Setting Timing On 25det Neo

[DaveB]

Hi all,

How are people locking off their ignition advance to set base timing? I've got an inductive pickup timing light with the pickup clipped around the white wire loop at the start of the coil harness (it's at the back near the firewall), but the ECU is constantly varying the timing and it's very difficult to read. How have other people locked it at 15 degrees?

I have tried Conzult's "idle setting" but that doesn't tell me what the timing is set to, and it doesn't seem to be constant. It just seems to adjust the idle speed.

Cheers

DaveB

[owen1r]

Did you unplug the TPS?

I believe that needs to be unplugged to lock the timing, picture of TPS plug from another thread

Edited August 23, 2015 by owen1r

[DaveB]

Really? No I didn't, I'll give that a go thanks!

[KiwiRS4T]

Really? No I didn't, I'll give that a go thanks!

Also it is suggested that you don't use the loop at the back but put a lead between the coil and plug and use that...

[iruvyouskyrine]

And check the sticker on you bonnet to see what it should be set at. I believe auto and manual base timing is different. And yes unplug TPS and use an old spark plug lead between cyl 1 coilpack and plug.

[DaveB]

Thanks guys. I don't have a spare HT lead unfortunately. Also the tuners I have been to have said they use a loop wire? I'm going to email one and ask but hopefully it will work...

[iruvyouskyrine]

Sometimes the loop works sometimes it doesn't. It's very hit and miss.

[iruvyouskyrine]

I should clarify. It will always give a reading, it's just whether it is correct or not is the issue.

[DaveB]

I will be testing both out this afternoon.

[zoomzoom]

Its about $10-$15 for a short lead. Also more of a pain in the ass to check the timing that way, but worth the extra effort to set something so crucial.

[DaveB]

I have an old style timing light with a long spring on the pickup so I'll see if that works first...

[DaveB]

Well I tried timing from various points and comparing them to the #1 spark plug using an HT-driven timing light, and I can now say for sure that timing off the loop wires shows about 15 degrees more advance than using the #1 spark plug method. I took some pictures if people are interested but I hope this is enough.

Some weirdness I noticed, has anybody ever seen this? With TPS unplugged (thanks owen1r) I loosened all 3 bolts on the CAS sensor, and then rotated until I observed the same timing with the light that the ECU was commanding (in this case 12 degrees). That was fine. But then I would notice that as soon as I tightened just one of the bolts to even finger tight, the timing would change back to like 5 degrees?! The CAS was definitely not rotating, and it would have to rotate a significant amount to make that much difference to the timing. Does anybody know what could be going on there? This is my second CAS too since I replaced it a while ago.

thanks

David

[Duncan]

Lots of timing lights (generally the less expensive ones) read double the actual timing from the loop at the back, so if you are seeing 30o you can probably read that as 15o

[DaveB]

Lots of timing lights (generally the less expensive ones) read double the actual timing from the loop at the back, so if you are seeing 30o you can probably read that as 15o

Interesting to know thanks Duncan. Do you have any suggestion for why it might be changing when I tighten the CAS? I'm a bit worried that the CAS is reading UNDER, and therefore I might have more timing than there should be.

Edited August 27, 2015 by DaveB

[Ben C34]

Lots of timing lights (generally the less expensive ones) read double the actual timing from the loop at the back, so if you are seeing 30o you can probably read that as 15o

I don't think it's that simple and I wouldn't like to just guess.

If the gun is picking up the leading edge of the current in the loop wire, the amount of dwell is added to the timing reading. It might look like double, bit that's basically just a fluke. It should really pick up on the falling edge of the loop wire to be accurate.

I would still not trust it, a plug lead between coil and plug is best option.

[DaveB]

I don't think it's that simple and I wouldn't like to just guess.

If the gun is picking up the leading edge of the current in the loop wire, the amount of dwell is added to the timing reading. It might look like double, bit that's basically just a fluke. It should really pick up on the falling edge of the loop wire to be accurate.

I would still not trust it, a plug lead between coil and plug is best option.

I compared both and I couldn't find any correlation.

With the inductive pickup timing light, off this wire:

...I measured about 22 degrees:

But with an older style timing light, that connects directly to the spark plug (it has a long spring which fitted into the coilpack), it read about 5 degrees!

[Ben C34]

Do some maths. I'm sure it would be able to be calculated back to the dwell of the coil.

I seriously can't be bothered looking I to it further!

It's enough to know to not trust/use the loop, especially without checking it to a lead.

[DaveB]

Do some maths. I'm sure it would be able to be calculated back to the dwell of the coil.

I seriously can't be bothered looking I to it further!

It's enough to know to not trust/use the loop, especially without checking it to a lead.

Sure. What I meant to say was, it doesn't look easy like 2 x the spark-measured value or something similar.