Looking at timing with a DiabloSport Predator

propellerhead · Dec 8, 2004

Using a DiabloSport Predator, I recorded the RPM and SPARKADV parameters during a WOT run from 5 MPH to about 70 MPH to see what the timing advance is doing. Pretty cool gadget.

Anyone care to comment or explain the following observations?

1) There's a drop in timing (to 0.75 deg) at the point I floored the gas pedal.
2) There's a small drop during the 1-2 shift.
3) There's a large spike after the 2-3 shift starts.

I plan to record a few more runs to see if the data is consistent.

hotrodnut · Dec 8, 2004

Very interesting propellerhead, I'd say when you first nailed it the knock sensor told the ECU there was some spark knock and the ECU retarded the timing that much, I have not seen it that low on mine. I really can't see why the spike in advance on the 3rd gear shift though but the 2nd gear drop looks like what it should have done. I wish I was more up on all that the ECU tells the timing to do and where it gets the info to do it from.

Thanks for posting that graph, I'll do mine one day soon trying to duplcate exactly what you did and bump it up against yours. I'll be looking for more from you too.

propellerhead · Dec 8, 2004

Knock sensors are in the DOHC engines only, according to the Haynes Manual for the 99+ Mustangs. I thought it might be a bad sample but the drop and the spike are not single samples.

jstreet0204 · Dec 8, 2004

Automatic cars use a torque modulation strategy vary timing during shifts. When the EEC thinks it's time to change gears, it can pull timing so the shift is smotther.

Red03Mustang · Dec 8, 2004

Tun torque modulation off, then what would happen?

jstreet0204 said:
Automatic cars use a torque modulation strategy vary timing during shifts. When the EEC thinks it's time to change gears, it can pull timing so the shift is smotther.

What if torque modulation is turned all the way off? Would that prevent what is happening there? I have mine off with my predator.

I don't have the extra hardware to run it into my computer. I need to get that so I can do some diagnostics as well.

jstreet0204 · Dec 8, 2004

Red03Mustang said:
What if torque modulation is turned all the way off? Would that prevent what is happening there? I have mine off with my predator.

I don't have the extra hardware to run it into my computer. I need to get that so I can do some diagnostics as well.

I'm not sure. I use a Tweecer and I have a 5 speed, so for mine I adjust the tip in retard to prevent the too much timing drop between shifts.

propellerhead · Dec 8, 2004

I have torque modulation off. I made another WOT run earlier and recorded it again. It doesn't have the drops or spikes like the one already posted. I'll post it tomorrow morning. I have the cool graphing software at work. I'll try to record another run tonight too. Hopefully, I'll have two logs to graph and upload tomorrow morning.

propellerhead · Dec 9, 2004

Here's another data log. It doesn't have any deep drops or spikes. It actually looks pretty normal. The only noticeable things are that one point before the 1-2 shift where the timing drops from 19.75 to 19.0 and couple of small 0.25 degree drops as I was winding out 2nd gear.

After 10 or so logs, I'll bump up the timing and see if I start getting more points where the EEC pulls back on the timing.

hotrodnut · Dec 9, 2004

propellerhead said:
Here's another data log. It doesn't have any deep drops or spikes. It actually looks pretty normal. The only noticeable things are that one point before the 1-2 shift where the timing drops from 19.75 to 19.0 and couple of small 0.25 degree drops as I was winding out 2nd gear.

After 10 or so logs, I'll bump up the timing and see if I start getting more points where the EEC pulls back on the timing.

That looks good, is there any difference in your tune from before? I know mine is a stick but I still want to see what difference it would make from the Mach1 4V and yours, maybe it's not a good compare to make, but either way, thanks for posting a graph again.

billyfe390 · Dec 9, 2004

The reason the timing drops on the shifts is because with the fox body cars they had a ton of transmissions getting replaced under warranty so ford decided to incorporate a way to reduce the torque when it shifts. I think it was in 94 when they started retarding the timing during shifts.

mustang70 · Dec 9, 2004

billyfe390 said:
The reason the timing drops on the shifts is because with the fox body cars they had a ton of transmissions getting replaced under warranty so ford decided to incorporate a way to reduce the torque when it shifts. I think it was in 94 when they started retarding the timing during shifts.

