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

[Rumesh88]

14 hours ago, rcmadawala said:

@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 !!!

@rcmadawala That's more like it. Just check if your idle RPM has come down too, say a bit towards 650.

[Davy]

Sorry, I was away during the last few days.

Interesting stuff there @Rumesh88. Honestly didn't pay attention to that first image because it was so tiny on my mobile and couldn't read anything. I don't think I would have been able to decipher it that well even if I saw it though.  Oh well, you learn something new everyday. 

Anyway, I think if the initial scan was done properly, a faulty MAF sensor could have been diagnosed. If the issue is related to excess fuel delivery due to the injectors being open for longer than normal, it could be that the MAF was indeed sending a wrong signal to the ECU and thereby causing the ECU to open up the injectors for a longer period. @rcmadawala, we'd like to know if this solved the issue. Keep us posted.

[The Stig]

17 hours ago, Davy said:

Sorry, I was away during the last few days.

Interesting stuff there @Rumesh88. Honestly didn't pay attention to that first image because it was so tiny on my mobile and couldn't read anything. I don't think I would have been able to decipher it that well even if I saw it though.  Oh well, you learn something new everyday. 

Anyway, I think if the initial scan was done properly, a faulty MAF sensor could have been diagnosed. If the issue is related to excess fuel delivery due to the injectors being open for longer than normal, it could be that the MAF was indeed sending a wrong signal to the ECU and thereby causing the ECU to open up the injectors for a longer period. @rcmadawala, we'd like to know if this solved the issue. Keep us posted.

Scans hardly show sensors which are giving false readings.

This has to be diagnosed manual. Reason is the same reason why no check engine light comes on, the scanner thinks the readings are correct. Most of the time faulty sensors can be diagnosed by scan only when they completely fail. 

[Davy]

16 minutes ago, The Stig said:

Scans hardly show sensors which are giving false readings.

This has to be diagnosed manual. Reason is the same reason why no check engine light comes on, the scanner thinks the readings are correct. Most of the time faulty sensors can be diagnosed by scan only when they completely fail. 

Depends on the scanner used. Most industrial scanners allow for the selection of a make, model and year and sometimes additional information like the engine model. Based on the information provided, the scanner outputs and highlights values that are out of range. This is why some scans are better done at the agents. They have model specific diagnostic tools that indicate when a certain reading is off the scale.

This a photo I took back in 2011 at my mechanic's place just before I was about to go for an emissions test. As you can see, the O2 sensor value is highlighted in yellow to indicate a marginal issue in the readings. Also the air temperature is highlighted in red. Both indicate potential issues, none of them output a Check Engine light.

The values on the right within square brackets is the normal min and max range for the selected vehicle.

 

Cleaning the O2 sensor connector solved the issue. The reason for the high air temp was a faulty AC fan.

So a scan can give out a lot of information if done with the proper tools/scanner by a proper mechanic.

[Jor-el]

1 hour ago, Davy said:

So a scan can give out a lot of information if done with the proper tools/scanner by a proper mechanic.

How much did the scan cost?

AFAIK a cheap OBD II bluetooth scanner can detect all those data and one costs about $4 at eBay

Edited April 3, 2017 by Jor-el

[rcmadawala]

29 minutes ago, Jor-el said:

How much did the scan cost?

AFAIK a cheap OBD II bluetooth scanner can detect all those data and one costs about $4 at eBay

heard that too. thinking about getting a one. 

[Davy]

25 minutes ago, Jor-el said:

How much did the scan cost?

AFAIK a cheap OBD II bluetooth scanner can detect all those data and one costs about $4 at eBay

I have a ELM327 OBD Bluetooth scanner and it never worked with my CS3. Tried Torque and Scanator Android apps but later found that the protocols are incompatible. You can search the forum in the DIY section and find a thread by Crosswind. 

It worked on a Toyota Belta though. It does give all the information, but just the readings. What I highlighted in my previous post is the fact that a good scanner can show if the readings are off and by how much. 

