SOLVED pop pop sound at WOT

[maik21]

hello.

i have a little problem right now. its a *pop* sound in exhaust of engine at idle. this sound dont show when driving car.

its a sr20de+t with ms2 v3, newer extra code.

firing order is 1 - 3 - 4 - 2

injectors wiring are :

megasquirt inj1 to 1&3
megasquirt inj2 to 4&2


is there a problem with injectors wiring? i think i need to rewire and put together "inj1 to 1&4" and " inj2 to 2&3" but i dont sure about this.

ignition timing at idle is 20° in megasquirt and timing light. i put more gas at idle to 14.0 afr and "pop" sound still there. then i rise afr to 15.0 - 15.5 and *pop" sound still there too. i forget to tell idle isnt hunting and is smooth.



thankyou very much for your time and help.

[PSIG]

... i think i need to rewire and put together "inj1 to 1&4" and " inj2 to 2&3" but i dont sure about this.

Hello! Yes. This would be the preferred injector wiring anyway, so I would re-wire to see how it affects your idle first.

David

[maik21]

thankyou. i will fix this and see what happend!!

[gruff511]

How do you control your idle? with the throttle plate stop screw? Just for some insight I had that problem but it went away when I started using the Idle Timing Advance. Try setting the idle timing low like at 8* that will allow you to increase the idle intake air to set idle rpm.

[maik21]

How do you control your idle? with the throttle plate stop screw? Just for some insight I had that problem but it went away when I started using the Idle Timing Advance. Try setting the idle timing low like at 8* that will allow you to increase the idle intake air to set idle rpm.

my idle is fine. i read how to tune for idle without iac and it works fine.

i set my timing idle to 20° for 800rpm, and 24° for 600 rpm and it is very smooth.

[maik21]

pop pop sound is not gone at all but is not to much. injector wiring are now right. 1&4 , 2&3. so this is okey!

i was tuning VE table today and this pop pop sound shown at high rpms(4000). so i notice afr was very rich (10.2) so i lean it in the 100kpa load and it went better. some "fine" tuning in the 100kpa(wot) with open wastegate (for no boost.) and this pop sound shown at 5000 rpms but it went to 112kpa and was rich again because in that place i didnt touch VE numbers.

then i put wastegate on and going wot with a 7psi of boots and afr of 11.0-11.6 and pop sound shown again. so i did a datalog.

megasquirt has his own high current coil driver installed and im using nissan coil driver too. so i dont know if it needs a special configuration.

spark output is going high(inverted) if using a single ignitor. but i use internal megasquirt ignitor in series with nissan ignitor so i leave this spark output to going low(normal). all of this with a single coil. so internal megasquirt ignitor drives nissan ignitor.

one thing i see in datalog is maybe a low battery voltage. its from 10.5 to 11.5 all the time. power supply is from key switch directly(switched) to megasquirt and coil, injector and distributor are powered by a relay from this same source. so this voltage is the voltage in coil.

can you helpme with this? i dont know if this low voltage in battery is the cause of pop sound at hight revs and maybe ignition configuration.

thankyou again for taking time reading this and helping. thankyou very much.

[maik21]

i forget something maybe important. i didnt configure the fixed timing in "more ignition settings" because timing light and timing in megasquirt were equal.
when tuning, i use a diy det can and knocks dont shown.

here are spark plugs. they looks a llitle gray !!

[maik21]

bump!!

someone has some advice about this problem?

[Matt Cramer]

One thing jumped out at me - there's a big IAT sensor malfunction that can be affecting your air temperature correction. Also there's a bit more MAPdot triggered accel enrichment and fuel cut at WOT than should be going on.

[maik21]

iat is not working because there isnt a iat sensor. in the MAT table all values(DEGRE and %) are to zero.

there isnt fuel cut. there is spark retard for rev limiter and is set to 7800 hard rev and 7700 soft rev limiter . and overboost protection is set to off.

there is only tps based AE and i think isnt working because i run this from a base map from diyautotune and is set to tune ve table without problems.




in a easy words, what i should check ?

i think power supply is low and i fix this but i want to know more things i need to check because i only be working on this car on sundays. if one thing dont work, i need to try another one without wait 1 week.

thankyou for your help.

[Matt Cramer]

iat is not working because there isnt a iat sensor. in the MAT table all values(DEGRE and %) are to zero.

Fix that. NOW.

there isnt fuel cut.

I did not mean a total fuel cut; you are having the Decel Fuel Amount multiplier applied at WOT, which you don't want to have.

there is only tps based AE and i think isnt working because i run this from a base map from diyautotune and is set to tune ve table without problems.

The Decel Fuel Amount will still be triggered if the MAPdot level goes over the MAPdot threshold. Raise the MAPdot threshold.

[maik21]

okey. i will do that. thankyou.

[maik21]

i put a relay from +12v battery to megasquirt and it works fine. i did a retune in VE MAP because it need less fuel at wot. it works fine all rpm to redline(7500).