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Lotus in the Peak
28th - 30th June 2024

Long Term Idle Problem Help


Jamie Triner

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Hi there guys

 

I own a lotus elise 111s k series 2003

 

Just posting about a long term problem I've had with the car. Wanted to see if anyone could shed some light before I go and take the engine apart.

 

Idle problem when engine is running. Only a problem when I'm sitting there but drives completely fine.

 

Replaced air vac valve

Replaced exhaust lamba sensor

New plugs

New ignition leads

 

Been to a few garages and they have ran the emission tests on the car and found them spot on. And the cars been on another computer and the only fault thru could find was a weak ignition lead hence why these have been replaced. There are also no fault codes coming up on the car which leaves me confused.

 

I then took it to a motorsport mechanic, he had a look at the car and he took off a sensor on the intake manifold (right hand side) off and he said he had up clean some oil off it? Apprantly he said there shouldn't be oil on there and he said a rubber or something may of gone on the engine side and allowing oil through the pipe and the oil maybe causing the sensor to give wrong readings and effecting the map sensor. He then cleaned it up and it ran better but not perfect. After 30-40 miles the car cleared up and ran perfectly for a month and on Saturday it's gone back to bad idle, which makes it a pain In the ass at junctions because it wants to die.

 

Since having the problems it's been intermittent. I gave the car a blast to Matlock, soon as I got back the problem occurred, it was ok for around a month and then out of nowhere back to poor idle. Was like this for a week or so, took the car out for a blast and it fixed itself again. Great for a month and then went back to bad idle.

 

My mechanic says he would look at changing the top lamba sensor on manifold before anything but the emissions seem ok? He also said if this cannot fix the problem were looking at leaking air intake manifold and replacing the oil seal on the head or something like that. He asked if the can belt was replaced and it had recently but like he said if it wasn't set up correct it wouldn't be a intermittent problem and it would of come up on when he plugged it in.

 

Didn't know if you guys could share some light?

 

Cheers

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A simple way to test if the pre cat lambda is faulty is to disconnect it (black plug on the vvc belt side of the head). If it runs better without than that's the problem, if not its something else. Disconnecting will cause an engine management light but this should reset after a few restarts if you don't have an obd2 reader.

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Car is fine at 3k. Really strange though. I've had it plugged into different computers or readers at both garages and can't work it out. Runs completely fine though it's just when low revs or sitting at lights. Something weird happened today on the way to work, driving like crap, so got on a straight bit of road, I booted it in 3rd gear and took it to 7.2k or something but no limiter came on and the car let reverted high till it was a high pitched sound. Soon as I did that the car went back to normal and is driving perfect. Pain is I've just order gaskets to replace on the inlet manifold. But could this possibly be a switch or sensor I've overlooked? I've herd that some switches being up engine management light when faulty though?

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Hi mate,

 

your idle issues and low rev issues sounds very similar to my problems. You have my thread here a few posts down and in it also a link to my SELOC thread.

Does your car have any engine mods?

 

I still have not managed to solve my issues.

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I am still suspicious of the post cat lambda sensor. Giving it a boot will presumably put some heat onto the sensor which could be getting it to operate OK for a bit. l'll have to try that one.

I've read a few posts that suggest a dodgy lambda sensor when it appeared OK, but replacing with a good one solved the problem.

Also, a lot of changing other bits that made no difference but not replacing the lambda....

Problem is it's £80 or so for the Bosch one.

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Hi,

 

to be honest I don't think taking the engine apart will solve your issue. Seems like it is electrical/ECU/sensor related just as on my car. Remember my engine was in molecules and put together again and idle issues from before remained...

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I am still suspicious of the post cat lambda sensor. Giving it a boot will presumably put some heat onto the sensor which could be getting it to operate OK for a bit. l'll have to try that one.

I've read a few posts that suggest a dodgy lambda sensor when it appeared OK, but replacing with a good one solved the problem.

Also, a lot of changing other bits that made no difference but not replacing the lambda....

Problem is it's £80 or so for the Bosch one.

I paid around £45 from my local motorfactors.
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I am still suspicious of the post cat lambda sensor. Giving it a boot will presumably put some heat onto the sensor which could be getting it to operate OK for a bit. l'll have to try that one.

I've read a few posts that suggest a dodgy lambda sensor when it appeared OK, but replacing with a good one solved the problem.

Also, a lot of changing other bits that made no difference but not replacing the lambda....

Problem is it's £80 or so for the Bosch one.

The post cat sensor does nothing other then tell the ecu if the cat is working.

You can get genuine Bosch sensors from a guy on eBay for £33 delivered.

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Was that for the genuine Bosch part or one of the "universal" type?

I don't know if there is much of a difference, but I've seen the universal ones at about the £40 mark.

They all work the same genuine or not makes no different,

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The post cat sensor does nothing other then tell the ecu if the cat is working.

You can get genuine Bosch sensors from a guy on eBay for £33 delivered.

Thanks for the tip, got one delivered today. Hope to get it fitted within the next week or two.

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