Fluctuating revs and flashing MIL light

Scottyboy · Post by **Scottyboy** » Sat Apr 28, 2007 8:35 pm

When I start my S2 elise the car revs increase and decrease every couple of seconds. This is accompanied with a fleshing MIL light. I have replaced the idle air control valve but this didn't solve the problem. Has anyone come across this problem? Does anyone have any ideas how to fix this?
Cheers

dezzy · Post by **dezzy** » Sat Apr 28, 2007 9:13 pm

Is it a rover or toyota engined S2? My (toyota engined) S2 has had the odd wee moment of the revs jumping around. I've been told it was a software thing and they reset the ECU. It's came back again recently.

I think if you're on the older version of the ECU they can reflash it with updated software to resolve it.

If it's rover-engined, then I ain't much help. Sorry!

Scottyboy · Post by **Scottyboy** » Sat Apr 28, 2007 9:25 pm

Thanks but it is the rover K series engine. I was looking through elise parts and my throttle potentiometer seems to be missing the metal strip, could a faulty potentometer be the problem?

Rich H · Post by **Rich H** » Sun Apr 29, 2007 8:36 am

IIRC the metal strip just helps hold it in place.

Did you do a recalibration of the throttle pot? Electrics on (don't start the engine) throttle fully open and closed about 5 times, electrics off. This recalibrate the throttle pot and ECU.

There is a MEMS rest but I can't remember what it it cos it didn't work for me. Something about holding the drivers door open and the trip meter button down when you turn on the electrics

robin · Post by **robin** » Sun Apr 29, 2007 9:33 am

Check your owner's manual! It should say about the MIL:

"If the lamp flashes, an engine misfire has been detected which is sufficiently severe to cause overheat damage to the catalytic converter. Slow down immediately and be prepared to stop.
- If the MIL then stops flashing and is lit steady proceed with caution and seek dealer advice.
- If the MIL continues to flash, stop the engine and seek dealer advice. Continuing to drive the car with a flashing MIL may cause overheat damage to the catalytic converter and increased toxic emmisions."

Cats are expensive and burning cats burn cars, so best get it sorted.

So, go get it onto an OBD tool ASAP (or take it to pretty much any workshop as they will all have OBD code readers by now). The code you get will be a clue, but typically this is caused by a coil, lead or spark plug - i.e. ignition rather than injection.

Cheers,
Robin

mac · Post by **mac** » Sun Apr 29, 2007 12:53 pm

Scott,

Chances are it will be your coil pack/lead on the way out. I've had to replace them on Mandy's car and clean up the ones on Rob's car.

Or you could be lucky and find out that it's just one of the plugs starting to fail.

If you can do as Robin suggests then that takes a lot of the guess work out - if not then it's just a case of trying to track it down - igntion side has the most "consumables"

HTH

Mac

Scottyboy · Post by **Scottyboy** » Sat May 05, 2007 3:36 pm

Fuse 8 was blown and that was stopping the tachometer from working and therefore feeding back to the ECU. Fuse 8 seems to be OK now, don't really know why it was blowing but it's stopped and the car is running fine. I still have a problem with fuse 15 which delivers power to the radio and to the instrument control unit â€“ Iâ€™ll need to find out where this is shorting. I tried to remove the dash but I can't remove it without taking off the plastic outer rim, which means removing the vents which have inaccessible screws into the dash. Has anyone got any tips for removing the dash or come across problems with fuse 15.

Cheers

robin · Post by **robin** » Sat May 05, 2007 9:00 pm

Scottyboy wrote:Fuse 8 was blown and that was stopping the tachometer from working and therefore feeding back to the ECU.

Can you explain this in more detail - I don't really understand what you mean by this?

Has anyone got any tips for removing the dash or come across problems with fuse 15.

No, sorry - never removed it

Do post up if you find out what the right way to do this is - thanks!

Robin