Overboost

[lotusflasherman]

I am in the process of fitting timing belt etc and would eventually like to fit a bigger bore exhaust to naturally increase bhp. Would I do any damage if I was to remove and ream out the waste gate now but not fit an exhaust until some time later?

Thanks

No. All you will be doing is removing the 'Achilles Heel' before it becomes a nuisance. As long as the flap valve still covers the enlarged wastegate port and you don't leave any swarf or abrasive material in the turbo it should be fine. Wastegate can't really be too big as the valve controls flow through it, but it can certainly be too small. There's a guide on Wikilec that HJ2 provided a link to on the first reply to the original post, so I won't repeat it here...

[lotusles]

I am in the process of fitting timing belt etc and would eventually like to fit a bigger bore exhaust to naturally increase bhp. Would I do any damage if I was to remove and ream out the waste gate now but not fit an exhaust until some time later?

Thanks

No. All you will be doing is removing the 'Achilles Heel' before it becomes a nuisance. As long as the flap valve still covers the enlarged wastegate port and you don't leave any swarf or abrasive material in the turbo it should be fine. Wastegate can't really be too big as the valve controls flow through it, but it can certainly be too small. There's a guide on Wikilec that HJ2 provided a link to on the first reply to the original post, so I won't repeat it here...

Thank you, it was the original ,link that got me thinking

[Elanlover]

I am in the process of fitting timing belt etc and would eventually like to fit a bigger bore exhaust to naturally increase bhp. Would I do any damage if I was to remove and ream out the waste gate now but not fit an exhaust until some time later?

Thanks

I've yet to hear of any negative impact from porting the wastegate even if the standard bore exhaust is used. I believe you'll be just fine.

[rip]

I am in the process of fitting timing belt etc and would eventually like to fit a bigger bore exhaust to naturally increase bhp. Would I do any damage if I was to remove and ream out the waste gate now but not fit an exhaust until some time later?

Thanks

No. All you will be doing is removing the 'Achilles Heel' before it becomes a nuisance. As long as the flap valve still covers the enlarged wastegate port and you don't leave any swarf or abrasive material in the turbo it should be fine. Wastegate can't really be too big as the valve controls flow through it, but it can certainly be too small. There's a guide on Wikilec that HJ2 provided a link to on the first reply to the original post, so I won't repeat it here...

I am sure the wastegate would have been designed to open & close fully in normal operation. A larger wastegate should not need to open fully with a std exhaust but this should not be a problem.

[Wallzaveerz]

I've now experienced overboost. Had the car out for its first proper run last Sunday. Out at 8am in cold damp foggy weather. Any enthusiastic use of the throttle resulted in a lowered rev limit and the EML flashing. Going back home at noon when it had warmed and dried up considerably it was perfectly fine.

[TrevorB]

I'm thinking I need to get my wastegate ported?!
I took Merlot out today and once it got really warmed up and I was on my way home, on a few occasions, when accelerating through the gears, at approx 4000rpm in 2nd and 3rd gear the engine juddered and didn't want to go any harder. Presumably this is an indication of over boost? I had no indication from engine management of any problems. Otherwise everything was fine and she run perfectly. Did not have this problem early in the run when I was also pushing through the gears.
Confirmation of my thoughts or any other diagnosis much appreciated.

Trevor

[HJ2]

Hi Trevor,

Did you do the paperclip test?
Any overboost will be stored

If no CEL and no errors stored I doubt if it was overboost you experienced.
You also can recognise overboost at better then normal performance just before the fuel cutoff takes you out of the dream

What were the last changes / service on the car before the overboost appeared?

I think sparkplugs with the wrong gap or sticky wastegate, so wiggle it!

[alan e]

Hi Trevor It's worth checking the timing it can move on our cars, i don't think Merlot got a chip fitted so when it cuts out what is the boost gauge reading.

[GeoffSmith]

If your nose isn't broken then it's probably not overboost.

