Nissan TIIDA High fuel Consumption

[rcmadawala]

Hi guys,

In my Nissan TIIDA 2008 (Automatc transmission) i had around 9 - 10 KMPL in city limits. This is after a full tune up. Before it had around 7 KMPL in city.

By mentioning full, I meant

• Replaced Iridium plugs
• EFI / Throttle body cleaning
• Engine mounts

In addition to this i had a engine miss due to burned ignition coil so replaced with two genuine coils. Also replaced air filter with a genuine air filter.

Also I've recently replaced lower arm bushings, sub frame bushings etc.

Now my problem is car doing around 6.5 KMPL in the city.

I have driven around 5000KM after the tuneup and now it giving me this fuel figure . I'm driving carefully not to push it more than 2k RPM.

Odo is around 96k and engine oil replacement coming in 98k. Never did a ATF change after i bought (ran around 15,000KM yet) this but when i check with dipstick oil having pink color.

Tyre pressure 30 psi for all tires. 

Tune up done by Ravi (Bulugaha junction). When i went to see him last week regarding this matter he did a scan and showed me this readings (see attachment) saying fuel consumption should be good. Also he told me if I'm having this problem again, come back to him and he will give me a ignition coil set so i can try running with those.

Do you guys have any suggestions on this problem ? Do i need to replace ATF and see ? 

 

Edited March 29, 2017 by rcmadawala

[Davy]

Did the diagnosis reveal anything abnormal with sensor readings? Were the injectors and MAF cleaned during the tune up?

Does the car idle at about 700 RPM when warm with a slightly high RPM during cold starts that gradually comes down to 700?

Does the car shift gears normally without holding it in one gear for longer than normal?

By the way, engine mount replacement is not part of a tune up. 

[rcmadawala]

2 minutes ago, Davy said:

Did the diagnosis reveal anything abnormal with sensor readings? Were the injectors and MAF cleaned during the tune up?

He said nothing abnormal with sensor readings. yes MAF and injectors cleaned during the tune up.

Does the car idle at about 700 RPM when warm with a slightly high RPM during cold starts that gradually comes down to 700?

in cold start as i remember, it goes up bit higher than 1000 RPM then gradually comes down to 800 - 850. car idle is around 800

Does the car shift gears normally without holding it in one gear for longer than normal?

I sense tiny struggling sound when it closed to switch 1st gear to 2nd gear but then shift is smooth AFAIK 

By the way, engine mount replacement is not part of a tune up. 

yeah i just mentioned it 

 

[PreseaLover]

If ravi said nothing is wrong, then actually nothing is wrong... I've visited him many time.. once the car didnt move at all, and didnt accelerate and the airflow sensor was gone.. unlike other garagaes, without telling to replace the throttle body, he removed all the pieces and ammended the sensor and car started working like never before with good acceleration... are you sure it did 9-10 in city? cuz given its nissan, its a miracle if it does 10.. 7 in city would be the ideal figure for nissan.. sometimes mine does 6.8 too after everything is in order.. 

[Davy]

Sounds like a proper job was done during the tune up and the EFI system is functioning normally.

As PreseaLover said, is it possible that you're measuring worst case fuel consumption? Did you measure by doing the full tank to full tank method?

[rcmadawala]

5 minutes ago, Davy said:

Sounds like a proper job was done during the tune up and the EFI system is functioning normally.

As PreseaLover said, is it possible that you're measuring worst case fuel consumption? Did you measure by doing the full tank to full tank method?

@Davy

I just ran in to the car to check how RPM works.

When i start the engine (cold start) it directly goes to 1500 RPM and quickly reduce to 1400 RPM. The gradually it reduce to 1000 RPM and the engine cold light goes off. Then after few minutes idle RPM hold on 700 RPM. This is without A/C.

@PreseaLover

Normally what I'm doing is when the petrol low fuel bulb is on I'm doing a a full tank and write down the mileage from trip meter. Then i reset the trip meter and doing the same thing on next refill. Maybe this is not the efficient way to measure fuel consumption.

But all i know is i was able to run around 300 - 310 Kilometers before the low fuel bulb goes on. Now it glows around 240 - 250 Kilometers and I'm losing around 50 - 60 kilometers per a fill 

[Davy]

Your idle control mechanism is working normally. 

