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Lawrence martin

iat correction problem

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hi my tuning is now going well! but have come across another problem, as it was a nice warm day today i was seeing inlet temps of 30 degrees and it needed adjustment on the iat table however as the temps went up the afr leaned out needing me to add more fuel not take away, i always thought (and the help menu confirms this) that higher temps means thinner air which needs less fuel is there an easy explaination for this (ive had to add 7% at 40 degrees to keep the idle at 14.7

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Adding fuel when the IAT increases is not correct, something else is wrong...

Here are some things to check:

  1. Check the location of the IAT.  Ensure it is measuring the actual air temp entering the cylinders as best as possible.  Make sure that heat soak is not causing a misleading reading.
  2. Check the calibration of the sensor is correct.
  3. Check that your tune is correct at the temperature where you have 0% IAT correction (eg 20 degrees).
  4. Make sure that at the temperature the engine normally runs (ECT) there is no warm up enrichment.  Otherwise if the ECT increases at the same time the IAT increases then you will be adding IAT correction to compensate for the removal of ECT correction.  Ie at temperatures above about 70 deg there should be no need for warm up enrichment.
  5. Check ALL other factors are the same.  If only IAT increases then only IAT correction is required to correct the AFR.  But, if ECT is also changing, IAT, engine RPM, fuel temperature, engine load etc... then changing IAT correction is not the correct thing to adjust!
If you cant get it sorted then you should probably get the car tuned by an experienced tuner as having to add fuel suggests there is another problem somewhere...

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Hi thanks for the reply my iat is located in the intercooler pipework just before it enters the manifold which is the recommended place on the gtr it was supplied from link so should be good. All warm up enrichment is off when it happens. Unfortunately I can't measure fuel temperature but this may be the issue as i have braided fuel hose but if you sit at idle with it fully warmed up you can see from 30 degrees to 35 degrees iat it becomes leaner by 1-2 afr you can hear the change in the engine also. My main issue with the experienced tuner bit is there are very few in the uk that ARE any good and many who claim to be and they are along way from me it should be something I can fix myself I will check sensor calibration tonight

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hi martin thanks although i struggle to find time during the day is evenings or weekends ok? i went to work in my car today this morning at 7am iat were at 15-20 idles at 14.7 afr spot on on the way home at 5.30pm iat started at 20 14.7 afr then up to 30 and afrs up to 15, between 30 and 40 (sitting idling) afr changes from approx 15 to 16, coolant temp is ranging from 65 to 85 going up with iat no ect correction is active iat temp sensor is calibrated correctly but there is no iat correction at these temps at idle anyway ect sensor is not calibrated correctly i have ordered the bosh unit but cant see how it will fix it as it reads 65 at 65 and 68 at 80 both positions where there is no correction the problem only really occurs at idle driving it behaves pretty much as it should do

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Sounds like the sensor might be suffering from heat soak.

On the IAT correction you have the option of trimming the correction at idle without effecting the correction at larger throttle openings.

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hi ive installed the bosch coolant temp sensor and that didnt fix it, is it possible that its an injector lag problem? maybe that the spray pattern is not correct and the temperature cause it to atomise early? i use sard 700cc had them cleaned before installation and all are ok and the lag time is set to 0.95ms the manufacturers time wouldnt even let it idle, im wondering trying to bump this up a bit more and see if it makes a difference again there is no correction active on the warmup or iat tables (so really the sensors arnt doing anything apart from reading) i do remember when i had the pfc installed it did idle at around 17afr, i thought this was the pfc leaning it out to get the correct idle speed (as it always ran really smoothly at idle) but maybe more is going on than i thought?

