111R : Intermittent "Misfire"

111Robin · Post by **111Robin** » Wed Nov 07, 2007 10:54 pm

Occasionally getting a 2-3 second rapid mis-fire (more like traction control operating), when driving at constant speed. TC light isn't coming on, neither is MIL. Otherwise runs perfectly. Anyone else experience this ?.

Edin430 · Post by **Edin430** » Wed Nov 07, 2007 11:06 pm

Do some exhausts not sound like they are misfiring but they are just popping etc............

Although dont know what exhaust you have..

(having a guess btw

)

111Robin · Post by **111Robin** » Wed Nov 07, 2007 11:11 pm

It's not on the overrun which is what you're describing, it's on a constant throttle, crusing at 70-80, there's occasionally a 2-3 second slight drop in power. It doesn't lurch or draw up, you can just feel the power drop off, then it just returns to normal. Does it approx. twice on a 2-hour journey. I've hooled up an OBD-II reader but it wouldn't "talk" to the ECU so don't know if there is a fault recorded.

Mr Momo · Post by **Mr Momo** » Wed Nov 07, 2007 11:16 pm

Robin - water collecting in the head/coil area ? Call out the AA/RAC if you're a member and see if they can see it with they're OBD machine.

BiggestNizzy · Post by **BiggestNizzy** » Wed Nov 07, 2007 11:22 pm

X7LDA wrote:Do some exhausts not sound like they are misfiring but they are just popping etc............

Although dont know what exhaust you have..

(having a guess btw )

erm i'm with you but expect to be flamed mine pops and bangs when cold it's great

robin · Post by **robin** » Thu Nov 08, 2007 12:40 am

Sounds like early-phase O2 sensor failure to me ... suspect you'll get a MIL in due course, and then it'll be the O2 sensor that's failed.

2-3 seconds of erratic operation is probably not enough to cause a MIL event.

Do you have a proper cat and both O2 sensors connected normally? I assume so on a Toyota - don't think there's any point in fitting a cat replacement pipe anyway.

The other possibility is the throttle control in a drive-by-wire car which if the pedal position sensor goes awol can cause the throttle to snap shut briefly I think. However, that's only on drive-by-wire cars and also I think you normally get MIL very quickly with these (and Lotus claim they don't fail anyway - or so I read elsewhere!).

Cheers,
Robin

Edin430 · Post by **Edin430** » Thu Nov 08, 2007 1:04 am

BiggestNizzy wrote:
X7LDA wrote:Do some exhausts not sound like they are misfiring but they are just popping etc............

Although dont know what exhaust you have..

(having a guess btw )
erm i'm with you but expect to be flamed mine pops and bangs when cold it's great

111Robin · Post by **111Robin** » Thu Nov 08, 2007 8:06 am

It's standard 111R, drive-by-wire. I'll try my OBD-II reader again. It does connect to the ECU and gives real-time sensor outputs but when I try to read the fault codes it goes into a never ending loop of trying to connect. It works fine on other cars therefore must be a prorocol issue with the Lotus software I guess. The fault isn't bad enough to put me off the road, but it's one of these ECU/sensor type faults that could I guess eventually cause a break down so I'd rather investigate it now before it escalates. Bummer as the warranty only ran out last month (it is just 1 year with a new car isn't it ?)

gorrie · Post by **gorrie** » Thu Nov 08, 2007 9:20 am

It should say the warranty period in your handbook... but my book says that it's 24month/20K milesfor UK & EU cars. So you should be OK.

ngaff1 · Post by **ngaff1** » Thu Nov 08, 2007 9:53 pm

Thought it was just my car that did this.
I loose power for only about 1 sec, also at constant speed, around 4k revs so would tie in with your speed. Had the car a year and only does it every couple of months. Have checked with the garage and got the usual "if it's intermittent we'll never find it" answer. However they asked that I check next time to see if the rev counter dropped dramatically. They suggested a crank sensor may be at fault??

ngaff1 · Post by **ngaff1** » Thu Nov 08, 2007 9:56 pm

Should be 2 years warranty.

Post by **simon** » Thu Nov 08, 2007 10:20 pm

ngaff1 wrote:Should be 2 years warranty.

And unlimited mileage from around late 2004 cars on (not that it matters for cars that old!)

111Robin · Post by **111Robin** » Thu Nov 08, 2007 11:04 pm

Sounds like the same problem. Should still record an fault on the ECU though shouldn't it, or does it need to be a complete sensor failure for that to happen ?

robin · Post by **robin** » Fri Nov 09, 2007 8:52 am

It won't record a fault unless it also lights the MIL, I think (how would you know the fault was there).

How often does it happen?

Cheers,
Robin

111Robin · Post by **111Robin** » Fri Nov 09, 2007 5:23 pm

I have read somewhere that fault codes are still stored even without the MIL light illuminating. The MIL light only comes on when the fault is sufficient to require attention. I would say that on a 2 hour journey with prolonged periods of constant throttle (4000rpm) it would probably do it once or twice for a second or two each time. Sounds like a deliberate cut in power, like the traction control, not just a random misfire. TC light isn't coming on so it isn't that, just feels like it. I'll try my OBD reader again at the weekend but I've tried it twice and it just goes into limbo trying to read the codes. I guess I'll drop it into MMC for a diagnosis but if there's no fault recorded they won't be able to do much unless it happens when it's hooked up to the diagnostic equipment.