Lotus Elan Central

by **Hinch** » Mon 20.03.2006, 17:00

Sufferred massive overboost yesterday whilst overtaking an Elise at speed on the M62. (was that you? Red with white stripe)

Quite scary because the engine cut out and I was in the outside lane with nowhere to go.

Read a few posts on here about this kind of thing and pleased to read that a dodgy earth lead may be the cause. Well Im off to search for it now with a pair of very crossed fingers.

by **Hinch** » Mon 20.03.2006, 18:24

Hmmm.. well I know from other posts that the earth lead terminates somewhere on the left hand side of the engine bay but I sure cant find it.
Could any of you guys kindly provide a more pinpoint description of its location or better still a picture or too.

Hinch

by **dans** » Mon 20.03.2006, 21:24

The boost transducer is on the left of this picture , orangey/red rubber end piece with red pipe going to it. (picture pinched from Monty!!!). In my experience the loose earth on this can give erratic readings on the boost gauge, but I don't think it cuts out the engine at all?!???

by **Monty** » Mon 20.03.2006, 22:18

Could off used a more recent pic LOL :roll:

Hinch,

Are u getting the over boost code? could be a sticky actuator arm on the wastegate also check pipes etc, the transducer just gives u a boost reading.

by **Hinch** » Tue 21.03.2006, 19:29

Thanks for that Dans and Monty. Did the ALDL test which was refreshingly straight forward. ERROR 31!! Which sure enough is overboost.

Checked that earth lead on the transducer which was slightly shakey, so decided to remove it and clean it before tightening the thing up.

This is where I have now run into a bit of a problem with what should be the simplest thing. Tried to remove the fastening screw, which turns well enough, but wont come all the way out and now wont fasten back in tightly either. Access to the rear is very limited, but I can feel a rubber gromit of some kind on the back of the screw.

Have any of you chaps had this thing off and can you advise on what Im dealing with here?

Nice photo by the way, would never have found the earth without it.

Hinch

by **TStevens** » Tue 21.03.2006, 20:12

They are held on by Rubber things I cant remember the name of (steve at SJ told me they are not scrivets but what was used instead of them at some point)

It's like a rubber bung with a nut in the end, as you tighten up the screw the nut pulls up and compreses the rubber. The ones holding in my transducer totally perished and the transducer was actually floating around on the inside of my wing :S.

You should be able to unscrew as far as possible then pull/push it back through the hole, not sure how much access there is but you could always cut any rubber away thats preventing it coming through. I beleive they're size M4. Have a bag around here somewhere for when I put my door back together.. :oops:

by **Ashaman** » Tue 21.03.2006, 21:03

Rawl Nuts.

But as Dans said, this is not the cause of your problem.

Might be the cause of a flaky gauge, but your problem is something else (usually a wastegate problem).

by **Doug** » Wed 22.03.2006, 00:27

agree with all above

not truly sure how the ground wire is "grounded" there as it is an M4 Rawl-Nut with rubber around it? Perhaps there is a wire to the rear of it too closing the ground circuit? Been in the wheel well that deep but didn't think to notice . . .

by **Hinch** » Wed 22.03.2006, 21:02

Having read other posts below, I notice mention of a whistling sound which accompanies boost problems. I have definatley heard this sound of late so I guess the wastegate is the first place to look.

Have to find the wastegate first of course. (Oh what a journey of discovery)

Is the wastgate something which can be easily repaired or replaced and what is the likely cost? Does anyone know how best to approach this?

Have to say, that whilst I have done lots of DIY stuff on cars in the past, I am very much an amatuer and dont have a great deal of confidence when it comes to the Elan. Changing the ignition leads was challanging enough.

Hinch

by **Enright** » Thu 23.03.2006, 00:55

Hinch, have you put one of Alan's chips in the car or changed the exhaust?

I did both and then started to get overboost problems.

But as the rest say, the first place to start is with the sticky wastegate. It's not necessary to repair or replace it, just free it up a bit. Cost - one pair of molegrips (or free if you have them already)!

To find it, in Monty's pic at the top of the page you would look vertically down through the gap between the gold sticker and the turbo heat shield.

You will see a rod which goes from a diaphragm unit on your right, and disappears off underneath the turbo to your left.

