Hello,

I`m driving a 94` EJ2 Coupe (DX) in Europe and MPG sucks.

I found no answers in other threads, like:
https://honda-tech.com/forums/honda-...leage-1035028/

What I know so far:

Driving like grampa.
Stock engine. 240k Km
No cel code. (cel is working)
Stock ECU P06.
Timing belt is new + set on 16 degrees BTDC.
New spark plugs.
New fuel filter.
New air filter.
New o2 sensor.
TPS sensor is working ok 0.5V - 4.5V at full open.
Valves are adjusted, cleaned, all good here.
Good tire preasure.
Fuel is good quality.
No leakings.
Engine olil level is ok.
Engine temperature is ok.
Custom final exhaust.

On deceleration my exhaust backfire quite a lot, Is this normal cuz I have a custom exhaust?

Car is running just fine, no issues, starts up ok, normal engine performance.

30 MPG outside the city is kind of crap for me, any suggestions?

Thank you!

 

It's winter, fuel economy always goes down during winter.

Also, is your car an automatic or a manual transmission?

 

Hi, thank you for the reply

My car is a manual 5 speed, stock gearbox.

combined MPG 28
hwy MPG 30-31
city MPG 25

 

injectors clean. Maybe it will help.

 

Did you jump the service connector to set the timing? If you try to set it in normal run mode (connector not jumped), you'll end up with it way late.

 

I would suggest doing a compression test. If the motor is tired it won't be as fuel efficient. Also, it is very probable that you have high amounts of ethanol in your gas. This lowers MPG. Pure gasoline gets way higher gas mileage than gas/ethanol mix.

Please study the table below as it is 3 years of monitoring two D15B7 motors in my manual CDM CX (USDM DX) hatchback:

