Standard Ignition Map Question re TPS / MAF

[Skinner_87]

Afternoon Guys,

Id like to know if the ignition map (CG13 with NATS in this case) is controlled by the input from the TPS or the MAF sensor or both?

The reason i ask is that i currently run bike carbs on the standard ECU & as its been kindly pointed out this will not give me the benifit of the full nissan engine map as the TPS & MAF sensors are unplugged so the engine runs on the basic spark.

My thoughts are that if i re connect the TPS to the throttle body & sync it (by a 2nd throttle cable maybe... i have a few ideas) to open & close in time with the butterflys on the carbs then it will give the ECU some information as to what the engine is doing & give me access to the ignition map.

I understand that to get the most i would need to run stand alone ignition maping etc etc but as a low cost solution to maybe a few more horses i wouldnt mind giving it a go :grinning:

Any thoughts or oppinions guys?

All the best

Paul

 

[frank]

if you connect the t/p/s to the throttle cable and a maf to the intake just to get the full sparkmap, you may as well refit the injectors and use the carbs as quad throttlebodies paul
you,re only getting the 2D rpm map without them surely ? (and no form of vacuum advance eh fwn)

 

[Skinner_87]

you,re only getting the 2D rpm map without them surely ? (and no form of vacuum advance eh fwn)[/QUOTE]

Thats exactly it Frank its slighty lacking at the very top and and im putting it down to the map not being advanced enough at the top end...... 6,200K+

Would just getting the TPS to work in real time again give me the full 3D map back? its not causeing a problem, i would convert to ITB's (maybe something for the future) but being able to play with the fueling with the jets is hand with not having any tunind companies on the island.

 

[frank]

i dont think there is any spark advance over 3 or 4k anyway paul, but you,re losing power on wot @ the bottom end because you,re having to run extra retard throughout because of having no vacuum advance fwn

 

[megamicra]

I like this thread.
Is it possible to add a vacuum take off the carbs to the original vacuum advance sensor ? This would pull some of data back into line, no.
Has anybody tried quad throttle body with stock ecu and sensors ! Sounds like a good (realitivly easy) mod. I think she would sound amazing.
And while i have your attention guys, what are the limits of the maf. Do they work if fitted to the airbox, ie up stream from where they are as std.(Y)

 

[frank]

I like this thread.
Is it possible to add a vacuum take off the carbs to the original vacuum advance sensor ? This would pull some of data back into line, no.
Has anybody tried quad throttle body with stock ecu and sensors ! Sounds like a good (realitivly easy) mod. I think she would sound amazing.
And while i have your attention guys, what are the limits of the maf. Do they work if fitted to the airbox, ie up stream from where they are as std.(Y)

there,s no vacuum advance on the injected micra,s as such mm, its a bit missleading really because you,re "more accurately" retarding the spark @ low vacuum on a k10 for instance.(to avoid pinking)
so an injected car will use the t/p/s, rpm and maf sensors to sense those conditions more effectively than a vacuum sensor

 

[frank]

And while i have your attention guys, what are the limits of the maf. Do they work if fitted to the airbox, ie up stream from where they are as std.(Y)

my CG maf has been cut off and mounted in the airbox (upstream of the SR throttlebody).....so yes

 

[Machi san]

MM, iam on the same channel

I have been thinking for a little while now whether i could fab up an individual throttle body setup, with an airbox. The just mount the maf on the entrance to the airbox!

Itbs work better with an airbox and cold feed anyways

Use stock injectors, maf, tps ect. Ditch idle control!

Might work! But Iam kinda sceptical

 

[Machi san]

You can see in my blog, how I cut away the standard throttle body leaving the standard maf by itself. I also have an sr20 tb!

The tb part is 45mm and the maf is 60mm, so they need splitting

The Sr tb is 60mm

 

[megamicra]

my CG maf has been cut off and mounted in the airbox (upstream of the SR throttlebody).....so yes

got my hands on a spare motor, with inlet, so im gonna have a good look and see what i can do. Thanks for the help Frank. That maf seems to be the key to keeping the costs down.

