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gt /3f runs rich- wont run lean


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steveo3002

my 3f conversion failed the mot today , 10% co

 

at 10% its running fairly normal , sounds and drives "okay" 

 

so i gets home and mess with the afm , i can get it lower towards a pass , but it just hates it a pops and bangs and really doesnt like it all

 

all service parts new /good , o2 unplugged,temp sender looks good on scanner , tried another afm , messed with ign timing etc  checked all i can think off , cant really get my head round why it wants to run so rich and wont /struggles near normal readings 

Edited by steveo3002
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was about -.75 bar so around 22 inches

I found 10.5 on Wikipedia, lol https://en.wikipedia.org/wiki/List_of_discontinued_Volkswagen_Group_petrol_engines   Yes, it's not awful. I'd prefer to see over 140psi and #4 is more tha

right - getting somewhere now    new /refurb head is on , confirmed it is the gt cam too   exh sounds smooth now with an untouched afm ...havent tested the emissions yet but should

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steveo3002

original ones , just back from testing /cleaning which said theyre okay

 

wouldnt mind trying a spare set if anyone can loan me some

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steveo3002

erm from memory hc 1300 ...didnt pay alot of attention

 

no codes

 

regardless of engine type ...i dont get why any engine wouldnt run at a sensible c/o mixture ..its like theres a massive air leak but theres not that i can see

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That's rather high unburnt fuel. Could it be enriching unnecessarily  because it thinks engine is still warming up?

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steveo3002

scanner tool suggests the ecu is getting the correct temp , really lost with it 

 

doesnt really sound that bad at 9% no obvious chug chug like on carb cars when you need the choke pushed in

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Ok, that's good.

 

High HC happens when timing not sufficiently advanced, can bang and pop in hot exhaust too.

Are all cylinder exhausts the same temperature?

Or is maybe one of 4 playing up.

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steveo3002

no idea on each exh temp...ive thrown pounds at this in parts and equipment trying to chase it

 

would the fact it smooths out with a few revs / richer mixture satisfy you that the internals are sound , maybe you recall i ran this freshened up abd with a carb for a year or so with no issues , so im fairly sure its still good , but im lost 

 

pops bad down the exhaust ...sounds like delboys 3 wheeler

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I'm sure piston and valves are good, but spark at wrong time (too late) for engine speed means injected fuel is not burnt in the cylinder by the crucial point of power stroke.

As you run faster ignition point has to move earlier because fuel burns at same speed regardless.

 

if you don't have an IR thermometer to point at each cylinder exhaust port you could inspect the plugs for sootiness. 

 

other ideas

Might be excess fuel pressure or another duff sensor (throttle position?)  

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steveo3002

yeah i have a wideband kit that im trying to tune it with at home

 

the rich readings are because ive made it like it ..so it ran smooth /okay

 

the real question /problem appears to be why wont it run smoothly with the mixture at normal levels

 

fuel pressure tested ok with new gauge..tps okay on scanner data you can watch it live as you move the pedal 

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steveo3002

stock polo 3f ecu ...also tried a spare one 

 

its a 1400 ( ran fine on carb)   all standard 3f inj fitted with charcoal can and hot air flap deleted /plugged off , all new good parts used nothing bodged at all 

Edited by steveo3002
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Take it the conversion included adding a lambda sensor

 

Have a few spare sets of gt injectors, i pinch orongs off them though so would need to use some.of yours

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Is there an Intake Air Temp sensor?

ECU enriching because it thinks you are in a blizzard, despite engine being at operating temp?

 

Is there barometric (= altitude) correction?

Higher you go leaner it needs to be so in the Fens of Cambridgeshire can run rich until you climb proper hills where it would be none combustible at 9:1 AFR.

(clutching at straws) 

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On 12/09/2018 at 17:47, steveo3002 said:

my 3f conversion failed the mot today , 10% co

 

at 10% its running fairly normal , sounds and drives "okay" 

 

so i gets home and mess with the afm , i can get it lower towards a pass , but it just hates it a pops and bangs and really doesnt like it all

 

all service parts new /good , o2 unplugged,temp sender looks good on scanner , tried another afm , messed with ign timing etc  checked all i can think off , cant really get my head round why it wants to run so rich and wont /struggles near normal readings 

You say o2 unplugged, do you mean lambda? 

It will run rich if it is

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steveo3002

it has an air temp sensor , and coolant temp sensor , they both check out via a meter and live ecu data

 

more i think about it , it shouts air leak but cant find anything

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inlet air leak would let engine race and run lean with throttle closed. Then lambda sensor (once up to temp from its own heater) would make ECU enrichen longer pulses to reach near stoich at idle, not to overcompensate and go rich.

Are you running the wideband kit with a slave 0-5v or 0-1v narrowband output to the ECU or do you have 2 lambda bungs and sensors?.

 

exhaust leak will ruin feedback accuracy.. but you would hear it, spot the soot at a joint..

Edited by dvderlm
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steveo3002

lm1 wideband kit with controller ..fitted instead of o2 sensor

 

im saying the engine will only run nicley when set rich by me ..ive made it rich so that it runs "okay"

 

the issue is with the afm set back to standard and co levels in a sensible range its unhappy.....the air leak thoughts was standard amount of fueling + extra unmetered air = pops n bangs in exhuast   , richen it and theres enough fuel to mask the air leak 

 

i dunno...happy to listen , if i knew what was wrong id have fixed it by now

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steveo3002

maybe thr title /description is bad

 

car pops and bangs through exhaust and wont idle well , unless i severly richen the mixture?

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3 minutes ago, steveo3002 said:

fitted instead of o2 sensor

But how does the ECU do closed loop control?

 

I can understand AFM needs a small tweak to.adjust for 1400cc versus 1272cc (9% capacity), but cylinder filling is very poor with throttle closed so that might need more ignition advance instead. Without you get unburnt fuel high HC. 

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steveo3002

im not running closed loop ...other owners confirm it should run well enough without (better than it does )  my mate has the same car and it runs well with it unplugged

 

if and when its sorted it will be connected and used , but the basic map should be near enough for now

 

when i have had it connected it does what it should...tries to bring the co down to the correct level ...then as ive mentioned for some reason the car doesnt like it and likes to run rich

 

ive tried ign timing all over the show , seems to run best around the stock settings 

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