4g VTEC Ignition timing tweaks

[chrismc]

Today I reset the timing to factory standard on our 4g using my trusty timing light...

To do so I had to retard the timing ever so slightly to line up the timing mark on the Fidanza flywheel (has a mark at TDC as well as 15degs).

On the test drive I noted that the car felt generally flatter & the throttle response was all woolly. Fortunately I had marked the initial position of the dizzy so put it back there & hey presto it was back to normal...

Got me thinking whether the Fidanza marks are inaccurate &/or the stock factory timing errs on the side of caution?? (Poor fuel/hot climates etc)

As such I decided to advance it up further from the initial setting & the car has really come alive- probably only another 3 degs advance but has made a world of difference.

Much more punchy low down & nice crisp pickup- no pronounced surge into VTEC (more torque below?) & no pinking despite my best efforts using low speed, high gear & WOT. I wouldn't say it has altered the top-end either way, but then it only has a cheap manifold & stock decatted exhaust so top end breathing is far from optimised.....

Just wondering if anyone else has tried deviating from the standard Honda settings & found an improvement?


Chris

[4thgenphil]

i thought it was timed at 18degs standard?

[chrismc]

Yes maybe it's 17?

It's running about 4degs advanced from the standard timing mark on the flywheel now anyhow!!

[littlefeller]

my vtec kicks in with a kick, should it not do this also is it posible to adjust the timing if i have a knock sensor fitted?

[judderod]

Before I went with an aftermarket ECU I ran pretty far advanced by the distributor. It certainly felt more powerful that way. The stock ignition map is safe to run on camel pi$$ for fuel on the hottest of hot days up a mountain somewhere. So if you're using decent fuel (V-Power) then there's a safe margin of a few degree's to be had.

I think my flywheel is F1 motorsport (?), and the timing marks were off a bit too. You can make your own by finding TDC with a slim long extension bar down the spark plug hole of piston 1. Carefully turn the engine by hand back and forth near TDC until it's bang on and then put a dab of white paint on the flywheel tooth that's lined up. A bit of maths will get you to 17 degrees advanced so mark that with a blue dot. Then mark a red dot on the next tooth along in the advanced direction so you know which way to go.

If you want to really fine tune it, go for runs as above and listen carefully for knock, advancing a couple of degree's each time. If you hit knock, back off at least 2 degrees, reset the ECU and do a few more runs to be sure it's gone. Then before finishing up, ideally put clean/new spark plugs in, go for a few more WOT runs and pull the spark plugs to check for tiny (pin head size or smaller) black or silver dots on the ceramic cone which indicates knock is still happening so retard a bit more.

Finding knock is a bit of an art. It's best to take somone along who knows how to tune. Remember if you hear knock, damage is being done already so play safe. You won't be able to hear knock at high revs unless you've gone way too far advanced. But at sensible advance, the fuel map is rich enough at WOT/high revs to allow for more power to be released - especially with breathing mods.

I've tuned this way and with Neptune (full control over all ECU maps and settings). If you only have basic mods (no internal work), I'd say there's a good 6 - 10% additional BHP and torque to be had safely this way on good fuel, as long as you stay well away from knock.

Knock sensors are ignored by the ECU at high revs - they can't be relied on as a safety margin.

[littlefeller]

Knock sensors are ignored by the ECU at high revs - they can't be relied on as a safety margin. i didnt know this, always wondered if the ecu used the knock sensor for resetting itself.

[chrismc]

Before I went with an aftermarket ECU I ran pretty far advanced by the distributor. It certainly felt more powerful that way. The stock ignition map is safe to run on camel pi$$ for fuel on the hottest of hot days up a mountain somewhere. So if you're using decent fuel (V-Power) then there's a safe margin of a few degree's to be had.

I think my flywheel is F1 motorsport (?), and the timing marks were off a bit too. You can make your own by finding TDC with a slim long extension bar down the spark plug hole of piston 1. Carefully turn the engine by hand back and forth near TDC until it's bang on and then put a dab of white paint on the flywheel tooth that's lined up. A bit of maths will get you to 17 degrees advanced so mark that with a blue dot. Then mark a red dot on the next tooth along in the advanced direction so you know which way to go.

If you want to really fine tune it, go for runs as above and listen carefully for knock, advancing a couple of degree's each time. If you hit knock, back off at least 2 degrees, reset the ECU and do a few more runs to be sure it's gone. Then before finishing up, ideally put clean/new spark plugs in, go for a few more WOT runs and pull the spark plugs to check for tiny (pin head size or smaller) black or silver dots on the ceramic cone which indicates knock is still happening so retard a bit more.

Finding knock is a bit of an art. It's best to take somone along who knows how to tune. Remember if you hear knock, damage is being done already so play safe. You won't be able to hear knock at high revs unless you've gone way too far advanced. But at sensible advance, the fuel map is rich enough at WOT/high revs to allow for more power to be released - especially with breathing mods.

I've tuned this way and with Neptune (full control over all ECU maps and settings). If you only have basic mods (no internal work), I'd say there's a good 6 - 10% additional BHP and torque to be had safely this way on good fuel, as long as you stay well away from knock.

Knock sensors are ignored by the ECU at high revs - they can't be relied on as a safety margin.

Much as I thought then.

There is definitely potential for more power from the standard engine with fine tuning of the map.

My old ITR picked up 8bhp peak & 15bhp in the mid range from a proper map on eCtune- it also needed more advance combined with pulling fuel out of the map

They certainly map them rich as standard- but then with VTEC engines' appetite for revs it doesn't take long for detonation to cause real damage- so best to keep em safe