VVC Misfire/Rev limit

[Andrew Bennett]

A question for a the K series experts out there. I acquired a 2003 1.8 VVC a few months ago and have only started to stretch its legs. 

I noticed that I am hitting the rev limiter at 6,000 rpm (in all gears) although when I say hit the rev limiter it could also be misfiring as I am not sure I could tell the difference. Apparently the rev limiter should be at 7,100. Somebody on local whatsapp group (very helpful bunch) asked whether the VVC is kicking in at 4,000 and it's not something I noticed but as I haven't driven another VVC I can't compare. 

The engine has done 12,000 miles and from what I can see from documentation is standard. 

Any views on rev limiter vs missfire and possible causes? 

Thanks 

 

 

                

[simon_h]

From memory the VVC has a low rev limit,  set at around that value, when the VVC isn't working. Could be the oil temp sensor in the VVC housing or the solenoids playing up. 

[revilla]

VVC RPM Limits & Associated Failure Modes

 

5500 RPM

 

VVC Solenoid Low Resistance (Should be 6.6 to 8.8 Ohms)

VVC Control Circuit in ECU Failure (from Wrong Battery Polarity)

Cam Position Sensor Failure

 

6000 RPM

 

Engine Coolant Temperature Sensor Low/Error

Manifold Absolute Pressure Sensor Error

VVC Oil Temperature Sensor Low/Error

[revilla]

PS: If it's all set up properly you won't feel the VVC kicking at 4000, it's continuously variable cam duration so it comes in smoothly, unlike something like a VTEC.

Have you got an OBDII scanner, preferably one that shows live data? That will most likely either show fault codes for one of the above sensors or the live data will show silly values for one of them. Just remember that a sensor fault can just as easily be a wiring or connector fault. Temperatures reported as -40°C generally mean a broken wire or port connection, temperatures reported as 140°C generally mean a short to ground.

[Andrew Bennett]

Thanks.  Yes I do have a OBDII scanner. I didn't think a 2003 car would be readable but if you think it will be I'll try. Sod's Law I am in London tomorrow so will try on Wednesday. Fortunately the car is under warranty from the dealer I bought it from but pain in the behind if it has to go back just as the weather picks up. 

[revilla]

A 2003 car should have a MEMS3 ECU like this:

If it does, it supports OBDII. There should be an OBDII socket dangling in the wiring loom somewhere above your right knee, it's often tucked away or cable tied back out of the way so can take some finding.

Sometimes the ECU can be a bit fussy about connecting. Best thing is to leave the car powered off for a while until the ECU powers down (can take a few minutes as it would run the engine bay fans on a Rover), then plug the scanner in and turn it on, and only then turn the ignition on and try to connect. If the ECU finds the OBDII socket disconnected (no pullup resistor from a scanner detected and line low) on power up, it stops listening.

[Andrew Bennett]

So I managed to find the OBD port and following your instructions connected ok. Cleared fault codes and two new ones came up 

P0443 Evaporative Emission System Purge Control Valve Circuit

and 

P1521 (no description against this code)

my reader didn't enable me to see data for some of the parameters you refer to but engine coolant looked OK at 148 degrees F. 
 

MAP was fluctuating quite a bit 0.22 to 0.35

 

B1S1 O2V (0.08 to 0.70V), B1S1 O2% (-0.80 to 4.70%)and B1S2 O2V (fairly constant 0.46V) were all giving readings 

but B1S2 O2% was constant at 0%  

I have no idea what these mean! 

 

 

[SM25T]

First item sounds like redundant or removed carbon canister.

[revilla]

P0443 - As Ian (SM25T) says. Ignore it.

P1521 - Yes, VVC actuator solenoid issue. Check the solenoid resistances are about 8 ohms. Worth taking the ECU connector off and checking the resistance as seen from the ECU pins in case there's a wiring issue. I've recently discovered that the ECU will report a solenoid "Circuit Fault" when what it really means is "the solenoid isn't having the effect on the cam timing I was expecting" so things like a stuck VVC mechanism can give this fault, as well as the more obvious electrical issues. Give me a shout if you want instructions on what to measure where!

MAP will fluctuate as the ECU manages the idle. Probably not  a million miles out there.

B1S1 (Lambda/Oxygen Sensor, Bank 1, Sensor 1) is the only lambda sensor you will have installed. Bank 2 is only for V engines and Sensor 2 is post-catalyst which won't be fitted on a Caterham. If it's cycling regularly over that voltage range it sounds about right. B1S2 will not be installed, and the ECU's input circuit biases to 0.46V when disconnected so that's all you're seeing there.

The P1521 will be the culprit here. You need to work out the cause of that.

Don't be worried if you sometimes see P1520, it looks like it should be related but it's not. All K Series and especially VVCs (in Rovers as well as Caterhams) are prone to show it, it's a phantom code that you can just ignore).

Have a check on the solenoid resistances and let us know, we can tell you where to go from there.

If you need a replacement VVC solenoid I've got a bag of the things here and they're a doddle to change.

Cheers,

Andrew

[Andrew Bennett]

Thanks very much you are a star. Is it safe to drive (conservatively) until fixed? I am not confident in doing this myself and it's under warranty. But It won't get looked at until next week and Easter weekend is coming up with decent weather! 

[revilla]

It might not be the best idea to use it.

If it is a sticking VVC system it won't do it much good if the hydraulics are trying to force it.

And even if it's just an electrical gremlin, if the VVC mechs aren't opening up then the engine's mapping will all be wrong, which is why it's stopping you revving it higher, to protect itself.

A gentle drive back to base to get it fixed should be OK, but any kind of spirited/enjoying yourself kind of driving is probably best saved for when it's resolved.

Performance will be well down if the VVC systems aren't working.

[Andrew Bennett]

update. Car is back with GP7. Solenoids replaced and wiring checked. So that's the two easy bits done but problem remains. 
 

ECU now been sent to Kmaps to be checked and if that proves to be OK they will start checking the VVC itself. 
 

[Andrew Bennett]

Turns out the Hydraulic Control Unit piston was stuck. This has been freed up and is now, apparently, running OK. I am off to pick it up tomorrow. 

I've learnt a lot about the VVC mechanism through this problem and big thanks to Andrew R who has given lots of good advice and gone out of his way to help. 

[SM25T]

He is The VVC expert 

[Golf Juliet Tango]

I'm glad to hear it has been solved.

[Andrew Bennett]

Well it was solved for about an hour!  Problem has reoccurred. 

[Golf Juliet Tango]

That's a shame, I'm sorry to hear that.