The correct and most accurate way to measure consumption is:

1. Fill up full tank. Ask the pump operator to stop filling after the pump automatic cut-off triggers for the first time. Some pump operators keep squeezing the trigger to fill it to the brim and that can skew the result. 

2. Reset the trip meter

3. Drive

4. Fill up to full tank again. Follow same procedure in step 1. 

5. Fuel consumption is:

Reading on trip meter/litres reading on fuel pump 

6. Go to step 2 and repeat for another cycle of measurement 

You need to do this several times to get and average out the results to get a good idea about the consumption. 

[Jor-el]

26 minutes ago, Davy said:

 

The correct and most accurate way to measure consumption is:

 

Just curious, how efficient is the ralliart ?

AFAIK it requires RON 98 petrol, how much does it cost for a 1L of RON 98 gasoline in Au?

[rcmadawala]

50 minutes ago, Davy said:

Your idle control mechanism is working normally. 

The correct and most accurate way to measure consumption is:

1. Fill up full tank. Ask the pump operator to stop filling after the pump automatic cut-off triggers for the first time. Some pump operators keep squeezing the trigger to fill it to the brim and that can skew the result. 

2. Reset the trip meter

3. Drive

4. Fill up to full tank again. Follow same procedure in step 1. 

5. Fuel consumption is:

Reading on trip meter/litres reading on fuel pump 

6. Go to step 2 and repeat for another cycle of measurement 

You need to do this several times to get and average out the results to get a good idea about the consumption. 

Thanks @Davy

I'll do that and post the figures here. I'm wondering if i change ATF result will be better or not ?

Because i know the fuel consumption i had and now it is reduced 

[Davy]

29 minutes ago, Jor-el said:

Just curious, how efficient is the ralliart ?

AFAIK it requires RON 98 petrol, how much does it cost for a 1L of RON 98 gasoline in Au?

Regular city driving gives me around 8 km/l. Best was about 15 km/l during a long drive on the highway. Worst I've got it about 7 during an bit of an aggressive drive along a twisty road. I reckon it will be less if pushed harder, but who cares.

98 Octane is around 1.40 AUD these days. So about 160 LKR. 95 is about 140 LKR and 90 is 120 LKR approx. 

[Davy]

5 minutes ago, rcmadawala said:

Thanks @Davy

I'll do that and post the figures here. I'm wondering if i change ATF result will be better or not ?

Because i know the fuel consumption i had and now it is reduced 

If your ATF was changed according to schedule and if it shifts without holding onto gears, you shouldn't replace oil yet. Just verify your measurements again first. 

[dhachamila]

Last month same thing happened to my Tiida, suddenly fuel consumption dropped to 7kmpl ( before 9.5 - 10kmpl in city limits) and experienced engine knock (cutus cutus sound) in full throttle. Did efi tuneup, acceleration improved slightly but fuel consumption remain 7kmpl and engine knock also there. So i google why efi engines knock and i found low  grade petrol and bad knock sensor causing engine knock. So i pumped 95 octane 2-3 times and felt the difference, now engine runs very smoothly no any engine knock and fuel consumption also back to normal. (However i dont know how high octane petrol results for better fuel consumption). @rcmadawala make sure to change atf in every 35000km-40000km. 

Edited March 29, 2017 by dhachamila

[rcmadawala]

37 minutes ago, dhachamila said:

Last month same thing happened to my Tiida, suddenly fuel consumption dropped to 7kmpl ( before 9.5 - 10kmpl in city limits) and experienced engine knock (cutus cutus sound) in full throttle. Did efi tuneup, acceleration improved slightly but fuel consumption remain 7kmpl and engine knock also there. So i google why efi engines knock and i found low  grade petrol and bad knock sensor causing engine knock. So i pumped 95 octane 2-3 times and felt the difference, now engine runs very smoothly no any engine knock and fuel consumption also back to normal. (However i dont know how high octane petrol results for better fuel consumption). @rcmadawala make sure to change atf in every 35000km-40000km. 

