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PollyMobiles Rebuild

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pollyp

pollyp

Club Member
that would still require alot of extra unnecessary time n money purchasing, installing, setting up & pay someone to retune on a dyno plus it loses nats security.

the hardware is fine, nistune is fully programmable. the issue is correctly setting up the parameters of the inj multipliers, latency, MAF VQ etc to match the real airflow, injectors etc so what I adjust in the mapping matches what the wideband reads and consistantly.

at the mo I'm having to tinker n guess the multiplier, latency, fuel map etc till the afr gets close to what I want but is prob the wrong way to do it if the MAF map isn't correct in the first place.
 
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pollyp

pollyp

Club Member
this morning when I started her n drove out the garage, she was smoking abit but clear once warm.

I wonder if all the symptoms:
  • smoking and lumpy cold start,
  • smoke under high boost following prolonged high vacuum,
  • 4 damp/wet cylinders,
  • no smoke under no boost
could be bad stem seals?

I really need to do a wet compression test too to check if all 4 rings are consistant
 

Enuo

Glorified Electrician
Leaky valve stem seals are a common problem on triumph engines is why I suggested it early on, could only be a small nick oil can squeeze past if it take a while under vacuum to get some smoking
 

frank

Club Member
nah, stemseal wear is a thing of the past ;) with the old rocker tappets there was a side loading on the valve from the arc of the rocker.
but these CG seals are shrouded by bucket, and its a direct/vertical direction, with no side loadings on the valvestem
 
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pollyp

pollyp

Club Member
starting to think it could be stem seals and they're much easier n cheaper to replace than say removing pistons.

how could I verify if its the seals?
I'll try stick the endoscope down the inlet port once stone cold to see if oil is leaking down the stems over time.
 

frank

Club Member
starting to think it could be stem seals and they're much easier n cheaper to replace than say removing pistons.

how could I verify if its the seals?
I'll try stick the endoscope down the inlet port once stone cold to see if oil is leaking down the stems over time.
we had this discussion on the 1st build of this forged engine iirc paul :) its not gonna suck oil down the stems under boost eh
 

Enuo

Glorified Electrician
nah, stemseal wear is a thing of the past ;) with the old rocker tappets there was a side loading on the valve from the arc of the rocker.
but these CG seals are shrouded by bucket, and its a direct/vertical direction, with no side loadings on the valvestem
Ahh fair shout.
Stupid qu, it's definately smoke not steam? Could the head need retorquing?
 
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pollyp

pollyp

Club Member
we had this discussion on the 1st build of this forged engine iirc paul :) its not gonna suck oil down the stems under boost eh

no oil won't be sucked down the stems under +ve boost but it could be sucked down the stem into the cylinders during high manifold vacuum if the stem seals are leaking (closed throttle at high rev) and coating the non-burning cylinder in oil.

when i resume high boost combustion, the fire burns away this small residual coating of oil till its all gone n dry (smoke for the initial few secs then runs clear throughout the acceleration) until it close the throttle and it all starts building up again with the manifold vacuum.

when I first start the cold engine it's lumpy cos its trying to burn off all that pool of oil.
once the pool of oil has burnt away and lumpyness goes away, if I stop the engine while its still cold and restart the engine, it starts fine.
 
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pollyp

pollyp

Club Member
Ahh fair shout.
Stupid qu, it's definately smoke not steam? Could the head need retorquing?

definitely blue smoke and pistons are definitely coated in oil not runny coolant and coolants not bubbling at all so HG is perfectly fine.
 
I'm voting rings. All symptoms suggest it.
They're not necessarily at fault its those cylinder score lines.
Keep running that break in paul. It'll clear itself up
 

Kamarley

If it aint Jap its Crap!
photostream
http://www.flickr.com/photos/[email protected]/7986575862/in/photostream/ I found a picture of you chatting my misses up :D
Who's Micra is it though I likey
 
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pollyp

pollyp

Club Member
Mik's? http://www.micra.org.uk/threads/micra-madness.52345/page-2#post-554738

@ Paul, glad to see things are going a little better with the engine mate, how long left on the running in?

yea was gonna say its Miks.

