Car Performs Better After 2-3 Min Idle Warmup

[DuFFR32]

I have same probs as my above post states, Im leaning towards the ecu being in a cold start mode, but that being said it dosnt always go into this mode. so it buggers me as to why it does it lol maby i could ring nistune n see if it could be fixed with a tune

Di disconnected the battery yesterday n turned ignition to ON n pumped the brake pedal a few times to try reset the ecu. will see how i go when i drive to work in a few mins

[stolen-gtr]

As a matter of interest what type and viscosity oil are you using?

using motul turbolight 10w40. have tried penrite hpr10 10w50 extra ten, which says its for use with 10w40 situations... same problem still occurred

will be interesting to see what result DuFFR32 has. i might try that too just to see if it in fact was a coincidence.

Edited October 6, 2010 by stolen-gtr

[stolen-gtr]

Yeah for sure, it would be interesting to see what causes this as I'm pretty sure that those ECU's don't learn. You don't seem to be the only one experiencing the symptom though. What are the theory's behind disconnecting the battery and the effects its meant to have?

I tend to agree that it may be placebo effect, but can't really say without experiencing what you're saying.

Cheers Matt.

Interesting that you say that the rb20 ecu's dont learn, ive heard the exact opposite

I can only guess and say that disconnecting the battery resets something in the ecu and makes it 'work properly' for a few starts. i will try to confirm this

i can tell you its definitely not a placebo effect, i understand what youre saying but i can assure you it is happening.

[DuFFR32]

reseting ecu did not fix it I also suspect a dodgy O2 sensor in my car as its leaning the mixtures out when in cold start mode and making it cough and backfire while making next to no power and wont rev when i disconnect o2 sensor it goes alright

[DVS JEZ]

02 sensor is in open loop when cold right? so shouldnt be affecting it

[DuFFR32]

yeah it is in open loop when cold so i think my o2 sensor is buggered I will unplug it tomorrow morn before I drive to work n see if it was the same as this morning

[YawRate]

yeah it is in open loop when cold so i think my o2 sensor is buggered I will unplug it tomorrow morn before I drive to work n see if it was the same as this morning

I'm with DVS32R, I thought when in "open loop", the signal from the o2 sensor is being ignored, therefore it shouldn't be the culprit.

For reference, an open loop control system is one without feedback, the outputs a direct function of the inputs. A closed loop control system is one with feedback, the outputs a function of the inputs and the feedback. In the case of the skylines ECU the injectors outputs (amongst other outputs) are subject to the o2 sensor signal (feedback), but only when its running closed loop, ie. at low engine loads and not on cold start enrichment as far I understand.

[mattymagoo22]

I'm with DVS32R, I thought when in "open loop", the signal from the o2 sensor is being ignored, therefore it shouldn't be the culprit.

For reference, an open loop control system is one without feedback, the outputs a direct function of the inputs. A closed loop control system is one with feedback, the outputs a function of the inputs and the feedback. In the case of the skylines ECU the injectors outputs (amongst other outputs) are subject to the o2 sensor signal (feedback), but only when its running closed loop, ie. at low engine loads and not on cold start enrichment as far I understand.

Yeah thats right when engine is at normal operating temp, under light throttle and cruise conditions it with use the O2 sensor as an input(closed loop).

[r32man09]

hi all

Ive just recently noticed that in the mornings if i let my car idle for 2-3 mins before i drive it, it performs as it should.

If i drive it straight away or within about 30 secs of starting it...it is quite sluggish...sounds more raspy and really have to plant it to get any sort of boost

I was wondering if maybe its not coming out of "cold start" or something to do with the thermostat but i have no idea hence the question

any help would be greatly appreciated as its driving me nuts haha

thanks

Hey

I have the same problem i just let mine warm up for atleast 5 mins

[stolen-gtr]

Hey

I have the same problem i just let mine warm up for atleast 5 mins

hey Ryan long time no see haha

the most annoying thing with mine is that some days it will be fine from the word go, and some other days it will remain sluggish even after its fully warm

wish i could find out why it was so intermittent...

[Birds]

Without getting into a debate about whether warming up your engine is a good/bad thing, you WILL notice a difference in the feel of the car after warming it up and there will also be a difference in power. Reason being is that oil is significantly thicker when cold, creating more inertia / resistance against moving internals...which also have looser tolerances when cold. This creates a feeling of roughness. Note also that despite "instant" oil pressure, oil still takes some time to circulate through the entire engine. So it is not really a placebo effect, most engine wear occurs during startup and cooldown for these reasons - this is also why taxis get so much mileage out of an engine, as it is seldom allowed to cool for a given number of km compared to your typical daily driver.

Personally I warm my car up for about a minute or two prior to driving it...but this is just to get some circulation happening and settle the idle. Be aware that your engine will become warmer in 2-3 minutes of driving than it will in 5 minutes of idling, so there's really no point leaving it too long to warm up...it will just be spending longer in a "cold state" which some would argue is more detrimental than just getting in the vehicle and driving it.

[stolen-gtr]

thanks for explaining it like that Birds very useful

can you suggest a reason why on different days it reacts differently from a cold start?

might be a long shot, but would the temperature of the oil initially have anything to do with it? (could it vary enough between days to make a significant difference?)

