Timing Advance (?)

[AFTDRK]

hi there,

i had a dyno run done on my car yesterday.

the tuner told me he was going to change the timing a little to raise my power.

(R33 gt25t: stock ecu, stock turbo, turbo back exhaust, 12psi, fmic, pod.)

the car initially only pulled out around 150kw's and then after playing with timing it brought it up to 191.3kw's

i was advised that the car would cough/hiccup at idle due to that change in timing.. and it does every couple of seconds - which i dont like.

what i wanted to ask though is if this was safe ? my car feels faster but i dont want to push it if the timing advance poses a danger to my engine.

Any advice would be greatly appreciated

Edited May 13, 2009 by AFTDRK

[femno]

Tuner?

Just anyone can advance the base timing to make more power, its pretty dodgy and dangerous in my opinion. Although with those mods you should be making around that 190kw anyway.

How much did he advance it by? I think factory setting is 15 or 20, cant remember, should be on the engine info sticker under the bonnet.

I would have the car checked by someone with a dyno and proper standalone knock monitor to see if its knocking at all, which could very well be possible.

Even high knock for a split second over time can cause damage to the engine. Id put it back to standard base timing if i was you.

[Guilt-Toy]

hahahahaa look at that power curve! it goes up and then down and then back up again LOL

I would get a power fc and get it tuned properly. the car would go heaps faster.

and i love it how he stops the runs at 160k's a hour on the first 2 runs, and then on the last final power run he takes it all the way to 180 where it makes the extra power lol

[juggernaut1]

Looks like swine flu to me...

[StealthX]

hahaha +1

the "coughing" you're hearing at idle is valve overlap.

more specifically, its unburnt fuel escaping into the exhaust and exploding there.

nothing to worry about. just means your timing had been optimised for mid-high rpm power production, its a good thing!

[Turbz RB-25]

lol, get a SAFC of PFC dude.

[Adriano]

hahaha +1

the "coughing" you're hearing at idle is valve overlap.

more specifically, its unburnt fuel escaping into the exhaust and exploding there.

nothing to worry about. just means your timing had been optimised for mid-high rpm power production, its a good thing!

I hope you aren't serious. "valve overlap" good one

[StealthX]

all cars have a certain amount of overlap at idle.

its just he cant hear it in the exhaust now from a little fuel escaping.

in my experience, most performance alterations you do, will lead to a lumpier sounding idle.

i wasnt referring to a change in anything vlavetrain related.

I hope you aren't serious. "valve overlap" good one

no need to be patronising mate, i dont know everything there is to know about engines, and i dont claim to either.

[zebra]

all cars have a certain amount of overlap at idle.

its just he cant hear it in the exhaust now from a little fuel escaping.

in my experience, most performance alterations you do, will lead to a lumpier sounding idle.

i wasnt referring to a change in anything vlavetrain related.

no need to be patronising mate, i dont know everything there is to know about engines, and i dont claim to either.

All ENGINES have a certain amount of overlap at all RPMs

my car doesnt over lap with another car at idle

[Kinks]

no need to get narky and pick peoples' words apart. besides, valve overlap remains constant unless you use cam gears to change your cam timing. you're either advanced or retarded (talking about the engine here, not the owner ) but the amount of adjustment in an RB is not much, shouldn't be enough to cough/hiccup at idle.

Paul, I highly recommend you take your car to another tuner for a look over. Pinging is audible but to be avoided and you're better off being safe than sorry. Takes 5 seconds to check timing on an RB so a competent workshop familiar with skylines should be able to put your mind at rest. Standard timing is 15 degrees and I would not put it any higher than this running 98RON fuel.

[rob82]

Looks like he stopped the run at 160km/hr because it was missfiring as per what any competent dyno operator would do.

The extra timing helps with reducing the energy required for ionizing the spark plug gap as the cylinder pressures are less the further you are from TDC on the compression stroke.

Sometimes with std ecu's on R33's its a real blend as too much CAS advance can cause detonation at low rpm. The popping at idle is most likely from small spark plug gap, not from advancing the CAS.