HIGH PITCHED SCREECH AT 0.5 BAR BOOST

[Monty]

I still get the fluttering noise when lifting off. Mine is a lot higher frequency than that and increases in pitch and amplitude from ~5000rpm to 7000rpm.

Why did you remove the dump valve Monty? I thought they saved the turbo and gave better pickup changing gear.

It was Dave at Peco who noticed the dump valve passing whilst doing the rolling road. So when i got home i removed it

[JIMBO]

Well the good news is as follows, It's not the turbo,- it's not a high pressure air leak,-it's not the plenum chamber,- it's not the intercooler.

The bad news is, it can't be traced through normal means so it will need to go on a rolling road to trace it back under load. Gerald, an ex Lotus employee who used to build and service these Elans believes the problem to be "exhaust related" and in his words "it's not a nice noise" and he wouldn't want to put up with it .
I will speak to David jones at Peco and see if he can help in any way.
Regards
Jim

[GeoffSmith]

So it's Jimbo, Rathead and Me. Jay_Thomas doesn't, but he's getting higher than normal boost. We don't know the various states of upgrade the whistlers and non-whistlers have been subjected to - e.g. Kili/Everest chips, MBC, air induction etc. I might give mine a try with different ESM chips over the weekend to see if it is boost related. I think it would be useful to record some data for the Peco owners, so mine is as follows:

geoffsmith: Whistler at 5000-7000rpm under load. Bog standard apart from the exhaust. Boosts to ~0.5bar but will eventually boost creep to fuel cutoff.

[GeoffSmith]

So it's Jimbo, Rathead and Me. Jay_Thomas doesn't, but he's getting higher than normal boost. We don't know the various states of upgrade the whistlers and non-whistlers have been subjected to - e.g. Kili/Everest chips, MBC, air induction etc. I might give mine a try with different ESM chips over the weekend to see if it is boost related. I think it would be useful to record some data for the Peco owners, so mine is as follows:

geoffsmith: Whistler at 5000-7000rpm under load. Bog standard apart from the exhaust. Boosts to ~0.5bar but will eventually boost creep to fuel cutoff.

[GeoffSmith]

So it's Jimbo, Rathead and Me. Jay_Thomas doesn't, but he's getting higher than normal boost. We don't know the various states of upgrade the whistlers and non-whistlers have been subjected to - e.g. Kili/Everest chips, MBC, air induction etc. I might give mine a try with different ESM chips over the weekend to see if it is boost related. I think it would be useful to record some data for the Peco owners, so mine is as follows:

geoffsmith: Whistler at 5000-7000rpm under load. Bog standard apart from the exhaust. Boosts to ~0.5bar but will eventually boost creep to fuel cutoff.

[RatHead]

Mine is standard aside from the exhaust. I get the noise when boost hits about 0.75 - the other day I kept my foot to the floor in 3rd and the boost did not get any higher than the 0.75 - so no fuel cut off (not sure if I would reach fuel cut off in 4th or 5th doing the same thing).

[Dovey]

Well, I can't bring too much to the table as mine works perfectly

Bog standard except for the exhaust. Boosts to 0.5 then after 2 seconds creeps until fuel cut off. No strange noises or fuss. But I had my timing checked when I had it fitted. Of course I don't know if that made any difference, but I'm not scratching my head right now wondering WTF?

[algirdas]

Dear Geoff:

I realize that I am posting without any portfolio on this matter and please excuse me if they prove to be wrong or downright silly, but what about that braided stainless steel flexible bit? If there were a leak there, I can only imagine that it might sound like a whistle. One way to check it would be to take a length of muffler bandage (that is what we call it here) and wrap the potentially offending area. I would start slightly upstream of the flex area and end slightly downstream and then double back. Be sure to overlap the edges while wrapping the bandage.

My thinking is that the flexible section might be a bit too short. When you are giving the engine all of the chocolates it rotates and the flex part needs to compensate for the change in angles. If the flex part is too short, then the stresses placed upon it might be such that the braid separates allowing exhaust gases to slip past and whistle. Or the flex part may have been damaged during installation, been defective, etc.

Just an idea. Please forgive me if I am talking out my exhaust pipe. If that is the case, I assure it will not be a whistle that you hear. Much more bass. No need for a sub-woofer if you know what I mean.

Sincerely,

Algirdas

[GeoffSmith]

Algirdas,

All contibutions are greatfully received - it's one of the aspects that makes this forum truly outstanding. It's an interesting point worthy of consideration and I'm just trying to remember which way the engine rotates i.e does it compress or stretch the flexi?

Anyway, I must get back into the sun (it's pushing on 30° here) and sort out this ALDL interface.

Thanks for the suggestions.

Geoff

[algirdas]

Dear Geoff:

Off the top of my head, I can't answer that. Let me noodle it around some this weekend.

Sincerely,

Algirdas

[ESM]

It'll move the opposite way to the wheels - the equal and opposite reaction we hear about so much

[algirdas]

Dear Geoff:

Thanks to Alan for reminding me of the incredibly obvious. But then again, we lawyers are the ones who noticed that Godiva rode a horse.

On acceleration the engine should rock back and flex/stretch the flex joint.

Sincerely,

Algirdas

[JIMBO]

algirdas
you may be onto something here as the mechanic sugested trying a replacement flexi pipe as he felt that welding on the outside would leave an open lip on the inside. Air could be pressurised into this area and any "pin holes" would result in a whistle. The sound on mine is similar to a slipping fan belt / siezed bearings in the alternator.
To the best of mine knowledge my car is standard with no mods as yet.

Jim

[Humph]

Okay - on very limited use, here are my findings.

Peco exhaust and everst chip, no dump valve. I get the screech like the finger round the wine glass noise, but only when really nailing it in 2nd and 3rd i.e 5500rpm + so far (not been anywhere long enough to nail in 4th )
No issues of hitting the fuel cut off (yet).
Boost guage its the 1 mark no problem.

As an absolute numpty on the mechanical side, I shall offer no suggestion as to what it is at all.....

Humph

[Dovey]

Oh yeah, mines got no inner tail pipe. I believe Rambos and Montys are the same, who dont have any problems either. I may get corrected on that, but you see my point.

I may be hopelessly wrong but lets see, does it whistle and what tailpipe? Is there a pattern?

Mine is no whistle, no tailpipe.

[Monty]

Mine is no inner pipe on the silencer and i`m not getting the screeching noise but i`ve got the stiffy fitted.

could be a possiblility on the flexi, might be worth ringing Dave at Peco.

[JIMBO]

Mine is standard and un-circumsized, however the noise seems to come from the front of the car.
Jim

[GeoffSmith]

Mine is as nature intended - un-circumcised.

I had another go at frightening the bus queues today and I tend to agree with Jim - it seems to be coming from the front rather than below or behind.

There's been a suggestion elsewhere to check for evidence of exhaust leaks around the flexi. Well I'm sorry, I can't remember what my hat size is but it's closer to fat-head than pin-head and there's no way to fit it in the 5½" gap under my car!

Geoff

[algirdas]

Dear Geoff:

Has anyone tried muffler bandaging their flexi?

Sincerely,

Algirdas