Revs Dropping Jerkily and 'Searching'......
Discussion
Yesterday, whilst out for a drive, my Mk2 111S had what can only be described as a 'funny turn', accompanied by the MIL coming on.
As I entered a 30 zone and took my foot off the gas I noticed the revs dropping in a jerky, unusual kind of way - as if I had been applying gas and then abruptly taken my foot off. At first I thought it was driver error but then it did it again several times. Whenever my foot was off the gas the revs from the engine were not settling. Instead they seemed to be 'searching' slightly, even jumping a little bit. With my foot on the gas this seemed to stop, although I was still in a 30 zone so hard to test properly.
As the journey was nearly over I only experienced this for about two minutes, until I pulled over and turned off the engine. After an hour and a half pub lunch break it started up and drove home fine.
It just didn't feel right so I have three suggestions for a possible cause (with no idea as to how they could possibly cause this problem!):
1. Too much oil - just had the car serviced and when I checked it today at cold it seemed to be over the max mark.
2. Decat pipe on a 111S - now the weather is cooler, could this possibly have an impact? Incidentally I have had no issues with the decat and the MIL has not come on before with it in place (4 months).
3. Lightweight flywheel - again, been there a while with no issues. Although I have occasionally had the engine 'searching' when sat in traffic on a cold morning, which I had thought was due to the lightweight flywheel.
Any ideas anyone?? I really don't want to break down in this weather!!
Cheers.
As I entered a 30 zone and took my foot off the gas I noticed the revs dropping in a jerky, unusual kind of way - as if I had been applying gas and then abruptly taken my foot off. At first I thought it was driver error but then it did it again several times. Whenever my foot was off the gas the revs from the engine were not settling. Instead they seemed to be 'searching' slightly, even jumping a little bit. With my foot on the gas this seemed to stop, although I was still in a 30 zone so hard to test properly.
As the journey was nearly over I only experienced this for about two minutes, until I pulled over and turned off the engine. After an hour and a half pub lunch break it started up and drove home fine.
It just didn't feel right so I have three suggestions for a possible cause (with no idea as to how they could possibly cause this problem!):
1. Too much oil - just had the car serviced and when I checked it today at cold it seemed to be over the max mark.
2. Decat pipe on a 111S - now the weather is cooler, could this possibly have an impact? Incidentally I have had no issues with the decat and the MIL has not come on before with it in place (4 months).
3. Lightweight flywheel - again, been there a while with no issues. Although I have occasionally had the engine 'searching' when sat in traffic on a cold morning, which I had thought was due to the lightweight flywheel.
Any ideas anyone?? I really don't want to break down in this weather!!
Cheers.
RHY 11S said:
2. Decat pipe on a 111S - now the weather is cooler, could this possibly have an impact? Incidentally I have had no issues with the decat and the MIL has not come on before with it in place (4 months).
I'm not sure this will have an effect suddenly after running with it for four months. My 111s S2 has a decat and doesn't suffer at all, whatever the weather.With regards to the throttle position sensor - if you can get your hands on a Lotus code-reader device, they have the capability to monitor whether your throttle position is accurate if you are unsure.
Don't no much about engines but here`s just a thought before your drive yesterday did you go to a petrol station and fill up because could it be dodgy fuel you put in your car, because do you remember what happened to a lot of people a few years back with the dodgy fuel they were selling at the petrol station`s just some of what you have said sounded the same to what happened to them
Edited by Lotus Lewis on Monday 5th November 18:01
Have a look at this and try first resetting the TPS and then cleaning the IACV if that doesn't work.
http://wiki.seloc.org/a/Throttle_Position_Sensor
http://wiki.seloc.org/a/IACV - if unsure, search on the SELOC tech forum and I'm sure you'll find more info.
http://wiki.seloc.org/a/Throttle_Position_Sensor
http://wiki.seloc.org/a/IACV - if unsure, search on the SELOC tech forum and I'm sure you'll find more info.
Thanks S Works, that was very interesting.
Am I right in thinking that if it is either a sticking throttle body or a faulty throttle sensor then replacing the throttle body (with say the 52mm one that is on special offer at Eliseparts!) should fix the problem as it comes with a new sensor??
As for dodgy petrol, I hadn't recently filled up and was actually near the end of the tank. So I don't think that was the cause but thanks for the suggestion!
Am I right in thinking that if it is either a sticking throttle body or a faulty throttle sensor then replacing the throttle body (with say the 52mm one that is on special offer at Eliseparts!) should fix the problem as it comes with a new sensor??
As for dodgy petrol, I hadn't recently filled up and was actually near the end of the tank. So I don't think that was the cause but thanks for the suggestion!
Hi!
I had this exact problem on the exact same car.
There's two things at play here. The first is that you have a decat pipe. Very very occasionally the emissions fall out of the range that the lambda sensor looks for (because you no longer have a CAT) and so the MIL light comes on. This should stay on for about 5 starts of the ignition (it does say in the manual - double check). When the MIL light is on the car is a pig on a light throttle as it's overfueling it slightly. On full throttle it's 100% fine, but in traffic it makes it look like you have kangaroo petrol. When the light goes out the problem fixes itself. However, when my car did that it never "hunted" when idling.
Which brings me on to point number 2. My car did have a problem where, when idling, it hunted. Not by much but it definitely did it. Turned out to be a broken/fraying wire somewhere in the engine bay which Lotus Lipscomb traced and sorted for me. Unfortunately I don't know more than that as it was done under warranty but I do know it wasn't mega expensive and that I had the exact same problem.
Hope that helps!
Tony
I had this exact problem on the exact same car.
There's two things at play here. The first is that you have a decat pipe. Very very occasionally the emissions fall out of the range that the lambda sensor looks for (because you no longer have a CAT) and so the MIL light comes on. This should stay on for about 5 starts of the ignition (it does say in the manual - double check). When the MIL light is on the car is a pig on a light throttle as it's overfueling it slightly. On full throttle it's 100% fine, but in traffic it makes it look like you have kangaroo petrol. When the light goes out the problem fixes itself. However, when my car did that it never "hunted" when idling.
Which brings me on to point number 2. My car did have a problem where, when idling, it hunted. Not by much but it definitely did it. Turned out to be a broken/fraying wire somewhere in the engine bay which Lotus Lipscomb traced and sorted for me. Unfortunately I don't know more than that as it was done under warranty but I do know it wasn't mega expensive and that I had the exact same problem.
Hope that helps!
Tony
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