Integrator value very low! Ideas?

[sailorbob]

The downpipe to turbo flange has been overtightened and it should be flat. The distortion probably isn't detrimental as long as there's enough space between it and the turbo to allow sufficient tightening of the joint.

[Sparky]

The 'other possibility' is related to this - clearly it's been overtightened, maybe to force a seal due to some kind of back pressure? Blocked cat? Still clutching at straws..

[SteveSmith]

The cat is completely hollow - I remember testing that with a long screwdriver when I replaced the exhaust...

So are you thinking that at some point there was enough back pressure created to somehow blow a route through the turbo from exhaust side to inlet side ?!?

If thats the case then, another point to note is that the EBPV was completely devoid of its 'flaps' when I removed it whilst replacing the exhaust. Significant ?!?

[Sparky]

That's another wild theory discarded then! Nothing like that could breach the turbo, but it could have explained some strange behaviour. Gutted EBPV is standard.

Home now. Here we go again. Taking my lucky rabbit's foot outside with me...

Steve - when did you replace the turbo gasket? Strange that you should have to do that following a turbo rebuild...

[SteveSmith]

I replaced the turbo gasket in Oct 2005 although the gasket was blowing when I bought the car a year previous. The local Lotus specialist was meant to be replacing the gasket for me whilst doing a C service. I provided the gasket but they told me they couldn't replace it because it was the wrong gasket. I knew it was the correct gasket so can only assume they didn't want the hassle of removing the turbo... Anyway, I finally got around to changing the gasket myself in the hope that it might miraculously solve the poor running issues. As we know, it didn't...

[Sparky]

So, tonight's instalment: it's official - I'm losing my marbles. The cheese has slid off my cracker.

I was maybe a little too hasty at the weekend: it was HOT here, and what the turbo outlet was producing was probably ambient around the engine. It's considerably cooler tonight. However, at engine idle, the compressor is turning incredibly fast, producing (I'm guessing) a forced induction multiples of the norm. Allow the plenum to suck in ambient and BLM is fairly good; close the system and it drops by around 25. Stop the compressor from turning (no mean feat) and things head towards normal.

Looks like cat is gutted, sports exhaust and no EBPV.

I'm trying to extrapolate how the ECU and various sensors will interpret this extra volume of air. Pop quiz...

[SteveSmith]

I'm sooooooo sorry this is proving to be a real nightmare for you

I officially lost my marbles about all this about 7 years ago so I feel your pain

So just to recap - we're talking new injectors which should resolve the rich running and figuring out what the hell is going on with the turbo as back pressure doesn't seem to be the issue ??

[Sparky]

It's certainly a challenging chestnut.

Injectors, yes, but they're not a huge problem. Need to find out what is making the turbo spin up so much, as that's the major tangible issue now. Maybe it needs some back pressure!

[Vulcan Grey]

If you still have the intercooler disconnected, then the compressor side of the turbo will be pretty much freewheeling, without any restriction of a pressurized manifold... So, I'd guess the fast spinning is normal in that case... I don't normally run the engine without the plenum connected, so I'm guessing.

Also the same if you have the exhaust removed, looking at the turbine side.

Having the cat gutted and the EBPV gutted helps here, because we can rule out an exhaust restriction causing a poor running condition... unless the muffler is badly restricted???

[Sparky]

Comparing it to mine, spin and therefore pressure is way higher. I'd expect to be able to stop the turbine by hand; this one will take your finger off! Haven't looked at restrictions, but plenty of flow from the tailpipe.

[sailorbob]

You cannot compare the turbo characteristics with yours for a couple of reasons; firstly, the SE and GT3 run different turbos and, secondly, the turbo may not have been rebuilt to OE specs.

I suggest the leaking injectors and MAP sensor wiring need to be sorted before any more fault finding is carried out. Also, bear in mind that the BLMs will always read low due to using a chip that mismatches the VE tables with the engines actual efficiency.

[SteveSmith]

I think its fair to say that you can instantly rule out exhaust restrictions because the problem existed when I bought the car with OE exhaust and still existed after I changed to a Quiksilver sports exhaust.

Could a gutted cat with its cavernous chamber be causing a lack of back pressure ?? A cat bypass pipe would obviously restrict things but only for the approx 30cm of the length of the cat before the gases head into the tailpipe.

Derek has aluded to the chip mismatch with the car. Is there any merit in / possibility of swapping the chip with a standard SE one ?? Might be a worthless test as we know there are many SEs out there with S4s chips running without these problems...

Are there any other SEs available to test the turbo outlet flow at idle ??

Edited August 21, 2012 by SteveSmith

[Bibs]

I had an empty cat for a couple of years before replacing it with a cat bypass pipe, made no difference to my SE.

[steve930]

Just a stab in the dark, so forgive me.