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well i played around with injector lag yesterday and no difference however studying the run times has revealed that the voltage from the tps lowers with the heat going up, im guessing meaning that the ecu tries to remove more fuel giving me my lean issue it starts at 0.8%tps and 0.41v to 0-0.1% and 3.9v at 35degrees if i slightly hold the throttle open and recreate the 0.8 with my foot then the afrs look ok, now i just have to work out why its doing it, im guessing an engine earth problem for that sensor, as all others look ok

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if im suffering from heatsoak what can be done about it? as when i leave the car for half hour then go back to it the afrs are really lean 18-21 as the iat is around 40-45 much leaner than when reaching the same temp on idle then a quick drive and all lowers its ok the weird thing is i never had this with the power fc and my setup is the same except the link

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"the weird thing is i never had this with the power fc and my setup is the same except the link"

" i do remember when i had the pfc installed it did idle at around 17afr, i thought this was the pfc leaning it "

Has the vehicle been tuned on a dyno at all?

do you have any data logs of the dyno runs and also this leaning out ?

Send through your map and a discription of your setup and i will have a look through it  for you

if you would like

Regards

Dave

dave@dtechmotorsport.com

www.dtechmotorsport.com

 

 

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Hi Lawrence

I have had a quick look over your map and i believe you are not suffering from heat soak

but suffering from an incorrectly mapped engine

trying to tune a multi throttle engine is a tricky thing especially if trying to do it yourself  with minimal experience

i would suggest get it tuned properly by someone experienced in this type of mapping

or if you are determined to do this yourself  I would change the mapping mode to MGP on main load axis and then maybe set a tps map as over lay as you may find this easier to get your head around.

trying to tune with tps as main map needs access to a GOOD dyno that can hold the vehicle steady and go through the load sites at one particular rpm get this right first with no map overlay  then tune the map overlay to fix driveability this includes idle load fluctuations like you are seeing

Regards

Dave

dave@dtechmotorsport.com

www.dtechmotorsport.com

 

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Hi dave thanks for looking at my map I also have a log now if you want me to send it to you I am pretty determined to sort this myself every tuner to which I've been to before charges a fortune for a not 100 percent map which I understand as different variables cause different results which may not be reproducible in the setup they have/use also I can't really afford to spend 100s of pounds on trying to sort this issue The way I have setup My map was recommended to Me by Simon off of here I'm Not sure how much I can change to be a mapping fault unless it's a setting I've Missed surely it's just getting that cells fueling correct and timing correct ESP at idle what more is there to do apart from stuff such as the iat control which really i shouldn't need to use at these temps I'm sure you know what your talking about and I really thank you for your help I'm just not sure what I need to change to sort it out ( I did try mgp but without 4d activated and It behaved the same as tps as per the fault, is it your thought that there is a slight variation in mgp that needs sorting at these temps then using the tps to ovelay?) Again many thanks I know Osborne critical it's just that the rest of the map makes the car drive great! Regards Lawrence

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ive been out today to try to fix this issue, i am sticking with tps vs rpm for fuel table 1 as i logged it happening and it seems to be very small fluctations in mgp causing the issue, especially after turning off vehicle then restarting after a couple of mins so i setup up 5d fuel as a mgp correction spanning it from -70 to -30 and rpm from 500-1200 the areas where idle is are roughly in the middle, i then logged and adjusted to get the right values it took absolutley ages but it seems alot better i still had to remove 6% of fuel at 20 degrees but at 30 and 40 degrees its all good with 0 adjustments on the iat im not sure why i had to remove the fuel there but it was making it too rich below 25 degrees after adjusting the mgp values when iat warmed up over 25, air temp def affects it somehow as there is still no warmup active at these values

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mate excuss my bluntness :   Dave from Dtech and myself tune these cars in our sleep 24 / 7 .  The guys at link (Simon) use him and i and also some  others  to help with problems like this,

Dave worked for link and helped link  develop this ecu please listen to him as he is 99.99% of the time correct ( i know as i use him too at times )    

where is the o2 reading being taken from? is it the exhaust near the turbo or at the back of the car ? what is the battery voltage doing and at the same time what is the ecu and voltage doing at the fuel pump? what is the fuel flow doing and has it got good fuel reserve, how close to heat does the fuel rail run. what is the dwell timing, what has the injector timing and dead times been set to, does the water and or air temp increase with revs at a unreasonable rate ? is it running a plug and play or wired in ecu ( factory looms have major earth issues that need rerunning somtimes to be any good, what model car  as these are all faults that can cause the problem you are having  and easily checked by a good dyno shop

