Hi all

Ive noticed my car seems to run very rich when starting from cold.
The car is never difficult to start, even when its icy outside the garage.

What sort of AFR should you be seeing when cold starting?

EDIT: forgot to say. i wanted to know AFR at IDLE. when starting from cold (if there is an ideal?)

I know this is a job you only really get one go at per day LOL.

the car is on aftermarket managment, so can be adjusted easy enough, just wanted to get this side of it sorted. cheers!

 

you need to get a lamda sensor on it and see what af ratio it is seeing then adjust accordingly, as you say you'll get one shot per day.

you can buy kits that will read af ratio that seem cheap enough could try one of then

 

Every engine is different and it depends on the inlet runner design and how fast they warm up to a temperature that atomises the fuel correctly so we dont have to literally waste it to get enough in the actual cylinder. Cams and headwork tend to make this problem much worse as lower gas speed does not bode well with cold runners and fuel that doesnt atomise properly.

Aim to get as close to stoich that the engine design will allow, but on most engines you are likely to be running between 12.5 and 13.5:1

 

Jimbo. yeah have access to a wideband and display. thanks!


Stu, i didnt realise every engine was SO different!
yet another aspect of mapping that is way more complicated than it first seems then LOL
will try and get it a little better tomorrow morning if i can.

thanks guys!


Ps; can possibly see now why a few cars ive seen on aftermarket managment dont like starting from very cold!

 

would it make it easier to start if you ran a really low ign value ‹800rpm aswell, something thats only seen on crank over..

not sure on the effect tbh

 

would that only have an effect when actually cranking/starting the car?

 

yes, as you never idle below 800rpm...

 

Phil,
Dont forget, any ecu will have seperate cranking/starting enrichments too as well as the cold start ones !

 

Simon, yeah ive been looking at the enrichment tables on the map... not that im gonna change anything lol.
leave that for someone who knows what they are doing lol

 

Phil, I should have added that some of the starting parameters decay with time after the engine has started so that may influence AFR when you dont expect it to.
Although generally I have never seen these go beyond about 60 seconds.

 

 

thanks guys!
will leave it well alone! LOL

 

Phil, the problem is cold start mapping, you only get ONE chance to do it as the engine warms up and the inlet is wetted with fuel.

This is the most time consuming and difficult part to get right. Getting power is easy ..LOL

Its also the hardest to measure as you would need to data log the whole warm up cycle so you could make adjustments.
Doing it live is a bit hit or miss as your engine is warming up as you make adjustments !!!

I would start by taking off a small percentage (say 10%) of each value in the cranking table and wait till next time its cold and see if it starts nicely on the first start.

 

yeah i can see why some tuners dont wanna bother with doing the cold stuff lol
like i said in first post, you only get one go at it per day! lol

 

The best advice.... Keep the laptop with you for the next year or so....

 

I found on mine I needed to increase the decay time considerably.
Just go to F8, look at temp on screen, then go to idle control make sure idle stabilisation using ignition advance is ENABLED, as this helps a lot.
Then go to inj corrections and note the values of each that you need, then you can adjust on F8, as this will have a LIVE effect, so say it responds better with 15 more on injection, look at temp and then you can add that to the table for injection correction versus temperature.
Do this on one map, that you can have as your play map, leave one std as it is, so you can always go back if necessary, if only using one map, get a switch so that you have THREE, and move map into all positions, to start with.
tabetha

 

You are about to discover why we ideally want a car with major mods for a week to live map it when other propose to do as good a job while you wait.

We not only make sure it starts and runs ok, on days 4 and 5 we make sure you can drive it in traffic stone cold too. Turnkey, handbrake off, drive.

 

The first thing i work on, is getting the engine to fire from cranking as quickly as possible, even if it then dies straight away - you can then leave the cranking pw alone for that temperature. Remember you need your warm idle perfect before you start messing with enrichmets. Set them high initially, so that the car starts and you can get it warm - then each day you tune, attempt to get the cold idle as lean as possible.

Rick.

 

Agree Stu, and i'd say in a week you are doing damn well!

