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Home > Help Needed / General Tech Chat > Not much happening on Number 2 Cylinder

Graham T

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291 Posts
Member #: 1106
Senior Member

Hungerford, Berks

Guyís,

Iím just looking for some advice before I start a strip down.
Iíve just swapped the Mini over from Injection to Carb and taken it out today for itís first run, hoping I could get it to the dyno before the really cold weather gets here.

However, all is not well apparently.

Last run out with injection was around 2 Ė 3 weeks ago and I certainly never noticed anything odd.
I should have realise it was not running properly before I set off, because the engine had a different noted to normal on tickover, but I just assumed the changes I have made were responsible for the difference in sound.

Iím not running any boost at the moment (or very, very, very little) and have not been for several months.
Anyhow, the car ran shockingly badly, very sluggish and just no real power there.
Ultimately I realised the odd note of the engine and lack of performance meant a problem, so I started pulling HT leads when I got back from my drive out and it appears Number 2 cylinder is not doing very much at all.
In the below you can see a log where I have pulled each HT lead in turn, 1 to 4 and the result: drop in Revís, rise in MAP and lean Common AFR each time.
That is all except where Number 2 HT lead being pulled should be. The Marker line should be centre of the 5 second interval the lead was pulled.







So Iíve swapped HT leads 2 and 3 around, swapped spark plugs, put in new plugs, replaced leads and even swapped the coil pack.
Always the same, so Iím convinced itís not Spark related.

Iíve run compression tests on all cylinders.

1 = ~150PSI
2 = ~150PSI
3 = ~155PSI
4 = ~155PSI

Iím not seeing any signs of coolant in the oil, coolant being blown out the radiator or anything sinister.
So has anyone any ideaís on what could be going on or what else I could try before pulling it apart?


robert

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uranus

dp

Edited by robert on 17th Nov, 2017.

5 port mini 620 kg ,old falkens ,open diff.13.1s @109.1mph .

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robert

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uranus

too lean ? tried winding down the jet or pulling the choke on ?

not a chance or blue paper towel of death stuck somewhere ?

5 port mini 620 kg ,old falkens ,open diff.13.1s @109.1mph .

IF YOU CANNOT SEE PICTURES TRY THESE ADD ONS..


https://chrome.google.com/webstore/d...alioapbifiaedg

https://chrome.google.com/webstore/d...fegnfnflicjjgj


Turbo This..

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Previously josh4444

Australia, brisbane

something in the valve terrain gone a miss?

the jam nut on the rocker back out and self adjust losse?
worth a check under the rocker cover for anything strange lash? bent push rods? eyeball on full lift?

id assume an air flow problem might show up on the comp test but the engine is turning slow compared to running speed so perhaps something is open just enough to show a good read but not to the extent it should be?
ive never found any difference with the throttle open or closed for instance so there only needs to be a tinny gap for air to show a good reed


Graham T

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291 Posts
Member #: 1106
Senior Member

Hungerford, Berks

On 17th Nov, 2017 robert said:
not a chance or blue paper towel of death stuck somewhere ?



I hope not! But looking at the plot again with a fresh set of eyeís a bit earlier this morning, the effects to AFR on pulling the HT lead for Number one are nothing like that of 3 and 4 Cylinders, so this could be a blockage in the inlet tract for 1 / 2 cylinders, affecting 2 more than 1.

It looks like I need to pull the inlet manifold off as see if Iíve been a complete cock and left something like rag/ towel in the port on Number 1 / 2.


On 17th Nov, 2017 robert said:
too lean ? tried winding down the jet or pulling the choke on ?


I have not since discovering this problem. Iíd do that after Iíve looked in the ports.


If not, Iíll pull the rocker cover and look at the valve train.

Thanks for the suggestions.


Graham T

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291 Posts
Member #: 1106
Senior Member

Hungerford, Berks

Sorted Ė or at least I know whatís wrong now.





Iíve been able to partially rectify the problem, but not fully.

At least now pulling the HT lead for Number 2 registers, though it is far from right.

Also, pulling number one HT lead shows more of an effect than it did, but more significantly tick over MAP has dropped from 38 Ė 41Kpa, back down to its usual 29 Ė 33Kpa.

It was not blue paper towel and not a problem with the valve train.

There was a rather large air leak on the inlet Manifold flange to head.

Basically, it looks like the flange is crooked on the runner ( It looks like it has been welded up in a previous life), hence it was not pulling down flat on the gasket.

Iíve carefully filed the flange so that it is square with that of Number 3 / 4, but ultimately I need to get the flanges machined properly. Something I cannot do as I do not have a mill.

Anyhow, I now know what the cause is so at least I can move forward!


wil_h

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Betwix Harrogate and York

Had I read this before you found it, I'd have guessed air leak on the manifold.

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

www.twin-turbo.co.uk

On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


robert

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uranus

rub it down on a sheet of glass and some 40 grit ?

5 port mini 620 kg ,old falkens ,open diff.13.1s @109.1mph .

IF YOU CANNOT SEE PICTURES TRY THESE ADD ONS..


https://chrome.google.com/webstore/d...alioapbifiaedg

https://chrome.google.com/webstore/d...fegnfnflicjjgj

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