Running rich

[Evoman]

Hi folks

I'have acquired an S1 Exige - what a wee machine it is too, my word, an absolute experience from the minute you see it, and then starting her up,, wow! But that's where it is perhaps a little more eye watering than it should be. It does smell a bit rich and that was confirmed at the MOT yesterday.

Are there any suggestions on starting points to check first?

I was thinking sensors may be an area to check (can they be checked) or just change them - coolant temp sensor perhaps? Lambda sensor?

It seems to run well just smelly and definitely looks a little sooted on the exhaust tips.

Hoping to get the car running nicely for a trip to Knockhill on 26 this month.

Cheers

[Shug]

The quick and easy stuff to check is the temp sensors - if the ECU thinks the engine is cold it'll overfuel and they are cheap to change. There's a brown and a blue on the coolant elbow exiting the block - can't remember which one talks to the ECU and which one to the dash, hopefully someone with a better memory will

The VHPD does tend to be mapped rich, mind you. Do you know what map it has - the original factory one, or the 190 upgrade? Or is it (as a lot are) running an Emerald ECU? Has it got a cat in it?

At the end of the day, it's essentially a race engine, so tends to be a bit twitchy, so there's a few things it could be. If it actually, genuinely, passed the MOT, then it's probably running to spec - but it can be better with a little spend on an ECU change and proper map, if it's still on the factory ECU.

[Dominic]

Wot he said.

I probably have a spare temp sensor and IACV in my garage if you want to borrow them. I had issues with running rich quite a few years ago, turned out to be a leaky inlet gasket - having changed temp sensors IACV etc. Quick and easy way to check that is to spray carb & air filter cleaner at the gasket while the engine is idling and see if the idle changes at all.

[Evoman]

Cheers Shug, I'll seek out some replacement sensors - Elise Parts I guess is the best place?

It is running completely standard (190 factory upgrade) and original exhaust with cat I believe.

Emissions for HC, CO and lambda were all high. The garage suggested putting in Forte engine clean stuff - I'm not so keen and would rather establish why it is running rich first.

[Evoman]

Wot he said.

I probably have a spare temp sensor and IACV in my garage if you want to borrow them. I had issues with running rich quite a few years ago, turned out to be a leaky inlet gasket - having changed temp sensors IACV etc. Quick and easy way to check that is to spray carb & air filter cleaner at the gasket while the engine is idling and see if the idle changes at all.

Cheers Dominic for the offer. IACV? Excuse my ignorance what is that?

The idle is just evil, it sounds really good and stinks, but I assume they do idle with a good spluttering unevenness because of the cams which are no doubt quite a wild profile?

[Shug]

The 190 upgrade did run rich - the 177 standard tune was what got it through type approval, IIRC.

The "upgrade" involved a cam sprocket that was slightly offset (getting the timing a bit more in the ballpark) and a one size fits all map for a handbuilt engine, which was supposedly just a case of pumping more fuel in everywhere to be "safe". You can get them to idle much better than it will be. Not great work by Lotus TBH.

To get it to run really properly, you'd be a wise person to invest in some proper setup - adjustable cam sprockets so you can time the cams properly, plus an ECU that can be mapped specifically to that engine.

Not saying it's not worth trying a sensor swap out or the like, but it may be a case of They All Do That Sir with the Lotus 190 map...

*edit* - To be fair, the map would have been done at a price to ensure that it wouldn't break any of the engines and would provide near enough the figure they quoted at wide open throttle - not many at Lotus would have thought people would use an Exige as a road car, so low rev fuelling probably not a priority.

[Dominic]

Wot he said.

I probably have a spare temp sensor and IACV in my garage if you want to borrow them. I had issues with running rich quite a few years ago, turned out to be a leaky inlet gasket - having changed temp sensors IACV etc. Quick and easy way to check that is to spray carb & air filter cleaner at the gasket while the engine is idling and see if the idle changes at all.

Cheers Dominic for the offer. IACV? Excuse my ignorance what is that?

The idle is just evil, it sounds really good and stinks, but I assume they do idle with a good spluttering unevenness because of the cams which are no doubt quite a wild profile?

IACV = Idle Air Control Valve ... just before the inlet manifold.

[Evoman]

Aha, IACV noted, I'm on a learning curve here. I guess it is a little 'old school' to go for the run it at the rich end of the spectrum though I have heard of bore wash in engines occurring from over fuelling. I guess that is more from rich running throughout the rev range other than just idle?

I would like to figure out it is running as 'standard' for the 190 version upgrade or do I need to look at getting it running cleaner. Maybe I should have bought a Prius, haha!

[Dominic]

The learning curve never ends! ...and I am still near the bottom of it

As far as I know, Ferg will have his S1 exige at KH on the 26th, so may be a good opportunity to compare. In fact, he will be at KH this Sunday for the autosolo (see motorsport forum).

[Shug]

Yeah - park up next to Ferg and sit idling - see how many people keel over

[robin]

They shouldn't over fuel that much if the O2 sensor is working correctly. My money would be on the O2 sensor being borked; it's easy enough to test with a multimeter once the engine is hot, assuming you can find the loom connector.

Bore wash might well be a concern if massively over fuelling. The other issue is whether it's over fuelled or misfiring. Both spew unburnt fuel out the exhaust ...

Cheers,
Robin

[Sanjøy]

This is running rich.

[Evoman]

Cheers Robin, that's another helpful pointer. Is there an Elise / Exige parts catalogue or manual available from anywhere? Something that shows with a diagram where each part is located? I've seen something like that for exterior trim.

I haven't noticed any flamage out the back yet but then I've been mainly focused on whats ahead of me.

Misfiring - can't say I've noticed that either, on the MOT test at 2500rpm it just sounded sweet but angry and snarling, no missing at all that I could detect.

[Ferg]

Hello,

I had significant issues passing the MOT last year that we believe was due to a failing but not completely broken O2 sensor. So if your car passed an MOT it can't be that bad

Mine was so bad when cold that it would make you gag and eyes water. Much better now but it's still a bit rich. I plan to get it mapped properly. Money going into house right now though, commitments eh...

To fix mine actually fitted a Wideband Lambda to aid future tuning as it wasn't too much more expensive. The car has an emerald so I was also able to trim the idle fuel down a little to help at MOT time. It worked thankfully.

Regarding IACV. I believe the VHPD one isn't common to other variants but don't quote me on that. It is known to stick though and it's in a rather unfortunate position.

As Dom says, I'm at KH this Sunday or next Saturday. Happy to talk over the cars. I've only had mine a year but been through s bit with it. It's quite different to the Elise I had before

[robin]

Cheers Robin, that's another helpful pointer. Is there an Elise / Exige parts catalogue or manual available from anywhere? Something that shows with a diagram where each part is located? I've seen something like that for exterior trim.

I haven't noticed any flamage out the back yet but then I've been mainly focused on whats ahead of me.

Misfiring - can't say I've noticed that either, on the MOT test at 2500rpm it just sounded sweet but angry and snarling, no missing at all that I could detect.

Great - a dodgy sensor better than a misfire

This is the parts manual page for the Exige S1 sensors:

http://www.deroure.com/images/diagrams/16/17_06.gif

It may be possible that there is a copy of the the Exige wiring diagram out there too ...

Cheers,
Robin