HIGH PITCHED SCREECH AT 0.5 BAR BOOST

[JIMBO]

Hi Bobc,
I havn't had the car out for some months now, but I know how to get rid of the screech. Sell the Lotus and buy a Porche. Shame I can't do the same with the mother-in-law !!
Regards
Jim

[Bobc]

Hi Jim, great plan, if only things were that simple!!

[philip_sloper]

Did anyone resolve this problem? I have just had a Peco exhaust fitted and I too have the screach.

[Monty]

I`ve not had the screech problem but when my headgasket went there was i small drip of water coming from the weld on the flexi joint and wonder if you guys have a hole in the weld and maybe thats whats causing the screech

[JIMBO]

Hi Phil,
nope ! still got the screach. the mother-in-law and the car.
The exhaust noise is ok for bumbling about, but becomes very
wearing on a longer journey, especially the popping and banging
on overun. I must be getting really old to complain about a
sport's exhaust.
Anyone want to buy a Lotus Elan ? mother-in-law comes free !!
Jim

[GeoffSmith]

Monty,

I had a good prod around the flexi because that seemed like the most likely place for it to come from. I couldn't see anything wrong but it might be worth another look. Did you see any soot around the hole?

Geoff

[Monty]

Monty,

I had a good prod around the flexi because that seemed like the most likely place for it to come from. I couldn't see anything wrong but it might be worth another look. Did you see any soot around the hole?

Geoff

Geoff, thats whats wierd there was no soot and when i checked in the past couldn`t feel any air leaking out, but if water can get through it then obvious that the air can.

The leak is were the weld starts and finishes, so the weld must not overlapped correctly. The weld i`m talking about is the 1st joint on the flexi just after the down section, but don`t forget there`s 3 welds ie the flange & 2 on the flexi, could be any of those causing the screech.

Solution
Blow the headgasket and let the ehaust fill with water to find leak

BTW don`t forget these are SS welds

[GeoffSmith]

[quote="MontyBlow the headgasket and let the ehaust fill with water to find leak [/quote]
Hope I'll give it a miss!

[philip_sloper]

Hi Phil,
nope ! still got the screach. the mother-in-law and the car.
The exhaust noise is ok for bumbling about, but becomes very
wearing on a longer journey, especially the popping and banging
on overun. I must be getting really old to complain about a
sport's exhaust.
Anyone want to buy a Lotus Elan ? mother-in-law comes free !!
Jim

JIMBO
Mine only has a very low key popping on the overun, even with the Peco fitted. It's normal for an Elan. My guess is that if you have particularly bad popping and banging it will be caused by the ignition timing.

[philip_sloper]

Monty,

I had a good prod around the flexi because that seemed like the most likely place for it to come from. I couldn't see anything wrong but it might be worth another look. Did you see any soot around the hole?

Geoff

Geoff, thats whats wierd there was no soot and when i checked in the past couldn't feel any air leaking out, but if water can get through it then obvious that the air can.

The leak is were the weld starts and finishes, so the weld must not overlapped correctly. The weld i'm talking about is the 1st joint on the flexi just after the down section, but don't forget there's 3 welds ie the flange & 2 on the flexi, could be any of those causing the screech.

Solution
Blow the headgasket and let the ehaust fill with water to find leak

BTW don't forget these are SS welds

I am doubtful that the sound I have got could be from the new flexible joint in the Peco, if that is the joint you mean. Surely it would sound similar to a small hole in any other part of an exhaust? My guess is that the gas causing it is a much higher pressure and/or velocity.

I need to do some more road tests, but as far as I can tell so far it only happens at around 6,000rpm (corrected: 5,000) and upwards.

I am open to all suggestions on how to cure it, except for keeping the revs below 5,000!

[algirdas]

Dear All:

Is anyone with a Peco installed on their car planning on doing any dyno bed (rolling road) tuning in the near future? Might be the best way to find out once and for all from where the screech is coming.

Just an idea.

Sincerely,

Algirdas

[bobface]

Just wanted to post that my S2 with it's new peco is screeching too, same deal as others, in low gears (1,2) at 6000 odd revs, doesn't seem to do it in higher gears.

Only thing i've noticed since adding the peco is worse fuel economy (and soot all over the end of the shiny pipe), and the mother in law. Mother in law doesn't seem to effect performance.

I'll see if i can find a local rolling road, and someone who knows what they're doing to take a look see.

[Enright]

Only thing i've noticed since adding the peco is worse fuel economy (and soot all over the end of the shiny pipe), and the mother in law. Mother in law doesn't seem to effect performance.

Are you sure that's not just because you like the noise more so your right foot has got a bit heavier?

[bobface]

I DO like the noise, especially in my underground carpark at work - the old pipe never had actual black soot over the back tho, seems to be running a little rich, is that to be expected?

[Enright]

I think it's unrelated. I'd recommend checking your timing hasn't gone astray. If it's OK then it might be worth changing your thermostat, and maybe even your CTS.

[ailwyn]

Might be a daft suggestion, but can't one of you guys with the screetching smear washing up liquid around the welds on the exhaust? It should start making pretty bubbles if it is leaking.

A.

[Monty]

Might be a daft suggestion, but can't one of you guys with the screetching smear washing up liquid around the welds on the exhaust? It should start making pretty bubbles if it is leaking.

A.

as thats my thinking, as i know mine has a hole in the weld even thou u can`t see it

The only thing is it might only leak at boosting

[ailwyn]

The only thing is it might only leak at boosting

I would have thought that revving the car would put enough through the exhaust to show up a leak.

[Monty]

The only thing is it might only leak at boosting

I would have thought that revving the car would put enough through the exhaust to show up a leak.

If u get Paul.P with u he could stick his large foot over the tailpipe to get more pressure LMAO

[philip_sloper]

I ran mine up on a dyno recently, without being able to pinpoint the source of the noise. We were able to simulate it perfectly, and could hear the screach quite clearly from inside the car but only incrediby faintly with head under an open bonnet. Very odd. Any ideas on that one?

One idea suggested is that the noise may be generated by the wastegate gas flow.

The wastegate actuator rod looks like it might have some adjustment, and maybe altering this would alter the wastegate characteristics a little? Slight variances in this from car to car might explain why some of us get the screach and others don't.

Has anyone tried adjusting this rod. You can see it down to the right of the turbo, and it is also illustrated on page 62, section EC of the Elan service manual version 2.

I might try adjusting it, I think I will need to remove the turbo heat shield to get at it. Are there any more bolts holding it on other than the one on the top and one lower down at the front?