I bought an audi s2 many years ago which had all sorts of erratic running issues, changed all injection components with a friends car, no change, turbo/exhaust all ok, in desperation I changed the ht leads (recently fitted before I bought the car) and the engine ran perfectly. It seems the cheap ht leads fitted were spiking/interfering with the ecu/sensors.

[SteveSmith]

I like your thinking Steve. Alas, the car has had at least 2 changes of HT leads in my 8 years of ownership and always with the Lotus spec leads.

However, as the original posts in this thread detailed, the first 100 odd miles after each service its had, the car seemed to run well implying that something done during the services temporarily rectifies the problem but it deteriorates again.

You may be onto something with your suggestion Steve, but I'll have to leave it with Sparky to determine whether to pursue it as I'm beyond the point of rational thought with this car now !!

[Sparky]

Derek - I hear you, thanks. Guess desperation is showing through! Definitely need to remove the known issue first, so with your OK, Steve, I'll get the injectors sorted. At least I'll have a better baseline then. Please confirm they've not been replaced/reconditioned in your ownership?

Gotta say, though, never had a turbo pushing out that much at idle.

Then I'll look at replacing leads, brakes, windscreen...

If I disregard the pain, heartache and sleepless nights (that includes the missus), this is a really fascinating thread.

[SteveSmith]

Go ahead with the injectors - if they're leaking they need replacing - simples !

As far as I'm aware, they've never been touched in my ownership - certainly not by me at any rate and no mention or cost from those who have worked on the car in the past.

[Sparky]

Roger that, mate.

I feel the need, given the subject matter of this thread (and indeed my perhaps erroneous title) to stress the real issue here.

The car runs RICH. I need breathing apparatus in the vicinity. My neighbours leave the street if I start it up. British Gas are conducting sniff tests in the neighbourhood. We've run out of wet towels in my family's attempt to hermetically seal the abode. You daren't light a match. Greenpeace have set up a camp in my garden. The canary died.

That should cover it.

[SteveSmith]

<tannoy>STRAIGHT JACKET FOR MR CLARK. WE NEED IT NOW. SUSPECTED FUEL POISONING</tannoy>

[Sparky]

My hovercraft is full of eels.

[steve930]

Restriction/blockage in fuel return pipe to tank

[Trevsked]

I think Sparky has tested the fuel pressure when running and doesn't read high which I would have thought it would if the return was a problem.

Trevor.

[Sparky]

fuel pressure is spot on (apart from loss due to leaking injectors), and I can blow bubbles into the tank via the return pipe!

[SteveSmith]

Just been chatting to a friend who is pretty knowledgable about turbo systems and, having described the high outlet pressure at idle, he is convinced its a vacuum issue.

Here's a quick grab of the conversation:

Me: What would you expect the compressor in the turbo to be doing at idle ??

Him: f**k all

Me: So freewheeling basically and stoppable by hand ??

Him: well i wouldnt stop it by hand.. but yes

Me: Mine is spinning up significantly and incredibly difficult to stop by any means

It is creating a huge amount of pressure

With the car idling

Him: it is a regular turbo init?

charge feed or anything?

Me: Regular - nothing special

Him: then it can only be fed from exhaust gasses

and therefore cannot be diverted correctly

Me: Exactly

How else can it be diverted though ??

Him: it cannot - only through atmospheric

but atmos pressure is about 4psi!!

which will do naff all

I would suggest blocking it off and running it first without the blower

Me: Blocking it off ??

How ??

Him: hosing out and block it off...

and see what it does as it *should* idle correctly

Me: Well, he's disconnected the pipe from the turbo outlet to the plenum and it then idles really well and ECU data is much more sensible

Him: right - thats a good start

Me: As soon as the turbo is reintroduced, it goes stupid again

Him: there HAS to be a vacuum issue

the blower cannot cause this by itself

Me: Any suggestions on what/where the vacuum issue may be ??

Him: well there can only be a handful of vacuum feeds to the blower and I would pinch them off one at a time

you will have some form of recirc system

that would be my first guess

diverting that to atmosphere would give you a bodge cure for the idle

but would run like a bag of s**t when it comes on to turbo

Me: But thats the big problem, its at the point of coming on to turbo (2500 to 3000 rpm ish) that it stutters and stumbles

Him: well I am not b****y surprised !!!

if the pressure at idle is too high then what will it be doing at 3-4k!!!

it will be causing major league back pressue on the turbo prop

which will ultimately butcher the bearings of course!!

Anything useful in that little lot ?? Have you swapped out the MAP sensor yet ??

[Trevsked]

Steve,

Your friend lost me there :-). I can't get a handle on the vacuum he refers to. Later cars have recirc systems but not sure if the applies on the Esprit, being an earlyish turbo system. Perhaps someone will be along to educate me.

Trevor.