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gti205jb

Vvc Doesn't Turn On [Elise S1 111S]

14 posts in this topic

Hi,

 

I currently have some issues with the VVC system of my Elise S1 111S (2000). The inlet cam doesn't switch any longer when I drive the car past 4000rpm. I'm trying to find the root cause but first I'd like to know if some of you have already experienced similar issues on your cars. My second question is : can you get where the problem comes from if you plug it to a diag system ? My current analysis is :

 

case 1 : one of the input (signal) to the VVC system is not ok --> no cam switch

- VVC oil temperature sensor ; I've checked it and it seems to work fine.

- camshaft sensor issue ; I've seen on internet that it would cause the engine to limit revs between 5600 and 6000 rpm. I can rev past 6000 rpm (6500rpm) so I think it's fine.

- MAP sensor faulty ; I haven't checked but I tend to think that it would have so other impacts, right ? How can I check it by the way ?

- crankshaft sensor faulty ; I would have no speed on the speedometer, so ok

 

case 2 : the inputs are ok but the VVC system itself is faulty --> no cam switch.

- the VVC solenoids are faulty ; I have been told that the resistance should be between 6.6 and 8.8 ohms. I've got a little bit more on mine when I measure at the solenoid plug pins (around 8-10 ohms for each solenoid); could somebody tell me how much he's got on his car ?

- Hydraulic Control Unit faulty ? is there any way to check ?

- Ream camshaft belt ; looks good and would be already noticed if not ok

- issue with MEM2J ECU, VVC drivers faulty ; the engine would be limited to 5500rpm. Needs to be checked

 

If anybody has any idea, please let me know !!! clap.gif

Thanks for your help !

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I have just check the VVC solonoid coils on an EU2 VVC engine i happen to have sitting in my conservatory. The resistance on both is about 9.5 Ohms. Dont buy any sensors AFAIK the ones on this engine are OK. You are welcome to try them if you want HTH.


I have just remember something. You have not connected the battery the wrong way around at any time have you? Sorry im not being insulting buts is a common mistake that frys the VVC drivers in the ECU.

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Thanks Martin for your message !!! smile.gif (by the way, I've updated my first post so that all the potential root causes are listed, might be useful for somebody else in the future).

 

I haven't been "playing" with the battery polarity recently but you're right, I can't rule out this possibility so it's definitely worth checking (especially at this stage because most of the items listed above have been checked as you can see). This ECU potential issue brings me two additionnal questions :

- is it possible to get the ECU checked and repared easily if faulty ? Or does it have to be changed instead ?

- is it impossible to swap the ECU with another one without bothering about the current alarm module ? (sounds too nice to be true, right ??!! lol)

Thanks for your help !

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Can you find someone to do a diagnostic check? The EU3 engine uses an OBD11 reader which is easy. However the S1 VVC elsie is earlier than this. A bit of information i stole from SELOC.

 

In the boot on the left. Behind the carpet on the boot wall there are two round holes. One for the fuel pump fuse and the other for the diag socket.

Get them to read the live data and rev the engine. If the VVC mechs are working you'll be able to see the cam advance figure change in the live data.

 

HTH

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The HDU works by oil pressure and the Solenoids. I had a leak from the casting in the HDU and the performance only dropped off a bit. So I would suspect ECU or sensor.

 

Have you checked the Timing? Have you noticed a real drop in performance or poor running? I take it that it revs to 6.4k regardless of whether in gear or not?

 

 

I have used these chaps below a few years ago.

 

http://www.autotekelectronics.com/autotek/

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Thanks for your messages guys. HDU is a mechanical part and I would also be surprised if it was found to be faulty. I would tend to think that a faulty MAP sensor would cause some other issues (maybe idle issues, drop of performance, etc). So far the engine pulls ok, except that I have about 25hp lost because of the VVC not working ! laugh.gif

I believe that a shifted timing would cause poor running and lack of performance so I've ruled out that possibility. It looks like I need to check my ECU !!!

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A suitable diagnostic tool would tell you if the ECU is driving the solonoid valves?

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Maybe, but I struggle to find a diag tool at a decent price ; the S1 is not OBD compliant and I need to find a diag tool which is MEMS2J compatible. From what I've seen on internet, the diag tool mainly checks all the inputs which goes into the EMS (by comparing the actual measured valued with the referenced values) ; I'm not even sure if there are any checks for the output signals going into the actuators..

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I was not suggesting buying one. It might be worth ringing around a few of the local specialists though to see if they have one? :) It might be worth trying a few MG specialists as well. The engine also went in the MGF.

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From what I've seen on Seloc (Techwiki), a fried ECU would limit the engine to 5500rpm. However I'm keen to investigate that option ! Any idea if a straight ECU swap for checks purposes might be easy to do (I mean, will I have to worry about stupid alarm & immobilizer ; I fear that the answer is Yes as the ECU seems to be coupled to the alarm immobilizer) ? Cheers.

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I did just that. After winter storage I connected the battery to my 2005 Lotus Elise 111S the wrong way around.
With a OBD2 I got error code 1490 and 1492 - decrement/increment solenoid open circuit.

Will a new ECU fix my problems, or is there a break som where else in the circut/damaged solenoids?

Is it possible to test the circuit with a multimeter?

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