What would pull timing at idle

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sdaigle240
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What would pull timing at idle

Post by sdaigle240 »

In certain situations, somethings pulling 10* of timing at idle. confirmed via consult and a timing light. (setups in the sig link)

Upon start up the car idles around 900 and vac is only 16-17, it doesnt sound smooth. timing reads 10* but fuel stays ok. A quick blip of the throttle and right back to 20*, 1100 rpm, 19 vac - as it usually idles. this timing drop wont happen again until a few seconds BEFORE the fans kick on. My fans are ran directly off the OEM AC plug and the temps in the tune are adjusted to regulate coolant. I THINK this means that the idle up valve works when the fans go on, as i think it does in the factory orientation with the small stock AC fan. if i unplug the fans after start up and let the car get past temp, it will not drop timing. As soon as i plug the fans back in, it does it.

i was really just trying to calibrate my base idle and IACV (till actual idle matches number in tune) as i had just totally cleaned my IACV. i think adjusting things just brought the issue more to light as it was happening to an extent previously. i had been band aiding the gunked IACV by setting idle to around 2500 in the tune and that would get me my 11000 rpm. BUT it still did this odd stuff at start up, but i do not notice it when the fans kick on.


So... im unsure if this is:

-draw on the system? my voltage is kinda low - high 13s, and it drops by .2 when the fans go on.

-a function in the ECU thats pulling timing - Dave? JKTUNING?

-a dirty Idle up valve. definitely never cleaned that thing before


Its as simple as bliping the throttle but it pisses me off not knowing why its happening.

thanks doods!
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Re: What would pull timing at idle

Post by OnTheChip »

What bin are you running on the Calum?
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Re: What would pull timing at idle

Post by sdaigle240 »

Not sure how to host a file, I could certainly email it. Started as a base tune from Calum 7 years ago, and just evolving since. Rt v1 s14. I def appreciate your input!
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Re: What would pull timing at idle

Post by OnTheChip »

I believe there is a cat converter warmup retard that is applied under certain conditions during warmup. Also, if your idle rpm is above the target idle rpm setting (like a vacuum leak), the ECU will pull timing to bring the idle speed back down.
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Re: What would pull timing at idle

Post by sdaigle240 »

OnTheChip wrote:I believe there is a cat converter warmup retard that is applied under certain conditions during warmup. Also, if your idle rpm is above the target idle rpm setting (like a vacuum leak), the ECU will pull timing to bring the idle speed back down.
unfortunately with all the XDF's i have i cant find any tables that indicate timing pull like that function. its there, i just don't know the locations to define them on the xdf i guess. if you know em' im all ears!


on that idle comment...

that's really the source of my whole issue i believe. the car is functionally sound as far as leaks and calibration of sensors etc. Yet in tuning the base idle i haven't had luck with anything beyond putting huge values into the target table. my actual idle is lower than the target idle in the bin. I have to make the target quite a bit higher to get a desired result. im entering like 1600+ to get 1100 actual, and 950 with fans. ive adjusted the IACV every way possible all while doing this too. Its like everything i do its still keeping it at 10*. even after a quick blip it reads 20 then right back to 10.





Leaving this here for myself
viewtopic.php?t=47898

some great info, although i KNOW my car idled at 20 before, it even sounds funny at 10*. my voltage is lowish so maybe the quest alternator wouldn't hurt.

going to reset my throttle plate and TPS and see what happens.
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Re: What would pull timing at idle

Post by 8-bit »

This is FACT:

The KA24DE does not idle at 20 deg BTDC. That is the exact place it will idle if you force the car into timing-setting mode. It may idle there sometimes, but by and large it will vary the idle timing to stabilize the idle. The only time it stays firm at 20 is when you force it, or possibly during some situations like neutral-decel, etc.

I usually observed idle timing between 8 and 14 BTDC.

I hope this helps you.
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Re: What would pull timing at idle

Post by sdaigle240 »

i def appreciate the reassurance on it cody. While i cant disagree, it seems the cars not idling as smooth as usual. when it is at 20* with full vacuum it sounds so much better and ill say "normal" to my ear. i guess with 264s i could conceivably have 16-17 vac at 900 rpms. in no way do i not believe your timing records but whats odd is every time ive ever checked my idle timing (prob 20+ times) ive observed 20-21* via light and consult - perhaps this was a result of a crudded IACV and cheated target idle in the bin. sounding more like my IACV revamp has uncovered a truth rather than an issue. interesting! thanks for the insight.


random related question. did you ever find the location of the TTPMin for the s14 ECU? My XDF's have only Max and that would certainly help smooth things. nice to see your still rockin the tuning world.
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Re: What would pull timing at idle

Post by 8-bit »

This is late, but I can say this. Use Tunerpro if it gives access to it. I'm not sure though. If nistune isn't allowing it then just leave it be. Did you ever clean that IACV or just open it some more?
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Re: What would pull timing at idle

Post by sdaigle240 »

8-bit wrote:This is late, but I can say this. Use Tunerpro if it gives access to it. I'm not sure though. If nistune isn't allowing it then just leave it be. Did you ever clean that IACV or just open it some more?

I did end up cleaning the IACV, and with a bit of adjusting was able to get the car to idle better. it still drops from like 1100 to 900 with electrical load but its pretty smooth feeling/sounding still (and my vac is no longer dropping to 17). just odd it never used to drop like that. oh well. Im going to be experimenting with the stock mechanical fan this summer so that issue may even go away. looking to see if the stock clutch fan is "stronger" than properly setup alti fans. always battling coolant temps at the track.
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Re: What would pull timing at idle

Post by Bubba »

A properly setup clutch fan (I'm going with the GK Tech) with the fan shroud still intact will cool better than Altima fans.
My car is dead stock.... ish

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Re: What would pull timing at idle

Post by sdaigle240 »

Bubba wrote:A properly setup clutch fan (I'm going with the GK Tech) with the fan shroud still intact will cool better than Altima fans.

...so you read....


guess whoes going to quantify that with data? :D

all the old skool jdm bois say it so i believe it... but being an engineer i just gots to quantify it.
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Re: What would pull timing at idle

Post by 8-bit »

sdaigle240 wrote:
Bubba wrote:A properly setup clutch fan (I'm going with the GK Tech) with the fan shroud still intact will cool better than Altima fans.

...so you read....


guess whoes going to quantify that with data? :D

all the old skool jdm bois say it so i believe it... but being an engineer i just gots to quantify it.
Can't you just trust the engineers at the manufacturer that do this as well?
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Re: What would pull timing at idle

Post by sdaigle240 »

8-bit wrote:
sdaigle240 wrote:
Bubba wrote:A properly setup clutch fan (I'm going with the GK Tech) with the fan shroud still intact will cool better than Altima fans.

...so you read....


guess whoes going to quantify that with data? :D

all the old skool jdm bois say it so i believe it... but being an engineer i just gots to quantify it.
Can't you just trust the engineers at the manufacturer that do this as well?

haha true... although a ka altima has e fan and 240 has mechanical. clearly the e fan is due to the direction the engine is pointing. the mechanical fan might even be cheaper though... so which is better isnt exactly cnailed down by the oem. more so just each applied better for the particular application. im sure the mechanical is better lol.
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