Blog entry - Eng Refresh, etc

[Kaz-kzukNA1]

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After spending years on the lift, glad to be able to report that this NSX just passed the MOT this week.

Although I drained the fuel tank empty and added fresh fuel together with the new O2 sensor, just didn’t know whether I can make the CAT hot enough.

The car was SORNED and thus, only possible to drive to/from the MOT place with the proof of MOT booking in case stopped by the authority.


On the way to/from the MOT place, noticed the volt gauge only showing 14.0V when it should be around 14.5V.

It has fresh battery and I’m quite sure it was not like that when I fired up few times last week.

When the IGSW is in P2 On, the volt gauge shows just above 12V so can't be the volt gauge calibration offset.


Typical.... just when I don't have much spare time.....


Will start looking into this from tomorrow but most likely, I’ll end up overhauling the alternator.

Fortunately, have all the parts including the aftermarket rectifier except for the regulator.


Details and photo will be in the blog.



By the way, if we upgrade the Forum platform, it is very likely that all the existing blog posts would be treated as separated thread entry in one of the Forum section.

I need to think about this carefully before posting any further blog entry from now on.


Kaz

[Kaz-kzukNA1]

Well, initially I thought it was the alternator causing the low voltage reading.
As in the above post, when IGSW in P2 On, it was showing above 12V and didn’t drop below 10V while cranking so thought couldn't be the volt gauge calibration.

Turned out, I was wrong.

With the fresh battery, the volt gauge should have been much higher when IGSW in P2.

Didn't help when my own battery was 5.5 years old yet showing just over 12.0V in P2 and just about holding 10.0V during cranking.
Later, I found that my battery is getting fairly tired but no slowing down or hesitation during cranking.




With the battery tester connected, the alternator was outputting 14.7V and when rpm increased to like 2,500rpm,
the voltage regulator adjusted the field current properly to regulated the output power so nothing wrong with the alternator.




The ripple current waveform suggested potential one diode failure but I saw the same shape on my alternator with perfectly checked rectifier so the rectifier on this one should be fine as well.



So, with this photo, the volt gauge should be around 14.5V and not like 14.0V.



After discussing with the owner, we agreed to refurbish the gauge cluster and overhaul the alternator as well.

So, I will be busy with these for about 2 weeks.

I don’t want touching the centre console again to investigate the audio noise issue that I couldn’t reproduce.

There is very sophisticated security system on this NSX so I even had to assist the MOT operator last month.

Don’t want ending up not being able to move the car.

Probably replace the L-side door speaker AMP first for testing purpose and ask the owner to cover some mileage as I just couldn’t reproduce the issue he mentioned.

More to follow.


Kaz

[Kaz-kzukNA1]

Quick update on this NSX.

So far, no drama with the gauge cluster.
Lots of cap leakage but nothing new.

As reported in previous blog, just takes much more time with European spec MPH speedo than the JDM KPH one.
One of the calibration pot can max out.
Will continue.




Now the alternator.

As expected, really rusty internal metal and lots of debris.

Nothing new and even experienced similar situation with different screws in the past.

However, with this one, just couldn’t remove this screw.

Despite using my super-duper Nepros JIS driver, it damaged the screw head.

Fortunately, it’s the one between the regulator and the brush holder so not going to prevent me from disassembling further.

Rectifier removed and looked to be fine apart from one of the diode but will check.

Considering the mileage, I will replace it with new aftermarket one as it’s not expensive.

In the process of replacing the front/rear bearing.




Don’t want any significant shock to the regulator so going to use router with cutting disc to deal with the damaged screw.





Good decision to overhaul now.

Just less than 1mm to go before hitting the limit.

Though, seen many brushes on other make/models went well over the limit.

Informed the owner that I’ll aim to put everything back on the car by this weekend.

Then, finally can carry out the proper test driving session.

Must put extra fuel in the tank.


Once I’m happy with the test driving result, finally I would be able to return the car to the owner.

Hope I’ll be ready some point next week.


Kaz

[Kaz-kzukNA1]

Encountered another issue so behind the schedule.

Quick update while servicing the gauge cluster in parallel.

The rounded screw mentioned in the last post removed.
The OEM regulator saved.
Some refresh done.




Already knew going to have problem with the long body 7mm bolt at the bearing cover.
So much oxidation, debris and rust.
Although the alternator can get extremely hot, didn’t want using blowtorch or any excessive heat on such thin aluminium body.




At the end, one of the four bolt head seared off but expected.
Can drill out from the back but didn’t want damaging the thread.
Going to leave it as it’s not a sealed cover.


The structure is pretty much the standard package.
Using the wing washer at one side of the rotor shaft held by the bearing at each end.

