Timing randomly being pulled in upper RPMS
 

I've been banging my head against the wall trying to figure this out. From 7400 RPMS on up, timing keeps being randomly pulled to 5* from what it is supposed to be set at{7-8*). There is no knock in the logs, AFR is 10.7-10.8. Timing in the logs looks like this:

6-6-6-7-7-7-5-5-7-7-7-5-5-8-8-5-5-8-8-5-5


I've double and triple checked for loose things in the engine bay and tighten every bolt/nut, checked grounds, replaced IAT, replaced cam position sensor, and just replaced the crank position sensor. There are no blown fuses. I've tried a stock ignition, iridium plugs, copper plugs, my mini battery is new as of May-June, and has been on a trickle charger when the car is sitting since day 1. Car was boost leak tested to 35psi with no leaks. I've done multiple compression tests as well and the numbers are exactly what they were last summer.

Im out of ideas. Has anyone experienced this before? I can attach logs/rom if someone would be willing to take a look. Car is being tuned remotely by a very reputable tuner, I highly doubt the tune is the problem, but I guess you never know.

Have you zero'd out all your corrections to ensure one of them isn't playing in the background?

I haven't touched the ROM, I just flash what my tuner sends me. We started tuning for boost about 2 months ago and this issue has been there since after the first couple pulls.

Show us a log and why 10.7/10.5 afr

Thats just where we're at so far in the tuning process, I've been trying to figure out whats causing this issue before proceeding. Log is attached.

I have that table changed so the map shows what the cars actually running, however he says the air temps doesn't exceed past 20F of what's outside, so roughly in the mid 90's, which would be 0 on my table cell.

Won't hurt to zero the rest out just to see, but i don't think it'll fix this one.

This triggered me to ask him once again if he has any break up or misfire at WOT. before he said no, this time he said yes when i asked on facebook. maybe the o2 sensor is recording leaner than it really is due to the location of the sensor, and it is rich enough to break up. lets hope its that. thats an easy fix if so. typically misfires create lean conditions though and i dont really see any of that occuring uptop.

Either way, i leaned it out more and we will see what that does. The target afr for the car in general is around 11.5ish on 93oct.

I will report back new findings. Thanks for helping guys.

Here is a log from tonight with a new rom. Still broke up up top a bit, timing issue still there, no knock. :confused:

whats the eng spec , peak load is late 5600/5700 and 11.1 afr

Map stage 2 2.1l
PTE 6766 CEA, Twin Scroll 1.15 a/r on the hot side
Comp280 cams
3.5"-4" exhaust
5" ETS FMIC
3" i/c pipes
stock throttlebody
stock intake manifold

the spool is amazing for this setup with a 2.1L and 6766 on 93oct.

http://www.tscomptuned.net/_images/d...n-r/6766-1.jpg

Just need to figure out whats causing the timing to scramble. its not the AFR. I leaned the car out to be 11.5 straight across still does it.

I think its something to do with the crank trigger plate.

Turn on FLASH CEL For knock and is it flashing during the pull?

You can have the issue were ecu will pull timing so quick it wont pick up on logger, as well as you can see knock voltage getting high at the point it pulls timing. Have you tried turning knock background noise table up to say 30 and do a pull and see what it does?

Its at stock filter uptop at 20 and the roms set to flash cel at 3 counts low and 6 counts high.

no we haven't tried to jack the filter uptop high to see what it does. i dont think thats going to fix this issue but worth a shot. we will try it then report back. knock voltage is normal no spikes.

i personally think this is something to do with the trigger plate / crank / cam signal.

or maybe bad ground or ignition.

This is a long shot, but the ECU adjusts timing to 5 degrees if it gets the start signal input. Maybe there is some wiring fault/short that causes that input to go "live" at higher rpm due to vibration etc. You could disconnect the pin from the ECU connector as a test and see what happens.

Another possibility would be if the vss is working intermittently and the launch maps are enabled and happen to have 5 degrees in those load cells (I have seen something like this before).

Tom this is probably also what my Idle dip problem is... remember my timing dropping itself to like 5*? even though we never had that on the MAP. Maybe its the starter signal like someone said? Hoping to find a solution for OP and me :)