B125AHM

[simonf]

Swapped the induction trumpets back over last night and sealed the plenum. Took her for a test drive and it is much improved! But sadly still not perfect! The car is still not revving round to 7000rpm but drives much better, still not getting full boost, but at least i can tell when the turbo cuts in. The spluttering has just about been cured although i am getting a splutter just before the turbo cuts in!

I am now thinking that maybe the float levels are wrong and this is causing the car to starve of fuel at around 6ooorpm, would everyone concur with this diagnosis. I have tried the rev limiter and it is not that!

The turbo is spooling up more than before and you now get the feeling that it wants to fully boost but can't! When the car splutters as the turbo cuts in you get a lurch which feels like full boost is on the way but doesn't quite materialise. Would this be due to mixture now do you think?

Your advice is always appreciated

Simon

[910Esprit]

I dont fully concur, but I do a little bit..... I tend to agree its fuel starvation, but not caused by float height - which I think would have more impact on the entire rev range. You seem to be leaning out at maximum demand - i.e. as if the maximum fuel you can deliver is less than is needed. Possibly fuel pump, fuel filter blocked, low fuel pressure/defective regulator.

Have you treated yourself to a pressure gauge yet?? With A tee piece you can monitor fuel pressure on the road under boost. This would enable you to rule out all the suggestions above.

Its still worth checking your float heights anyway, as its not too difficult

cheers Steve

[simonf]

No still haven't bought a presseure flow meter! I must treat myself this weekend maybe!

So you think it may be fuel filter, regulator or filter related! I see your train of thought however i am surprised that the symptons have come on so suddenly! I supose start with the filter as that is probably the cheapest item to replace and work on from there!

[andydclements]

The cheapest thing is strip, clean and set float heights.

[simonf]

On returning home from a rather enjoyable AEG evening in Cambridge last night, i think i may have moved one step closer to having my car running properly!!!!!!!

After dropping andydclements off at his house, i decided to give the car some beens even if it wasn't performing. I was most surprised when i heard a sort of rubber boiiing come from my engine bay. This was shortly followed by a faint metalic rattle and then in turn my boost gauge whizzed round to 1Lb of boost and i shot down the road like a stung leopard!!!

Yippee, i finally have the performance i paid for because until now it has been driving like a N/A. I suspect that i may now need a new wastegate diaphram as i am overboosting. What gets me is that i was discussing the possibility of trading her in for an elise that very evening as i was feed up that my labours bore no fruits (my car obviously heard me and thought better of it!)

Any one got any idea what actually happened? I thoroughly checked the wastegate and to the best of my knowledge it looked fine! What was the rubber boiing noise, what was the metal rattle noise? and where can i get a new diaphram from cheaply?

Cheers guys!

A very happy Simonf

Edited October 8, 2008 by simonf

[910Esprit]

I was wondering where this post had gone....

when you say 1LB do you mean 1bar (15 psi?)

The words cheaply and external wastegate diaphragm cannot be used in the same sentence, you may indeed have to make a few phone calls to find one. I would not expect too much change from

[simonf]

Do i meen 1bar? probably - the needle goes all the way round to the stop on the gauge! I am pretty sure that the wastegate was correctly assembled. The noise seemed to suggest that the wastegate valve was stuck open slightly leaking pressure, but when i checked it, there was no resistance and it moved freely (however that was when the wastegate was cold!)

I haven't stripped down the wastegate yet, but i am pretty sure i am going to need a new diaphram because when i change gear under boost instead of the lovelly chatter from the wastegate as usual, i am now getting a whoosh noise much more like a dump valve!

Steve where did you get your diaphram from? Might help save on some phone calls!!

Unsure about your blocked baffles diagnosis, although it is entirely credible - my exhaust is virtually brand new and stainless steel, unless something fell inside when it was off the car, i am pretty sure the exhaust was ok! All i can think of by the noise i heard was was something like an anurism in the diaphram that burst, it was that kind of noise if you know what i meen, hopefully the rattle wasn't the turbines conecting with its housing (it was a turbo related rattle) because i could really do without the cost of a new one!!!

The good news out of this is that i have re-inviggerated my enthusiasm for the car and the will to have it sorted and back on the road soon has returned after a brief period of 'i coundn't-give-a-damm-ness!

Simonf

[910Esprit]

Simon

Diaphragm from PNM. Something like

[simonf]

Ahhh good ol' pete from PNM - I will give him a go in the morning!

Thanks for the heads up on the e-bay seller, i guest that is on e-bay.co.uk? or is it on .com? Might be a bit of a gamble but if he doesn't want too much ofr the wastegate, it might be worth the gamble!

[simonf]

Stripped down my wastegate tonight and found that the diaphram was in pretty poor shape, although no evidence of an anurism!! No rips or tears but the outer coating was coming away especially where the diaphram fits into the cup! I noticed that one of the nuts(locking nut) that hold the retaining plate to the valve stem had come off but everything else looked to be in order, my appraisal is that the valve must have been stuck in the slightly open position allwoing the boost presure to escape straight down the exhaust because i can see no other reason.

Good news is that i found a new diaphram with ease! One phonecall to Strattons and it was done

[910Esprit]

Ah Ha - Yes you did! Your's must therefore be blue?

I must admit I was impressed that we all seemed to get there in one piece without catastophic overheating!

My diaphragm was exactly the same, but if you held it up to a light you could see that it was porous where the 'welts' were. The good news is that the new diaphragm will probably also improve the throttle response/feel. Mine was awful with the leaky diaphragm, the revs tended to keep rising as you changed up gears under acceperation (sort of felt like turbo lag).

cheers Steve

[simonf]

Samll world Steve!