Basically all you need to do is to spray oil at both ends of this rod, and then get the molegrips on it and give it a wiggle from left to right a few times.

I'll try to find a pic.

Edit: aha, got one! Dico was kind enough to remove his entire engine in anticipation of your problem, and has taken photos here!
You can plainly see the silver-steel actuator rod going from the diaphragm and off behind the heatshield.

by **Guest** » Thu 23.03.2006, 11:20

What a very brave man that Dico is, and how obliging of him taking the engine out just so I can see the wastegate thing. I am impressed, VERY impressed!!

This website never ceases to amaze.. you guys are brilliant!!

Off to buy my mole gripps!

Cheers Mr E13

Hinch

by **davidjt** » Thu 23.03.2006, 11:51

Mostly treading gently at the moment, until the re-map, but if I do accelerate hard the engine light comes on when I lift off.
I'll read the code at some point, but curious as to why the management system doesn't like deceleration?

by **pjohn151** » Thu 23.03.2006, 11:59

Its all in the ECU codes... :smt024

Phil

by **pjohn151** » Thu 23.03.2006, 16:01

Whilst on the subject of overboost...

I have just changed my standard paper element air filter for a K&N replacement. My car now feels more 'lively' and seems to come onto boost quicker BUT strangely I am getting less overboost, infact I am only suffering gradual boost creep in 4th and 5th, with all the other gears seeming to hold boost to around ~0.7bar. Only modification other than the filter is the SJ s/s exhaust (with less of a squish than standard).

Phil

by **Hinch** » Thu 23.03.2006, 23:24

Finally making some progress on this thanks to all your help. That earth securing screw was an absolute pig. Couldnt get much access to the back of it at all but managed to get it loose and then finally cut it off. Not sure what was on the back, certainly not a conventional nut or anything else you could get a spanner on. (Assuming you could get on in there). Getting the nut on the new bolt was one hell of a task too. Stuck a bit of double sided tape to a spatula and then stuck the nut to that and then pushed it through the very narrow gap and onto the end of the bolt.

I think these cars are a nightmare to work on and I have every respect for you guys who seem to know them inside out.

Lubricated the wastegate bits, again very hampered by lack of access. Could only really get to one end.

Some significant progress anyway. Overboost is far less regular though still occuring. Still getting a whistling sound from time to time and often I get a boost reading of 0.5 or so without any sensation of boost.

Need to get the car on ramps I think so I can lubricate the wastegate a bit more effectively. Seem to be on the right track anyway.

Thanks again

Hinch

by **Enright** » Fri 24.03.2006, 01:06

Hinch, I agree with everything you say: access IS an absolute pig, and top marks to you for having the spuds to get stuck in and DIY! Sounds like you're making significant progress.

I don't consider the whistling turbo to be a particular issue - it's probably just more apparent now that you're listening for it. Even my Peugeot 306 D-Turbo whistles when it comes on song. I would be more worried if you COULDN'T hear anything!

PJohn, when I put a K&N in, the main thing I noticed was that the fluttering noise caused by the turbo blades stalling during gear changes was much more apparent. This is what a recirculating dump-valve would eliminate (I don't want one of the "atchoo" type - they're a bit too "Trevvy")!

I think that it's right that you would get less overboost, because the airflow through the wastegate is more free-flowing. I'm just surprised that you're getting any overboost in the first place. Perhaps the squish was engineered in there to prevent boost creep, rather than Lotus going for the more expensive option of porting the wastegate on every single turbo.

by **Sy V** » Fri 24.03.2006, 05:20

Enright13 wrote:...the main thing I noticed was that the fluttering noise caused by the turbo blades stalling during gear changes was much more apparent...

That's wastegate flutter Neil.

by **pjohn151** » Fri 24.03.2006, 09:07

Perhaps the squish was engineered in there to prevent boost creep

(and in combination with the restriction of the stock silencer)

I personally think that the K&N flows that much better than the paper element (especially in the recent cold and damp conditions - must be harder to suck through a damp paper element

) that there is now less of a pressure drop between the turbo intake and BSV outlet, and hence the BSV can do its job more efficiently - or at least that is my theory

Phil

Sy - 04.20AM :shock:

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