ECU:How does it calculate Timing??

TomsSVX · #1 09-11-2008, 10:15 PM

Hi all. Been messing around with the datalogging software in correlation with the select monitor. I took the car out last night for some extra hard runs to see exactly what is happening with the ECU... Here are some points.

1. Spontaneous acceleration and hard driving are fine... Car pulls well but seems to have a minor restriction... Just doesn't feel 100%.

2. 1/4 mile run.... half way through 3rd gear the car falls flat on its face. Monitoring the MAF signal, load, TPS, knock correction... Nothing seems out of place and all seems to be working properly. Only problem is, my advance has gone to ****. At full load it has about 6-8* advance BTDC which is absolutley killing the engine's performance not to mention spiking my EGT's up to about 1500*F. I looked at knock correction (retard) with both the evoscan software and with my select monitor and it registers 0 at all times. But monitoring the advance on both confirms that it is drastically low...

3. Car runs great through normal driving yet I am still having an idle issue.

My thoughts were always that the only way to pull timing out of the base advance is to have a knock condition in which the ECU could pull up to 10 degrees from the advance.... BUT since the retard function on my SSMI and the evoscan software say 0 all the time... how could this be possible?

I am at a loss of thoughts as to why my timing could be so low??? any ideas?

Tom

Tim · #2 09-12-2008, 07:53 AM

DId you end up using race fuel as mentioned or did you stick with pump gas?

TomsSVX · #3 09-12-2008, 08:31 AM

Yea.. was using 103 octane race fuel as well b/c when I got to the track... my fuel light was on... I originally wanted to get two runs on pump gas and 2 on race fuel at least.... But It was too low to both racing on what I had left of 93

Tom

oab_au · #4 09-13-2008, 05:55 PM

I guess this is the blowen engine running 9psi-12psi?.
What do you expect the spark advance should be at full throttle?

Harvey.

SVXRide · #5 09-13-2008, 06:08 PM

yeah, more info, please!

-Bill

TomsSVX · #6 09-13-2008, 06:44 PM

Quote:

Originally Posted by oab_au

I guess this is the blowen engine running 9psi-12psi?.
What do you expect the spark advance should be at full throttle?

Harvey.

I would suspect the advance to be around 20-30* BTDC. Yes it is supercharged again running the "9psi" pulley. When I smack the throttle it will jump to 10psi and once i get to around 6500-7000rpms the boost will climb up to 15psi more than likely due to the fact that the cam profiles don't allow the engine to consume enough and it backs up in the intake. BUT just to be clear, the timing advance starts having issues around 3k rpm. Remember this is the totally stock engine it is on and it ran flawlessly N/A.

Tom

SVXRide · #7 09-13-2008, 07:08 PM

YT,
Any possible "back doors" to the timing tables? Any sensors that you're not datalogging that could be sending a signal that is causing the timing to be pulled back? I'm wondering if you aren't producing a combination of inputs that are putting the ECU into "self preservation" mode, thus pulling timing.
-Bill