The only exception with Honda is the way the mainshaft held inside the Gbox.
Three beatings positioned at different parts/structure and the mainshaft is quite long.
Don’t think other manufactures would do such thing.


Took so many photos but just some them here.



Majority of the new parts.




Slip ring gently reconditioned.





Although existing rectifier was fine, considering the mileage, went with the new aftermarket one.

New Denso brush holder, new screws and aligned.

As my standard procedure, will run the rotor at slow speed later to bedding in the brush tip against the slip ring.




Now closed, will tighten the pulley nut later.

Ready to be back on the car.


Continuing with the gauge cluster circuit board.

Will keep eye on the weather forecast as don’t want driving in the strong wind or heavy rain.


Kaz

[Kaz-kzukNA1]

Took more than 200 photos just for the gauge cluster service.
Only some of them for here.


On removing the gauge cluster, found aftermarket devices breaking into the factory loom.
Probably something to do with the sophisticated security system.
Not so sophisticated when leaving the wire unterminated.....







Probably the owner didn’t notice this but upto around 50mph (80kph), the speedo accuracy was just about OK.

Thereafter, it started showing lower than the actual car speed.

Real speed [mph]	speedo needle [mph]
100	97
125	120
150	140
175	161

Also, it displayed the same phenomenon of ‘hanging/hesitating’ speedo needle movement at the higher speed range.
Don’t remember seen one on JDM KPH unit.

Not 100% sure but the only time I saw this phenomenon was on 95+ European clusters but very rare.

Honda did change some of the capacitor spec and the circuit board layout from 95+ but don’t know it’s related.



On the tacho side, the usual 300+rpm offset observed.

At 5,000rpm, the needle sat at about 5,300rpm and larger offset at higher rpm range.



Another unit with trace of excessive heat.

The sleeve of the big capacitors were sliding off from the body.


Was expecting much larger offset at the volt gauge calibration as that was one of the reason for this service
Will re-calibrate it later.


The cap leakage was not too bad around the warning indicator HIC.





Washing up.



Cleaned and treated both the odo and trip meters.





Volt gauge re-calibrated.





I’ll post in my own build thread but started paying much more attention to the oil pressure gauge.

On my NSX, I started seeing about 0.4 kgf/cm2 higher reading than it used to be since around Apr/24 but most likely,
it started much earlier, slowly/gradually increased and only spotted last April.

Before and after the service on this gauge cluster.

There is no adjustable calibration with the oil press gauge and only the resistor at the back.

Thus, replacing the capacitor and whatever other factors, that inclreased the reading at exactly the same simulated signal and environment.






Illumination light bulbs were fairly burnt out.
Replaced all of them with the new ones.





Calibrated speedo at 10kph interval.
With the classic coil arrangement and the vector force, must calibrate it in both direction.

Even when the gauge was at 3 o’clock position, confirmed that the needle returns to zero under sudden loss of power.
It’s one of the design spec.


Tripmeter accuracy tested using the simulated 160kph signal for 5min.

Odometer tested at the very end once everything assembled and added 2.0miles with the simulator.





Status/Indicator lights tested.





New illumination bulbs.







[BRAKE LAMP] warning operation tested.



Ready to be installed back on the car.


Already in discussion with the owner about collecting his NSX from my place but the owner needs bit of extra arrangements so will see how it goes.


Getting there.
Must work on the audio head unit and another gauge cluster in parallel this week.

Kaz

[Heineken]

Very nice work, Kaz.
PS: If you like, you can remove the hand-written markers 'A' and 'B' on the PCB side connector with Isopropanol alcohol. It might be confusing to have multiple markers.

[Kaz-kzukNA1]

Another updates but the timeline goes back and forth and not in order.

The alternator and the gauge cluster back in place.

The volt reading is better but not like other NSX.

Should be about 14.5V and not like 14.2V despite the volt gauge being re-calibrated and the alternator overhauled.

Must be the aftermarket wires breaking into the gauge power line somewhere on the car.

Lots and lots of security related wires observed under the bonnet, inside the cabin and even in the engine bay.

As the alternator is generating proper voltage around 14.6V, going to leave it as is.





Already knew when I first fired up this engine after my Eng Refresh that I would get good compression data.

The nice smooth engine sound....

You won’t get this by just following the workshop manual procedure and/or the adjustment spec.

Not much point in showing only the last digit but since I always used the same format, just going to carry on.

With the measurement from my own NSX, always showed the full data including the mileage.


#1: **4, #2: **1, #3: **3, #4: **0, #5: **5, #6: **5


All six cyl within the 5psi window.