Wow. Before tune up i used 95 petrol. After tune up got bit greedy and used 90 petrol for 5000 Kilometers. @Davy what do you think about this ?

[Jor-el]

1 hour ago, rcmadawala said:

Wow. Before tune up i used 95 petrol. After tune up got bit greedy and used 90 petrol for 5000 Kilometers.

If you can find the users manual for the tiida you can check if it calls for 95 oct petrol. BTW its 92 octane you've pumped not 90

[Davy]

3 hours ago, rcmadawala said:

Wow. Before tune up i used 95 petrol. After tune up got bit greedy and used 90 petrol for 5000 Kilometers. @Davy what do you think about this ?

You should have said so at the start of the thread! Would have made this much simpler. 

My opinion is that local fuel quality is generally poor and depending on the fuel station you fill up from, it can become worse. One of the reasons to why we need to clean injectors and throttle bodies so often is poor fuel quality. So the 92 octane you paid for might not actually be 92.

I'm pretty sure the Tiida can run on regular unleaded petrol, so try pumping fuel from a different fuel station and see if the situation improves. The owner's manual will say something like "RON 90 or higher", so you can use 95 as well. 

[PreseaLover]

7 hours ago, rcmadawala said:

Wow. Before tune up i used 95 petrol. After tune up got bit greedy and used 90 petrol for 5000 Kilometers. @Davy what do you think about this ?

facepalm

without pumping from lanka petrol sheds, try pumping from IOC sheds... lanka petrol sheds has the shittiest shit I've ever shat

Edited March 30, 2017 by PreseaLover

[Twin Turbo]

18 minutes ago, PreseaLover said:

facepalm

without pumping from lanka petrol sheds, try pumping from IOC sheds... lanka petrol sheds has the shittiest shit of all shits

Going back to the contaminated fuel issues and my concerns with the accuracy of the pumps.  Not to mention the fact that the cheapest fues is imported here suppliers .

it's a good thing that at least the car runs!

Edited March 30, 2017 by Twin Turbo

[Rumesh88]

@rcmadawala This is just a comment on the figures given in the picture in your first post.

According to the figures shown INJ PULSE-B1 value is 2.7msecs and B/FUEL SCHDL value is 2.3msecs. Regardless of the conditions under which these values were logged what they imply is that actual injector pulse width is 0.4msecs (2.7-2.3) more than the expected theoretical pulse width (B/FUEL SCHDL). To me this means that the engine is running richer by 17% ((2.7-2.3)/2.3) from its theoretical base value. What puzzles me is how one can arrive at the conclusion "fuel consumption should be good" based on these two figures? BTW I leave the matter open for discussion.

EDIT: One more thing - did they change the injector washers at the tune up?

Edited March 30, 2017 by Rumesh88

[rcmadawala]

8 hours ago, Davy said:

You should have said so at the start of the thread! Would have made this much simpler. 

My opinion is that local fuel quality is generally poor and depending on the fuel station you fill up from, it can become worse. One of the reasons to why we need to clean injectors and throttle bodies so often is poor fuel quality. So the 92 octane you paid for might not actually be 92.

I'm pretty sure the Tiida can run on regular unleaded petrol, so try pumping fuel from a different fuel station and see if the situation improves. The owner's manual will say something like "RON 90 or higher", so you can use 95 as well. 

Yes it does mention "RON 90 or higher" 

And  I've start using 95 octane now. Will post the figures using the method that you have mentioned 

[rcmadawala]

44 minutes ago, Rumesh88 said:

@rcmadawala This is just a comment on the figures given in the picture in your first post.

According to the figures shown INJ PULSE-B1 value is 2.7msecs and B/FUEL SCHDL value is 2.3msecs. Regardless of the conditions under which these values were logged what they imply is that actual injector pulse width is 0.4msecs (2.7-2.3) more than the expected theoretical pulse width (B/FUEL SCHDL). To me this means that the engine is running richer by 17% ((2.7-2.3)/2.3) from its theoretical base value. What puzzles me is how one can arrive at the conclusion "fuel consumption should be good" based on these two figures? BTW I leave the matter open for discussion.

EDIT: One more thing - did they change the injector washers at the tune up?