cheers Ross Honnor

 

dobsons99@xtra.co.nz

www.dynotune.co.nz

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thanks for the reply, be as blunt as you like i wont take offence, the reason i stuck with tps is that ive spent alot of time on it and did try mgp briefly but it still acted the same i will bin my map and start over, i just found tps easier to understand than the mgp then a tps overlay the o2 sensor is in the decat silencer which is after the downpipe, the car is an nissan r33 gtr, fuel flow is 3bar idle and runs a split feed to a sard fuel rail, never less than a quarter of a tank, the ignition dwell timing is set to 1.7ms they are splitfire coilpacks but i cannot find the dwell timing settings anyway for then apart from they are 1.7ms at 14v injector dead times are set to 0.95 and timing ids set to 400degrees they are sard 700cc with the standard timing of 0.65 ther car barely runs( i am thinking of changing these to the injector dynamics 1000cc's) its an xtreme ecu using adapter link and ive run a earthing kit in the engine bay, water and air temp stay solid air temp goes up at idle down when driving coolant always at 67 degrees when warmed up (using bosch sensor), fitted a new battery fuel pump has same as battery voltage as ive bypassed the fuel pump speed ecu to give it full 12v constant the reason i want to do this myself is that i find it very interesting for one, ive done all the work on the car myself and want to ideally keep it that way, also ive used 3 tuners before and all 3 have had great reputations, the tunes were to say the least, alot worse than ive been able to do myself this has cost me about £400, each time and has been a waste of alot of money i am very very reluctant to spend this again especially as ive just moved house and am getting married next month (so money is short) eveyone has to learn somehow i even assume the professionals need to learn by trying things themselves!

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one more bit of advice is needed if you would be so kind! i assume the tps overlay is needed for different gears as you can hit the same mgp with different throttle positions due to being in the different gears, so my question is this which is the best gear to do it in? if i was to use third is it best to use very light throttle to get the smallest opening of the throttle as poss then use the tps overlay to correct up and down when using the other gears to be honest i found tps with mgp overlay easier to understand!

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give me you email address i will send you a map of a customers gtr to look at it may help you  it runs e85 fuel but should give you a good idea of the map shape

if tuning on the road i would drop the boost back to say 8- 14 psi keep it nice and low and stable (spring pressure is good )  after all the base timing checks bla bla bla are done set a base map like the one i will send you then turn off the mgp over lay ( i use tps with mgp when road tuning as it is faster and easyier on the dyno i go the other way but thats just me. you choose what way suit you ) run the engine up in third gear slowly adjusting the main fuel to suit you mixture lets say 4000rpm 8psi full throttle 11.7 afr make the 80% 90% and 100% rows the same just so its easy make sure that the accel tps is lifted to at least 3% so it wont upset your tuning  also turned off when doing road tuning  then run at  2000 rpm set the three top load cells (ie 80 90 100% load cells) carry this on right up to approx 6000 - 6500rpm you will then see that the numbers will start decreasing the higher it goes from this point normally two whole numbers

then repeat this process for the 70 to 40% throttle range use 12 afr for this area 

after this do the light throttle area still using third gear tho use 13 afr for this

once this has been done start tuning the 4d table, completete this the same way but you can start at a low rpm and work your way down the map after this is perfect then bring the timing up rule of thumb is 8.5:1 compression 14psi 6000 rpm 16% timing with 96 octane fuel (in new zealand anyway) and every 2psi take out 2deg of timing you will see this in my map

when you have sort ed this then you can start bringing  the boost  up  but dont change the tps map EVER if you do start the process again from the start   ( this suxs ) take your time and if you think this is easy it isnt it takes time and always watch the knock if you can        

then bring in your accel etc to finish off the job

hope this helps

ross honnor

dobson99@xtra.co.nz

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Thanks so much ross that is awesome my address is martinloz80@hotmail.com I was just doing the mgp map as well I will switch back to tps to be honest it felt more responsive than mgp vs rpm One other thing though where do you take the map sensor reading from I've used the balance tube thing on the inlet the other end to the for take off it was used for factory boost Pressure sensor but I've binned this

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