A few noobish Qs (rb20 ecu/rb25de head/rb30)

[ST240]

After dicking around with a timing belt that was horribly tight and solving numerous unrelated problems, i finally got to tuning.

I pulled the rb20 image off the ecu, and resized injectors stock 270 to DW 740s. She fired up first try but idled lean as hell ie >17 somehow.

So, a few questions (ive scoured all the guides multiple times, just need clarification):

1. Im kind of confused on this whole timing issue. I disconnect the tps, set to 15* (doesnt match consult), and reconnect tps and check again (still doesnt match consult). Is that correct, regardless of what consult says? I also find it idles at around 17*. However, if i adjust the thottle cable ever so slightly (more open) it goes to 15* with tps idle lit up. Is a guy supposed to have 15* bang on at idle?

2. I disabled the o2, zeroed the map, synced, adjusted kconst (114), got around 14.5 idle, noted kconst, reloaded stock maps/enabled o2, adjusted kconst to 114. Now idle is around 15ish. But boy does she idle/rev like a champ, the thing sounds sooooo strong and smooth (havent had a chance to drive it though). I just adjusted the kconst based AFR at idle and that was it. Did i do that correctly?

3. Do map adjustments take effect immediately, or am i supposed to sync everytime i make a change?

[Matt]

May need to do further adjustment with the K value (Injection multiplier) so it runs correct AFRs throughout the rev range

Also if its just an idle problem then make sure your latency is about 840uS inside Nistune
viewtopic.php?f=12&t=1574

Base timing is 15deg BDTC at idle when 85 degC. Nistune must show 15 degress firstly (which it should if it thinks TPS=idle so check that in consult. Didnt think you needed to disconnect the switch) and then your timing light should match 15 also

You will see the idle timing map is 15 degC unless there is a problem with maintaining 800rpm idle then the ECU will add more timing to maintain idle

So fix your AFR problem first and then it should idle better and then you can fine tune your timing to get it right

2. So you have done most of this already which is good. Make sure you did the latency also, and check AFRs throughout rev range (see tuning document)

3. Yes they take adjustment immediately. make sure you burn when finished tuning to keep changes in the board

[ST240]

Excellent. I got her timed pefectly. Man Nistune is the absolute tits!!!

The map definately needs work. But she runs like a god damn champ on that rb20 map! Oh also my latency seems to be pretty good at 720 ish, is that uncommon?

A few more Qs:

1. Is the process then, resize maf/injectors, play with Kconst till you you get roughly 14.7 at idle, THEN play with the map until you get 14.7 roughly through the low load range (ie flags area) while the o2 is disabled? I really dont get the point of disabling/enabling it really...

2. Further to that, its very hard to hit the first two columns whilst holding the throttle. It seems like you only hit them on when you let off the throttle, what about those, can they be allowed to stay leanish?

Heres a vid

http://www.youtube.com/watch?v=VW_rbIvaC7I

[Matt]

latency will just add more fuel. if your AFRs are good around all of the map then you should be fine then

1. Yes and yes. It should then start heading towards around 11-12:1 as you get richer. O2 flags disabled so it doesnt go closed loop regardless of what is in the map. You want to get mixtures right without closed loop firstly to make sure your injection mutliplier etc is correct otherwise the O2 sensor will assist in compensating for incorrect adjustments

2. Just smooth around where you can access since those dont get used much as you found out

[PL]

I'm probably coming in a bit late here, but just for the benefit of others who may be reading this - the important thing with setting your timing is that what you read from the ECU (ie: in NIStune) matches what you read with the timing light. If it doesn't then move the CAS until it does. That's it.

Whether it's 15 degrees or 17 or 12 isn't that important. Ideally you'll see 15 degrees on most Nissans (some are 20) when everything is set up correctly. But just to set your timing correctly you don't need to worry about it being 15 - as long as the ECU matches actual timing.

What often happens is that the ECU will add/subtract timing in an attempt to maintain target idle speed. So if idle is turned up too high for some reason you'll often see less timing than you'd expect. If idle is too low it'll tip in a bit extra. So if you can get your idle speed set correctly first - then you'll usually see a nice solid 15 degrees and it'll make checking/setting the timing a bit easier.

PL

[klattr1]

I'm probably coming in a bit late here, but just for the benefit of others who may be reading this - the important thing with setting your timing is that what you read from the ECU (ie: in NIStune) matches what you read with the timing light. If it doesn't then move the CAS until it does. That's it.

Pete - I know you know this but just trying to clarify even more for others...you want to sync the timing light up with what the "Consult Gauges" is showing, not the cell that map tracing is highlighting under the primary timing map. Otherwise, you may get off sync when other timing corrections are made on top of that (like coolant temp timing retard tables, etc)

[PL]

Exactly. Yes I should probably clarify that. It's no use looking at the values in the main timing table because you don't know if they're being accessed (most likely not at idle cos it'll be using a separate table) and the ECU interpolates across multiple cells anyway.

You need to look at the timing value being reported via Consult - in NIStune this is read from the Consult Gauges. In any of the basic diagnostic programs (Datascan etc.) it's simply the Ignition Timing value.

PL

[Matt]

Hence why I mentioned the idle timing table would probably be used in that case (its where the 15 deg BDTC comes from)

Since in workshop manuals you didnt have access to consult in prior days, they advised getting the engine warm, 800rpm and TPS=idle to ensure you were using those particular cells where they knew it should be 15 degrees (reported by consult) to then line your timing up against

With the luxury of consult you can just align it to what your laptop says it currently is on the gauge

[ST240]

Thanks guys. And ironically enough, we did that at first. But then she started idling at 15*, set it to 15* on the gun and done.

Another question... For some reason it's not letting me change the values in the timing map. Anyone know why?

[klattr1]

Another question... For some reason it's not letting me change the values in the timing map. Anyone know why?

are you working in "Raw" mode?

[ST240]

ah thats prolly it ill check tonight.