@Rumesh88

I don't think they changed washers. It was just a cleaning job and a scan 

 

Edited March 30, 2017 by rcmadawala

[Rumesh88]

@rcmadawala The washers look OK in the picture but only the person who removed the washers can say if they were good enough for re-use. After being exposed to many heat cycles over a period of 9 years in this case they may lose their resilience and in some cases may even develop cracks. It is just one possibility for a vacuum leak into the inlet manifold. However, with scanner data one should be able to determine if there is a vacuum leak resulting in air entering without being metered. BTW how steady is your idle at 700 RPM after the engine is fully warmed up and with AC off? Observe any vibrations?

[The Stig]

On 3/30/2017 at 2:41 AM, Davy said:

You should have said so at the start of the thread! Would have made this much simpler. 

My opinion is that local fuel quality is generally poor and depending on the fuel station you fill up from, it can become worse. One of the reasons to why we need to clean injectors and throttle bodies so often is poor fuel quality. So the 92 octane you paid for might not actually be 92.

I'm pretty sure the Tiida can run on regular unleaded petrol, so try pumping fuel from a different fuel station and see if the situation improves. The owner's manual will say something like "RON 90 or higher", so you can use 95 as well. 

Agreed, contamination happens mostly because of the way our sheds store petrol. However switching to 95 will be no better unless the knock is caused by detonation. Local 95 is just 92 + toluene, there is no special filtration process contrary to popular belief. 

[rcmadawala]

18 hours ago, Rumesh88 said:

@rcmadawala The washers look OK in the picture but only the person who removed the washers can say if they were good enough for re-use. After being exposed to many heat cycles over a period of 9 years in this case they may lose their resilience and in some cases may even develop cracks. It is just one possibility for a vacuum leak into the inlet manifold. However, with scanner data one should be able to determine if there is a vacuum leak resulting in air entering without being metered. BTW how steady is your idle at 700 RPM after the engine is fully warmed up and with AC off? Observe any vibrations?

@Rumesh88 I stared at RPM for five minutes and it gave solid 700 RPM. I see small wiggling between 700 - 800 here and there but it gave me 700. Also no noticeable vibrations and i could barely feel the engine.

[rcmadawala]

@Davy

I've measured according to the method you mention as result is worse.

After initial fill, ran about 50 Kilometers and refilled.

Filled liters: 10.358 L

Trip meter: 58.1

Fuel consumption: 5.60 Kilometers per liter 

 

This is on octane 95 and bumper to bumper traffic in Malabe -> Kollupitiya route.

But i knew car was doing more than this because i travel daily by car. Suddenly it drops to this 

@Rumesh88 

 Any inputs on what to check regarding this matter ?

Edited April 1, 2017 by rcmadawala

[Rumesh88]

Well according my past experience (used to travel from Battaramulla to Bamba daily for several years) with the traffic on your route I consider you are lucky to get even 5.6 kmpl. 

BTW do you get any raw fuel smell in the engine bay? If so check things like EVAP control hoses. It can be due to many other possibilities like bad MAF sensor, sluggish O2 sensor, fuel pressure gone high due to a bad pressure regulator, fuel return line blocked etc. Instead of searching in the dark most sensible thing is to to get your emissions checked while performing a scan to check on the sensor data at the same time. 

[rcmadawala]

2 hours ago, Rumesh88 said:

Well according my past experience (used to travel from Battaramulla to Bamba daily for several years) with the traffic on your route I consider you are lucky to get even 5.6 kmpl. 

BTW do you get any raw fuel smell in the engine bay? If so check things like EVAP control hoses. It can be due to many other possibilities like bad MAF sensor, sluggish O2 sensor, fuel pressure gone high due to a bad pressure regulator, fuel return line blocked etc. Instead of searching in the dark most sensible thing is to to get your emissions checked while performing a scan to check on the sensor data at the same time. 

@Rumesh88

I went to see Ravi again and this time he replaced MAF sensor. Then he done a scan. Now INJ PULSE (2.3) and FUEL SCHEDULE (2.1) values gone down. This time i forgot to get a pic of new values. He said try running with this sensor and get back to him. Fingers crossed !!!

Edited April 1, 2017 by rcmadawala