mapped imprezas and cold start issues
08 February 2015, 09:41 AM
#1
mapped imprezas and cold start issues
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.......
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.......
08 February 2015, 09:51 AM
#3
just seems strange so many people have cold start issues
08 February 2015, 09:54 AM
#5
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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.
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08 February 2015, 10:51 AM
#12
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?
Just a thought?
08 February 2015, 11:13 AM
#14
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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.
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.
08 February 2015, 11:16 AM
#15
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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.
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.
08 February 2015, 12:01 PM
#16
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
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
Last edited by JohnD; 08 February 2015 at 12:06 PM.
08 February 2015, 12:40 PM
#18
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.
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.
Last edited by ALi-B; 08 February 2015 at 12:43 PM.
08 February 2015, 03:01 PM
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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.......
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.......
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.
08 February 2015, 04:16 PM
#22
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?
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?
08 February 2015, 04:28 PM
#25
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?
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?
08 February 2015, 05:41 PM
#28
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........
08 February 2015, 05:42 PM
#29
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........
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........