VTEC no longer working after returning from the Nurburgring

[Baldilocks]

Hi all!

Been lurking for a while, will probably do a proper post at some point on my DC5.. for now, I‘m in need of some technical help!

Spent Easter weekend doing laps at the Nurburgring, no issue at all. Come off the tunnel on the way home and all of a sudden, VTEC no longer kicking in no CEL, which is strange..

As at the beginning of the year, the car threw a VSS CEL error in the pissing wet. After getting it dried out I checked the connectors on the VSS socket and covered in dielectric grease. No further issue... until now

So yesterday I managed to limp the car home in the wet and my speedo is doing weird things, fluttering around, going to zero and then returning to accurate speed. I figure it‘s a dodgy ground or the VSS, but really odd that no CEL light came up. Ah well, long weekend of driving, get home sleep and sort it out tomorrow.

I drove the car to work today, still no VTEC but the gauges are fine and still no CEL. Do some research and figure it‘s either the sump (I had pretty big thud moving carriages on the tunnel due to a big drop..! Maybe I hit the sump on something and that‘s causing the issue..?!)

Checked the sump this evening - not a scratch. I took the sensor ground (gearbox) off and gave it a wire brush and a sand. I also checked the VSS connector whilst I had the air box off and was still covered in dielectric grease.

Put it all back together and... still no VTEC, still no CEL!!

The oil level has been fine, have been checking religiously due to spending time on track.

Any other ideas? Maybe my CEL light has burned out? Which would be weird as it worked only a month or so ago..

Maybe I need to check the other ground? But looking at the manual it wouldn‘t seem related?

I figure an issue with the VTEC system would cause a CEL?

Any and all help much appreciated!

Pics of ring trip for attention:

 

[SamDC5]

The CEL should come on with the ignition IIRC, you can do a self test on the clocks which tests all the lights etc.

The VTEC system not working won't necessarily cause a CEL. VTEC only needs a few things to work, a speed reference, throttle position, coolant temperature and oil pressure. If you have a friend with a Snap On diagnostic tool you can check the solenoid is working by using one of the tests.

Might also be worth checking the filter before the solenoid as these are prone to clogging.

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[MilanoChris]

It will be the speed converter or the gearbox speed sender. I had the same this time last year.

 

[Baldilocks]

The CEL should come on with the ignition IIRC, you can do a self test on the clocks which tests all the lights etc.

The VTEC system not working won't necessarily cause a CEL. VTEC only needs a few things to work, a speed reference, throttle position, coolant temperature and oil pressure. If you have a friend with a Snap On diagnostic tool you can check the solenoid is working by using one of the tests.

Might also be worth checking the filter before the solenoid as these are prone to clogging.

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Many thanks - I can confirm the CEL light is working!

I will check the VTC screen later this evening and see how gunked up it is..

I don‘t have access to the snap on diagnostic tool... I do however have a paper clip I‘ve been using to read CEL codes. However without a CEL light present, I presume this isn‘t very helpful?

It will be the speed converter or the gearbox speed sender. I had the same this time last year.

Thanks for the info, what did you do to fix the issue? Do you mean the speed converter in the back of the gauge cluster? By gearbox speed sender are you referring to the VSS?

 

[Baldilocks]

I went to check the VTEC solenoid and VTC strainer last night, but noticed the VTC strainer cover in the front of the engine is blocked by the compressor for the aircon. Am I right in thinking this needs to be disconnected (and the refrigerant removed) for me to be able to get to the strainer cover?

The VTEC solenoid on the back of the engine seems accessible, if a bit tight.

I plan to take a look at this properly over the weekend, when I have time to take the aircon apart too!

 

[Baldilocks]

By way of an update, cleaning the VTC strainer and the VTC solenoid seems to have fixed the issues - I got VTEC back yay!!

For those that come after, this video was really helpful! You will need to remove the power steering (not aircon!!) pump, aux belt and tensioner. If you‘re a muppet like me, you‘ll forget to hold onto the tensioner pulley nut and spend 3 hours removing bumper, light, radiator, front panel and alternator in order to get it back...!

https://youtu.be/YYKikGysXqE

Thanks everyone who helped

 

[Baldilocks]

And you can have another ring pic, on carousel, for reading this far

 

[SamDC5]

Glad you got it fixed mate.

