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MASTER TECH, Honda Service Technician
Category: Honda
Satisfied Customers: 5745
Experience:  28 years of Honda training and a master Honda tech
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Accord hybrid: , I have a2007 Accord hybrid. I let the

Customer Question

Hello, I have a2007 Accord hybrid. I let the car sit for about two months and when I started driving it again the gas mileage dropped greatly and it runs very rough like a judder specifically when the eco mode kicks in. I do not have a cel. I've changed the plugs twice, changed the oil and air filter. Help please
Submitted: 2 years ago.
Category: Honda
Expert:  MASTER TECH replied 2 years ago.
Hello welcome to just answer I'm Master Tech and will be able to assist you today.
can you tell me how many miles are on the car and what is the fuel mileage drop from ?
Customer: replied 2 years ago.
there are 140,000 miles on the car, it was running perfect before I stopped driving it for two months. the mileage dropped from around 31 average to around 24 average. Same commute every day. I took it to Honda they hooked it to their computer and said they do not know what's wrong with it. It feels like it has a miss when the ECO vcm kicks in and it just runs a little rough all the time. I also plugged a gauge into the front cat to test the pressure, but the gauge did even move checking for a plugged cat. It runs worse at low stop and go speeds.
Expert:  MASTER TECH replied 2 years ago.
OK thank you for the info. Do you known if they looked at the data readings like map sensor and short and long term fuel data.
This engine does require the engine valves to be adjusted at the 105k service. So these readings will tell me a lot if you have this info.
So this is a possible fuel issue, lazy laf sensor or tight valve.
Customer: replied 2 years ago.
They didn't give me any readings, they just said everything was communicating the way it should. I don't know about the MAP or long term fuel data. When you say laf sensor, are you talking about oxygen sensor? If it were a sensor, shouldn't the Honda garage found that when they were getting their readings? As for the Valve adjustments, would I take that to Honda to do as well? I don't have a lot of faith in that garage at this point.
Expert:  MASTER TECH replied 2 years ago.
Sorry for the term. Yes this is the 02 sensor.
Well before you spend money for the valve adjustment I would really try to find this data out. But my hunch is probably right valves. Now why this just started after sitting 2 months is probably a coincidence. But as a Honda professional I am not a fan of doing a repair until I can confirm a failure like this.
As far as a shop I would either seek a reputable shop that does Honda and Acura repairs..
Typically on a hybrid the valve adjustment is around 4 hours labor plus the gaskets and tube seals.
Customer: replied 2 years ago.
So,when the vcm or eco kicks in, it shuts down the front 3 cylinders correct? so the bad or lazy o2 sensor would be in the back bank correct? And a good honda garage should be able to verify the car needs this work done prior to doing it correct? Or for the cost, should I just replace the rear sensors myself? It seems to get worse when it's raining or very humid too.
Expert:  MASTER TECH replied 2 years ago.
Correct.i would check the 02 sensor connectors and make sure their is no corrosion in the terminals
I would hate to have you replace the rear 02 sensor and the problem not be corrected.this is the reason for the live engine data to see what' the pcm ( power train control module) is doing
Customer: replied 2 years ago.
Also, I almost forgot, when I put higher octane gas in the car, it actually gets worse gas mileage, by a couple of mpg. I guess I will take it back to a dealership and see what I can find out.
Expert:  MASTER TECH replied 2 years ago.
Hmm that's very odd the obtain rating should give better performance. I'm beginning to wonder if you picked up some bad fuel.
Customer: replied 2 years ago.
I've tried seafoam and have ran probably 15 tanks of gas since it has started. I ran two tanks of premium and noticed it got worse, so I switched back to regular and it actually improved sightly. The crazy thing is, that it doesn't always run the same, some days are worse than others, but it always runs rough. I even thought a possible vacuum leak, but couldn't find anything. I also thought maybe a mouse or rat built a nest somewhere or chewed something as crazy as that sounds.
Expert:  MASTER TECH replied 2 years ago.
If thwir was roadant damage the check engine light will come on
Let's continue with having the engine data. I don't wanr to get to far off track.
When they check this make sure the radio and ac and blower is off or you will get a false readings.
Customer: replied 2 years ago.
OK, so I found my printout from the dealership and it reads: Cause: Technician road tested vehicle ten miles to verify problem, Found torque converter judder at slow accel at 25 mph. Engine Has excessive vibration at idle indicated engine mounts deteriorating. Vibrations felt when vehicle is on a light load when it shift into 3 cylinder mode(VCM). Scanned for trouble codes, none stored, Scanned for misfires, no misfires found. Map sensor reading .89-.91 volts at idle indicating good vacuum. Checked operation of the active engine mounts, both operate but do not suppress the vibrations completely in three cylinder mode. No DT'C storedfor the ACM system indicating a bad control at this time. EGR lift at 1.12 v indicating that the valve is closed at idle. Performed ACM/VTEC/VCM test and vibrations could be velt when VCM is activated and vibrations were reduced slightly when activating acm with vcm indicating the active engine mounts operate to an extent. 07 drivability 2272 C 0.30 Will need further diagnosis and need to contact honda techline for further information. $59.00
Expert:  MASTER TECH replied 2 years ago.
The map is more on the high side. Typically a good map for me is 85-87..
Now will this cause the mileage drop your having is unclear.
What is your tire pressure set at? The reason I ask is this affect mileage also.
Personally I set my psi high cause I commute and I have seen the mileage difference from 36- to 49 mpg. And this varies greatly in my tire psi.
Customer: replied 2 years ago.
Tire pressure is at 32 psi. I was going up a hill yesterday, I accelerated hard the car responded well, but but ever since the car is telling me that my mpg has dropped another 4 mpg to 21 mpg highway. I'm so frustrated
Expert:  MASTER TECH replied 2 years ago.
OK going off the average mileage will be affected by fuel and drive styles. If the system is reading correctly as indicated then this issue is related to the fuel. Here in California we use different blends all the time and we see this fluctuations in mileage all the time.
So either a fuel Injector issue or the fuel your using. As far as mechanical I don't think anything is wrong at this time.