This is the reward after spending hours/days of specific process and the know-how.

Hope the owner enjoys the engine sound again.





Haven’t sealed the base idle air adjust screw yet.

Years ago, when I first looked at this engine, there was mistake made by someone resulting in strange base idle air amount.

From the service history, it was even before the ownership of the current owner.

Now that the engine properly assembled, the screw position is close enough for the start line.

Will carry out the final adjustment later once I can move the 2 cars blocking the garage door.

One of them is my boss’s MX5 and encountered misfire recently and couldn't move it.

Will touch on this later.





Pretty much done with this side.

Just need adjusting the alignment of the eng cover.

Always takes time with the NSX-T model....

And also the alignment of the eng bay air inlet/visor.





Spare wheel holder back in place but should have checked the A/C pressure first....




Once managed to open the garage door, will remove the L-side door card and replace the Bose door speaker AMP with my well tested spare one.

Then, final test driving session, wash the car, vacuum clean the cabin and carry out eng bay and under the bonnet dressing.....



Kaz

[Kaz-kzukNA1]

Seems like the bot changed its behaviour again.

Since disabling the guest access to my Blog, the server was fairly stable but recently, had to satrt rebooting twice a day, in the morning and the evening.

Hope I can start spending time on the platform upgrade some point this month.







Outside temperature was about 10 - 13degC so even if you forced the A/C compressor On continuously, the evapo sensor would detect below 3 – 4degC and cut off the compressor.

So, not ideal for checking the refrigerant pressure but at this low side pressure, the sat temperature is between -10 to -5degC and the high side at +35degC.

Didn’t measure the pipe temperature but from standard performance chart, close enough.

It was charged with 840g of refrigerant long time ago but using the aftermarket larger diameter receiver.


Already carried out the test driving session and for now, happy with how the A/C performed.


By the way, the compressor and the newly installed aftermarket compressor CL assy were really quiet on this NSX.

I really want replacing my A/C CL assy especially the pulley bearing as it’s making noise now.





As reported earlier, only managed to re-produce the noise-like issue from the L-side door speaker once over the years.

So, don’t really know whether it's from the L-door speaker or the audio head unit.


As a first step, decided to replace the L-side door speaker AMP with my well tested spare one.

I refurbished the existing one years ago for the owner.









First, have to remove the spare one from my NSX.

Already covered about 2,750miles over full 9 months without any issues.













Now installed into the owner's speaker box.

The speaker cone looked fine and no damages.


As expected, the removed existing Bose AMP showed no issues on the testing bench so far.


As I’ll be servicing many electronics components very soon, will keep it on the bench.


If nothing happens, I’m afraid we need to re-visit the audio head unit that had fairly big services by someone in the past.

I refurbished it afterwards but I found another potential failure mode that no other person reported.

So far, only on 1 unit happened at the specific area using the specific parts.

[Kaz-kzukNA1]

The usual treatment of the water gutter to reduce the amount of water dripping over the rear bank IG coil cover.

Not perfect at all but at least, it has some effect.







Time to adjust the base idle air screw.

My trusted 090 connector for the DBW model.

Had to open the screw slightly as the engine stalled on starting up.

Once started, closing the screw slightly and settled at exactly the same position as other NSX.







If the engine healthy, one should be able to idle even at around 600rpm.

It’s DBW MT model so once SCS terminal opened, the ECU just aims for the 800rpm.





Now the base idle air screw is sealed.


Time to reset the ECU.


Went out for the sequences of final test driving sessions but split the menu in multiple outings.

Was aiming half tank of fuel but added too much so not ideal for testing but still, prefer this suspension setting than my Type-S one.

The road surface around my area is in such poor condition.....



Engaged VTEC once after the 2nd outing.

Happy with all the results.






Despite filling only about 2/3 of the tank, the washer fluid manged to seep out through the tiny hole used for checking the fluid level.

To the owner: If you find tiny amount of blue fluid under the radiator, it’s not the coolant but the washer fluid.









Cleaned the cabin and vacuumed but then my 5.5 years old Dyson decided to cut out randomly.

No blockage or filter issue.

Either the battery protection circuit or something else.

Turned out it was both the battery and the red plastic trigger.

Poor design and not so great plastic material....

No wonder why so many experienced the same issue.

Quite surprised to find such thing from Dyson.....

Ordered replacement battery and for now, repaired the plastic trigger.




Wiped all the internal glass surface first with the soft water followed by IPA.

This will keep the glass clean and no misting up for awhile.



Just need washing the car but the owner needs extra days before collection so will wait for now.



Thank you for honouring my decision over the years and respecting my skill and the service.

Really appreciated.


Kaz