detonation under full throttle help!

r_honda · Post by **r_honda** » Mon Apr 11, 2011 3:09 pm

hey iv got a d series a6 block z6 head built forged motor im runnin ectune .. heres my problem iv got the ignition map in low and high cam very low and im still getting detonation thru vtec engagement timing isnt more than 15 deg in boost. i retarted the cam a few degress which took most of it away when i timed this motor since it being a different block from head and i dont have a degree wheel to properly time this motor i have jus been adjusting the cam accordingly to how i hear the motor and how it reacts should i go back another mark on the cam or could there be another underlying issue i am over looking ... any information u have wuold be greatly appriciated. PS- AFR is 11.5 in boost and the motor is on 12 lbs right now thank you, Dayne.

thething96 · Post by **thething96** » Mon Apr 11, 2011 6:23 pm

what spark plugs are you running? what type of fuel?

r_honda · Post by **r_honda** » Tue Apr 12, 2011 12:37 am

bkr7e ngk . 30 gap 94 octane chevron fuel

rich777 · Post by **rich777** » Tue Apr 12, 2011 6:10 am

Have you checked your timing with a timing light ?

r_honda · Post by **r_honda** » Tue Apr 12, 2011 12:41 pm

check it witha light im watching it live on ectune as i do pulls

9400RPMS · Post by **9400RPMS** » Tue Apr 12, 2011 5:01 pm

Gap your plugs down more......

r_honda · Post by **r_honda** » Fri Apr 29, 2011 1:36 am

.28 ?

r_honda · Post by **r_honda** » Fri Apr 29, 2011 2:11 am

its also not missing its detonating how would plug gap come into play ?

Bindegal · Post by **Bindegal** » Fri Apr 29, 2011 3:31 am

I donÂ´t see how gap comes into play, however I find it likely that thereÂ´s a mechanical reason of some sort. For example, either: 1) Base timing is off. Make sure the TDC mark on the crank is accurate against actual TDC, then check/adjust distributor with a known-good timing gun. eCtune allows you to lock ignition at 16 degrees or whatever as you make those adjustments. 2) Static compression is higher than you think. Only real and true way to check this is by measuring the ccÂ´s of the actual combustion chamber. I once had a customer with a built B16, stroker crank etc. he had been to 3 other shops before me trying to resolve detonating issues. It quickly turned out to be caused by a diesel-like compression ratio

/Allan

r_honda · Post by **r_honda** » Fri Apr 29, 2011 1:26 pm

iv got srp 8.5 pistons cr should be 9.1 -9.3 with the a6 block and the z6 head im having troubles finding my tdc cause the deck heights are different so iv been trying to slowly adjust cam 1 deg at a time till the detonation goes away next investment is a degree wheel so i can properly time this motor if i retard cam timing does ignition timing advance or retard ?

12sec1/4 · Post by **12sec1/4** » Sun May 01, 2011 7:14 am

Ghetto way to check TDC is put a screwdriver down Number 1 whilst turning the crank... You can then eye it up to TDC... Just a case of getting the cams aligned then. *edit* scrap that... It's the cams you can't align... What is your base timing? You havn't mentioned this yet. Just because it says 16* on eCtune does bot mean that is set to 16* using the Dizzy...

TopMountGSR · Post by **TopMountGSR** » Mon May 02, 2011 6:14 am

How do you know its detonating? Do you see it on the plugs? Knock sensor? By sound? You should post the map.

r_honda · Post by **r_honda** » Mon May 02, 2011 6:40 pm

isnt the live ignition in my display the ignition that the engine see's ? im not talkin about the value i have in the map .... although the i am at 16 deg base in my map and the live ignition reads the same number

Vtec6000 · Post by **Vtec6000** » Mon May 02, 2011 9:38 pm

r_honda wrote:isnt the live ignition in my display the ignition that the engine see's ? im not talkin about the value i have in the map .... although the i am at 16 deg base in my map and the live ignition reads the same number

have you put a timing light on the crank pulley to see if its at 16degrees? just because it says in live window its 16degrees doesn't mean it is if you haven't sync'd your actual timing with timing in software.

RolexTM · Post by **RolexTM** » Tue May 03, 2011 8:13 am

that's the exact point you need to sync your distributor to what the ECU thinks your timing is!