Anyone work magic ?
Turbo Mini Forums

Difficult to diagnose whilst i'm over here Phil, but I know you're not a muppet and have checked a lot of stuff.

The gear-dependant thing is curious. It sounds like you need to visit a rolling road to actually see what is happening to the CO and sparks as the lean-out occurs...


Remind us:
Does this only happen as you're cranking up the boost or at low boost also?
Disconnecting the intercooler pipe totally (so the carb is basically nat-asp - what happens in this case?

I'm really stuck on this one (it's even harder trying to diagnose behind a monitor)...

I think a rolling road session, with a gauge connected to the carb vent-valve pipe, another gauge connected to the fuel leaving the regulator, and your boost gauge should reveal something.

The big question - It must have worked at some point - what has changed since then?

Did you test the fuel pump flow delivery under pressure? Disconnct the fuel inlet from the carb and direct this into a measuring cylinder/container. Also disconnct the top pipe to the regulator, and connct this up to a foot-pump or similar. Basically, you want to build up 15-20psi pressure in the regulator pressure signal line (equivalent to 12-17 ish psi of boost in real money) and then check if the pump is playing ball.

Whilst in this area, I suppose you've inspected all the hoses for chaffage / leaks?


oh, and before messing around with fuel, have a bucket of water / fire extinguisher handy. Disconnect the LT side of the coil to be safer still....

Edited by turbodave16v on 1st Jun, 2005.

how far are you from baldwins or stuart gurr's mate? I'd be getting my cash out now

Team Racing

"Does this only happen as you're cranking up the boost or at low boost also?"
Using the T-piece trick {this slightly improves things} i can run about 9psi. Running anymore makes it to lean. I can't really take much more from the needle as it's stupidly thin already.

"Disconnecting the intercooler pipe totally (so the carb is basically nat-asp - what happens in this case?"
I haven't tried this yet, though i had thought of it. This is next on my list of "things to try".

"The big question - It must have worked at some point - what has changed since then?"
This is what's stumped me ! I though the carb just needed an overhaul, but it's made no difference.

"Did you test the fuel pump flow delivery under pressure?"
No just tested it flowing unrestricted and it semed ok.
"Disconnct the fuel inlet from the carb and direct this into a measuring cylinder/container. Also disconnct the top pipe to the regulator, and connct this up to a foot-pump or similar. Basically, you want to build up 15-20psi pressure in the regulator pressure signal line (equivalent to 12-17 ish psi of boost in real money) and then check if the pump is playing ball."
This sounds a good idea, cheers for that Dave i'll give it a try.

"Whilst in this area, I suppose you've inspected all the hoses for chaffage / leaks?"
Yeah all seems ok.


"oh, and before messing around with fuel, have a bucket of water / fire extinguisher handy. Disconnect the LT side of the coil to be safer still.... "
Yeah don't want to learn the hard way like you.

Cheers for all the help mate. I'll get there in the end. :cool:

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daves advice is sound, as usual

the problem will lie with the reg or the pump as you havent got owt else phil except........

if you place a fuel line direct to the inlet manifold ..LOL


Think about it!!!

i feel that the carb needle you have profiled it for about 900 psi of boost now phil

after you sort this fault buddy

Edited by BENROSS on 1st Jun, 2005.

phil, I have a pare fuel pump and regulator if you want to try them

Team Racing

Thanks for the offer Jim that's very kind.
I have had 3 different pumps on it now and 2 regulators, so i don't think this is the problem. If i need them i will let you know.
Thanks again mate !

Phil.

WWW.TURBO-MINI.COM

Not got a crushed fuel line by chance have ya ?? under the car or somewhere you can't see it ?

Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

i just thought the same thing!

phil, you say the fuel filter is new

have you tried it without the filter ???

Right update !

I have now fitted a brand new pump and regulator = No difference .......
Tried without any fuel filters = No difference ......
Tried my mates "proven carb", {which is currently running 16psi on his car with no problems} = No difference ........
Drilled the jet holder in the carb out and removed the gauze = No difference .......
Got a length of rubber 10mm hose and fitted it straight from the pump to the regulator = No difference ........
Tried the same for the return = No difference ......
Turned the fuel pressure up = No difference .......
I even tried driving along and pulling the choke out = No difference .......

I've got a couple of thing left to try. I'm going to connect the Turbo straight to the plenum and i'm also going to measure the fuel flow from the regulator under pressure, as Dave suggested.
I'm basically at my wits end with this fuckin thing, i've got this mega spec motor and yet i can only run 8-9psi.
I could take it to the rolling road, but i cant see what they'll tell me that i don't already know ? i know it's not right, i just don't know why ?

This is what the needle looks like at the moment. As you can see it's like a sewing needle, i certainly cant take any more from the end.
I'm fast running out of patience and ideas !!

Cheers all.
Phil.

WWW.TURBO-MINI.COM

Time to get the fueling checked whist driving on the road...

Bring it round mine and we can have a look, if you want :)

Alex

AlexF

Without even getting it on the road, that needle profile is saying to me that it's overfuelling low down, and the thickness of the needle is all that's stopping it overfuelling.
It should be thinner than that in the mid thru to mid/high range, especially with the turbo you have... There should also be only a slight (and i mean slight) in the bottom 20mm or so of the needle - certainly not what you have!

