Fuel Trim Chart

I ran into a very informative chart at Eastern Catalytic Tech Tips.

Read more here on their write up here - http://www.easterncatalytic.com/education/tech-tips/fuel-trim-can-be-a-valuable-diagnostic-tool/


I like this diagram they have.

Image credit goes to the Eastern Catalytic.

X-trail: 02 Sensor

I was comparing the O2 sensor signals between the X and a i10. The i10 looks like it has a more healthy 02 signal.

When i floor the pedal, the O2 signal responds shows exactly as described in scannerdanner's tutorial. As for the X, there was plenty noise & deviation from the expected signal form.

Do i have a lazy O2?

Gonna need more tutorials........

X-trail: Fuel Trim

Kind of dragged my feet updating this.

Plugged in the OBD2 donggle. Ran the software.

What did i find?

Short Term Fuel Trim -> +10 range

Long Term Fuel Trim -> +10 range

That would make total fuel trim -> +20% range 

This would mean I have a lean condition

When I throttle the car to >3000RPM total fuel trim drops under 5%. Per scannerdanner's tutorial information, he would say I have a vacuum leak.

So i need to detect where that vacuum leak is by doing one of the below

- spray bottle

- carb cleaner

- propane

- smoke

Which should I choose?

Notes: Fuel Trim

High Total Fuel Trim at Idle

Low Total Fuel Trim at higher RPM

-> Possible vacuum leak

Low Total Fuel Trim at idle

High Total Fuel Trim at higher RPM

-> Possible dirty MAF sensor

Paul Danner - Dirty MAF Case Study Video below.

Case Study: Lean Condition Variables

This is one very interesting case study shown to us by Paul Danner. Interesting how one missing air filter can force the ECU to make the engine run lean (also poor on FC since the fuel trims are all the way to the roof)

Short Term Fuel Trim
Long Term Fuel Trim

Engine Noises - Knocking Sounds Types

So here's what I've gathered so far in regards of reading up about knocking sounds. 

PISTON SLAP: 

Makes a sharp metallic noise. Idle engine and short out each cylinder plug. The noise will disappear when plug with bad piston is shorted. Noise will also disappear at acceleration. This can be caused by worn or out of round cylinder, or broken piston ring. 

VALVE NOISE: 

Makes clicking or rattle noise. Caused by excessive wear on valve stem or lifter, out of adjustment, or stuck valve. Correct by adjusting valve clearance, replace worn valve or lifter, regrind cam, replace valve guide and /or valve. A stuck valve can sometimes be loosened by passing oil through the carburettor while engine is running. 

ROD BEARING KNOCK: 

Makes sharp metallic noise similar to a piston slap. Detection is opposite of piston slap. Rod knock is not heard at idle. Knock becomes louder as engine speed is increased. Caused by excessive rod bearing clearance. 

REAR MAIN BEARING KNOCK: 

Makes dull knocking or thud noise. Knock will normally decrease or disappear while pulling or decelerating. Noise will be detected the loudest at normal driving speed, when not pulling or decelerating. If knock is excessive, crank should be checked for out of roundness. 

WRIST PIN SLAP:

This can not be detected by shorting out the cylinder plugs. Rapidly accelerate and decelerate the engine speed. The engine will pass through a certain speed range when the wrist pin will rattle at about the same pitch as a valve tappet noise. 

Post top overhaul & engine noise/rattle

I have been testing the car for a few days and through extensive testing, its sad to say the knockings are still there.

What was fixed

- long crank during start or can't start 

- water/coolant loss from radiator/spare tank

The long crank & coolant lost definitely confirms the issue with the head gasket.

Now into the main issue the knocks. After the top overhaul, the knocks are now much more harder to replicate and observed.

Recreating the Knock

It is now harder to recreate the knock. Its less audible and happens less regularly.

