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Rich when engine fan on


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Hi All,

new to link and working through getting tune setup. Have come from Nistune years ago, and most recently HP tuners so reasonable handle on tuning.

Car is a turbo LS1, on E85. Puzzling issue is running rich when fan is on. Definitely as a result of the electrical load, as if swapping fan output to AUX6 when it turns "on" (software only, fan not wired to that aux) does not effect the fuelling.Using onboard lambda and confirmed with Zetrionix ZT2 gauge display.

Tune is in early stages, and log of general drive attached. noticeable particularly at approx 8:44. Added extra breakpoints around idle to try and smooth out the table , planning to get rid of those once this is sorted. Thanks for any help/suggestions.

Fuel table does go higher with less vac as you would expect however impact on fueling seems to be coming form somewhere else?

The voltage recorded by the G4+ doesn't move much, i have the dead times all entered as per what i was using in HP tuners. Next plan is to measure voltage at injectors, however not sure how useful that would be as going richer would mean higher voltage so not sure that i expect that.

I feel like there is something I am missing, and don't know what it is!

I appreciate any help/assistance, thanks

Ben

Log 2020-09-20 12;21;33 pm.llg VY_BASE_Hp VE_REV12.pclr

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2 hours ago, Ben C said:

Hi All,

new to link and working through getting tune setup. Have come from Nistune years ago, and most recently HP tuners so reasonable handle on tuning.

Car is a turbo LS1, on E85. Puzzling issue is running rich when fan is on. Definitely as a result of the electrical load, as if swapping fan output to AUX6 when it turns "on" (software only, fan not wired to that aux) does not effect the fuelling.Using onboard lambda and confirmed with Zetrionix ZT2 gauge display.

Tune is in early stages, and log of general drive attached. noticeable particularly at approx 8:44. Added extra breakpoints around idle to try and smooth out the table , planning to get rid of those once this is sorted. Thanks for any help/suggestions.

Fuel table does go higher with less vac as you would expect however impact on fueling seems to be coming form somewhere else?

The voltage recorded by the G4+ doesn't move much, i have the dead times all entered as per what i was using in HP tuners. Next plan is to measure voltage at injectors, however not sure how useful that would be as going richer would mean higher voltage so not sure that i expect that.

I feel like there is something I am missing, and don't know what it is!

I appreciate any help/assistance, thanks

Ben

Log 2020-09-20 12;21;33 pm.llg 4.75 MB · 1 download VY_BASE_Hp VE_REV12.pclr 173.09 kB · 2 downloads

I should add the car has a camshaft in it, nothing too big.

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I had a similar problem on my car and the solution was to eliminate the Fuel Steps(found in the Idle Speed Control) and the values found in the Idle Load Trims tables.

Essentially, my issue was when my ECT reached a given temp (the same temp that my fans kicked on - this was the biggest clue)the car would die-out if it was idling or it would run crazy rich and try to die if I was below ~1500rpms ...

 

 

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35 minutes ago, BeallJK said:

I had a similar problem on my car and the solution was to eliminate the Fuel Steps(found in the Idle Speed Control) and the values found in the Idle Load Trims tables.

Essentially, my issue was when my ECT reached a given temp (the same temp that my fans kicked on - this was the biggest clue)the car would die-out if it was idling or it would run crazy rich and try to die if I was below ~1500rpms ...

 

 

Hi ,

thanks for posting. I did come across your thread when searching and thought I was on the right track, however I am running modelled fueling so those trims are not in use , and confirmed when logging there is no fan trim being applied.

I am sure it is something obvious, but for the moment it is a mystery to me.

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Agree with Remski, it is just coming from your VE table.  With fan off fuel table is 44%, MAP is 49kpa, inj PW is 1.15-1.19, with fan on fuel table is 47%, MAP is 53, inj PW is 1.4ms.  That is about 18% more fuel going in.

S4Mmuk7.png

 

I suggest you greatly simplify that fuel table, there is no need to have that many breakpoints at low RPM/low loads, VE isnt going to drastically change in this area as there isnt much going on in terms of effects from overlap, wave tuning and scavanging etc (unless it is a big cam but your MAP signal doesnt look like it).  A column at close to normal idle speed and 500RPM either side should be all you need.  Load breakpoints at 20kpa increaments should be fine too.

I always start with as little breakpoints as possible and only add extras if there is a drastic change in VE that is not linear.  

Below is an example fuel table from the last LS I tuned.  Even in this one the first 3 columns are nearly the same so I could delete two of them with little effect. 

efdLZRd.png

 

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Thanks for the suggestion to simplify the table. I added the breakpoints due to the fueling going rich, thinking that would make it easier, however that hasnt been the case!

I have made some changes, removed breakpoints however still seeing the mixture go rich when the VE table value stays the same. Not sure if i am overthinking it or should just leave it alone. idle log attached if anyone is interested!

I have just noticed accel enrich is kicking in briefly when fan turns on . that cant be helping but dont see the obvious way to stop that.

 

 

Log 2020-09-26 2;44;45 pm.llg

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Tune has been adjusted, i have gone with 10Kpa steps in vaccuum. Came from the factory ecu that had 5kpa steps, and i think i need the extra resolution.