MPG	Odometer	Liters	Distance Travelled	Date
0.00	299521.1	37.130	0.0	2/17/2013
30.18	300025	39.270	503.9	2/24/2013
29.87	300489.4	36.570	464.4	3/1/2013
32.96	300985.75	35.420	496.3	3/7/2013
30.36	301470.06	37.530	484.3	3/14/2013
31.83	301967.44	36.760	497.4	3/21/2013
36.23	302517.34	35.700	549.9	3/24/2013
34.20	303026.22	35.000	508.9	3/29/2013
34.54	303598.88	39.000	572.7	4/3/2013
31.18	304129.28	40.010	530.4	4/17/2013
31.63	304667.16	40.000	537.9	4/25/2013
35.02	305210.9	36.520	543.8	4/29/2013
35.99	305807.63	39.000	596.7	5/5/2013
33.02	306341	38.000	533.4	5/12/2013
34.35	306874.1	36.510	533.1	5/21/2013
31.75	307346.8	35.020	472.7	5/26/2013
31.20	307797.8	34.000	451.0	5/31/2013
34.30	308322.72	36.000	524.9	6/5/2013
32.42	308860.4	39.010	537.7	6/10/2013
34.83	309482.3	42.000	621.9	6/15/2013
33.95	310002	36.010	519.7	6/20/2013
37.34	310377.6	23.660	375.6	6/23/2013
32.33	310886.2	37.010	508.6	6/28/2013
33.22	311408.7	37.000	522.5	7/3/2013
33.89	311956.28	38.010	547.6	7/9/2013
31.46	312417.7	34.500	461.4	7/13/2013
34.07	312895.8	33.010	478.1	7/16/2013
34.18	313477.2	40.010	581.4	7/18/2013
32.23	313956.8	35.010	479.6	7/21/2013
28.24	314345.6	32.380	388.8	7/26/2013
29.50	314690.88	27.530	345.3	7/31/2013
29.76	315178.63	38.550	487.8	8/6/2013
32.87	315716.7	38.510	538.1	8/11/2013
31.06	316185.5	35.510	468.8	8/17/2013
30.77	316625.1	33.610	439.6	8/23/2013
30.82	317087.9	35.320	462.8	8/29/2013
33.25	317626.8	38.130	538.9	9/9/2013
31.84	318151.2	38.740	524.4	9/15/2013
30.71	318636	37.130	484.8	9/19/2013
31.75	319082.63	33.090	446.6	9/23/2013
33.04	319616.6	38.020	534.0	9/28/2013
30.89	320114.8	37.940	498.2	10/2/2013
31.92	320588.8	34.930	474.0	10/8/2013
32.38	321086.5	36.160	497.7	10/12/2013
32.23	321552.63	34.020	466.1	10/14/2013
29.07	322031.8	38.770	479.2	10/19/2013
31.61	322476.3	33.080	444.5	10/23/2013
30.31	322952.1	36.920	475.8	10/27/2013
33.81	323469.34	35.990	517.3	11/1/2013
32.37	323966.06	36.100	496.7	11/6/2013
29.49	324417.34	36.000	451.3	11/10/2013
32.50	324938.75	37.740	521.4	11/15/2013
31.55	325424.34	36.210	485.6	11/21/2013
30.69	325899.25	36.400	474.9	12/4/2013
28.73	326373.94	38.870	474.7	12/8/2013
31.26	326828.3	34.190	454.4	12/14/2013
32.75	327273.84	32.000	445.5	12/28/2013
30.78	327745.34	36.030	471.5	1/3/2014
31.45	328244.34	37.320	499.0	1/8/2014
31.57	328739.94	36.930	495.6	1/15/2014
31.00	329235.16	37.580	495.2	1/21/2014
30.21	329646.16	32.000	411.0	1/26/2014
31.55	330119.3	35.280	473.2	2/2/2014
30.57	330600.16	37.000	480.8	2/16/2014
34.59	331143.03	36.920	542.9	2/28/2014
31.62	331679.06	39.880	536.0	3/6/2014
34.50	332215.47	36.570	536.4	3/15/2014
33.43	332671.1	32.060	455.6	3/20/2014
32.16	333134.22	33.870	463.1	3/28/2014
32.98	333645.6	36.470	511.4	4/2/2014
33.21	334356.97	50.380	711.4	4/9/2014
32.95	334757.44	28.590	400.5	4/24/2014
33.81	335219.56	32.150	462.1	4/27/2014
33.27	335736.28	36.530	516.7	5/3/2014
37.12	336239.25	31.870	503.0	5/13/2014
33.74	336679.34	30.680	440.1	5/17/2014
35.03	337226.25	36.720	546.9	5/25/2014
33.60	337781.56	38.880	555.3	5/31/2014
34.79	338206.06	28.700	424.5	6/7/2014
35.46	338741.66	35.530	535.6	6/10/2014
34.37	339263.8	35.740	522.2	6/16/2014
35.48	339763.34	33.120	499.5	6/22/2014
33.21	340162.88	28.300	399.5	6/27/2014
34.47	340648.25	33.120	485.4	7/3/2014
33.95	341111.66	32.110	463.4	7/8/2014
36.65	341663.34	35.410	551.7	7/16/2014
34.07	342150.34	33.620	487.0	7/23/2014
35.81	342698.56	36.010	548.2	7/27/2014
38.58	343271.1	34.910	572.5	8/1/2014
37.04	343775.94	32.060	504.8	8/7/2014
33.98	344297.06	36.080	521.1	8/13/2014
37.16	344849.13	34.950	552.1	8/19/2014
36.50	345362.88	33.110	513.8	8/26/2014
37.38	345824.66	29.060	461.8	9/3/2014
35.77	346365.78	35.580	541.1	9/4/2014
36.49	346929.75	36.360	564.0	9/11/2014
37.56	347475.16	34.160	545.4	9/16/2014