I remember hearing about that. How much performance gain is there by getting rid of the timing retard?

billyfe390 · Dec 9, 2004

mustang70 said:
I remember hearing about that. How much performance gain is there by getting rid of the timing retard?

Mike wesley wrote in an article that he found a tenth or two. It will make a difference but to what degree I am not sure because personally I havent raced an auto mustang. IMO I think it is one of those things that by itself wont make a huge difference but if you couple that into a package it will help alot more.

propellerhead · Dec 9, 2004

billyfe390 said:
The reason the timing drops on the shifts is because with the fox body cars they had a ton of transmissions getting replaced under warranty so ford decided to incorporate a way to reduce the torque when it shifts. I think it was in 94 when they started retarding the timing during shifts.

Interesting... I knew it was meant to make the shift granny-friendly but now I wonder if I am adding a lot of wear and tear on my transmission. I get serious second gear scratches at WOT with torque modulation off, which in the Predator it is set to 100%. I could easily back it off to 50% but almost every vendor I dealt with when I was shopping for a tuner said they would turn off torque modulation.

Both data logs were done with the same Performance Tune. No changes were made between runs.

billyfe390 · Dec 9, 2004

propellerhead said:
Interesting... I knew it was meant to make the shift granny-friendly but now I wonder if I am adding a lot of wear and tear on my transmission. I get serious second gear scratches at WOT with torque modulation off, which in the Predator it is set to 100%. I could easily back it off to 50% but almost every vendor I dealt with when I was shopping for a tuner said they would turn off torque modulation.

Both data logs were done with the same Performance Tune. No changes were made between runs.

Turn it off and leave it off and dont worry about it.

mustang70 · Dec 9, 2004

I don't see it causing any wear and tear with it off. What kills the autos is the slipping. If you're barking tires I think you don't have to worry about slipping though.

propellerhead · Dec 9, 2004

mustang70 said:
I don't see it causing any wear and tear with it off. What kills the autos is the slipping. If you're barking tires I think you don't have to worry about slipping though.

I have read stuff on www.tccoa.com about slipping and the heat it causes. I have the Shift Pressure bumped up to reduce slipping and get a quicker firmer shift. I couldn't get a straight answer from DiabloSport but I believe these settings are PSI added to the stock pressure. The first number is what the Performance Tune had. The second number is what I have it set to currently.

Part Throttle 1-2: 20 psi, now 45 psi
Part Throttle 1-2: 10 psi, now 35 psi
Part Throttle 1-2: 4 psi, now 14 psi

I can't remember what the original WOT shifts were set to but this is what I have now:

WOT 1-2: xx psi, now 60 psi
WOT 2-3: xx psi, now 40 psi
WOT 3-4: xx psi, now 20 psi

Do you know if these are settings might be too high?

mustang70 · Dec 9, 2004

propellerhead said:
Do you know if these are settings might be too high?

They don't seem to high to me. But I'm not an expert. As long as it's not blowing out any kind of seals I would think it's alright. Must be nice not have to drop the pan to change the shift points.

propellerhead · Dec 10, 2004

One more graph, with LOAD this time...

The tip in spark retard is a huge drop. I guess that's normal.

I'll probably add a little more spark advance and make a few more WOT runs. I'll just watch out for those drops in SPARKADV. It seems 100x more reliable than listening for knocking.

propellerhead · Dec 13, 2004

Here's last night's WOT run.

What is the tip in spark retard for anyway?

jstreet0204 · Dec 13, 2004

tip-in-retard is the amount of timing pulled when you first step on the gas.
Here is a good article to read.
http://www.mustangworks.com/articles/electronics/eek-vs-eek.html

Looking at timing with a DiabloSport Predator

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