forged engine has reached 683m upto now.
connected the O2 back on, enabled the closed loop regions in nistune so now it adjusts itself to 14.7 during low throttle (can see it adjusting the afr from the original base map in datascan)
went for a normal cruise (steady 0psi & 14.7afr & 2-3k rpm) during lunch. plugs are white coated with burnt oil, pistons still 10% dry centre and compression is 10.9 11.3 11.7 11.2 bar
 
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pollyp

pollyp

Club Member
15th June

when I park the car at work at 9am and start the ambient cold engine after work at 5pm, she starts fine with no throttle assistance or smoke. but its only when the cars left 8-9hrs overnight that the stone cold engine seems to struggle starting on her own while clearing out some pool of oil and briefly smoking. which seems to suggest the stem seals allowing oil to slowly trickle down n pool n thicken over the valves making stone cold morning starts tricky.

cruised home, rechecked compression and its 11.3 11.7 11.9 11.4 bar after 696m

went for a long normal drive through the country, low rev, low boost, some cruising at 14.7afr


the pistons now have a 30% dry patch, plugs are white from burning some oil, compressions ok at 11.1 11.2 11.7 11.1 bar

whilst checking compression at a parking lot, a guy called dave in his k12 thought I was having trouble starting :p I explained naa i was just checking the engine, and we got talking bout our micras n various stuff, nice fella.

anyway twas late so drove some more at night and recheck compression before heading home.
to see if the mani vacuum was actually sucking abit of oil past the stem and into the cylinders, I first cruise along at 0psi 60mph to allow combustion to clear the oil stain off the piston and the 0psi prevents the stem from leaking.
as I approach my usual stopping point, turn off IGN to cut power and begin deceleration while also fully opening the throttle WOT to maintain 0psi manifold pressure so oil doesn't get sucked down the stems and collect in the cylinders.

the pistons still appear bout 30% dry,
dry compression shows 11.6 11.6 12.1 11.4 bars after 774m

also did a wet compression. results were very dependent on the amount of oil I dripped in and didn't wanna pour too much in (too little = bout 13psi, little more = 14psi) so the test isn't consistent.
got an average wet reading of 12.9 13 13.1 13.4 bars.

the difference from wet to dry are 1.3 1.4 1.0 2.0 bars

this morning with the stone cold engine, I'll remove the injector rail and have a look at the inlet valves for oil pooling
 
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pollyp

pollyp

Club Member
Nope no obvious signs of pooling on top of the closed inlet valves. They just appear to have a glossy oily sheen.

The pistons themselves this morning seem to have a slight damper region on the inlet side.
 
i dont understand all of these problems paul,

there is no way a freshly built engine should or would give these issues of built measured correctly on a fresh engine, im not saying youve done something wrong at all so dont hate me, but how can it be smoking etc? ive only seen fresh engine some on first ever start and thats because of oil in the bores and assembly lube on everything, once that burns off there shouldnt be issues for at least 5k and thats if abused.

i just cant get my head around whats going on, it must be something to do with your machinist or something if the bores are that scored up, and maybe its the finish thats too harsh still.
 
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pollyp

pollyp

Club Member
i dont understand all of these problems paul,

there is no way a freshly built engine should or would give these issues of built measured correctly on a fresh engine, im not saying youve done something wrong at all so dont hate me, but how can it be smoking etc? ive only seen fresh engine some on first ever start and thats because of oil in the bores and assembly lube on everything, once that burns off there shouldnt be issues for at least 5k and thats if abused.

i just cant get my head around whats going on, it must be something to do with your machinist or something if the bores are that scored up, and maybe its the finish thats too harsh still.

I'm trying various tests to figure that out myself.
it only smokes for few secs on "stone" cold starts (and not during cold/warm starts) and for few secs after prolonged high vacuum +4k rpm coasting with a damp piston. once warm and just driving normally, she's fine no smoke at all and only partially damp piston. all of which points me towards the stem seals.
compression is also good and even.

if the rings are bad wouldn't it smoke all the time hot/cold/idle/cruise/boost/coast?
 
