VVT Problems on Mk2.5 1.8

Technical Area Engine, Transmission, Exhaust etc
2

We used to have a thread going on the old forums about VVT issues, which I hadn’t given much thought till recently when I finally got round to some engine enhancements.

It started off with the old VVT problem that lots of people seem to have, having spent some time with the issue I purchased a fault code reader (so I could reset it), played around with it a bit I have noticed a few things…

  1. The fault code it always the same: “P0012 “A” Camshaft
    Position - Timing Over-Retarded  (Bank 1)”

  2. The fault only ever occurs when the engine is warming up i.e. abt 1/4 the way up the temp gauge (rests up at 1/2 way)

  3. The fault only ever occurs when the engine is warming up and I get my foot down (i know I shouldn’t) - never when hot

Quite often I just reset the fault code and go on my merry way without any problems, but its been bugging me for a while so recently I spliced into the VVT valve cable (2core) and hooked up a 12v LED which sits next to my dash, this is what I’ve noticed:

Engine cold, Ignition on : ECU checks systems, powers up valve to 12v, then drops to 10v

Engine start : ECU checks again, 10v (LED dim)

Start driving : Whilst the engine is cold the voltage stays at 10v (LED dim)

Engine warm : let engine idle, no gears engaged, blip throttle  - voltage at 10v. Revs drop back to idle - after about 2 secs of idle speed there’s a brief 12v surge i.e. LED goes bright for about 0.25sec

Engine warm : start driving, 12v (LED bright) when ever I am “accelerating” i.e. NOT cruising. It doesn’t turn off at all even when on the red line.

Now all this flys in the face of what I thought (or had been told) about the VVT system on the Five. It seems that the VVT system doesn’t kick in at 3500-4000rpm but is in fact active all throughout the rev range but when you are accelerating.

Now quite how this relates to my VVT problems I’m not sure but I thought I’d share my findings, maybe get some thoughts back from you guys.

Look forward to hearing from you…

Best regards,

Rich

 

3

Sounds like the same symptoms I have.

See here: <http://www.mx5oc.co.uk/forum/forums/t/3499.aspx>

4

Yep, exactly the same problem. I would check the solinoid operation before you replace it. I had mine swapped out just before warranty period ended but it didn’t make a difference. If it works ok I wouldn’t waste the money.

The more I think about this problem the more I think it has to do with oil flow to the VVT actuator, as in too little or too much. Given that it seems to happen during warmup when oil is thicker I’m thinking too little. I did originally think it could potentially be a blockage somewhere but I took it apart and couldn’t find any problems.

Meditate on this problem I will…

Rich

5

Exaxctly. I’m sure the valve solenoid is working, otherwise the error would be permanent rather than intermittent. It has to be something to do with the oil flow through the valve before it’s fully up to temperature. It’s fine when it’s cold or when it’s hot, but somewhere in between it triggers this error.

If I can find a cheap unit from a scrappy, I might try swapping it out, otherwise I’ll take Robbie’s advice and leave it for now.
There seem to be no symptoms other than the engine warning light.

6

There’s some stuff on Miata.net about this

http://www.miata.net/garage/tsb/sb01-025-06-1648.pdf

http://forum.miata.net/vb/showthread.php?t=311462

http://forum.miata.net/vb/showthread.php?t=318855

http://www.miataforum.com/vb/showthread.php?t=276340

http://www.miataforum.com/vb/printthread.php?t=259912

7

Awesome stuff Geoff. Looks like it is pointing to an oil problem, I’m thinking a good flushing out and some new 5w30 might help.

Will probably take out the valve and make sure there’s no crap in the filter too. Just hope it’s warm on Saturday :slight_smile:

I’ll report back with some findings…

Rich

8

Quick Update:

The engine flush, new oil filter and 5w30 seems to have helped. Have been running it for a few weeks and I’ve tried to force the error a few times - no problems yet, fingers crossed !

Might also add that the engine seems much happier on 5w30 than other oils (managed to get a 5L of Millers long life full synth 5w30 for £30), I’m pretty sure that the mpg have increased too. With fresh oil I’d expect to see a little increase but perhaps the VVT is working properly now which is helping things? Not sure TBH as the weather has been good I’ve been ripping up tarmac hence MPG have plunged [6] but I will keep an eye on it…

 

9

Didn’t want to start another thread…

I’ve just had my engine warning light come on, fault code at the garage was the exact same as the OP’s. Reset the ECU and it hasnt come back on, my only worry is that I’m driving around for a few hours tomorrow, should I be overly concerned? I see you mentioned that you often just reset yours and carried on your way. Garage said that they can only reccomend a tming belt change ASAP.

