Idling when hot...concerns.

[nick_j007]

Hi all.

When the car (111s) is hot at about 90-95 degrees, the revs bounce up and down and it's not right.

It will constantly go from about 900 RPM down to 600 RPM, and then recover to do the same again. feels as though it might stall, though this hasn't happened yet.

Due for an A service next week and has done 29k miles.

Your thought please

Nick

[Trixster]

Sounds like the temperature sender is on the blink. Mine did pretty much the same when the sender went up the spout. Cheap easy fix.

[Gooby]

Trixster said:

Sounds like the temperature sender is on the blink. Mine did pretty much the same when the sender went up the spout. Cheap easy fix.

Ding - same thing happened to Just1's first liz. Short job, not expensive...

[nick_j007]

I'm guessing it's one of these? http://www.eliseparts.com/shop/index.php?main_page...

Please tell me which one and can I really do this myself? I'm ok on most practical issues, but am by no means a mechanic

Thanks peeps.

Nick

[Gooby]

if I remember correctly there are 2 sensors. a lotus tech has to tell you which one is faulty

[Gad-Westy]

This is an S2 isn't it? Unless its a very early car, you need the black S2 ECU temp sender. Only thing I would warn you about is that my car showed similar symptoms but its just a dirty connection at the ECU end. Maybe worth checking as well.

[nick_j007]

Sorry, yes an S2.

This is where I'll end up stopping before I've started...where will I find what you're referring to that might be dirty?!

Nick

[Gad-Westy]

Ok, I'll describe for the S1, if any bits are different on an S2, maybe somebody else can say. The temp sender is located between the engine and the firewall (wall between cabin and engine bay). With the engine cover up, stand next to the passenger side rear wing and look at the lefthand side (exhaust side) of the engine. Next to the fat rubber cooling hoses you should see a black bit of plastic with wiring going to it. That's your temp sender. You can remove the wiring by squeezing the little metal clip around the connector and pulling the connector off. I'm clean up the metal contacts with WD40. You can remove the sender itself by simple turning it with a spanner. Stick the new one back in quickly to avoid losing too much water (I should say at this point, don't do this if the engine has been warmed in the last 2 hours or so). Reconnect wiring.

The other connection I referred to was the ECU plug. The ECU on the S1 is mounted behind the engine, passenger side on the back of the boot divide. Looks a little like this:


On the S1 there are 2 large wiring connectors, one red and one black, they both just pull off, again spray with Wd40 and reattach.

Good luck with it all.

Edited by Gad-Westy on Saturday 20th September 19:05

[Justin S]

you could have a dirty IACV valve that would give hunting at tickover too.Have a look here. Hopefully this is the S2 version
http://wiki.seloc.org/a/Idle_Air_Control_Valve

[nick_j007]

Ok great thank you both very much. Might have some time to do this tomorrow...looks 'doable' to me.

Nick

[nick_j007]

Ok thank you for that. Could not see my ECU on my S2, though I did the other things you suggest, and after a run the revs seem stable.

I also removed the idle valve conctrol unit and cleaned it out with carb. cleaner and if I'm not mistaken it seems to run better overall as a result.

The carb. cleaner can from Halfords suggested cleaning in and around the throttle body with it also which I did.

The car seems to idle at 900RPM when hot...sound right? Would it also figure that if I were coasting down a hill with the car in neutral the revs are picking up...I assume this is due to the increased air flow into the engine bay??

Temp. gauge was hitting 105 degrees before the fans cut in and then it would drop back to below 100 no problem. If this sounds good to you I can relax.

Thank you all once again.

Gad-Westy said:

Ok, I'll describe for the S1, if any bits are different on an S2, maybe somebody else can say. The temp sender is located between the engine and the firewall (wall between cabin and engine bay). With the engine cover up, stand next to the passenger side rear wing and look at the lefthand side (exhaust side) of the engine. Next to the fat rubber cooling hoses you should see a black bit of plastic with wiring going to it. That's your temp sender. You can remove the wiring by squeezing the little metal clip around the connector and pulling the connector off. I'm clean up the metal contacts with WD40. You can remove the sender itself by simple turning it with a spanner. Stick the new one back in quickly to avoid losing too much water (I should say at this point, don't do this if the engine has been warmed in the last 2 hours or so). Reconnect wiring.

The other connection I referred to was the ECU plug. The ECU on the S1 is mounted behind the engine, passenger side on the back of the boot divide. Looks a little like this:


On the S1 there are 2 large wiring connectors, one red and one black, they both just pull off, again spray with Wd40 and reattach.

Good luck with it all.

Edited by Gad-Westy on Saturday 20th September 19:05

[Gad-Westy]

nick_j007 said:

Ok thank you for that. Could not see my ECU on my S2, though I did the other things you suggest, and after a run the revs seem stable.

I also removed the idle valve conctrol unit and cleaned it out with carb. cleaner and if I'm not mistaken it seems to run better overall as a result.

The carb. cleaner can from Halfords suggested cleaning in and around the throttle body with it also which I did.

The car seems to idle at 900RPM when hot...sound right? Would it also figure that if I were coasting down a hill with the car in neutral the revs are picking up...I assume this is due to the increased air flow into the engine bay??

Temp. gauge was hitting 105 degrees before the fans cut in and then it would drop back to below 100 no problem. If this sounds good to you I can relax.

Thank you all once again.

Sounds promising mate. Somebody else can confirm but I think on the S2 the idle is raised when the car is moving (via use of a wheel speed sensor), not sure why but I have read similar before. I assume we're not talking huge increases?

Fan temps sound about right BTW.

[Chris49]

Check you don't have a plastic throttle body.

I think these were still used on early S2's and can warp when the engine heats up.

Had excalty the same problem on my S1 and was resolved with a new alloy one.

[nick_j007]

Gad-Westy said:

nick_j007 said:

Ok thank you for that. Could not see my ECU on my S2, though I did the other things you suggest, and after a run the revs seem stable.

I also removed the idle valve conctrol unit and cleaned it out with carb. cleaner and if I'm not mistaken it seems to run better overall as a result.

The carb. cleaner can from Halfords suggested cleaning in and around the throttle body with it also which I did.

The car seems to idle at 900RPM when hot...sound right? Would it also figure that if I were coasting down a hill with the car in neutral the revs are picking up...I assume this is due to the increased air flow into the engine bay??

Temp. gauge was hitting 105 degrees before the fans cut in and then it would drop back to below 100 no problem. If this sounds good to you I can relax.

Thank you all once again.

Sounds promising mate. Somebody else can confirm but I think on the S2 the idle is raised when the car is moving (via use of a wheel speed sensor), not sure why but I have read similar before. I assume we're not talking huge increases?

Fan temps sound about right BTW.

Only increasing up to 1300 RPM approx...nothing wild.

Good. All sounds good.

Thanks.

Nick

[nick_j007]

Hmmm, any images to this. I hardly know my ar*e from my elbow under the cover, so help is always useful.

I do like the way that I've been able to do work needed so far, so the learning curve is...well just that...a learning curve!

Nick

Chris49 said:

Check you don't have a plastic throttle body.

I think these were still used on early S2's and can warp when the engine heats up.

Had excalty the same problem on my S1 and was resolved with a new alloy one.

[nick_j007]

Justin S said:

you could have a dirty IACV valve that would give hunting at tickover too.Have a look here. Hopefully this is the S2 version
http://wiki.seloc.org/a/Idle_Air_Control_Valve

Well I got that part off and gave it a clean up as wiki notes and it seems a great deal better, though not perfect still. In for service tomorrow, willask them also.

Thank you all.

Nick