• going uphill, RPM ranging 1500-1750 -> rattles if you can maintain at 1750
• cruising and accelerating after that -> can only get a occasional metal slap/tick with overdrive with RPM about 1500-1750 & speeds of 60-70kmh
• braking from cruising (observed occasionally but unable to recreate)

Current conclusion for the knock to occur (below conditions must fulfill)

• under engine load
• 1500-1750 RPM -> rattling
• Undefined RPM range -> tick/slap
• tick/slap happend at high gears & low gears - updated 29 July 2013

Next steps

• Feedback to the service center of course. Didn't pay them  RM1.7k to not fix the problem.
• Need data and lots of it. Nobody so far has been able to give me a proper diagnosis and support it with data. Guess work most of the time.
• Sell the damn car =P
• Ignore the problem by turn the volume up on the radio =P
• Floor the pedal more often to drive > 2000RPM =P

Update: 19 Aug 2013

• Cleaned the MAF sensor with contact cleaner yesterday. Better response but still knock. :(
• Revert to paper type air filter. Bought from spare part shop. Interesting that the Japan oily one continues to be out of stock
• Poured a can of Bardahl 1 in the engine

Update 16 May 2014 - All my research and troubleshooting points into the direction of the tensioner kit. If it was the rod bearing, it the car would have been getting worse. So far fuel economy is still within range and I've survived a few long round Malaysia trips covering over 2000++ kms. This Youtube vid had the same sound and symptoms as well and theirs was the tensioner.

To confirm and fix this I would need to send the car into the shop and spend close to RM1000++ but I guess I'll just hold back since its not really giving me any grief currently.

Blower motor decides to go

Bye bye blower motor.
It became a roaring tiger yesterday driving around town. Going through bumpy roads activated this one. The sound disappeared when you increase the fan speed to max or switch it off.

Comes back with the bumps. lol

Got this fixed at Beng Lee A/C Sg Dua next to the vet clinic.

They found the "blower resistor" in a possible bad state. 2 pin have melted some plastic. I think this is the PCB for the variable speed drive for the blower motor. On a long shot I was hoping thing might be causing electrical noise that is causing the knocking but tough luck.

Damage to today RM455

Find the culprit time

Symptoms

1. Radiator expansion tank losing water
2. Knocking during low rev 1500rpm-2500rpm
3. Long cranking to start (chugging engine if it starts sometimes don't start at all)
4. No fault codes

What new symptoms will appear next? @_@

K&N Drop in Air Filter

Its finally arrived !!
My first K&N. Well I resorted to buying this after driving around town for 2 weeks and nobody has got the Japan type air filter.

Got it from Whybee Ltd on Ebay - GBP39.04 (about RM182 according to Paypal exchange rate)
The cheapest I've found on the websites in Malaysia was going for about RM270.

Guess the extra I could splurge it on the cleaners.

On to replacing it and to experience it for myself all the hype about K&N Filters.

Update: 19 Aug 2013
It definitely feels easier to push the car when you floor the pedal, aside from that, not much else observed. I have a light foot so not much difference really.

The new "old X" is finally here.

Year 2005 2.5 Full Spec Silver Gray Unit

I get Xenon lights, climate control, more horses and worn leather seats. 

Love the HID. So bright. I can see everything.
Love the low rev the 2.5 does on the street

Sway bar bush and possibly the links are gonna need replacements. No wonder the tyres were balding out. It definitely looks like all X-trails in needs to have their sway bar aka stabilizer bar bushing changed at 5 years or less. 

Would you consider me an 'expert' since this is my second X-trail ? hahaha

So far the throttle position sensor issue hasn't show up yet. 

Need to monitor that 'small oil leak' at the valve cover the ETCM guys found. Hopefully not noticeable

Updated 17 March 2013:
Stuff that are confirm having issues
- Stabilizer bushings definitely out
- The air blower motor might be dying
- LH side mirror motor probably busted as it won't retract
- FR RH speaker no sound. Needs to be checked out
- engine rattling during throttling. TPS? not sure yet

Update 28 March 2013:
- Replaced the stabilizer bushes.
- air blower motor humming didn't hasn't shown up again
- Replaced cabin filter
- the stabilizer links feels like it could be due for replacement also.
- bought some new plugs but haven't replaced them yet
- ordered a drop in K&N air filter from UK after going round town for a week and nobody has the oiled air filter from Japan
- tinted the main screen IR Black + 4 mil security
- found that they listed my old car on mudah selling for 46888K!!! >_< If you plan to get that car come talk to me first :)

A new ride is coming...

 'what is it with you and that car ?' ~friend

ETCM visit today revealed

• Small leak to the valve cover
• Cracks to lower arm bushes, more severe on the right side
• Fault by throttle position sensor.