[Jor-el]

15 minutes ago, Davy said:

What I highlighted in my previous post is the fact that a good scanner can show if the readings are off and by how much. 

True but if the car is compatible you can compare the readings with the specs mentioned in the service manual - saves the money for a scan 

Edited April 3, 2017 by Jor-el

[Davy]

3 minutes ago, Jor-el said:

True but if the car is compatible you can compare the readings with the specs mentioned in the service manual - saves the money for a scan 

Agreed. That's actually why I got one. But does a professional scan cost much these days in SL? It was only a couple of hundred rupees back in 2011.

I use a D900 for personal use here. Only had to use it once on a friend's car. Got it off eBay and pretty good IMO. 

[Rumesh88]

1 hour ago, Jor-el said:

True but if the car is compatible you can compare the readings with the specs mentioned in the service manual - saves the money for a scan 

In fact it is not that simple like measuring the blood pressure and declaring an abnormality if the reading falls outside the 80/120 norm. Particularly with MAF and O2 sensors, the parameters are dynamically set as the engine continually goes through its learning cycles. O2 sensors operating in the narrowband mode complicate the readings further because they only give an indication whether the mixture is either rich or lean at a given instant but not by how much. Hence, with regard to fuel consumption you get long term fuel trims (the base parameter setting) and short term fuel trims (sort of instantaneous setting) but even these values keep on changing. So one needs some tacit knowledge in deciphering the scanner readings.  However, still it is a good idea to have your own scanner.

[rcmadawala]

On 4/2/2017 at 2:20 PM, Rumesh88 said:

@rcmadawala That's more like it. Just check if your idle RPM has come down too, say a bit towards 650.

@Rumesh88 @Davy 

I've try running around 60KM with the replaced MAF sensor and still no improvement over it. I got 6 KMPL. 

Also now i can see my idle RPM is 800 after full warm up (without A/C) 

Will an emission test helpful to diagnosis this problem ? I already did one on February because i wanted to update revenue license. 

 

[Rumesh88]

@rcmadawalaDid they perform an idle air relearn procedure after MAF was changed? According to the new PULSE and FUEL SCHEDULE figures I expected the idle speed to go down. What were the results of your last emission test at both idle and 2500 RPM?

[Davy]

If the ECU wasn't reset after replacing the MAF sensor, you can manually reset it yourself by disconnecting the negative battery cable, switching on the headlights to drain the capacitors, and leaving it for about 15 minutes and and plugging the battery back in.

At this point I think you're better off taking the car to the agent to have them check it out. 

[rcmadawala]

11 hours ago, Rumesh88 said:

@rcmadawalaDid they perform an idle air relearn procedure after MAF was changed? According to the new PULSE and FUEL SCHEDULE figures I expected the idle speed to go down. What were the results of your last emission test at both idle and 2500 RPM?

@Rumesh88

I don't think he did that. Just showed the changed values using an Android tab 

 Here are 2016 and 2017 emission test results.

[Rumesh88]

Well those are near perfect emission reports. Why did you go for a tune up then? Do you experience any issue with the pulling power of the car (under/over powered) at low or high speeds? As for any further action, I agree with Davy. You are better off with the agent for a second opinion to clear out any doubts in your mind.

[rcmadawala]

1 hour ago, Rumesh88 said:

Well those are near perfect emission reports. Why did you go for a tune up then? Do you experience any issue with the pulling power of the car (under/over powered) at low or high speeds? As for any further action, I agree with Davy. You are better off with the agent for a second opinion to clear out any doubts in your mind.

@Rumesh88

Actually went for a tune up because of the fuel consumption issue. When i bought this it did around 7 KMPL in city. But after the tune up it became around 9 - 10 KMPL 

But now I'm back to square one. First I'll try to reset the ECU using @Davy 's method. If no luck, I'll pay a visit to agent