32.41	347983.72	36.910	508.6	9/22/2014
35.89	348466.34	31.630	482.6	9/27/2014
36.67	348971.75	32.420	505.4	10/2/2014
33.51	349493.94	36.660	522.2	10/8/2014
36.48	349983.34	31.560	489.4	10/19/2014
33.17	350462.4	33.970	479.1	10/27/2014
31.40	350934.66	35.380	472.3	10/31/2014
35.86	351448.06	33.680	513.4	11/8/2014
33.77	351991.66	37.870	543.6	11/28/2014
35.14	352420.94	28.740	429.3	12/2/2014
31.38	352936.47	38.650	515.5	12/11/2014
33.71	353461.34	36.630	524.9	12/13/2014
32.28	353962.4	36.510	501.1	12/19/2014
36.59	354536.06	36.880	573.7	12/24/2014
31.44	355034.16	37.270	498.1	12/30/2014
33.39	355537.4	35.450	503.3	1/7/2015
33.44	356067.44	37.280	530.0	1/14/2015
34.66	356605.34	36.510	537.9	1/20/2015
31.40	357110.25	37.820	504.9	1/27/2015
32.46	357617.66	36.770	507.4	2/4/2015
31.94	358143.44	38.720	525.8	2/13/2015
33.44	358682.13	37.890	538.7	2/17/2015
33.42	359160.56	33.670	478.4	2/17/2015
30.99	359703.56	41.220	543.0	3/3/2015
32.30	360202.34	36.320	498.8	3/16/2015
32.97	360696.75	35.270	494.4	3/26/2015
35.95	361234.03	35.160	537.3	4/7/2015
37.37	362002.94	48.400	768.9	4/16/2015
33.25	362538.16	37.860	535.2	4/23/2015
32.52	363073.03	38.690	534.9	5/2/2015
34.21	363620.38	37.640	547.3	5/9/2015
35.19	364199.2	38.690	578.8	5/15/2015
34.19	364755.4	38.270	556.2	5/21/2015
34.66	365313.1	37.850	557.7	5/27/2015
34.91	365837.3	35.320	524.2	6/6/2015
36.06	366352.9	33.630	515.6	6/12/2015
33.06	366788.3	30.980	435.4	6/17/2015
37.09	367280	31.180	491.7	6/28/2015
31.44	367780.4	37.440	500.4	7/4/2015
36.62	368342.6	36.110	562.2	7/12/2015
37.20	368944.28	38.050	601.7	7/18/2015
35.19	369443.4	33.360	499.1	7/21/2015
36.53	370002.9	36.030	559.5	7/29/2015
34.98	370518.9	34.700	516.0	8/6/2015
37.22	371089	36.030	570.1	8/13/2015
34.42	371638.2	37.530	549.2	8/21/2015
32.68	372197.03	40.220	558.8	8/31/2015
33.07	372648.1	32.080	451.1	9/12/2015
36.24	373115.4	30.330	467.3	9/17/2015
34.00	373650.8	37.040	535.4	9/23/2015
34.50	376031.1	162.310	2380.3	10/22/2015
33.85	376590.4	38.870	559.3	10/29/2015
32.63	377118.78	38.090	528.4	11/8/2015
32.67	377665.1	39.330	546.3	11/17/2015
32.66	379549.2	135.710	1884.1	12/8/2015
32.71	380004.7	32.760	455.5	12/15/2015
31.52	380447.7	33.060	443.0	12/22/2015
34.22	380960.28	35.240	512.6	12/31/2015
28.11	381404.7	37.190	444.4	1/9/2016
31.55	381913	37.900	508.3	1/18/2016
34.09	382434.6	35.993	521.6	1/26/2016
29.52	382887.28	36.066	452.7	2/3/2016
31.86	383411.13	38.675	523.8	2/10/2016
31.12	383862.78	34.140	451.7	2/16/2016
30.95	384376.72	39.058	513.9	2/23/2016
34.06	384847.1	32.484	470.4	3/2/2016
34.82	385363.5	34.886	516.4	3/6/2016
30.29	385788.88	33.032	425.4	3/12/2016
31.93	386278.3	36.055	489.4	3/19/2016
35.63	386793.8	34.036	515.5	3/24/2016
36.78	387326	34.036	532.2	3/29/2016
34.27	387800	32.534	474.0	4/2/2016
35.79	388302.5	33.027	502.5	4/7/2016
31.59	388833.5	39.536	531.0	4/13/2016
40.45	389418.9	34.039	585.4	4/17/2016
30.16	389923.22	39.326	504.3	4/22/2016
41.87	390491.8	31.943	568.6	4/27/2016
36.26	390991.5	32.414	499.7	5/3/2016
35.54	391495.6	33.365	504.1	5/7/2016
36.56	392050.2	35.686	554.6	5/13/2016
37.02	392609.6	35.549	559.4	5/20/2016
33.31	393093.2	34.149	483.6	5/24/2016
33.27	393601.6	35.946	508.4	6/8/2016
35.48	394106.9	33.496	505.3	6/14/2016
35.94	394663.1	36.399	556.2	6/19/2016
36.09	395199.28	34.945	536.2	6/24/2016
37.48	395750.28	34.578	551.0	6/29/2016
37.40	396227.7	30.028	477.4	7/5/2016
36.38	396678.2	29.126	450.5	7/9/2016
35.98	397193.2	33.667	515.0	7/15/2016
35.35	397685.38	32.753	492.2	7/20/2016
35.22	398202.97	34.570	517.6	7/25/2016
34.78	398712.16	34.440	509.2	8/1/2016
30.32	399025.75	24.331	313.6	8/4/2016
0.00	200884	0.010	0.0	4/28/2016
33.18	201462.3	40.997	578.3	4/28/2016
33.82	202013.8	38.359	551.5	5/26/2016
31.41	202548.5	40.040	534.7	6/10/2016
32.57	203067.7	37.498	519.2	7/6/2016

