Weird Problem - Speedo Needle Erratic Behaviour

[wixer]

Over the weekend, my speedo needle would randomly drop momentarily. Once I'd stopped and was on my return journey and over the remainder of the weekend, it hasn't done it again. I also had the engine light appear the next day, when the car was cold but again, since having stopped, it too hasn't re-appeared. Could the two events be linked ? I've done a bit of a search and the only thing that sounds similar, is when the VSS is faulty, according to a link on Prime.

Anyone have any other possible suggestions as to why ?

Cheers

[Pride]

Over to you Kaz. :)

[goldnsx]

I had that behaviour years ago but it cured by itself somehow! I've already ordered the VSS but it's still good.

[wixer]

I had that behaviour years ago but it cured by itself somehow! I've already ordered the VSS but it's still good.

Maybe it's the Swiss air. I'll be there in two weeks, so maybe it'll help mine too.

[duncan]

Had the same with the both the speedo and rev counter dropping momentarily, picked it up a couple of times over a couple of days before the car stopped dead and wouldn't restart. Both occasions warning lights and the assistance to the steering went (which I didn't pick up until parking the car). The symtoms were a precursor to the main relay failing. If you already have a spare relay in the car you can guarantee it won't be that, however if not, chuck one in the car.

[Kaz-kzukNA1]

Hi, wixer.
Whenever you saw any warning lights, please read the error code first before doing anything.
The speedo playing up and CEL the following day could be caused by intermittent VSS signal failure and if so, you would get CEL #17 so again, please read the code.

Two phenomenon could be not related and caused by different issues but at least, you got CEL so you have something to start with without spending anything.

If VSS related, then the VSS signal on any Japanese production cars must follow JIS spec that the sensor core is shared by many models but different shape/installation.
So, fairly easy to find the replacement parts.
The one on our NSX is actually from Accord, Civic, etc.
Some owners had good experience using the one from ebay, etc.

Again, it could be nothing to do with the VSS so first thing first, please read the error code.


Kaz

[wixer]

Hi, wixer.
Whenever you saw any warning lights, please read the error code first before doing anything.
The speedo playing up and CEL the following day could be caused by intermittent VSS signal failure and if so, you would get CEL #17 so again, please read the code.

Two phenomenon could be not related and caused by different issues but at least, you got CEL so you have something to start with without spending anything.

If VSS related, then the VSS signal on any Japanese production cars must follow JIS spec that the sensor core is shared by many models but different shape/installation.
So, fairly easy to find the replacement parts.
The one on our NSX is actually from Accord, Civic, etc.
Some owners had good experience using the one from ebay, etc.

Again, it could be nothing to do with the VSS so first thing first, please read the error code.


Kaz

Thanks Kaz, I plan on reading them tonight. Read up last night on how to find the codes, from your post. Paper clips are all ready and waiting.

Cheers

[wixer]

Update, error code stored in the ECU is number 23, 2 long flashes of the CEL light followed by 3 short flashes. Found the list and it states error 23 is Front KS Malfunction. Can anyone (Kaz ?) now elaborate on what the Front KS is please ? I've been searching the site but nothing yet has come up and likewise on Google but I'll keep searching.

Thanks

[wixer]

Found it, it's Front Knock Sensor.

[Kaz-kzukNA1]

Hi, wixer.

We already exchanged several email but in case another owner experienced the same/similar issue, I'll extract some of the things I wrote for you.


Looks like you have intermittent VSS issue and separately, another intermittent issue at the Front knock sensor.

First, please check basic electrical connections/components such as the battery terminal and the Main Relay.
I have seen faulty Main Relay triggering CEL and TCS warning lights although very unlikely to be the cause for your case.
Based on your other posts, looks like you are heading for the long trip so best replacing the Main Relay now (if it was never done before), re-solder and carry the existing one as an emergency spare.

Poor battery connection or weak battery can trigger all sorts of issues as the wake up sequence is different from one components to another and depending on the timing, it could trigger false warning lights, etc.

VSS from ebay, etc are cheap and if you remove not just the sensor body but the entire drive unit, it's not that difficult to replace it.


Regarding the knock sensor….






https://lh3.googleusercontent.com/XPtgIx3C47cqhsq-y2d3a4QIWBLDKEuq7UZU2wyYOrlDPobI9nfpfdOq0p2-4Sczx4ZlX1gzrSCUbvIA3cGwR7AcI2ZG32mKVZYIY1yqBkE9ai PmM2PF37yFoBN0cbgs5ph-d0KKQ8wAHqoojykyh9kiNUXidCfGFvjNNI_WN2VN5tTDGxr5wK qToxD7HHbqeganfbLguPV-uHKdaNpxaCquSDQuqgOvI4EjpOD3LrSh2xoR2Yz5VmrAgs9sJr Vg3t1sv9n_jAoHKB9RM3uSsCLigij_w7mfcW8UBFQ59e67F4Gr hbxxFJJkyyJamxJPuSXqy3VzDVdn4c-97KfBPj6scHa0CjLTcWSrdhIRgAS9bEPEtTuYEloZY37a3XHBp 2KMRL46touNf_NpOUH2HMfF4If6YcNZD5EIi2t-90IqCIl9JY332tpN1F_afu3q7bU6oSHMKFs17PTQxEZ9-k4ftX0E3zV6_n605Tje3OgaG1e0k7r5ieNzr49N9nGOld9MAfL d961HU_oIakJ7RDkNlgpp_3iGJl28f9cl5x0tldezjAKmNUF97 V1c427Uk4oMfQhbl8uCaslrXvRBp_V6c2wEYlS4STPoH5ehMaF n_HVRjLtBhQ=w1080-h810-no
I'm afraid they are located under the intake manifold/VVIS chamber and you must remove it first before you can access the sensor.
They are located very close to #2 and #5 cyl port.

