anyone seen this before?

ignition timing set to 15btdc with timing light.

check on conzult and it reads 25btdc at same rpm.

checked out anoither Z and it was 15btdc on both timing light and conzult at same rpm

is this a sign of the cas being at fault?.

Seen this a lot, many times it is just a corrupted signal but do check engine temperature readings though, have found some zeds with the thermostats removed, that the engine then especially at tick over ( bonnet up)will not get up to full working temp and hold the timing at a higher figure, taken to extream often turbo zeds will drop in and out of cold running safety boost for the same reason.

 

Jeff TT

If you use an inductive timing light on the PTU loop, sometimes it will read wrong unless you pull the clip back. Do it off an HT lead plugged into No1 coil is best.

"HT lead plugged into No1 coil is best"

Only ever do it this way and have seen the 25deg timing that will not come down a few times.

 

jEFF tt

ignition timing set to 15btdc with timing light.

check on conzult and it reads 25btdc at same rpm.

 

Just wondering - what RPM were you setting & checking at?

 

Looking at what I think are the stock timing maps, if the throttle is closed and idle RPM, timing is 15deg, but if the throttle is slightly open the timing jumps to 25deg (at idle, 40deg off idle) - so it might be worth checking your TPS voltage.

 

I've not tried proving this on my own car, but might at some point.

 

(I say I *think* they're stock maps as I can't be sure - it's whatever came with the ZEmulator demo. Can't see anyone wanting to change the timing that low down though really)

aaronjb,

 

Yes you right, as the throttle opens and the hard idle switch also opens the timing raises up as part of the engine speed adjustment, oddly though on the cars I have seen the 25 deg minum reading problem, all the settings for tps etc have been ok,

 

Sorry ED for highjacking your thread, would be nice to have a definative answer though.

 

Jeff TT

thanks for the replies guys, just to make things a bit more helpfull in the diagnosis,

the timing was taken from No1 cyl with HT lead connected.

the idle speed was 800rpm.

tps voltage reads 0.4 volts.

hard idle switch is closed.

coolant temp is at 80c.

please keep the ideas comming as Jeff says it would be nice to get a definitive answer,

its interesting that it has been seen on other Z's.

i have tried a different ECU but it is still the same i have another cas to try so i'll let you guys know tommorow if this shows any difference.

There's a separate 2D timing map in the ECU for idle, I'm presuming it's used when hard idle closed or TPS

Don't have the figures to hand, but it's 15deg upto x rpm then 25 afterwards.

Still wouldn't explain this problem though.

 

When it's off idle, does the conZult match the actual figure? Just wondering if it's a problem with conZult misinterpreting the figures, or if there really is an offset. The only way to know for sure is to see if it matches under some load.

What I'm wondering is if conZult looks at the timing figures on the primary timing maps and shows those even if the actual figures are coming from the idle map. Eric ??

Erm if the conZult shows 25 degrees then that is what the ECU thinks the timing is at - in your case, the ecu thinks its 25 degrees but its actually 15 :eek: You should set the timing to match what the conZult says.... However, if its not at 15 degrees, then something is pushing it out. 800rpm is a little high IMO, stock is 750 - is the base idle set correctly???

Doesn't the consult always assume 15 degrees base timing, and adjust movement from there?

No thats what the ECU assumes. If the conZult is saying the ECU is setting the timing to 25deg, then thats what you should see with the timing light....