 

Mine starts first time, but agree with stu, in an ideal world would be left, as I am just up the road(and left car) a few times for a tweak, perfect now.
I suppose this must be the hardest bit ?
Tuners do bloody well considering how long a manufacure takes to do ecu's etc in all climates.
tabetha

 

Yes it is. So many Cosworth's out there with Idle that hunts up and down or revs its nuts off cold because the mapping is garbage its unbelievable and one of the things that has given the YB scene a bad name as outsiders looking in just see these horrid smelly old Sierras and escorts that don't even idle when cold or the owner cant drive unless its flat out because they hesitate and jerk.

Making one fast is child's play and anyone with a little mapping skill can get reasonable results. Making one drive properly and return decent fuel efficiency is where the skill comes in.

Its also of critical importance that people understand this:
Those with no understanding of an engines needs will almost never get a car to drive right or be efficient, especially when cold. Laptop skills do not enable you to map.

 

I have a problem with my cold start on an old clio F7R aswell

Basically, having difficulty starting it from cold, and it does pop out the front and back when it's hot. Takes about 10seconds to start from cold, normally miss fires for 5 or so seconds with abit of throttle it clears. Very predictable and i'm sure it's down to the map.

So i'm currently looking at the KMS firmware in the startup field, this is what i'm faced with...

(sorry it's a picture taken by my camera as the laptops not on the network atm)

This sucks. I've had enough of putting up with this problem. Anyone fancy putting in their thoughts on the cold start map setting above?

 

What size injectors are you using ? Is it turboed ?

 

It's N/A, throttle bodies, 2068cc, 12.5:1 compression ratio, 278* 11.5mm lift cams, 330cc (iirc) injectors

 

I dont suppose you know the fuel pressure and if its sequential or banked injection ?

Also, can you get a picture of the warm up correction table.
This is the table used for normal running.

Sorry to ask for more info but I typed my last post too fast to think properly..LOL

 

Unsure what is meant by sequential/banked injection. Fuel pressure was 4.2bar iirc

A shot of correction table...



Just so you know, I have no map sensor obviously and no air temp sensor so ignore those mate

 

I will download the KMS software tomorrow have a look for you

I think I can see the problem but want to be sure.

 

thanks Simon!. Lordy is another local boy

 

I found out my ECU runs full bank fuel injection too cheers pal

 

have you had any time to have a look yet Si?

 

Yes had a look,

I reckon ALL the values in the start up crank rotations enrichment table need halving.
(The black on white data fields in the very first picture but not the start up pulses.)

 

my 1.8 xr2i runs rich all the time its bad when its cold if you try and drive at 30 it cangaroos and the mot station said the emissions are worse than my bosses v8 landrover.
but its had all the rs1800 top end throttlebody,ecu full magnex exhaust and a k&n filter i was told it had a chip too but im not too sure how to check.
would a remap be good for mine to help it run a bit quicker?

 

Fez,

A remap will always gain more power and reduce emissions.
Only a few can map the original managment properly. (if you still have it)
It will be the best thing you can do for the car as it will transform it !
(Not cheap at about Ł400 - Ł500 for a proper pro job but well recomeneded )

 

i want to try and save for some throttlebodys (i heard a rs2000 with them on) it sounded like thunder but i dont want to spend shitloads of money as ive got a house and baby to pay for but i need to get it running better because it cuts out on the misses never on me thoe and she keeps winging on about the steerings heavy and she preferred the escort gti,s i dont know weather to get rid and get a rs2000 or stick with it and put p/s on it and spend on the engine

 

Superb! it's vastly improved cold start. Took around 3seconds to start and only had a slight miss fire for no more than 3seconds. Altered all the crank rotation sites as stated and got her up to 50*C where it would normally back fire on crank and it started faultlessly. Minor adjustments to ignition advance for a stronger idle and it just sits there humming a nice cammed note Excellent Si, thanks for your time!

 

Nice one Simon

 

An example of how PF can be SUCH a good site when it wants to be!

 

Ahh excellent. I would take a small bit more off each still as the fuel pressure is quite high.

 

Thanks again mate so happy it starts so well. Will reduce figures slowly to find a decent balance now that I know i'm heading in the right direction

 

Nice one Simon.