Problem? Or Not?

[Jonathan]

You can't reliably set the wastegate up like that - as we've discussed before you need to spend the time to get this right and do it propperly or you risk booting it on the motorway overtaking some car and then 'BANG' with lots of black smoke, a 4 grand repair bill on the engine and lots of people pointing and laughing until the pickup truck arrives.

Bear with me on this one:

On a normal turbo car the boost is controlled by the wastegate (more on that later) as the pressure from the turbo overcomes the capsule spring it opens the wastegate which moderates the gas flow in the turbine wheel of the turbo - this is refered to as 'mechanical boost' - it's boost moderated / governed mechanically. On the Esprit it is 0.65 bar.

My GT2 is plumbed in for mechanical boost only whilst I run it becuase I do not want overboost yet, the pipe simpoly goes from the turbo outlet tap to the capsule and bypasses the wastegate solenoid valve altogether. You could do this to set the wastegate up but it is not ideal and unless you know EXACTLY what you're doing it could be a costly way to do it.

However, the Esprit has an ECU controlled bleed valve (called the wastegate solenoid valve) which vents air from the wastegate capsule, this governs boost using a combination of the MAP sensor (air pressure inside the manifold or turbo boost) and the Wastegate Solenoid and with this the ECU can control boost over 0.65 Bar to what ever the chip inside the ECU tells it....it most Esprits it is 0.85 Bar (I dont know what the S4s is but I do think it's about 0.9-1.0 bar perhaps someone can correct me) - this is called overboost or electronic boost. It only comes into operation at about 70 degrees when the engine is warm and the oil is sufficiently thin to prevent cold engine / high boost issues - below working temperature the wastegate solenoid is in-operable to prevent overboost.

Whats most likely happening to your car is the mechanical boost setting (ie the rod) is not right for some reason and needs sorting, the over/electronic boost will sort itself from there.

In theory the ECU can control boost what ever the capsule is set to which is why it is important to have the baseline datum fixed - ie the mechanical boost setting - for the best results.

If there is another way to do it the manual would have said - so it shall be written, so it shall be done sort of thing.

One last note on the wastegate, everyone calls the capsule and the rod, a wastegate actuator, this term is incorrect - it is actually a wastegate inhibitor.

The wastegate is a flap operated bypass valve in the turbo itself - the flap is held SHUT by the wastegate capsule/rod as a kite is tethered by a piece of string. When the boost presure overcomes the spring in the capsule, technically the rod does not move the flap, the flap opens under the pressure of the exhaust gas and is allowed to move by the rod moving. If the rod was disconnected many people think the turbo would over-run to destruction, but it doesn't, the flap would just open at the slightest wiff of exhaust under it's own accord.

As Bibs says, Matty could quite easily and quickly sort this out for you, with the right tools it is a 10 minute job.

These cars, if you cut corners on them, really...really bite you in the ass.

[fesuvious]

Thanks

Right, so it all now boils down to getting the correct setting for the wastegate/inhibitor when NOT running through the solenoid?...

In other words correctly setting up so the 0.65BAR is showing, certainly no more. I am presuming the correct method now is the hand pump and dial guage? As set out via the links to LEW that you provided?

How come you can't use freescan's MAP readings for this? Just curious as Id thought that this might work to set the 'base line'?

Oh, someone (on here) said S4s setting is 0.97 BAR but despite extensive internet searching I cannot confirm this for certain.

This is an obvious question, but I am right in thinking the gate should be all the way to the closed position..not forwards in the direction of travel at all. I had the mount point for the rod at the fully closed (furthest shut) position when I reconnected the rod. i.e towards the capsule NOT away from !

The primary reasons for not getting Matty to sort this is that I do like to get to grips with my cars and learn them myself. Secondly, I cannot deny having a loss of faith having bought a car with the engine check light not working - even though I queried it, not too mention having bought a car with a CODE26 even after having asked if it had any fault codes, to which the answer was 'no its been hooked up in the workshop'. So, how much faith can I have? Id rather take it steady and learn the car and if ness purchase the tools for the job. Oh, and a car that the vacumn pump was working overtime on as it had leaks all over the shop, again, was told 'totally normal'

However, all said and done, it is an S4S in a beautiful colour combo, with 47000 miles and a full file, and I am in love with it - head over heels (even if that full file seemingly means feck all in the real world)

Not too mention I can document and photograph everything I do for the history file.

Edited May 12, 2010 by fesuvious

[CarlC]

No idea where the 0.97 came from. That is not the stock boost level or even overboost level for S4s SE or S4.