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[impne]

Glad it‘s sorted and good link, not so sure on him using his underwear though on world wide coverage 😂

 

[Baldilocks]

Glad it‘s sorted and good link, not so sure on him using his underwear though on world wide coverage

Funnily enough, I had a pair of old pants in the garage that I used for that step... worked a treat

 

[Baldilocks]

REVENGE OF THE SKETCHY SPEEDO!

I believe the issue I was having previously with the VTC strainer and the speedo going haywire are two separate problems. The first one, solved. The second... not so much..!

Rather than starting a new thread, I'll continue on this one.

Recently the speedo has been randomly fluctuating, usually between 0 and accurate speed. Sometimes I can drive for several tens of miles with no issue. Sometimes it'll be going cray every few seconds. It doesn't matter what speed/accel/direction, or what the weather is, or whether any other specific electrical systems are on/off (aircon/lights/headunit etc). Random as hell!

When the speed reading is 0, I get no VTEC - instead I hit a rev limiter at the VTEC changeover point. Frustrating, to say the least!

This evening I carried out some further diagnosis work, but seem to be no closer to an answer as to what the issue is:

- I removed the airbox and traced the wiring back from the VSS sensor, in the hope of locating the speed converter - as this has been mentioned as being a common weak link. However, the insulated loom of three wires from the VSS sensor just a plastic cover/trunking and joins the main loom, disappearing off into the bulk head. No speed converter to be seen. There are no loose wires or cracks in the insulation, all seems good.

- Whilst I was there, I removed the signal cable from the back of the VSS plug, the connection looked good, with no dirt/rust/dielectric grease. I gave it (and the plug) a clean, for good measure. I also re-greased the outside of the connector, once reattached.

- In the hope of locating the speed converter, I removed the instrument cluster. All the connectors (and contacts) in the back seemed ok. There was a section that had different electrical tape to the rest (there was also grey tape, but I believe this is from factory..??), but I could see nothing spliced into the harness. Still no speed converter :xno:

Put it all back together to see whether my poking around and cleaning made any difference. Guess what? The issue persists...! ☹️

My intentions for next steps are:

- Using my mate's multi-meter, test connections in the circuit and see if I get any anomalies. Wiring diagram from the helms manual below... the issue is either speedo side only (blue circle), speedo and/or ECU connection (red and green circles). Given that I‘m not getting an error code, I‘m inclined to think that the converter (and the issue) are in the blue circle.

- Try and track down the original importer of the car, and see if they can confirm where the speed converter is likely to be located. Maybe I am being blind and it is staring me in the face? Maybe it is tucked away somewhere more subtle..?

- Try a replacement VSS/VSS connector. I don‘t have spares available to test, so would be expensive. Not to mention I think this unlikely to be causing my issue.

- Try a replacement speed converter.. just need to locate the current one..!

Car was imported in 2004 and sold to the previous owner in early 2007.
A quick look up would lead me to believe that the garage whom sold the car to the previous owner was bought out a while ago, so unlikely to have details of my car.. will give them a call anyways just in case!

Anyways, the whole point of this post (besides venting my frustrations) is to ask whether anyone on here has any words of wisdom that may point me in the right direction? Anything I may have missed that I should check?

Any help much appreciated, thanks for reading this far! 🤪

 

[Baldilocks]

P.s. I checked the fuse and it‘s all good (just before anyone pipes up with this suggestion! )

 

[Baldilocks]

Managed to track down the company that imported the car... huzzah! However the guy that installs the converters (same guy does it now as did it back then) isn‘t in until next week... hopefully he can shed some light on where the elusive converter is hiding!

Also, I had another thought... if I had Hondata, could I use this to override the need for a speed signal, to engage VTEC?
An expensive solution, but I want Hondata anyways and this excuse would help justify some of the cost I can live with a crazy speedo, so long as VTEC is still coming in strong!

 

[Baldilocks]

Update for any one that comes after..

I ended up fixing this by cutting all of the black insulation away and chased the bare wires. Lo and behold there was a tiiiny little converter doubled up inside the tape. Pulled it all apart and re-soldered it, fresh shrink wrap and (so far - did this back in May!) all good.

 

[badeshi]

Good work! I don't have this issue currently but good to have some details in posts which will prove very helpful to future readers

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