Without getting into a debate about whether warming up your engine is a good/bad thing, you WILL notice a difference in the feel of the car after warming it up and there will also be a difference in power. Reason being is that oil is significantly thicker when cold, creating more inertia / resistance against moving internals...which also have looser tolerances when cold. This creates a feeling of roughness. Note also that despite "instant" oil pressure, oil still takes some time to circulate through the entire engine. So it is not really a placebo effect, most engine wear occurs during startup and cooldown for these reasons - this is also why taxis get so much mileage out of an engine, as it is seldom allowed to cool for a given number of km compared to your typical daily driver.

[Birds]

Yes ambient temperature where the engine/car is stored will affect the viscosity of the oil. As an example, in some vehicles and climates people run 15w40 in winter and 20w50 in summer to counter the effects of hotter ambient (and therefore running) temperatures and maintain a similar engine oil viscosity all year round.

As far as ease of starting, cars are often more difficult to start in winter for a variety of reasons - components stick, there's more resistance to the engine kicking over, oil is thicker, electronics sometimes don't work as well in lower temperatures, air is denser (requires richer mix to start and idle initially).

If you have left your car for a couple of days without starting it, it will feel different to starting on a daily basis because the oil has had more time to drain down into the sump. There are more reasons for different starting and feel, I'm just not enough of a whiz in physics and chemistry to explain them all lol - but yes, time between last start and temperature at the time will affect it.

[stolen-gtr]

okay well if it is to do with that, which it could be now that you have explained it like that....i guess theres not really much that can be done about it. but now i realise why it happens ill be able to accept it, its just when it feels different between days for no apparent reason i wanted to find out why haha.

thanks birds!

Yes ambient temperature where the engine/car is stored will affect the viscosity of the oil. As an example, in some vehicles and climates people run 15w40 in winter and 20w50 in summer to counter the effects of hotter ambient (and therefore running) temperatures and maintain a similar engine oil viscosity all year round.

As far as ease of starting, cars are often more difficult to start in winter for a variety of reasons - components stick, there's more resistance to the engine kicking over, oil is thicker, electronics sometimes don't work as well in lower temperatures, air is denser (requires richer mix to start and idle initially).

If you have left your car for a couple of days without starting it, it will feel different to starting on a daily basis because the oil has had more time to drain down into the sump. There are more reasons for different starting and feel, I'm just not enough of a whiz in physics and chemistry to explain them all lol - but yes, time between last start and temperature at the time will affect it.

[simpletool]

Apart from the oil situation - yes it is more viscous - which actually gives you MORE oil pressure. (but oil pressure certainly isn't the best gauge - it is more the result of resistance to flow).

Anyway....hmmm....RB20 Nistune very sluggish at cold start but variable depending upon the solar wind (or temperature, or whether your level of guilt or horniness or whatever is you thang)

Possible because the timing in the table "warmup timing" is too conservative. Or the enrichment tables of which there are 3 might be too rich or very different between them so when they switch there is a marked difference......After start enrich, cold start enrich, warm start enrich....although not sure how many of these are used with RB20.

[simpletool]

In any case it probably is repeatable.....but you just need to know the right variables. And well.....it's not a ghost in the machine.

[Birds]

okay well if it is to do with that, which it could be now that you have explained it like that....i guess theres not really much that can be done about it. but now i realise why it happens ill be able to accept it, its just when it feels different between days for no apparent reason i wanted to find out why haha.

thanks birds!

This will always be more obvious with sports car engines than daily drivers because they are tuned and built differently. Also, another variable is a manual gearbox...clutches and gearbox oil need time to warm up too. Automatic transmissions have their own cold issues too, but from my experience don't feel as rough when you drive off first thing in the morning because it's a different setup with less variables affected by heat and human interaction.

[Rolls]

Get a consult cable, run ECU talk and log the ignition timing values in both situations. I had similar issues with two cars, seems almost like it is getting stuck in the low octane/knock/cold start map where it pulls timing and makes it richer, for what reason I don't know.

It is possible that it is detecting knock when warming up for some reason and changing maps, you could have a dicky temp sender also.

Need to do some datalogging to find out why it is getting slower then you need to trace the cause of the low ignition timing or running extra rich, anything else is just guess work.

[stolen-gtr]

Get a consult cable, run ECU talk and log the ignition timing values in both situations. I had similar issues with two cars, seems almost like it is getting stuck in the low octane/knock/cold start map where it pulls timing and makes it richer, for what reason I don't know.

It is possible that it is detecting knock when warming up for some reason and changing maps, you could have a dicky temp sender also.

Need to do some datalogging to find out why it is getting slower then you need to trace the cause of the low ignition timing or running extra rich, anything else is just guess work.

hey Rolls, thanks for that info. since its a nistune modded ecu it has a usb consult, so i could just find someone (a tuner) with the software and get some data logged like you said.

but i tend to agree that it seems to be getting stuck sometimes the wrong mode. it just feels TOO different to just the ambient temperature or something like that...

[Rolls]

You need a laptop plugged in when driving to log the data, if you take it to them it is already going to be warm, that plus you have to pay for it. Just get a cable and do it yourself as the software is free.