No road testing is going to sort out a problem elsewhere.

My money's on the return line being too restrictive for the fuel supply... Thought you'd already checked this?
edit - You say you have swapped out the return line?
Well if you have, fair enough. As it's getting towards desperation, I'd be plumbing one single 8mm (ID) right from the bottom of the regulator return line, outside the car and into the filler neck or something - so you can be totally sure there is no restriction..

After this, I'm not sure. Suspect cam / timing maybe?

Edited by turbodave16v on 16th Aug, 2005.

A few questions:

1) what lambda sensor/ gauge are you using?

2) When the gauge indicates that it is leaning off does the car feel like it is short of fuel? i.e. does it miss/pink etc.?

What I'm trying to get at is is the lambda gauge believable?

I've seen lambda sensors/gauges read lean when ifact the car was overfueling, causing the sensor to go funny.

just a thought.

A RR session woud be a good callibration for the sensor/gauge if nothing else.

Wil

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

"Without even getting it on the road, that needle profile is saying to me that it's overfuelling low down, and the thickness of the needle is all that's stopping it overfuelling. "

you lost me!

Alex

AlexF

I never had you... that's GayDar's area.

LOL...

let me rephrase...

what do you mean by that sentance Dave, I'm thick and don't get it!

Alex

AlexF

"Bring it round mine and we can have a look, if you want "

Cheers mate, bit of a long trek for me though.


"It should be thinner than that in the mid thru to mid/high range, especially with the turbo you have... There should also be only a slight (and i mean slight) in the bottom 20mm or so of the needle - certainly not what you have! "

Oh i know the needle is not properly profiled, i was just thinning it at the end to see how much difference it would make. The profile is almost stock BDD until the last 25mm or so.

"My money's on the return line being too restrictive for the fuel supply... Thought you'd already checked this?
edit - You say you have swapped out the return line?
Well if you have, fair enough. As it's getting towards desperation, I'd be plumbing one single 8mm (ID) right from the bottom of the regulator return line, outside the car and into the filler neck or something - so you can be totally sure there is no restriction..

I have tried the return yes. Got some brand new 10mm rubber hose and put it straight from the regulator to the tank. I guess i could put it straight into the filler neck, just to be sure.

Will - When the car leans off you can tell you can feel the power drop off. It will missfire if you keep driving it hard. The gauge does seem pretty accurate .......

"A RR session woud be a good callibration for the sensor/gauge if nothing else"

I think you're right, good point.

Thanks again chaps.

WWW.TURBO-MINI.COM

Where abouts are u ?

Alex

AlexF

Hmmm, doesn't make any sense now I re-read the first post...

I was thinking the wrong way round - that the problem was it was just running rich, So I just went and reminded myself what the original post said - and it has a symptom of indeed running fine, then going lean ultimately....

So Phil - Why is you needle not any thinner in the low to mid-range before going silly at the end?


I've just plotted your needle in excel - what did you file it from? A BDL or something? I don't recall the stock BDD being even that rich in mid-range!

As an example, the only point that your needle and mine are (ballpark) the same is the first three points. After that, you're VERY lean.
Only at 1.40mm are we beginning to converge onto my profile (and that of others I know works ), then it completely overshoots and goes to waaaaaaay too rich.

Try plotting it in excell and you'll see what I mean.

Did you try the whole carb (incl. needle) off the other - working - turbo mini, or did you attempt to retain your own needle?

If the latter, it could be that the spring you're running with this needle is exagerating the resultant mixture as a result of the wild profile, giving this 'gradual leanout' effect. What spring are you running?

TurboPhil from TurboMinis- it seems to me that maybe you have concentrated on leaning out the full stroke position of the needle a bit much, have you considered thinning out the mid part as well??

It is not uncommon to find "tuned" engines that will run fine at WOT but are a bag of shite at part throttle??

Edited by turbodave16v on 16th Aug, 2005.

Good news at last. Have been running 12psi for about 3 weeks now. The problem seems to be sorted, touch wood ! Not sure how really lol, but i had noticed on the last few runs out that the lambda was reading richer than usual and the car seemed and little flat on acceleration and to be smoking a little from overfuelling. So i decided to risk a twist of the bleed valve, three weeks later and it's still in one piece.
Now i'm pretty happy it's running well, but on the other hand i'm pissed off because i don't know why it suddenly decided to work. I haven't tried more than 12psi yet, so i'll have to see how it goes .........
I have been removing my boot install, dash and monster stereo install so all i can think off is that there was a blockage in the fuel line somewhere [which runs inside the car] and in removing my boot install and dashboard i've disturbed something ? Though these all checked out ok before .....
Oh well at least it's working, bloody Minis !! lol

Phil.

PS. Cheers for all the help guys
Oh and Dave excuse my numbness, but what's excel ?

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Excel is the best, most useful, programme on your PC... If you have 'word' you should have excel.

Doh !! I do indeed have it, thanks.

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cool, gald it working :)

Alex

AlexF