OMG!!!!

Thank You Sparky...+1

So, i should lower the timing immediately now...

 

What is the highest octane gasoline that is available where you are located?

 

I imagine that if you are running pump gas that you are limited to about 90-93 octane(R+M/2), or if in Europe, you may be able to get the 98-100 R.O.N. Shell premium high test gasoline.

If you are in doubt proceed with caution. You may want to install an exhaust gas temperature gauge with the probe placed in the number two exhaust manifold runner about 2" from the head/ex. manifold flange. If EGT's exceed much over 1500 degrees F. then back off on the timing or reduce boost.

The Zeitonix digital readout A/F package with EGT capability is sweet. This will allow you to log EGT's and provides an output for an audio/visual alarm which is adjustable to any selected maximum temp in C., or F. It features a playback feature and peak hold.

Alternately, you might want to look at the SPA instruments, dual digital readout EGT gauge. It also features alarm function with adjustable limits, a peak hold and play back, etc. Above all, don't play in the dark.

 

With a turbocharged car I prefer to run a low timing/ high boost map on pump gas, especially when initially sorting out the tune and finding the limits of knock resistance of the particular fuel that you are using.

So I personally set timing low at first and find the octane limits by dialing more boost in incrementally. Until knock is detected. Then back the boost off a bit.

Then with the boost limit determined I go back an start adding timing one degree at a time until knock is detected. Once it knocks, then back it off a degree or two. Bets to play it safe.

This is from a guy who is not a tuner though. So, you may want to consult with an experienced Evo tuning expert.

 

I think is 91octane as its Ron 97 but its still crap fuel over here.

And the most Beauty of it which just happen today is "Fuel Price Increase Again"!

Can i lower the timing and on which rpm & load should i start to bring down the timing?

 

Thanks Sparky...

 

Great post, Sparky. Should be one of the first questions you ask your "tooner". If he/she does not know the difference between pre-ignition and detonation, then you should probably find another tuner for your car.

James, one of the problems you'll find with lower octance fuel is that it is less "knock" resistant (here in the US the AKI on the octane rating actually stands for Anti-Knock Index), meaning that it is more prone to pre-ignition and detonation. So if you're going to play around with lower octane fuel, you'll have to be extra conservative, as a few clean runs (i.e., no knock) may not be enough data to ensure long-term knock-free operation.

l8r)

 

[quote=Ludikraut;10077173]Great post, Sparky. Should be one of the first questions you ask your "tooner". If he/she does not know the difference between pre-ignition and detonation, then you should probably find another tuner for your car.

James, one of the problems you'll find with lower octance fuel is that it is less "knock" resistant (here in the US the AKI on the octane rating actually stands for Anti-Knock Index), meaning that it is more prone to pre-ignition and detonation. So if you're going to play around with lower octane fuel, you'll have to be extra conservative, as a few clean runs (i.e., no knock) may not be enough data to ensure long-term knock-free operation.

Thanks Ludi,
will bring my ride for some runs and lower the timing later...

 

when was the last time you heard of an Evo (or any model petrol car) with "pre-ignite" problems?
If "pre-ignition" is James problem, how will changing the ignition timing help him?

I think we can rule it out.

 

Wow...I do love this post as the experience & senior forumers shared their valuable information...

Hi RSMike, i'll monitor my knock count closely for this few days as ive advance some timing on the lower RPM (1200~4800) - load (20-100).

Should i lower my timing even if my knock counts lower than 30 most of the time on my pfc ecu?

 

I'm pretty sure anything below 50 is ok.
If you are unsure, try what i suggested earlier and reduce the timing 2 degrees and try again.
If you're not sure, tuning can be very dangerous.
Maybe you could look at some advanced tuning tools like knock detection?
This is what we for every single car that we tune, both on the dyno and road tuning

http://www.linkecu.com/products/Tuni.../g4-knockblock

Cheers, Mike

 

If im right, you need a higher octane fuel and the right timing advance to minimize the risk of knock. I would imagine the same goes for pre-ignition? Or maybe an afr adjustment?

Great thread!

 

Repeat post

 

Mike is correct. Since by definition preignition occurs before the spark plug fires, then altering the ignition timing should have no direct effect on reducing pre-ignition. But, ignition timing can be related to detonation. Detonation in turn can lead to pre-ignition. I realize that this seems like circular logic.

But, preignition and detonation can be and often are directly related to each other. Detonation often time leads to, and in fact causes pre-ignition. How? A byproduct of detonation is higher combustion chamber temps. Higher combustion chamber temps and uneven flame propagation can lead to localized hotspots in the combustion chamber( i.e., glowing hot spark plugs, exhaust valve edges, carbon deposits, sharp chamber contours, etc.). These hotspots, in turn, can pre-ignite the combustion mixture.

So detonation can lead to pre-ignition.

 

Thank you RS Mike, Sparky and others Forumers...