I’m new to 5’s, so just abit anxious!

Cheers for any advice,

Adam.

10

See this discussion which I contributed to HERE

I had this same problem with the P0012 code on two seperate occasions.  My view is that if it’s intermitent then it’s nothing to worry about.  It seems to me that it’s a bit of a design fault with these VVT engines.  If you read my exchanges with Robbie you will see that I had the VVT gubbins out, tested it and cleaned it but found no problem.  On the two occasions it’s happened I have simply reset it with the code reader.  I have done over 5000 miles since it first happened and the engine runs great.

I believe that the light does not come on until there have been 2 reports to the ECU so the time the light comes on is not really significant.  I did see somewhere that people have suspected that these VVT mechanisms do not like the 10w/40 oil as recomended in the handbook as the winter figure is a bit too thick to get up to the valve quickly, so for my last oil change I changed from 10w/40 semi to 0w/40 synthetic which is believed to “pump up” quicker from cold.  I have had no light since over about 1000 miles ?  fingers crossed.  My engine still runs smoothly.

In short, no-one has ever got to grips with this issue, even Mazda who for earlier cars had a redesign due to the valve clattering.  My car already had the new design but it still happened.

My advice is to check the valve electrical operation, make sure it’s clean and the tiny OCV oil filter in the flange on top and all the pipes are all clear. Do an engine flush when you next change the oil and use a lower winter grade oil than 10w (much the same as

								        Riscyrich said above - 5w/30, 5w/40 or 0w/40) and see how it goes.

As for the garage telling you to change the cam belt, well if it’s due to be changed then fine, but IMO it’s not the reason for intermitant codes P0012 on VVT engines.

Hope this helps and puts your mind at rest a bit.  Carry on driving!

 

11

I also am begining to think that 5W30 or 5W40 oil is the way to go with these VVT engines.

12

Yes Robbie it would be interesting to do a bit of a survey to see what grade oil VVT owners are using and whether they have had the mysterious P0012 light.

13

Hi All

I’ve had the Five stood up for 12 months due to buying an A4 that was going
cheap and the family car needed an upgrade. Hoping to get it back on the road
this year and get shut of the good old BMW. Prior to the mothballing I had run on
5w30 for some time and had many miles free of the ‘P0012’ error. If it did pop
up the ScanGaugeII was quickly on hand to silence the petulant ECU.

I don’t honestly think there is a problem as such here. I’ve surmised through
many hours of tinkering that my engine appears to be behaving mechanically as
it should. The ECU is keeping everything in check and reporting correctly/controlling
logically based upon sensed inputs.

The different grades of oil do make some temporary differences but the problem
if like mine will return. With oil based experiments out of the way I’m going
to move back to 0w40 full synthetic Mobil One as I found this to be oil the
engine really likes in all climates.

What I think is happening here is there’s an alarm/notify parameter set in
the ECU that is either alerting before it
should be i.e. this audit routine should not run until engine temp >65
degrees etc or set overly sensitive - more likely the latter.

Any which way I looked at this I came to one conclusion which to this day
saddens me somewhat as I’m not one to give up on these issues…

The one simple way to prevent ‘P0012’ torture ----> Do NOT go above 3000rpm
until the engine is warm.
By warm I mean when the temp gauge needle is vertical
or you have something plugged into the ECU that shows you engine temp to be

65 degrees C. Be patient – the 1.6’s and 1.8’s in ‘The Five’ warms up faster
than any engine I’ve run.


If your problem is like mine and you are sure you engine is behaving as it
should then stick to this rule and you will I’m sure avoid PooTwelve Torture or
PTT as I now call it (I tried to work VVT in there but I couldn’t make it fit).

ATB

Rich

14

This is good advice for all MX5 engines. If you rev the nuts off it before it’s up to temp you shorten the life of the engine considerably

15

 

Good advice Rich.


Although we’re still not sure of the exact issue here, we seem to be coming up with some tentative recomendations.  These would be mine:

1.  This P0012 is nothing to get too concerned about providing it doesn’t happen too often, if so get a code reader (£25) and just reset it.