In the 10+ years that I've been playing with minis and various classic cars oily smoke on (cold) start up has always been worn valve seals/stems
 
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pollyp

pollyp

Club Member
as mentioned, this morning I removed the injectors to inspect the inlet valves n other stuff.
the only signs of oil are partially damp piston tops, light sheen on the inlet valves and the inlet mani has a very thin spot of oil from the pcv (my old stock engine used to have a much larger pool of oil down the manifold).

when I crank it without any throttle she struggles or floods. try again with throttle and she struggles as if the cylinders are full of oil and shoots a big ploom of smoke like what I get after doing a wet compression test then it clears after few secs.


continued more driving through the country with low rpm low boost cruising.


pistons are still 30% dry.
dry compression was 11.5 11.8 12.1 11.4 after 855m
wet compression was 13.5 13.4 13.8 13.3 (used 1/2 a mini syringe to inject the same amount of oil to keep readings consistent)
difference of 2.0 1.6 1.7 1.9 bar

cruised down the road under low boost to burn away the oil from the wet compression test, yup pistons are 30% dry again.

ok the next test is to resume the high rpm coasting, high boost runs and see if the previous symptoms return.


smokes after prolonged high rpm coasting and after just 1 lap cyl 2, 3, 4 are now abit damp after the hard run. if I go for more laps it'll prob get wetter.
so I'm guessing the stem seals are barely ok with low vacuum or +ve boost in the manifold but unable to hold back the oil during high rpm vacuum coasting.

dry compression was 11.5 11.8 12.1 11.5 after 866m
wet compression was 13.3 13.6 14.0 13.8
difference of 2.0 1.8 1.9 2.3 bar

cruise back home


going for more runs in the coming days till I receive the new stem seals then its:
check & correct valve shim clearances,
replace inlet valve stem seals,
re-bond timing side cover & rocker cover,
change oil & filter cos its very dark now,

then redo test n see if the pistons dry up
 
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pollyp

pollyp

Club Member
In the 10+ years that I've been playing with minis and various classic cars oily smoke on (cold) start up has always been worn valve seals/stems

thx for verifying my suspicion.

this forged engine head has new stem seals since last year but it was from an ebay gasket seal kit, so maybe it was the wrong type or poor quality?

I ordered 8 genuine stem seals from the dealers so hopefully they'll seal proper this time.

need to buy or make a stem seal slider-type remover tool now.
 
Basically if oil is forming in the cylinders when the engine is left over night etc it's the stem seals. Thanks to gravity oil can only travel downwards, so any oil is entering from the top.

When I rebuilt my head I didn't notice if there where valve seals on both the inlet and exhaust valves? But if you're ordered 8 I'm guessing it's inlet only?

In the mini scene it's well known that mini engines left the factory with stem seals on the inlets only and when rebuilding a head to fit them to the exhaust stems aswell to combat smokey start ups
 
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pollyp

pollyp

Club Member
Basically if oil is forming in the cylinders when the engine is left over night etc it's the stem seals. Thanks to gravity oil can only travel downwards, so any oil is entering from the top.

When I rebuilt my head I didn't notice if there where valve seals on both the inlet and exhaust valves? But if you're ordered 8 I'm guessing it's inlet only?

In the mini scene it's well known that mini engines left the factory with stem seals on the inlets only and when rebuilding a head to fit them to the exhaust stems aswell to combat smokey start ups

yeah 8 stem seals for just the inlet valves.

when my original polly1 engine head had a crack in the exhaust stem seal area, it used to always smoke abit once warm and idling, this one doesn't do that so its not exhaust seals.
 
yeah 8 stem seals for just the inlet valves.

when my original polly1 engine head had a crack in the exhaust stem seal area, it used to always smoke abit once warm and idling, this one doesn't do that so its not exhaust seals.
Inlet stem seals also smoke when warm and idling?
 
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pollyp

pollyp

Club Member

yeah dejavu smoke and wet pistons from 2011 that had the wrong sized bores and again in 2012 that had a rebored block but old rings that never bedded.

the difference this year from totally rebuilding the bores, rings, bearings, seals is that the pistons are actually getting drier and compressions gradually improving with miles so the top ring at least is bedding & sealing correctly.

previously with the incorrect bores or old rings where the oil rings were too loose or can't bed in, the whole piston was always completely soaked with a pool of oil, drank huge amounts of oil and spat it out the exhaust in a thick black dusty soot.

this time after bedding the new rings and bores the pistons are now only 30-40% dry and 70% slightly damp, only smokes during coldstart and briefly after any high vacuum, so just a little bit of oil is getting sucked in somewhere.
and all the symptoms upto now including the cold test I'm about to post below seem to suggest its the stem seals.
 
