Thread: Timing drift: Aem ems vvl n/a + 20v coils + 24-1 disk

Actually as soon as I pull in the throttle cable a bit timing drifts about two degrees on the pulley. Going to the 5K rpm I may see 3 degrees.

I don't know if it's just the spark plug cable I use to put between the coil and the plug ti measure timing

I forgot about this but it still does it.

This should be absolutely impossible. I'm sorry I missed this the first time around. When the ECU is locked in timing mode, the logs should show steady timing NO MATTER WHAT. There should be no possible way it shows anything different. Say you lock it to 15 degrees, the log should show 15 degrees DEAD the entire time. You're saying it will go up to even 16? That is completely bonkers...


I'm glad you mentioned this. This is not the source of your problems. This is the exact correct way to check timing with COP. Sorry I'm not of more help. =(

I meant logs of real runs. I have not logged the timing lock procedure. And I will now.

It must be something I set wrong or did not set on the AEM, or maybe installed the disk wrong? if that's even possible. It did not do it at all on the distributor with OEM disk. I kept the distributor as the CAS but switched automatically the OEM disk to the 24-1 when installing the 20V Coils. Unsure if the OEM works with Coils. Because as far as I'm concerned and contrary to AEM, the OEM disk was more accurate than the 24-1 in my case

That is completely normal and as expected unless your timing map is COMPLETELY flat/static above 5,000 RPM and you have absolutely no other ignition trims in use. This is most certainly not the case...
There's no need to log timing while locked in timing mode. It will log whatever timing you've set it to. Really, there's no need to do this. It is a waste of time. I hope you understand that...

It really is almost impossible to install the disc wrong unless you didn't tighten it down all the way? It should be able to be installed "backwards" with no ill effects. It is symmetric when flipped.
Are you sure changing the Pick-Up Comp Delay value has no effect? Are you pressing "Enter" on the keyboard to apply your changes? You can't just type a different number... You have to press enter for it to apply.
The OEM disc will work with multiple coils. IMO it has too many issues to consider using though.

Yes, changing the pick up delay comp does have an effect, but it never eliminates this completely. I set it to 300 where I see minimal timing drift, which is still 2 degrees as soon as I pull the throttle cable.

Checked my latest logs and timing on high rpms at WOT follows as commanded on the IGN MAP, with no other trims applied.

This remains unsolved but I'm using the car as is

Timing drift shouldnt show up in your log.
It's the measured difference of what the ECU wants vs what you read with a timing light....

Just saying, cuz reading some of this makes me feel unsure what you're saying.

I'm saying I have timing drift on the pulley when checking with a timing gun and ignition locked.

Let's forget the mention of logs, they really don't belong in this talk.

Ben checked his timing b/t coil and spark plug
....

http://www.sr20-forum.com/members-rides/554-benfenner-s-1994-black-se-r-40.html#post890151

Which way are you checking?

He said he was doing the same thing:

Yes. I take out No.1 Coil and use an adapted spark plug cable with a 90 degree boot on the end going to the coil and of course the plug end going to the plug.

I lock out the timing on the AEM EMS v1 in Configure > ECU Setup > Set Ignition > Ignition fixed ticked with various values 0, 10, 13, 15 (Gspec VE Pulley)

I get timing drift as soon as I start pulling on the throttle cable (accelerating), about two degrees at all values of Pick up delay comp (well to be honest 0, 50, 100, 150, 200...510, not that I have truly tried them all but hey I should have found something).

Now, I just checked the AEM instructions for the Nth time and realize it does say before doing Set Ignition to:

"· Go to the Ignition | Ignition Map
· Set the Ignition Map to a conservative value that is marked on the crank. This is
specific to the application. Most motors have at least a TDC mark (0 degrees) on
the crank.
· Go to the Ignition | Advance Ign | Ignition Trims
· Set all ignition trims to zero"

I thought all these would be cancelled when you hit Ignition Fixed.

Anyway I only used Set Ignition with the normal ignition maps when on distributor and all was fine with no timing drift