WTF just happened? - UPDATE

ninja · Post by **ninja** » Wed Jun 13, 2007 5:22 pm

this morning i started the lotus as per usual and off she went. but at the first set of traffic lights it stalled! strange i thought, that's not happened in a while. so restarted and went into work.

at lunchtime i was on my way home, doing 70MPH on the M8 when there was a sudden drop in power, just momentary then it picked up again. then the power went i looked down at the clock and both the rev counter and speedo dropped to 0, then when the power came back in a nano second later they both bounced back up to normal.

what the hell happened and should i be worried?

ninja

robin · Post by **robin** » Wed Jun 13, 2007 9:14 pm

Looks like power loss to the ECU - on an S2 the ECU controls both speedo and tacho outputs (and obviously runs the engine). Hence simultaneous loss of engine power, speedo and revs.

Check that the rain cover is properly fitted over the ECU, then remove it and check that the ECU plugs are properly connected. Also worth checking the ECU fuse which IIRC is on the ECU mounting plate - maybe it's worked itself loose or there is some heat-induced distortion of the fuse holder or fuse itself.

After that I would start thinking about checking that the MFRU is properly connected and then perhaps replacing the MFRU as it might be the main relay starting to flake out. People say they break - never seen it myself, but that doesn't mean it doesn't happen ...

Or wait for it to become permanent failure at which point it will be possible to diagnose exact cause.

Cheers,
Robin

P.S. It's probably worth removing the ECU plugs and checking that there is no corrosion in there - best disconnect the battery -ve before you do that, and best disable the alarm before you disconnect the battery -ve!

ninja · Post by **ninja** » Wed Jun 13, 2007 10:21 pm

thanks robin

looks like i'm going to be busy this weekend

is this a common fault?

ninja

robin · Post by **robin** » Thu Jun 14, 2007 7:31 am

Nope, first time I have heard of it. Did any/all of the warning lights on the dash light up, or was it just the needles that dropped to zero and back again?

I am trying to make sure you didn't lose power to the stack as well - I don't think you did, because the symptoms would be a little different, but just checking.

Cheers,
Robin

ninja · Post by **ninja** » Thu Jun 14, 2007 4:47 pm

there were no warning lights, just the needles dropping.

ninja

Stephen · Post by **Stephen** » Thu Jun 14, 2007 10:42 pm

Chris,
I had a simmilar fault on my S1. I did the silly move of trying two things at the same time so i don't know which one fixed it.
I changed the MFRU and dis connected and re connected the temp sender plug.
To be fair i think it was a dodgey connection on the temp sender that was the problem.
Anyway I have a spare MFRU which i am pretty sure is fine. If this is the same on S1 and S2 (Robin??)then you can have it to try.

S

robin · Post by **robin** » Fri Jun 15, 2007 7:51 am

It won't be the coolant sensor plug - why would the presence or absence of the coolant sensor make the ECU reset. Also, on the S1 I would only expect the RPM to drop as the speedo goes straight from the wheel sensor to the stack without the ECU being involved.

As Ninja's problem is intermittent swapping anything isn't really going to tell us much. We can inspect all the connectors for signs of corrosion and broken wiring but swapping one part for another isn't going to help.

I might be inclined to carry a spare MFRU and wait for the fault to become permanent, then replace the MFRU - but you need a 100% good MFRU and given what I said about the coolant temperature sensor, I guess your MFRU is broken.

Cheers,
Robin

ninja · Post by **ninja** » Sun Jun 17, 2007 3:42 pm

ok - update!

it's now permanent! car didn't make it out the driveway this morning. it started then cut out then just wouldn't start.

when i turn the key in the ignition, the stack lights come on and the car turns over but just doesn't fire up.

i'm about to go out and hunt down the ECU and check the connections.

any other thoughts?

ninja

Rich H · Post by **Rich H** » Sun Jun 17, 2007 3:51 pm

MFRU as Robin suggests, odd that it's intermittant to begin with though.

ninja · Post by **ninja** » Sun Jun 17, 2007 3:59 pm

what does MFRU stand for? so i can find it

ninja

Rich H · Post by **Rich H** » Sun Jun 17, 2007 4:23 pm

Multi Function Relay unit, does all the fuel pumps switching and a few other bits. Dunno where it is on an S2, it's a small black box with a load of wiring coming out of it and is right next to the ECU in my car.

ninja · Post by **ninja** » Sun Jun 17, 2007 4:38 pm

it's right under the ECU on my car. i'll buy a new one, all the fuses and connections are good so looks like the relay is goosed

ninja

robin · Post by **robin** » Sun Jun 17, 2007 11:55 pm

Hmm. When you turn on the ignition, do you hear the fuel pump prime?

If not, it might be worth making sure that the inertia switch hasn't popped.

Also, once the fuel pump has stopped priming, when you turn off the ignition, if you listen carefully you should hear the ECU "parking" the IACV.

Do you hear that?

Cheers,
Robin

ninja · Post by **ninja** » Mon Jun 18, 2007 3:08 pm

i think i remember hearing the fuel pump priming, don't recall hearing the IACV doing anything though. i'll check when i get home

where's the inertia switch?

ninja

ninja · Post by **ninja** » Mon Jun 18, 2007 3:14 pm

actually i remember seeing the inertia switch yesterday - how will i know if it's popped?

ninja