3-4 bars and resumes driving normally, or a positive recalibration occurs as follows:

Forced charging ends.
gauge "marches" up to 8 bars and begins performing normally.

Frequent negative recalibrations are common for a failing battery. Negative recalibrations followed immediately by positive recalibrations are the worst.

Typical mpg is 40-42 for somewhat conservative driving in a mild climate with minimal climate control use. If you're not getting that, and it's not attributable to driving style, conditions or climate, something may be wrong.

Per above, you should be replacing your CVT fluid every 15K miles (every other oil change). Honda recommends 30K, but the reality is keeping the fluid clean is the best defense against CVT replacement (no one repairs them for a reasonable price), and an extra $30-40 worth of fluid every 15K miles is pretty cheap insurance.

 

I'm going to replace the CVT fluid. My car has 159,210 miles. I had the IMA battery replaced at 90,000 miles under warranty. I live and drive in Miami, where the temperature is high, so I use AC a lot. The average consumption is 30 mpg.
Right now, I don't need to use the AC so I can try to see what the consumption is.
For what you wrote about negative recalibration, I don't think I have this problem.

 

30 mpg is absolutely terrible. Even a Civic with a failing battery doing recalibrations every 5 minutes should do better than that.

I live in Phoenix, and I scoff at your "temperature is high" comment...

Practicing light hypermiling in 105°F+ temps, I was able to routinely get 48-52 mpg on my daily commute (15 miles each way, almost perfect 50/50 split between surface streets and freeway). That was also a FANTASTIC way to kill my battery - which I did after a couple months. After replacing the battery, the same techniques produced 42-46 with A/C use.

Seriously, with HEAVY A/C use and moderate driving, you should be North of 38. If you're a leadfoot, then it's a different story, but even with somewhat "spirited" driving, mpg as bad as 30 should be tough to get.

Something is definitely wrong, and a test is in order. I recommend you conduct some experimental MPG tests. Do about 10-20 miles of continuous 65mpg driving on level terrain. If you're not getting close to 50mpg, something is definitely wrong.

It's also worth jacking each wheel off the ground and confirming all the wheels rotate freely; removing the upper cat, which is a pain, and checking it for obstruction or failed/broken guts; checking for over-filled oil; compare performance with air filter in place vs. removed, etc... anything that might add friction to the mechanical systems or restriction in the intake/exhaust.

With another 70K on the battery, the chances for failure are very high. Watch that gauge like a hawk, particularly when you perceive low power.

 

Yesterday, the covers at the bottom of the car (I don't know the exact name) were almost touching the floor, then the Indicator Malfunction Lamp came up. This morning, I used the OBDII code reader and the Torque app to detect code P0301. I brought the car to the garage and he tied the bottom covers, replaced 8 spark plugs and the ignition coil for $350.
The Indicator Malfunction Lamp turned off and the loss of power during acceleration disappeared.
Now, I have to measure gas consumption again.

 

This morning, I tried the Fuel economy add-on to the Torque Pro app. It showed me a gas consumption of 44 mpg. I still have to do a usual gas consumption test.
Then I scanned for fault codes. I saw the old P0301 code with "current fault", I assume it was still there because I didn't clear the code after that the Malfunction Indicator lamp turned off, am I right?
But a new code appeared: P0420 with "pending fault".
What does it mean? What should I do?
I still didn't flush the CVT fluid.

 

If you didn't clear codes, P0301 will still be present.

P0420 is the upper cat efficiency threshold code, i.e., the upper cat isn't performing to spec. This can also be influenced by P030X codes due to the incomplete combustion that occurs.

Recommend you clear all codes by disconnecting the 12V for 60 seconds and reconnecting (you'll need your radio/NAV code). At next fill-up, add a jug of concentrated fuel injector cleaner and use Chevron gas to help make sure your fuel system is in decent shape.

See if the P0420 comes back. If it does come back, it can often be ignored provided you can clear the code and it stays away for awhile; however, P0420 can be caused by clogging or structural failure internally where flow gets blocked. These are both mpg killers, and the cat should be replaced. Before you consider a dedicated fit drop-in replacement, check with local muffler shops as they will often be able to cut the old one out between the flanges and weld in a new aftermarket one for a tiny fraction of the cost (around $200) of a dedicated fit unit ($500+).

I don't trust the torque mpg values, but I never used it on the HCH2. On both of my '06 HCH2, the on board fuel mpg meter was about 5% conservative, i.e., when i calculated it at fill up, the mpg meter always read a little lower (typically about 2 mpg).