I realised accel enrich Deadband was set to 0.1%, changed that to 1% and the revs are much more stable when the fan turns on. There was a spike of accel enrichment occuring that definitely wasnt helping!

tune attached. I am using values in the idle ignition control that worked well with the factory computer.

 

still seeing idle go richer with fan on... can live with it just didnt think it would happen, and dont fully see why it is happening.

 

VY_BASE_Hp VE_REV19.pclr Log 2020-09-27 11;53;07 am.llg

got rid of engine fan step in idle control, that has helped. Now idel ignition is more consistent. still seeing rich condition.

Log 2020-09-27 12;09;41 pm.llg

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This snip of a log shows it occuring while driving.

something strange is happening as it is showing richer with same pulsewidth....

image.thumb.png.2fca400632959e95a0c42460fa5be26a.pngimage.thumb.png.e6af9a18a5bebc4831c93dcf676a599a.png

 

 

 

something weird is going on...... can confirm this does not happen with fan relays removed, not sure what to make of that!

 

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Make sure all gound points are clean and there this there is enough of them. Also make sure the power from the injectors are from the same realy as the ecu. 

As a band aid fix you can set up a 4d table with engine fan on the axis to pull fuel out when fan is on. 

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Cheers mate, Definitely have good grounding, the ECU is powered from the original oem ecu power, not sure how that relates to the injectors however confimred with meter at injectors with fan on voltage matches Link reading.

i think i am going around in circles, I believe i just need to sort out the VE table better and all should be good. Got in my head something else is happening, when it likely isnt!  For the moment I will use a filter to get rid of data with fan on (to ease my mind) , get the VE table sorted then see what happens when looking at the data with the fan on

In the process though have got the fan turning on much better, not using the Fan step has helped, now RPM barely dips when fan comes on.

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ok. I would love to put this to bed..... to me it really seems as though i am getting more fuel from somewhere. the last log i posted shows this , same value from fuel table and pulse width gets bigger. Looks like my differential fuel pressure changes. At idle the reg cant dump enough fuel to get to desired base pressure, tune is set to reference the FP sensor.

wonder if i should just turn it up to 4bar base and see how i go....

 

image.thumb.png.df329afa17a96d335468790ef8b772ad.png

 

 

 

 

 

**edit, that has made me realise something. Going from the GM data into LINK software i think i stuffed my injector flow rate at base pressure. it should be 920 at 3 bar base, I have 1030 entered. thats a fair difference.... In my defense the way the injector data is managed in the GM computers is a bit odd......

 

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1 hour ago, Ben C said:

to me it really seems as though i am getting more fuel from somewhere. the last log i posted shows this , same value from fuel table and pulse width gets bigger.

It looks to me like the change in pulsewidth is just from the change in MAP.  In the screenshot above your MAP is about 48Kpa before the fan turns on and about 54kpa after.  That is an increase of about 14%, so for the same VE, with 14% higher MAP, the PW would be increased by 14% also.

The change in fuel pressure should be taken care of with the reference set to FP sensor.

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19 minutes ago, Adamw said:

It looks to me like the change in pulsewidth is just from the change in MAP.  In the screenshot above your MAP is about 48Kpa before the fan turns on and about 54kpa after.  That is an increase of about 14%, so for the same VE, with 14% higher MAP, the PW would be increased by 14% also.

The change in fuel pressure should be taken care of with the reference set to FP sensor.

If i had entered the base flow at 400Kpa it would be correct, however i put it at 300Kpa. I will change it to 400Kpa like it should have been.

 

 

So it looks like i need a hole in my VE table, rather than a smooth transition that I am expecting? Is it not odd to need to reduce the VE with an increase in MAP?

 

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3 minutes ago, Ben C said:

If i had entered the base flow at 400Kpa it would be correct, however i put it at 300Kpa. I will change it to 400Kpa like it should have been.

It will mean your basic VE numbers are off, but I would still expect it to behave correctly.  

 

4 minutes ago, Ben C said:

So it looks like i need a hole in my VE table, rather than a smooth transition that I am expecting? Is it not odd to need to reduce the VE with an increase in MAP?

Earlier you had a log where the AFR changed with fan status even when the car was driving (ie not idle), so I dont think putting a hole in the VE around the idle area is going to be the solution.  I would probably take care of it by trying something more like Ducie's suggestion of a 4D fuel table activated with the fan.

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4 minutes ago, Adamw said:

It will mean your basic VE numbers are off, but I would still expect it to behave correctly.  

 

Earlier you had a log where the AFR changed with fan status even when the car was driving (ie not idle), so I dont think putting a hole in the VE around the idle area is going to be the solution.  I would probably take care of it by trying something more like Ducie's suggestion of a 4D fuel table activated with the fan.

Thanks Adam, i had thought of doing a 4d table to address it, and thats fine, however not understanding the real cause of it is bugging me. At the end of the day I want to move on, but not knowing is annoying.

i feel like i tell myself to move on, but cant do it! I have already moved on many times......

All good, i will update down the track if I come up with anything of interest!

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