2.  Check that the valve and filter are clean and operating properly electrically.

3.  Do an engine flush when changing oil and use 0w/40 in these engines  (I had 2 occurences with 10w/40, never had one with 0w/40)

4.  Let the engine warm up to normal before exceeding 3000 rpm.

 

Just thought! - Is it worth having a small article on this in STHT, perhaps asking for any other ideas - Robbie?

16
<!–[if gte mso 10]> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

<![endif]–>

Hi Phil - good point.

Only
take my view if you are 100% sure there is nothing wrong. As Phil said, check
the operation of all the associated system components before you head down the
same route.

I’ve
got one of the £25 code readers and a ScanGauge2 I both of which work well with
the MX5 ECU. The ScanGauge obviously being my preferred option as it’s always
connected and offers much more useful info.

Letting the engine warm up
seems foreign to people these days as I know most dealerships tell you to just
get in a drive (CAT warm up times reduced etc) but I’m firmly believe in the
warm up period. It allows seals to soften, oil to flow efficiently, fuelling to
normalise etc.

Having played many hours of
GT4 on PS2 I came up with a motto for myself, brother and brother in law (sadly
we did a full 24hr Le Mans race on it) as you have to wait for the tyres
to warm up (show green on the HUD) before you can even thing about giving it a
foot load otherwise you just spin out - “Don’t be giving it beans till you see dem greens”.
Couldn’t think of one for the Five though.

We have since got a PS3, GT5 and
the Logitech GT steering wheel - huge amounts of fun for all driving enthusiasts,
can not recommend enough. Some people take it too far though… http://youtu.be/4WDk1ndGWLQ

ATB

Rich


 

17

Hi All

It’s been a very long time since I last posted anything here but I have been messing with my MX5 (Mk2.5 1.8 ~50,000 miles) a little lately and thought a quick update to the VVT issue would be nice…

5w30 oil is what it likes, the 0w40 type oils trigger the P0012 fault code much more (during my personal testing). I think the camshaft actuator sticks or migrates from the retarded/normal position too slowly when it’s cold causing the ECU to record an error state. Whether it’s because the oil is too cold to flow with enough pressure or the contacting metal parts in the actuator are a bit tight I am unsure. Please don’t shout - I know, I know… but if when cold <65’C give a foot load in 2nd all the way to say 6.5kRPM the actuator doesn’t stick then :wink:

The oil feed to the VVT valve runs along the top of the engine which can take longer to get up to temp. Thinking being the cold oil is more difficult to force into the VVT actuator on the end of the camshaft.

As mentioned before if you don’t go above 3kRPM before the temp needle is vertical you are unlikely to see the P0012

Running on a good Fully Synthetic 5w30 oil will help avoid the P0012 problem, though it may use a little more as it’s thinner. Don’t waste your money (or engine) on semi-synth, most are 15% synth at best. A shot of Archoil AR9100 with the recent oil change has helped quiet down the cam clatter in the morning and I haven’t seen a P0012 error since even when forcing it, time will tell.

Other thoughts/observations:

My 1.8 VVT loves premium fuel. I get more power, more torque and more MPG. More or less pays for itself. The ECU knows what to do with the higher octane juice.

I went a bit nuts on oils and additives after feeling such a difference from the premium fuel fills. Decided to run a bottle of fuel system cleaner through, I wasn’t suspicious of much carbon build up but the 1.8 does run a touch rich. Bit of research suggested a cleaner with polyetheramines(PEA) in to breakdown any carbon build-up. Only professional products ~£20/bottle contain PEA so I got some AR6400. The free sample of AR6200 fuel modification that came with it was a welcome bonus and is a truly bizarre chemical to say you only add 5ml to a fill; makes the engine pull more low down. 

Heat shields are a pain in the arse. The one just before the CAT got removed recently as it was clattering around. I instead wrapped the exhaust in fibreglass banding and tie wrapped it in place with stainless steel ties. Should help keep the CAT warmer in the winter…

Best regards,

Rich

18

I had my engine Terra-cleaned, and it does seem smoother and more responsive now. Worth £100.

19

I looked at the Terra-clean process but didn’t bother as there aren’t many places to do it. Might be worth following up with the AR6200 to help prevent carbon build up after the clean. It is honesly amazing stuff but DYOR !