As you can seem, every winter (November - March/April) my fuel economy went down.

You will also notice, once in a blue moon my MPG spiked to near 40 MPG. I believe those were rare times I lucked out and got pure gas with no ethanol in it.

My average because of those high spikes was 33 MPG after 3 years of monitoring.

 

I`m sorry, I must have converted to UK MPG not US MPG.

I will try again:
city: 20 US MPG
combined MPG: 23
hwy MPG: 25

 

No issues starting the engine, no poor performance, but I guess I will clean them anyway.

@mk378

Yes, I did the timping test in limp mode.

@TomCat39

I will try a compresion test and have the injectors cleaned.
Here in Europe we have 95 to 101 Octane fuel, I`m using 95, is good quality.
I will study your table, thank you!

 

When you decelerate (defined as TPS at 0% and engine rpm above idle speed), the EFI system is programmed to cut all fuel to the engine. The backfiring suggests that an injector is not closing all the way. You may see a difference in one of the spark plugs being black in the cylinder that is getting too much fuel.

 

It backfires like crazy, like 3 times in a second maybe more. Also the exhaust is kind of black. Might I have 1 or more injectors uncalibrated?
My motorcycle backfires as well, but is carbureted, so it is normal. 4 stroke Honda VFR 750.

@TomCat39

With a full tank I can travel 500 Km, (310. miles) maybe 550 Km (340 miles)

 

Mate we have the same issue, i'd love to hear more people on this subject.. Specifically 1.5 d series. I've got a d15z6 {vtec-e even} And it gets about 500 km on a full tank aswell. Pretty poor in my eyes, my car does backfire like yours aswell, you hear it better during idling... I wonder if that could be related to poor MPG, my performance and everything seems good. Motor sounds/looks healthy aside etc

Did you notice a difference in KMs on a full tank before and after the tune-up? Spark plugs, filters, etc

GL!

 

Same story as yours, backfires at idle and deceleration, car works just great, poor mpg though.
Seems logical to be an injector problem, like not closing when it has to...I will start here.

And no, all the tunning i have done did not help.

 

i dont see wires/cap/rotor on your list.

 

Just to provide a little clarity.

Europe rating is RON based from my research. Which is low speed testing for anti-detonation.

There is also a MON rating (not sure where it's used) and it's the high speed anti-detonation number.

USA ratings is based on AKI which is RON+MON/2 so is an average of the the high and low speed for it's ratings.