Good news that you've got a new wastegate actuator on the way. The sticking and inconsistent performance of the old capsule can be very hard to recreate on a test bed. My old capsule move correctly with a hand pressure gauge test but on the car was wildly inconsistent with holding boost and giving excessive initial over boost. If its old just get it replaced, its an easy job and even better if Matty's are providing the part. As Jon says they should be happy to fit and correctly adjust given the apparent circumstances.

Good luck, it sounds like your getting there.

Edited May 12, 2010 by CarlC

[Jonathan]

Poor effort from Matty's then - personally I'd send it back and then check it myself.

Onto the points :

You can set the car using freescan and running the car on full throttle at high revs to see where it is at, but if your wastegate is not correctly set you'll damage it !

Worse still if the capsule is too far wrong you could blow the engine up - why take the risk ?

The spring/diaphram is only made to withstand 0.65 bar of boost, even though MAP reads higher than that on full chat it's beuase the wastegate solenoid is venting pressure to the capsule - if your wastegate is set to allow 0.8 bar you'll just stuff 0.8 bar into the capsule and 'poof' new capsule.

Much more kinder to do it using a pump+dial as you say...upto you but if you have £80 to throw at capsules every time you make that mistake you might as well buy a compressor and get it right 1st time.

0.97 might well be correct, phone Lotus technical, they should confirm that.

Boost is a really important issue for any turbo car, esp Esprits becuase engine rebuilds are expensive.

My little GT2 has done over 100,000 on the original engine becuase the boost is set correctly - so many times people arse around with the boost to get silly 0-60 times and then wonder why they pop the engine, things break and then they tell their friends that it's the car's fault becuase it's fragile.

You can if you're feeling budget billy goto halfords and buy a bicycle or car tyre inflator - chop the hose adapter off and plumb it into an adapter to plug right into the wastegate capsule.

Use the gauage on the pump and a T piece off to the Blitz controller to confirm the pressure and away you go - cost you about £20 and you'll have it done this afternoon.

[fesuvious]

We have a plan !

But not for today, in work till half five then off to a meeting tonight (in a carefully driven Lotus)

Tomorrow night however....

This forum is great, thanks,

I think Il fit the new INHIBITOR and test it with a pump on the car first to make sure I am not going to blow the car up.

Il then start very very safe indeed and take it slow from there using freescan, and indeed put a 't' piece in to the blitz.

No rush, and no need to go boost crazy. All I am after is the correct setting, nowt more, nowt less.

Will google for Lotus technical phone number shortly and call them

[sailorbob]

The stock S4S 'Boost Maximum vs RPM' table is 1 bar at all rpms. The SE is mainly 0.85 bar except at low rpms where it is 0.82 bar.

[fesuvious]

Good Morning

So, here's a question. If the car had been making low boost for quite a while, and is now fixed, could that upset the innards of the cat? I now have a rattle which I could swear is coming from round by the cat, checked the heatshields, and its not them. Also, car just threw a fault 42, which I cleared and it hasn't returned. 42 is the spark timing.

Have a freescan run which Il add once my membership has been activated. (sorry bibs, it completely passed me by that the option was there to subscribe)

The freescan run seems to show the car running lean at points, should the 14.6 value remain constant because it drops to 12 for some sections?

Ok edited to add

Fuelling looks ok compared to al previous runs.

Rattle is the wastegate, there is not enough adjusted on the rod and the wastegate is rattling. Plan now will be to adjust the rod just enough to take the rattle out. This makes sense as I elected to fit the new inhibitor on a VERY safe setting.

---------

Wastegate now adjusted just to the point where it won't rattle, on the theory that if it rattles, then it aint shut, and if it aint shut, it aint right.

This now gives me 12-13 threads showing. Which is in excess of the 10 that were showing when I bought the car. However, it was plain from the condition of the rod that someone had been fiddling (oh, and of course from the botched and broken dash bulbs etc etc)

Lets give it a go..........

--------------------------

ok, now I have too much boost again. 

So, with the gate adjusted just so it doesn't rattle, I have too much boost. Map reading on freescan went to 2.23, and the car was barely at 4000rpm. Obviously, I did NOT push any harder.

So, back to the mental drawing board for where and why it is set up wrong. Or just throw the car at matty's, but Id rather fix this myself.

The actual capsule has no adjustment does it? Thats pre-set. So the only adjustment would be in the rod, but with it wound out to a sensible setting the gate rattles........

Think Il check AGAIN for leaks.