 

[frank]

Ditch idle control!

i ditched mine 6 months ago kev
and fitted that hand control throttle lever thingy to add a fast idle during the cold weather, but i hav,nt needed it i have to blip the throttle for about the first 20 secs on these cold mornings (heal and toe) and then it idles perfect (Y)

 

[karlj]

my CG maf has been cut off and mounted in the airbox (upstream of the SR throttlebody).....so yes

Would this work with bike carbs considering they don't have an airbox as such

 

[megamicra]

there,s no vacuum advance on the injected micra,s as such mm, its a bit missleading really because you,re "more accurately" retarding the spark @ low vacuum on a k10 for instance.(to avoid pinking)
so an injected car will use the t/p/s, rpm and maf sensors to sense those conditions more effectively than a vacuum sensor

My back ground is bikes. All fuel injected bikes use a vacuum sensor, tps and map ( manifold air pressure sensor) I must have a look and see if this will cross over.
Steve

 

[frank]

My back ground is bikes. All fuel injected bikes use a vacuum sensor, tps and map ( manifold air pressure sensor) I must have a look and see if this will cross over.
Steve

ahh gotcha the early efi rovers had a vacuum pipe going to the ecu eh

 

[frank]

Would this work with bike carbs considering they don't have an airbox as such

you would have to build a plenum onto the carbs eh karl

 

[karlj]

I was thinking that would be a way to do it, but if you was to do that surely it'd just be easier to fit ITB's

 

[frank]

I was thinking that would be a way to do it, but if you was to do that surely it'd just be easier to fit ITB's

i think its the only way you could do it karl, unless you have a standalone ecu eh

 

[karlj]

Something like mega jolt

 

[frank]

Something like mega jolt

dunno but if you fitted a maf to 1 of the carbs or quad, it would only sense 1/4 of the airflow eh

 

[karlj]

I know what you mean, if a plenum was made would it be best to put the intake in the middle at the front to maximize the airflow to all 4 bodies

 

[Skinner_87]

Something like mega jolt

If you ran megajolt you could tap a takeoff from each manifold inlet & run it to the MAP ECU like the way Frank has mentioned with rover then you would have a full reading with having to build a chamber?

 

[Low Rider]

Most rally people I know who run bike carbs either make do with what you already have and tune the car on the rollers for the best possible compromise by moving the distributor, or junk it for an aftermarket ignition controller. Most people on a budget just stick with the OEM setup because it 'works'.

There is one problem regarding tapping in a MAP sensor and that's the amount, (or lack of), vacuum produced, especially if you have opted for cams. The reason being with a reduced initial vacuum your vacuum change with respect to throttle position and rpm is much less than with a stock plenum. Consequently you end up with much less resolution and therefore have quite a coarse map. Alpha-N TPS/RPM load based mapping would be much better usage of a 10x10 map offered on a Megajolt given the choice.

 

[Skinner_87]

Most rally people I know who run bike carbs either make do with what you already have and tune the car on the rollers for the best possible compromise by moving the distributor, or junk it for an aftermarket ignition controller. Most people on a budget just stick with the OEM setup because it 'works'.

Thats the way i had planned on tuning it in the new year low, have a play with the advance & jets on the hills and see what happens...

There is one problem regarding tapping in a MAP sensor and that's the amount, (or lack of), vacuum produced, especially if you have opted for cams. The reason being with a reduced initial vacuum your vacuum change with respect to throttle position and rpm is much less than with a stock plenum. Consequently you end up with much less resolution and therefore have quite a coarse map. Alpha-N TPS/RPM load based mapping would be much better usage of a 10x10 map offered on a Megajolt given the choice.

Thanks for the point about the MAP lack of vacuum, i had looked into megajolt but they had recommended MAP over TPS... without a mention of cams which im hoping to swap for a wilder set so avoided a problem (Y)

Which ECU do you run on your ITB's? Do you know what roughly dizzy advance other engines on bike carbs run?

 

[frank]

LR runs an omex paul and pollyp posted up his turbo and modded n/a ignition maps on his blog

 

[Skinner_87]

LR runs an omex paul and pollyp posted up his turbo and modded n/a ignition maps on his blog

Nice one Cheers Frank!

 

[Low Rider]

Yup, I run an Omex 600, which we will be challenging quite a bit on the next tune. Should be 'ok' but I may want more map resolution depending on how things go

I don't know what advance they end up running, they just do a few back to back dyno runs, look at the torque & power curves and try to make the best compromise based on output. It's a cruddy way of doing things in my opinion but the general consensus with the MSC is to get things 'working', I guess it just boils down to what one is prepared to accept really. I do generally tend to remain on the upper scale of things, which I realize is not for the majority

 

[frank]

I guess it just boils down to what one is prepared to PAY really. I do generally tend to remain on the upper scale of things, which I realize is not for the majority

fixored your lordship