9age bad pinging

[Whiteone]

Hi all.
Can anybody advise the best action for fixing pinging on a 9age 1902cc 16v bigport head mild cams?
It's running on 98 octane fuel but pings under acceleration.
Timing is set correctly and the AFR is OK.
Bit of a newbie to megasquirt so any help would be most appreciated.
It's an MS2 DIY auto tune PNP.

Thanks peeps

[jsmcortina]

[toyotaspeed90]

and since it's a 9age, which makes the 7age seem over abundant, you might want to include other information like what pistons you have/expected CR, injectors (etc)

[whittlebeast]

How sure are you that the base timing is set correctly? How was it verified?

There are combinations of issues that can make high RPM timing to not end up on the crank as expected.

[Whiteone]

Yes base timing is set correctly and reads find on the qauge cluster even under higher RPM.
11.5:1 compression.
CP flat top Pistons
213cc Denso high impedance injectors (beige same as bigport 4age)
Maybe I should start retarding timing in the advance table.

[jsmcortina]

You should start by posting a tune and a log.

James

[Whiteone]

OK James
Thanks

[slow_hemi6]

Hemi type heads combined with higher compression levels tend not to need as much advance as less efficient designs.
I have 11:1 comp, last time I detected pre ignition it was lean, an issue with secondary injectors.
Higher compression means higher engine temps.
I run colder plugs with higher compression.
Stockish cams don't play nice with higher compression, you tend to need a little overlap to reduce your dynamic compression levels.
Lastly what were the flycuts/valve reliefs like on those CP's. Sharp edges on the flycuts/crowns promote pre ignition and are a no no, esp on finicky higher comp engines.

[Whiteone]

The cams are 193a street cams.
The piston valve cut outs and crowns have rounded edges.
Must get a tune file and data log on here.

Many thanks.

[Whiteone]

Please find attached current tune and data log.
Every time I start the engine the idle is different at operating temperature and the pinging is bad.

Cheers Guys

[whittlebeast]

I don't think you enough Accel Enrichment.

Assuming this motor is normally aspirated, you need to rescale the fuel and timing tables to go from about 15 KPA to 100 KPA

[Whiteone]

Thanks Whittlebeast.
Yes it's N/A
I've not touched the acceleration enrichment at all yet.
I shall have a look.

Thanks.

[slow_hemi6]

Even through section where rpm is gradually increasing, it is lean.

[whittlebeast]

Here is a trick that may help you get your head around AE. I create a new field in MLV called PW Base. I define that field as

100*[PW]/[Fuel: Accel enrich]

I the lock down the scale of PW and PW Base in MLV to the same scale, say 0 to 20 MS. I do the same trick with Duty Cycle.

see

http://www.nbs-stl.com/tuning/Textbook%20Data%20log.png

I tend to increase AE till I get a clean increase in RPM as a response from the throttle snapping open. Your AFR will tend to lag about .2 sec as it responds to the new exhaust flow levels.

Andy

[Whiteone]

Great thanks so far I shall go and have a fiddle with it.

Cheers