Edited May 16, 2010 by fesuvious

[Simon350S]

I fear you are rapidly voiding any warranty matteys would have provided.

I can understand if the repair costs were coming out of your pocket but this is all covered surely and you risking an expensive failure.

[lotus4s]

Jonathan,

Great explanation in your previous post about how boost control works in conjunction with the wastegate, actuator and solenoid.

However, I would humbly suggest that we not call the actuator an "inhibitor" as it muddies the conversation and may be confusing to someone who searches this topic at a later date. In reality it is the "wastegate actuator" particularly at mechanical boost where it is what controls whether the wastegate "actuates" or not. If anything the solenoid would be more closely defined as an "inhibitor".

Cheers,

Jim

[fesuvious]

yes, true,

However, I have kept matty's informed all the way. Am wondering though.. I know that the wastegate is opening at .65 as it should when plumbed direct. Am wondering if the car has a chip in it???????

[CarlC]

Thats what I was wondering before I read your latest post.

On the Rattle...

I had to make the same adjustment on my new wastegate actuator to stop the rattle of the wastegate flap. If you have shortend the arm to stop the rattle you will get boost a little earlier in the rev range.

The ECU is below the right hand quater window panel. remove a few screws and you can see the ECU black box. IIRC you'll have to flip it over to see if the silver Lotus warranty seal is still in tact. If its not there is a good chance there is an uprated ECU in there.

The ECU installation guide on LEW is really good if you want to dig further and have a look at the MEMCAL and the actual chip thats in there.

Edited May 17, 2010 by CarlC

[lotus4s]

Carl,

How do you arrive at the conclusion that shortening the actuator rod brings the boost on earlier? Making the rod shorter increases the spring pressure on the flap meaning you need more mechanical boost to open the flap but I can't see how it would make the boost come on earlier but maybe I'm missing something...

[sailorbob]

Actuators start to open the wastegate a bit before they reach the desired boost setting, hence the need for a preload on the spring. Increasing the preload delays some of this opening which results in more boost earlier. The flipside to increasing the preload is that the maximum boost increases too. This is why systems using boost control solenoids or air to air injectors tend to have much better boost control.

[CarlC]

haha - What Derek Said!

After many boost problems my self, I came down to changing the actuator. During the setup and testing of the new actuator I tested with different actuator arm lengths to get the right amount of boost at the right time (rpm). The result of adjusting the rod length directly affected how quickly the boost came in. Far better explaination from Sailorbob above as to why.

At the time, I was surprised as to just how much difference, even slight adjustments of the actuator arm length made to bringing boost in.

I came to the conclusion that there must be some play within the wastegate in the turbo its self. This means that if the actuator arm is short the waste gate is shut very tight and slightly greater travel is required of the arm to open the wastegate. with the actuator arm longer less movement and so less manifold pressure, is needed for the arm to open the wastegate and bleed of the pressure.

Edited May 19, 2010 by CarlC

[fesuvious]

Well, thanks everyone this far

This evening I am going back to basics with it. Disconnecting the solenoid (electrically) and intend to do a full throttle run on a mega safe setting using freescan for the MAP value and come hell or high water Il keep playing until I get it on, or damn near a solid 0.65. I don't care how long it takes.

Then, once I have triple checked the readings, Il plug the solenoid back in. I have to assume the actuator is pukka as it is brand spanking new, and from Lotus so I see no real reason to check the preloading as it should be set right.

[lotus4s]

After many boost problems my self, I came down to changing the actuator. During the setup and testing of the new actuator I tested with different actuator arm lengths to get the right amount of boost at the right time (rpm). The result of adjusting the rod length directly affected how quickly the boost came in.

Carl,

That's what I thought you were saying and is the reason I asked the question. The only problem with that is you are using the actuator adjustment for something that it is not intended for.

The only reason to adjust the actuator is for it to be at the correct setting for the ECM to be able to control the boost properly and affecting the boost range is a secondary consequence of the setting and irrelevant. Using it to control where the boost comes on in the rpm range could cause overboost and dire consequences, particularly for someone who isn't completely familiar with what they are doing.

Cheers,

Jim

[fesuvious]

surely only the size of the turbo and the length of the 'feed' for the gases will affect where in the rev range the 'boost' appears?

[CarlC]

Fully agree Jim,

I wasn't advocating tampering with this to affect the cars performance. My point was simply to highlight the impact of adjusting the actuator arm in response to a comment made about adjusting the actuator arm to stop the wategate rattleing.

Set the actuator arm correctly and let the car handle the boost level appropriately.

[lotus4s]

I see, good deal then.