To answer the question: Tip-in retard

[deviousKA]

This question was asked in another post but was off topic so I started a new.

"tip-in" retard has been discussed a few times regarding the operation of the nissan ecu. I do not believe there is tip-in timing retard in any form on these ecus, and that the timing map itself is the only dictator of timing advance. When the throttle is pushed quickly, the airflow increases quickly as well and the ecu will jump to that portion of the map, which would be less timing advance. This is what you are seeing if you are monitoring your timing advance while pushing the throttle quickly. After the airflow settles at a steady throttle and rpm, the timing should pull back to more advance, depending on air flow.

Fueling, on the other hand, does have a "tip-in" or acceleration enrichment seperate of the fueling map (which is not a VE map like speed density ecu, but similar). These values of acceleration enrichment are adjustable and are located in the rom seperate from the fueling map.

If anyone would like to discuss other aspects of a NA rom tune for E or DE please do so, I would be glad to help out. I have given out my sohc NA tune, and would be willing to create a polished DE version and share as well, or work to create one as a group.

[vvaffle]

I didn't see the actual question so that may be why I am a little confused. Tip-in maps looked at when you open the throttle suddently and should increase respons right? Alright, so looking at the regular timing maps, the base timing is 20 degrees retarded right? In other words, the spark plug fires 20 degrees after TDC, right? I might be totaly wrong. So if in fact I am right, then does the timing increase or decrease as RPMs go up? And what kind of effect does throttle position have on the timing?

Ok, now as far as rom tuning, I have been to eccs.hybridka.com and while there is alot of information, most of it seems to start at a point where other (maybe basic)knowledge is necesary. Alot of the information also seems very spread throughout the different subforums and the basic information is usually sprinkled into advanced information which makes it hard to know where to get started. Also, with all the hardware and software a nice summary of what everything does and doesn't do would be nice.

In short, what I am trying to say is, it all sounds a little overwhelming, to me at least. I do appreciate all the time you take to explain things to me and others on this forum. Hopefully rom tuning a KA will become as common as putting on I/H/E and then you won't have to be the one explaining everything.

[DjPantsSpecR]

no, you're close though about timing

base ignition timing is at 20 degrees before top dead center (BTDC) so the plug fires while the piston is still traveling up on the compression stroke. When you advance this timing, the plug fires even more before TDC, so for the sake of argument we'll say 28 degrees before.

ignition advance will increase with rpm because since the motor is physically spining faster more events have to happen in a shorter time period. So if you fire the plug earlier and earlier, you'll be able to control the flame kernal a little better and have a much more complete burn.

thats why you can find a little top end by advancing you base timing on your distributor.

as for throttle position, i wish i could handle that a little better, but from a recent near discovery by InsanityInc, there was much discussion about the timing maps versus throttle position. if you want to see that map seach "possible mod" or "ultra-rich"

[deviousKA]

Timing will never be after TDC, that would be known as truly "retarded" timing (sparking after piston is at TDC). Timing is generally always above 15 degrees BTDC, for the sake of discussion. As Rpm increases timing before TDC will increase (more timing advance), as load or "boost" (airflow) increases, timing will generally decrease from where it is at a lower airflow.

When you hear people say retard your timing, they mean retard it from its current timing advance btdc. It will never go truly after TDC, sparking as the piston travels away from TDC. If it does, your fuel will be likely to ignite in the exhaust.

Now, to further explain the timing map a little bit, here is a picture.

Blue circle near the bottom indicates where the ecu is reading from during idle (general low rpm, low airflow). You will see on the left of the picture there is a scale of RPM, from high rpm to low rpm. As rpm increases timing advance increases.



Now, up on top you see the arrow and increased airflow. As airflow increases, timing decreases. So, if you were at full RPM and full boost (or airflow) the ecu would be reading at the top right hand portion of the map. If you were at low rpm and high boost (for sake of discussion), the ecu would be reading from the lower right hand portion of the map.

I know that over on eccs.hybridka.com the information is scattered around pretty bad, and is not the best for a beginner. The forum is rather fresh, hopefully in time there will be a "team" to help organize and make it easier for beginners. We are having some issues with the forum getting moderators set up. That will be a start to getting everything organized.

[skydragoness]

The person who asked the question in the other thread was me :PI heard from others about the 'tip-in retard' from some other people.Besides JWT, there's no one else that 'chips' ecu's? Just curious.

[vvaffle]

I forgot what this guys real name is but he goes by enthalpy. I think he also "chips" ecu's. Either way, I'm not a fan of going that route. Even though JWT has alot of experience with this, they are still tuning your car without ever even seeing it.

Either way thanks for the help guys. I'm interested in this for two reasons: 1. I am fairly seriously considering rom tuning my ecu sometime in the spring and 2. I recently removed my timing chain guides and when I put everything back I don't think I got the timing exactly right because the timing light I was using didn't make it very clear. I know I am within a few degrees but I'm almost sure it's not exactly at 20 degrees. So this discusion helped me better understand what goes on with ignition.

Seems to me like there is no real need for a tip-in timing map. Also, was it you devious that was selling consult kits?

[deviousKA]

I sold some ecu daughterboards.

There are some consult kits available over in the for sale section, offered by another member.

They are extremely good deal.

[PandaS14]

Gabe, long time no talk dude! Hit me up on aim or email or something. I'd like to catch up bro!