i see quite a few people with cold start issues on their impreza and it seems to be once they have been mapped.

my last impreza once mapped developed a cold start issue where it would pump out white smoke for around 7-10 seconds then fire up-if i were to pump the gas pedal it would make it worse.my current impreza had a cold start issue where as it would run really really lumpy for maybe 5-7 seconds almost as if it were running on 2 cylinders and really stink of fuel.i had paul @ zen check the map and he altered the cold start function and its a hell of a lot better now.

with both cars once warm they started fine.

is this a mapping issue?

is there a component that doesnt work so well once the car is mapped?

both my impreza's were worlds apart (2.0 sti8 engine in wrx/forged 2.5 in blob sti)

discuss.......

 

Mines never had any issues and hasn't had the standard map for years,emmas wrx never had issues either and that was mapped too.
Personally I wouldn't worry about a 10 seconds after start up issue of its been checked by zen.

 

it was more of a case of not trusting it to start and being stranded somewhere that bothered me,this one developed its issue when the outside temp started to get low and my old impreza did it in summer and winter

just seems strange so many people have cold start issues

 

never had a problem with either of my mapped cars either bud. i had a classic wagon running 315 bhp and now have a bug sti mapped as well and start ups are spot on, and i live in bloody freezing jockland as well.

 

As it was explained to me one time, a mapper only has one chance to get the cold running right usually, that's when the engine is cold, so any cold start issues can only be addressed in a subsequent mapping correction.

 

Never had any cold start issues on any of my mapped scoobs and the mapper never had any of them from cold

 

I Me too.
Mine was mapped on rcms rr straight after driving 30 odd miles there.

 

Mine starts straight away when cold but drives lumpy till temp gets to about 40-50 degrees

 

Yeah my mapped bug is the same little hesitant when cold but always fires up, momentum made it seem better for a couple months but I'm used to it now. Also lumpy for the first 1/4 mile then smooths out absolutely fine once warmed up.

 

I think a better question would be why would mapping a car change the idle ?
I cant see how or why when they remap your car it would need the idle touching, or anything relating to it.

discuss

 

This.

It's definitely a mapping issue.
It can be adjusted properly by leaving the car for the cold start tweak in mappers hands for a day or 2.

 

Could it be down to when mapping the tuner uses a wideband lambda for closed loop tuning,so when the car is handed back and uses the oem narrowband for the closed loop which is less accurate then this in someway affects cold start/idle/light cruise?
Just a thought?

 

I'd say it occurs when changing injectors etc.
Probably not such an issue on a standard car with just a remap

 

I don't think the context has been set correctly here.......

If you have a decent OEM ECU, that is mapped appropriately to your set-up, I doubt very much you would ever have an issue with cold start stuff (this never normally needs to change).

If you move to an after market ECU...... this is when the cold start mapping needs to be done, as it will ideally need to be set appropriate as per your specification. As already alluded to, this can only be "tested" on first cold start cycle. This is where the problem is, as to re-test you need to go through the whole cycle again....... this can end up taking days if you don't know what you're doing.

 

Point well made

 

Having suffered intermittent hesitant cold starting for years I discovered the 'stick on the throttle' trick and have no problems since (wedge the throttle open with a stick when leaving the car after use - ventilates the manifold/head. Remember to remove the stick when starting the car next time!) I know this isn't the correct cure, but for me and some others on here, seems to alleviate the problem. I originally thought it might be a dribbling injector but there's been an injector change some while back and it remained the same!
The use of the wideband sensor (as mentioned in a post above ) is to set AFR in the open loop stage when the engine is in boost, so would have no effect on the cold start regime even though the cold start part of the map is also open loop.
The cold start settings are usually ignored by mappers as the engine is usually way out of that stage when they receive the car for mapping.

JohnD

 

More to the point your mapper is Paul blamire ,ask him as he would know more than the rest of us put together x10

 

As Shaun points out. The requirements for cold engine operation and starting is different to running temperature. If this isn't right, then engine won't run right or be difficult to start.

Oxygen sensors can't be used when cold, so the ECU will run open loop, so it has no way of identifying over or under-fueling.

A cold engine will typically need the injectors to open longer, and the timing to be retarded along with teh idle control valve to be open more to hold a faster idle and account for the different timing. Thats the basic rule. But a factory ECU on bigger injectors and higher fuel pressures may over fuel if this hasn't been properly accounted for, an aftermarket ECU may do either depending on who has messed with it. Remember for a mapper to properly know how well a engine runs from stone cold, it must be stone cold. As in left to stand overnight, prerably outside...in winter. If the engine has been started a few hours previously, it'll be too warm.

You should never need to use the accelerator to start the engine in a EFi equipped engine unless it has some nutty camshaft profiles fitted (which Imprezas don't). So if you do need to give it some throttle, it ain't right.

A bit of lumpy running for the first 10seconds is generally acceptable. But it should still maintain a steady fast-idle (1000 to 1500rpm) and shouldn't hunt or try and stall.

 

Pauls mapping it again next month as I have a different induction kit/injectors to be fitted

 

Yer this is exactly the issue I'm having, identical to this.

Mapper wants me to take to Surrey Rolling Road to look at. But surely this will mean the car will be warm when he looks at it, so I might ask that he see's the car stone cold.

I'm almost certain its a map issue as pre map from stone cold it started fine.

 

Shrek you have a PM mate

 

Ali B and Shaun have covered it.
To add -
If you are running a Simtek ECU
They do not have closed loop idle and are very hard to get the idle right and can also take a couple of seconds to find there feet before they fire the engine into life

What ECU is it Shreksta?

 

newer ALKATEK ECU's (or original SIMTEK with the upgrade package) all have consistently good idle ability and cold start

 

Yes, I had my SimTek upgraded and the difference is like night and day

 

Just a standard blob sti ecu/forged 2.5/gt3071r/power enterprise 650cc injectors etc

 

Emmas wrx
Ive seen You both- unless it was Yours mother ,she could not fit in sti , im sure she would not buy wrx than , she needs wider car access

 

your made up posts make you look more stupid by the second

 

I think you need glasses as i have met emma and she is not big at all. If your going to abuse somebody the least you can do is state the truth.

Go and learn to read/write/spell aswell whilst your at it

Sorry I mean.......go then learn to reed/write/than spell aswel whilst than your are at then it........

 

this was kind of the point really, sniffing magic trees obviously makes you crazy.

 

I'm not sure it is magic trees they give away at immigrant washes as the ones I've seen are smiley faces that smell of oven cleaner