Thanks for being understanding with regards to me holding everybody up!

A have just had a phone call from Strattons, they can't get me a diaphram Pete at PNM wants to sell me one with a hole in it? I suppose its better than nothing, but if i am going to fix it, i want to fix it right and SJ Sprotscars phone is constantly engaged (have they gone on holiday again?

Any ideas where i can get one from in a hurry?

Scrub that SJ's answered their phone and had one in stock! Good ol' Steve!

Edited October 10, 2008 by simonf

[simonf]

Just a thought, but would it affect the wastegate operation if i had the diaphram in upside down?

[andydclements]

Not much (unless the wastegate was prevented from closing completely) but it could be that the wastegate valve moving to dump boost (allow gasses to bypass the turbo) rips the diaphram as it's primarily deigned to allow movement in one direction.

[ralphw]

Simon

Glad to know I wasn't far away from the problem resolution when we chatted at the AEG meet. Will be interesting to follow this saga from here on.

Cheers

Ralph

[simonf]

I can't believe it! I have put the new diaphram on and guess what! Back to only 0.5bar!! All i can say is that i must have assembled the wastegate wrong! and to make matters worse on the test drive the dip stick popped out and has covered my engine bay with oil!

I tried to find bigsi's diagram of the wastegate but i can't find it! and i have looked through my manual and i can't find it!

My waste gate has the spacer (asbestos maybe) then a gasket, then the diaphram, another gasket and then the retaining cup which is held up by a locking nut then the spring, is that wrong?

What i have noticed is that the spacer does not sit flush up against the top of the wastegate which seems wrong but the width of the hole in it is not large enough to get past the ridge on the valve stem?!

Edited October 13, 2008 by simonf

[mercman]

Simon, If your engine / turbo setup is standard you should only be running 8psi which is just over 0.5 bar .

Les

Edited October 13, 2008 by mercman

[910Esprit]

Simon can you take some decent close up photos of the parts? I'm slightly confused by some of your descriptions. None of the various washers or spacers should go past the ridge on the valve stem - its the ridge that locks all these parts when the 2 nuts are tightened up.

The order of assembly is:

1 large flat aluminium washer (NB - I chose to use an additional steel washer first as it better located the aluminium washer on the valve stem)

2 diaphragm with cup recess facing downwards

3 large aluminium cup washer with cup recess facing downwards (this fits snugly in the cup recess of diaphraghm)

4 small steel washer

5 2 lock nuts

The spring is the last part fitted and simply sits in the recess of the aluminium cup (at the top) and in the base of the aluminium casting at the bottom.

There are no asbestos parts on mine - there is however a large aluminium spacer that sits between the cast iron top and cast aluminium base? (the diaphragm sits on top of the spacer, sandwiched by 2 paper washers)

NB - I have another of my theories! you are assembling the assembly somehow incorrectly thats allowing the diaphragm apply a small downward pressure on the spring, thats effectively counteracting some its specified value, but still allowing everything to work. Whereas, when your diaphragm was perforated, the spring's function was effectively bypassed, thus allowing full boost?

cheers Steve

[simonf]

Simon, If your engine / turbo setup is standard you should only be running 8psi which is just over 0.5 bar .

Les

Oh, it does say 7.5psi on my wastegate but i naturally assumed that would equate to 0.75 because I was getting 0.75 on my guage before my engine refit now a fairly astmatic 0.5 and it just doesn't feel quick enough to me! certainly no where near as quick as the stats suggest and much slower than she was too!

If that is the case and my car is running correctly - how do i get my turbo up 0.75!!!!!!

[ralphw]

Simon

Visit PUK http://www.pukesprit.de/ they have an electronic boost control for sale. Will give you control of the boost when you need it and you can back it of when you dont.

Alternatively check this site http://www.owendevelopments.co.uk/index.asp and see if they do an alternative wastegate for your set up, chances are it is just a revised diaphram and spring.

Cheers

Ralph

[molemot]

The thickness of the spacer sets the boost pressure..iirc a thinner spacer gives more preload on the spring and thus a higher boost...but be careful, high boost can do 'orrible things to these engines, they're skating on thin ice as it is.

[ralphw]

John

High boost can destroy any engine if taken to extreme. I would have thought this level could have coped with 9.5PSI same as the HC version but with the failsafe that this one has a lower compression ratio to start with therefore reducing peak cylinder pressures marginally.

Regards

Ralph

[simonf]

Stripped my wastegate down again last night, everything seems to be in order! three things for consideration are:-

1) one of the bolts holes in the wastegate cover had a very week thread! Not sure it would have sealed very well!

2) The hole in the top of the wastegate (connected to the pressure pipe to the turbo) has some, not a lot but some debris in it!

3) Is it at all possible that the spring might have been mis-aligned causing the valve to operate at an angle?

One more thing does everyone else with a turbo have the boost gauge reading at 0.5bar (half way up the gauge!)

Edited October 15, 2008 by simonf

[mercman]

One more thing does everyone else with a turbo have the boost gauge reading at 0.5bar (half way up the gauge!)

I do

Les

[simonf]

I do

Les

Thanks Les, this is an interesting development! This could quite possibly mean that my car has been over boosting all the time i have owned it! I must admit, if this is the case, i am a little disapointed with the standard performance.

Would adding a spacer to the bottom of the wastegate (under the spring) increase my boost at all? My theory is that the spring would be under a touch more load making it operate at a slightly higher pressure??

I thank you all for your input and i have made a note of PUKESPRIT's number just in case but by the look of their webside they look expensive (more expensive than just putting a washer in anyhow!)

THank you to andy for helicoiling my wastegate cup! your help is always appreciated.

Edited October 16, 2008 by simonf