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pollyp

pollyp

Club Member
Inlet stem seals also smoke when warm and idling?

dunno. maybe during idle only a tiny bit leaks past the seal under the low vacuum pressure and burnt outwards as a small speck of soot dust on my hands, but during any high rev engine coasting (whether from blipping or continuous coasting in gear) there's more vacuum to overwhelm the stem seal n suck more oil into the cylinder till is visibly smoking once combustion resumes?
 
Then surely once the engine has cooled the seal "shrinks" allowing oil to pass leaving fresh on top of the valve/piston. It wouldn't be 'baked' on like you saw the other day. Where it would have to be there while the engine is hot no?
Did you look at the exhaust valves for that oily sheen?
It'd take more than a stem seal to coat a piston overnight especially if they only leave a speck of soot under little or no vac?
 
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pollyp

pollyp

Club Member
16th June

so this morning I did a little test.
theory is I start the stone cold engine till it clears up so all the pool of oil is burnt away and then stop the engine. when I start the cold engine again, it should start fine on its own without struggling with the excessive pool of oil.

I think I didn't clear enough of the oil pool on the 1st coldstart hence struggled n smoked on the 2nd coldstart. shall try again tomorrow.


wanted to lay down summore miles to bed the rings so me and dad had a sunday roadtrip up to scotland via country A roads and had a nice blast along the A708 near Moffat.

so the compression history so far

msd8.jpg


during hard break-in with the leaking stem seals oiling everything, the results are abit erratic prob cos the pool of oil was causing a semi-wet compression test and affecting readings.

once I begin cruising after 600m which reduced the oily piston, the readings become consistent and actually rising.

I think once I've fixed the stem seals and the pistons become dry so I can do a real dry test, the readings will improve
 
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pollyp

pollyp

Club Member
btw a friend brought up a topic that cos I run my turbo setup on the road which is different to what was tested during the MOT with the stock exhaust, it would invalidate my insurance if I have an incident cos the MOT doesn't match the cars tested spec? is that true?

we clarified that an MOT is not a proof of road worthiness for the whole year (only at the time of testing) and that I've declared every mod to insurance but just the idea that a mismatched MOT might affect the insurance cover confuses me.

mechanically she passes MOT but the turbo setup at the mo can't pass emissions. so does that mean I'm prob not covered or I'd have to try to make this damn turbo pass emissions (somehow fit another cat closer up the downpipe and/or remap properly) or abandon the turbo dream?

or the other extreme is to dedicate this turbo k11 for track only (no tax, mot or insurance) and buy another stock k11 for a cheap daily?
 
As far as I'm aware so long as it has a valid mot certificate then it's legal providing your insurance knows every detail.
Like you say they can only take the car as is on the day of the test. If you was to take it again now and fail your previous pass still stands anyway
mot is road worthiness and safety
 
Surely that would invalidate all our insurances, not only that but we'd need to get a new mot after each and every modification
 

frank

Club Member
Surely that would invalidate all our insurances, not only that but we'd need to get a new mot after each and every modification
that would probably depend if the mod was mot friendly eh ?, the insurance probably has some smallprint that says any "unroadworthy" mods will invalidate it (any mod that the police can do you for)
 

Enuo

Glorified Electrician
As long as your car is in the condition that you have declared to the insurance company your insurance is valid. You can insure a non-mot'd car, and mot an uninsured car. Both are only in any way inter-dependant when it comes to the subject of vehicle registration tax, and then only circumstantially.
 
