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ignition timing

Practical Standalone Tuning

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i have a honda f23a sohc vtec and the graph is like torque is good until it starts to dropoff at around 5000rpm drastically, ignition timing is around 28/29 degrees of advance around there till 6200rpm, af ratio is around 12.7 its naturally aspirated, i am using a chipped ecu tuning with crome, how can i improve the torque curve and not let it dropoff after 5k and maintain a flatter sort of band.

What is your VTEC switch point and are you sure it's working?

3800rpm, you can definately feel the difference

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that isnt my dynograph but its just a reference, my torque drops off like u see in that graph at around 5k rpm , any reason to why?, i have intake headers exhaust as boltons

It's hard to tell what's going on in that picture. You may be reaching a limit of the intake manifold and heads.

can u tell me how the ignition curve shud look for that type of engine , like wud u add more than 25degrees at around 5500rpm

Post screenshots of your map and post a screenshot of a chart showing a WOT pull. In the chart you should have rpm, throttle angle, timing, and AFR.


As already advised, you have better chances to get the correct answer if you post your fuel map showing the 2d plot that way we can see what the engine is doing from 5,000 rpm on,

the fuel table

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ignition high cam

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Can you post the actual table, and a screenshot of a datalog of a WOT pull

the blue line

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Unreadable picture.

i cant provide that sorry

dont have the hardware necessary to provide that information

dont have the hardware necessary to provide that information


There is nothing wrong with your fuel table looks good. And it shows that your peak torque is around 5300 rpms, although your dyno Pic is not clear you can see how your engine stops making power, this makes no sense your fuel table shows that makes Power up to 7000 rpm. There is no drop in the fuel curve, that could tell you that your head is a restriction or your intake or a posible valve float.

This looks more like timing issue, have you synchronized your crank timing with your E manager software?

I ike to tune my hondas to 13.3 Afr for n/a seems to be the sweat spot for power, I'm not familiar with sohc engines tho.

Is your ignition map tuned on the dyno?

it think its timing issue, im new to tuning,i did adjust the fuel on the dyno and i played around with the ignition map and did not see a difference in power beside the powerband just becoming more rough instead of being smooth, i am using crome software to tune ok so im not sure about the synchronizing of the crank timing to the software im not doing some research about it,

i would appreciate all the info on this thanks


I just had a look at crome, I didn't find the Ign. Sync tab, although Hondata has one, maybe crome gold has one too,

Either way it will be easy to do this and this is something you do before you even think about tuning your car, find the service connector is a 2 pin blue connector in most cases, you can look up on google to locate this conector on your vehicle, then you need a paper clip bend it in a "U" shape and short that connector that means you put in each paper clip leg into each pin in the service connector, this will prevent the ecu to make corrections to true timing,

With a timing gun/light, set it to either 15 or 16 degrees or 0 degrees if it is not a variable timing light, (again look up on google which is the correct degrees) on b series I know is 16 degrees,

Point the gun at the crank pulley and you will see 3 marks, TDC 16 and 18 degrees, TDC is a white mark the next is 16/15 red mark, that one is the one you need to line up with the timing cover pointer, if it is advance or retard use the Distributor to make your mark to line up with timing cover arrow. once you are done remove service connector paper clip, now your timing is sync.

I did find on crome something interesting, if you used the preload z6 map and you started from there, you have 38 degrees around 5,000 rpm as you said, but if you go to advanced tables, (that is where you have all sort of corrections) Ignition is at the very bottom, you'll see you have a base ignition table, and it is pre-configured to advance timing a lot on top of your low/high ignition table, for example at 5,000rpm aprox, its adding 9 degrees, so it means you have 38 plus those 9 degrees, there fore you have past your MBT reason why is falling the torque on its face, although this may not be activated,

What I would do is Sync the timing Do a pull see if it's better if not set that base ign. table to zero at all rpm cells do a pull and see if it improves,

Hope this help you

awesome! thanks for the help, ill try it and get back with the results

it lost power, aint feeling as torquey

Did you first set Timing?

or did you just jumped and remove timing?

what did you do before it lost power?

distributor timing is set stock, i set the base ignition timing values to 0 , that was found under advanced tables in crome, and then i set the high cam ignition to around 28 degrees around 4k-7k

Hi Curtis,

Well you took off a lot of timing, stock timing is around 34 degrees, reason why it feels weak, this depends on the engine load, do not just set to 28 degrees across the board from 4 to 7 k rpm, I would either load or copy z6 ignition table and go from there, as it has a nice smooth transition on the ignition table, you can find this table under base maps loaded on crome, although they are a bit limited, you can find more maps on Xenocrom web page, they have a good amount of honda maps, there again I'm not familiar with SOHC but for all B-series collection is good, hoop over and download some maps so you can compare Timing,

Hope this helps

whats the best ignition timing for mbt on hondas based on knowledge and experience?

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