[esprit888]

If your nose isn't broken then it's probably not overboost.

[HJ2]

... or a broken nose gets you into dreaming...

[TrevorB]

Hi Trevor,

Did you do the paperclip test?
Any overboost will be stored

Hi Henk, I will do a test next opportunity I get.

If no CEL and no errors stored I doubt if it was overboost you experienced.
You also can recognise overboost at better then normal performance just before the fuel cutoff takes you out of the dream

What were the last changes / service on the car before the overboost appeared?

Plugs were changed at last service in May.

I think sparkplugs with the wrong gap or sticky wastegate, so wiggle it!

I will try the wastegate wiggle.

Hi Trevor It's worth checking the timing it can move on our cars, i don't think Merlot got a chip fitted so when it cuts out what is the boost gauge reading.

Alan, didn't look at boost gauge as I was concentrating on whethere CEL was coming on. Not sure when the next opportunity will be to take her out again to check.

If your nose isn't broken then it's probably not overboost.

Geoff, nose is still intact

[HJ2]

And you checked the plug gap?

[Rocklobster]

It may be overboost that you're experiencing, but that doesn't mean the wastegate needs porting. If the wastegate was the right size last year, then unless you've put a big exhaust on, it's still the right size.

More likely that the wastegate linkage has seized or become stiff (hence the wastegate wiggle) or you may have a pressure leak and the wastegate actuator isn't actuating. There is a post on here somewhere about testing the wastegate actuator with a pump. If you find that the wiggle frees things up, wipe a generous amount of ceramic grease around the linkage. Not any other type of grease.

[TrevorB]

Some up to date information on my wastegate situation. First of all let me thank AlanE who I've spoken to for some advice and my next door neighbour, Scott, who has
helped with the mechanics.

First of all, I have not done a paperclip test or checked the sparkplug gaps. The reason being is explained shortly on how the problem has been resolved.

Following on from some advice that AlanE told me I went through a few checks, now remember I'm not an engineer, so getting under the bonnet and doing stuff is
completely alien. One thing I did check though was the hose between the wastegate actuator and solenoid. Once I removed the clips I did notice a split in the hose
below one of the clips. So the first thing I did was to order a new hose, but, Part No. A100E6468S is no longer available. I spoke to Steve at SJ Sportscars and he
advised that the Esprit Part No. A910E9280S, which is the same item for the Esprit would be suitable. It is slightly longer but obviously once cut down is perfect.
The next thing to attempt was the 'Wastegate Wiggle'. Now all of you know how fiddly, difficult this can be. I was unsuccessful in removing the heatshield, although
managed to remove the nut at the top but just couldn't get to the others. This is where I called on my next door neighbour who is an engineer and has been an
RAC patrolman in he past.
I printed off the guide to 'Wastegate Wiggle' and with his expertise he removed the 3 bolts holding wastegate actuator which enabled us to complete the wiggle.
I do believe that it was stuck previously because we were unable to move it prior to the removal of the wastegate actuator.
Anyway there was only one way to prove that the previous problem had been fixed and that was to take Merlot out for a
The problem that I experienced at 4000rpm was no longer apparent so I'm hoping the problem has been fixed but cannot be absolutely certain as I didn't go out
for a particularly long run but long enough to get the engine hot and give it a good blast to check out the problem. Hopefully before the winter really sets in
I'll be able to take it out for longer run, weather permitting.

Thanks everyone for your advice and help. It's great to have all this expertise to hand even for someone with my lack of knowledge.

Take care in this latest lockdown and stay safe.

Trevor

[rip]

Hi Trevor It's worth checking the timing it can move on our cars, i don't think Merlot got a chip fitted so when it cuts out what is the boost gauge reading.