that would probably depend if the mod was mot friendly eh ?, the insurance probably has some smallprint that says any "unroadworthy" mods will invalidate it (any mod that the police can do you for)
Biggest ones I see is window tints and decat pipes
 

frank

Club Member
Biggest ones I see is window tints and decat pipes
yes if the drivers vision was impaired from the tint, of the extra power from the decat :D had "contributed" to the cause of the crash, then the insurance will throw the claim out (or adjust a settlement in their favour :rolleyes: )
 
yes if the drivers vision was impaired from the tint, of the extra power from the decat :D had "contributed" to the cause of the crash, then the insurance will throw the claim out (or adjust a settlement in their favour :rolleyes: )
Those decats are good for like 100hp at the rear wheels right frank? :p Must cause a crash (more like skimping out of a payout yet again)
 

Stani1029

Club Member
I fit stock headlight bulbs and changed exhaust back to stock for my mot. The way i see it is that my car has passed a legit mot
 
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pollyp

pollyp

Club Member
thx for the input everyone.

yeah no car can possibly be examined every day its on the road, only once a year by law by an approved test station. for the other 364days its up to the owners trust to ensure its roadworthy.
odd that a car can be totally stock one day and at any other time of the year be completely radically different and still insured.

do MOTers note a cars spec on system if unusual? doesn't say in any sheets, its just the make model VIN miles and reg.
if not, then the insurance has no idea if the car they're insuring is what's passed the MOT, what's the point of an MOT then if it's just a false screen?

mot certificate says it relates only to the condition of the components examined at the time of test and does not confirm it'll remain roadworthy for the validity of the certificate.

I'll need to check my insurance small print frank just incase.
 
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pollyp

pollyp

Club Member
today driving to work and back as normal. pistons still bout 40% dry and 60% crusty damp but compressions actually rising :)

xgc.jpg


can't wait to replace these inlet stem seals and see if it fixes everything.
 
If your insurance was based on the mot then you'd have to have it tested daily.
Insurance relies on the v5/dvla for the correct vehicle details. Hence why people who dont register their engine changes get cheap insurance :)
 
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pollyp

pollyp

Club Member
Editing fuel map Raw values in Nistune

For people who use Nistune, there are afew rules I found when editing the fuel map which may be useful.

In the fuel map you can view the values as Raw integer numbers or estimated Air/Fuel ratio (and many other types), I preferably switch to Raw view when editing maps properly.

Here's a plot of how the integer numbers relate to the estimated air/fuel ratio.
0-128 makes it run open loop (no feedback from O2)
129-255 makes it run closed loop (allow O2 to help reach 14.7afr)

nistune Raw vs AFR 1.jpg


From 0-128 open-loop values, only the Plus key works.
From 129-255 closed-loop values, you can increase/decrease the number with both Plus & Minus keys.

You can also type the values between 129-255 (close-loop) directly into the fuel map cells at any time.
Values between 0-128 (open-loop) can't be typed into the cells.

nistune Raw vs AFR 2.jpg


The "O" key is used to toggle each selection between open & closed loop while maintaining AFR by adding/subtracting 192 (yellow region) from values that are only between 0-63 and 192-255.

nistune Raw vs AFR 3.jpg


The O key doesn't work below 192 cos the resulting value would be below Zero

nistune Raw vs AFR 4.jpg


and it doesn't work above 63 cos the resulting value would be beyond the 255 max number range

nistune Raw vs AFR 5.jpg


So if the cell value is between 63-192 and you wanna reach a lower open-loop number 0-62, first you have to increase the value up to 192 (whether by holding + or type 192 directly)

nistune Raw vs AFR 6.jpg


then press "O" key to subtract 192 = 0

nistune Raw vs AFR 7.jpg


Then press the + key towards the open-loop value you want.

Generally I think the O2 is a sort of bandaid, correcting the fuel map to reach 14.7afr when its misbehaving. A correctly tuned map should be able to produce the desired AFR on its own without the assistance of the O2.

during "tuning phase", to have the ability to increase/decrease the fuel map values freely & conveniently with the +/- keys without being disturbed by the O2:
  • first you'd have to disable the O2 (either via the feedback tickbox or ideally removing the O2 sensor)
  • tune the fuel map values using between 128-255 till you produce the desired AFR
  • select the areas you don't want the O2 to affect (open-loop regions) and press "O" to switch from closed to open-loop mode
  • reinstall & enable the O2 sensor & test everything is running as it should
 
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