So really, I think a direct comparison is very challenging at best.

The above table I posted has been using USA AKI of 87 as the motor sees no benefit on the higher grade gases. It's designed for the economy gas of USA.

I think the closest equivalent over in Europe would be your 93 RON, the lowest that appears to be offered over there.

Also in my research it appears much of Europe is doing E05 gas which is 05% Ethanol while only a handful of European countries are using E10 which is typically sold here in North America but is just marketed as gasoline that "may" have up to 10% Ethanol. This was the story as up to 2014, might be more E10 being used in today's times and your country.

Also, I run a quality fuel injection cleaner through my car about once a year religiously. This might be part of the difference as everyone else is pointing out.

So, your MPG seems to be fairly impacted in comparison to my 3 years of results.

I found the RON/MON/AKI information on this site:
RON vs. Octane (US vs. Europe) Differences explained? - Rennlist Discussion Forums

 

I will add them to the list, thank you.

@TomCat39

Lowest grade we can buy here is 95, so i have to stick to this. Some friends of mine who are driving civics can travel 650+ km out of a full tank, so I don`t think is the gas
Should I use a 16 degree BTDC with this fuel? or go more retarded?

 

That was my point. Your fuel likely has less ethanol which means you should get higher MPG not lower.
I am assuming your D15B7 is built the same as the USDM or CDM version with the same compression ratio, pistons, deck height etc.

If it is the same exact motor (ECU has the same designation of P06) then it should be 16 degrees.

I think you should follow everyone's advise of cleaning your injectors.

I know Wynn's makes a quality fuel injection cleaner called Power Charge. I don't know what products you have available to you in your country. Not all products are equal.

 

Yes, my civic is CMD, ecu P06, ignition set at 16 degrees, engine works just fine, I`m happy how it runs.
I will take the injectors down and clean them and check for defects.
I will update the thread once I finish this step.

Thank you everyone for helping! :D

 

What method do you use to calculate gas mileage?

It sounds like you are intelligent and would calculate it correctly, but I've seen a lot of people on car forums complain about poor gas mileage just to find out that they weren't actually calculating it correctly.

20mpg would likely be a huge loss in power as well, and youd likely notice something major is wrong with the motor.

 

Filled the tank to the maximum, traveled 100 Km and then filled the tank again.
I did this test many times and in different conditions.
Also, I run out of gas from a full tank to zero, in about 450-500 Km, 550 sometimes, depending where I`m driving.

Power wise everything is fine.

 

How many liters do you put in at 100km?

 

11.5 Liters (combined) that would be 3.037979 US gallons.
city only is up to 15 liters/100 Km, maybe more.

 

I'd like to echo TomCat here regarding the compression test. All the new parts in the world won't help MPG if the rings are worn.

 

I'd clean your injectors with additive, and also make sure there are no exhaust leaks near your primary O2 sensor. There should not be any holes or leaks a couple of feet before and after the sensor. Compression test will help also. GL!

 

Hello, I`m back

The problem is still there.

What I did:

Removed the injectors and cleaned them, changed the o-rings, injectors are fine, no leaks.

I tested the compression, cold engine: 150 Psi; 152 Psi; 151 Psi; 150 Psi;

Failed a smoke test, this is the result:

Not sure why the test machine was reading the engine temperature 14 and 15 degrees, the engine was at operating temperature and running 5 minutes before test.





According to Autodata this is what I should get:





No headers leaks as far as I can tell.
To be honest, I do not know what I should test now...

Thank you!

 

Ohm test the ECT sensor. If the ECU really thinks the engine is 14 C, it will be in open loop mode which means it runs it rich, resulting in high emissions and poor mpg. It is only supposed to do that until warmed up, then switch to closed loop where it uses the O2 sensor to lean it out. Along those lines also make sure your thermostat is OK (not stuck open) and of the stock temperature rating.

Fuel pressure should also be checked. If the vacuum hose on the regulator is not hooked up, the pressure will be too high and it will run rich.