I agree. I used to get overboost cut-out at 4000rpm but I wasn't getting much performance from the boost.
After a suggestion from Geoff, I experimented with the base timing. My timing wheel is a bit grotty so the mark is not very easy to see. Maybe there was a mark at the wrong place which looked like the timing mark?
The difference was amazing; Instead of a gentle difference as the boost increased, I got a smile-inducing push in the back.

Whenever I have got overboost in my own Elan, I've never been thrown violently forward. The car seems to hesitate very slightly before it actually restricts anything, allowing me to back off the accelerator.

[Richard205]

I've fitted a new stainless steel exhaust from PNM. IT sounds great but it has created boost creep. As much as I'm trying to drive within it, I find that the addictive nature of acceleration is finding me running into the fuel cut off. I need to port the wastegate as recommended. What I need is a step by step guide of how to remove the turbo to access the wastegate.
Does anyone know of one or point me in the right direction. It's going to be a stretch of my mechanical skills so unless someone near Gloucester would like to come and sort it for me, I need some clear instructions.
Cheers,
Rich

[TrevorB]

It was interesting to see that I first mentioned the problem 'Merlot' was having with overboost back in September 2020. The issue appeared to be resolved when the
'wastegate wiggle' fixed the problem. However it was still happening but it was so intermittent it wasn't bothering me too much as I never pushed the car as hard
as necessary. However when I did the London to Brighton Modern Classic Car run earlier this year, after the car had had it's annual service, it was happening too
often. Maidstone Sports Cars had it back but couldn't replicate the problem. So the intermittent problem reoccurred. A couple of weeks ago on my weekly run out
the problem was happening every time, in all gears once I reached 4000rpm.
A little history on 'Merlot'. I had a Piper 2.5" exhaust fitted soon after purchase, did not get wastegate ported, not chipped and has not had an O2 sensor fitted.
Reading through some of the posts relating to ALL those subjects the SE does not necessarily need any additional tweeks to resolve the issue plus the car has
been running perfectly over the years prior to starting these problems in 2020.
So back to the present. I again contacted Maidstone Sports Cars and they were very good and took the car in straight away. Within 24 hours they contacted me and
they had fixed the problem. An easy problem apparently. Not wastegate related, nor turbo related but the Turbo Boost Solenoid Valve Part No. A100E6080F.
When I looked on the DeRoure website to view the drawing as to where this part sits in the engine bay, interestingly it didn't bring up and states 'Not Illustrated'
although the part number is recognised and you can bring it up on SJS website. However I can see it in the engine bay tucked behind the air filter, photo attached.

The car is now running perfectly and when I push it to over 4000rpm no problems with .5 on the boost gauge which I understand is fine with a car that is not chipped.
It goes quick enough for me!!

2022-07-21 14.51.13 (480x640).jpg

2022-07-18 08.28.46 (480x640).jpg

Safe driving folks and anyone else having similar issues hope this helps with the problem.



Take Care

Trevor

[dapinky]

Trevor,

Having seen the simple repair for this problem, I bought myself one when I saw that you'd solved the problem with this part...... and Bell & Colville charged me £39.31 (inc VAT)....... far better than the £60 from SJs (and even a couple of quid cheaper than SWL who list it at £35+VAT+p&p).

It's one of those parts that I may or may not ever use/need - but decided that for £40 it was worth having one in the garage!!!!! (at Lotus list price of £131+ I probably wouldn't have bothered - but who knows if I may ever need it......)

[TrevorB]

Trevor,

Having seen the simple repair for this problem, I bought myself one when I saw that you'd solved the problem with this part...... and Bell & Colville charged me £39.31 (inc VAT)....... far better than the £60 from SJs (and even a couple of quid cheaper than SWL who list it at £35+VAT+p&p).

It's one of those parts that I may or may not ever use/need - but decided that for £40 it was worth having one in the garage!!!!! (at Lotus list price of £131+ I probably wouldn't have bothered - but who knows if I may ever need it......)

Dave,

I wonder if this will set a trend?


Anybody want to start a group buy?

Trevor