This will force you to replace these expensive intake manifold gaskets.
Green colour in the above photo but the latest one is just plain light brown glass fibre colour.

First of all, unless it's 100% MUST, never touch the knock sensor, even for removing the connector from it.

It's not just NSX engine but over the years, the sensor body is exposed to high heat making the plastic sensor body somewhat fragile.
Due to the layout of our NSX engine, it seems that there is not much air flow inside the V-bank that it can get really hot compared to other Honda engines that even just trying to disconnect the connector will snap the sensor body off.

OEM sensor is piezo and not cheap…..

This is the reason why I always keep 1 set of spare sensor at my place in case of emergency eng OH that requires the removal of cyl head.
And, I will only carry out the service with the prior agreement with the owner that if the knock sensor wires have to be removed, there is a chance that the sensor may break and resulting in new sensor required.

So, unless you are 100% sure that it's knock sensor failure and not wiring issue, etc, don't touch it.
If you are replacing, probably best replacing both the front and rear ones at the same time.






https://lh3.googleusercontent.com/BEApkiUeHsVDVyoPT97uqqZRXZJHfi8MoomQnqkXgERBx6R-wtGWnMdkuKIkaUdZgk3vMI6tvV6N4HrYeraGoUtKRRk-sGITalAyzZO_eN4vRDArQ_8ebncnE9iYSV9JVJ1JkQFVd94emG J81eF-xAQtTfHViVwl-p4asEyTKuykI_DxucnrztXafieWvQqtejbQ6qESm_kRJQGAO_H myWhwhVrHavOYjOeXCvf1666O8ZG5Myd2fYhkk70pHa-FIF83F6_B2TrHcOA2_FOyVp8Sc4rZSJw6WB9bFZFFrvV3SBTol oWjNF_CTu1_O7WRFw7EJ3dT7XrzTj7438-U1dks8vR2lcy69rp2TTMR7uUlNWZxD4rezC-Y5MpwtLCtChAU196CfLTYLCiTD15ofa-cv3r1StCzfVjdgOkNM_tqBkccObf-Da5G9X4Qk9O8Z-Q_iZHgcIRJgs_FJ7HbCwbxQr4XihVzYzVKG52E74bb9Q8HLuh1 eykHy7P-WKMMJdoQoS7hv42qvgzk413zlFC3sn0UDOi-56Q8XGgnONo9nZ-5qiQpbiIHYKHK-gQRkYJNGkEpuriqjV4qEQstMjOyKHgaQvOsUQ95Vqdt8S4GPRG DM0wF=w800-h600-no
And as you will be forced to remove the intake manifold, best cleaning the VVIS chamber at the same time.
The oil trapped at the bottom plate will eventually sucked back into the eng at high rpm range causing dramatic white smoke at the back so not good.





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https://lh3.googleusercontent.com/malbPhD6h1OWkTIfdX8vq27hWFVT9faVMFXyPN6x73URjuNjJ3 _3hyzbhep2Cc3v_YdkQpP_-MFuewX3FGNc-B2buR59sGHqS7I2P1t6YevSj5MfgtAU32XUxadaQQRyiJ-ceauI3fOqEm49fcf544MrOe2TZ0dPHXhibm8LFCBLW6agjFBU3 UQuctZp1IPMutmkCtV4LDJtNHKGoGJyAd8AwmvJYVMjx2lZsks rksZVpBY6aspAYfv2dVVzBiT--CvqK-sswtrDFQeVHEl85AX-mRVckyCmGnlxhvk0mjDDAV4hT3OtaxrnIbHy0cBxnalo0C9d7X OJB6CKQVXMs0kQWmJ44mLlk58beRMSraPeMKDq3hXkn5H8pngp OOAvM6kMLNtpGtaJiAWg4dtu5g9igGDyp5XbWH-pBVULOo4Dtcdmrp4rabD-iebkgfvWI0LkqHHxtEkVlZjgCD7SWhM1eu8Lwi0x3kGzd3WmkT _XxT9LTmKEGUrC3nB5hQhNPtqQ1PXIhSCOKTcCsZ57_NsKg5B1 4mgvSjj-2QDJRJ-WgDkg5M9SeD9noJvNkeeKx1XDXYrX1IekzghiqHTKdc2oCqV88 O6hJPqnlmf5BzDSaK8I7Jk9cw=w800-h600-no
If not done for a long time, you may want cleaning the INJ and replace all INJ o-ring while in there.


Kaz

[wixer]

Thankyou again Kaz.

[goldnsx]

Also check the grounds it the engine bay, front back, gearbox. Cleaning.

[wixer]

Also check the grounds it the engine bay, front back, gearbox. Cleaning.

All checked and ok.

Almost set for the trip into your neck of the woods, what's the state of the roads ? Are they all open ?

Cheers