trailing settings
 

What are people running for trailing settings? It's for an s5 t2 running 8psi, soon to be 15psi.

You want to use FC trailing... other than that, I'm not sure what settings you want.

how many degrees and at what kpa
I'm getting detonation from the trailing

Ahh, you want a full trailing map... you may want to check the other thread where BDC posted trailing ignition maps.

I typically use around 10-15 split at low load, decrease it to around 0 at 100kPa, then above that, I increase it again as boost climbs.

Ken

I started at 15 went gradually to 0 at 100kpa then up to 10 above that and still got detonation. I need to fix the interference my alt is causing first though, if I disconnect the alt and trailing coil the car pulls smooth as silk. Connect the alt back up and it misses a bit above 4500 and shows up on the datalogs as spikes in rpm. I'll do the mod on the ecu that's in the mega manual and get back to you.

thanks

That's not detonation. If you hear a ticking sound like metal, then it's knock caused by firing spark too early (a type of pre-ignition). I'd check with Ken on making sure the CAS is zero'd out properly to the MS prior to loading the motor out anymore. Might also be a good idea to verify the wiring to the trailing ignitor/coil pack so that the front coil isn't firing 2x the duty instead of front to back in sequence.

Edit: Just saw the engine RPM thing. You've got RF/EMI noise getting on to the CAS (trigger) harness. Ken, any particular tips you've got for this? I normally make sure the ECU is properly grounded, the alternator +12 hot harness is out of the way of the CAS harness, and also sometimes put a ferrite choke around the CAS harness.

B

my bad, your right, I should have said knock. All grounds and wiring are good, I've read the mega manual and there's mention of a mod for the ecu to eliminate the problem. I'll most likely try it tomorrow. The RF/EMI noise isn't the cause of the knock since it does it even with the alt disconnected. The leading and trailing are working properly, I've checked with a timing light. I was reading your thread on trailing time while you posted here BDC. How far can I safely retard the trailing and work back from?

Thanks for all the info guys, I'll let you know what I come up with over the next few days.

Also what's a ferrite choke? I'm running the stock sheilded wire. But it is rather close to the power wire, I'll definitely move it tomorrow and see if that helps. I built my timing maps based on the stock s4 maps that I use in my shop car. I'm running an rtek 2.0 and used that to see what the stock ecu does for timing under different loads then backed it off for boost. I've been running 14psi on similar maps in the shop car all summer with no issues however maybe I'll pull a few degrees to account for higher compression.

For the noise, it depends on where it's coming from...

For noise from the alternator, I've only ever had luck fixing it by replacing the diode in the alternator, or the whole alternator itself. That's assuming of course that the wiring tips from BDC were followed... good grounds, good clean +12v, power wires far from the CAS wires, etc...

You can try turning the hysteresis pot inside the MS to filter the Ne signal. Sometimes when I've had noise issues, putting a .01 uF cap across the G+ and G- signals inside the MS has helped as well.

I've never tried a ferrite choke, but would imagine that could help too.

As far as knocking when you have trailing wired... The only thing I can think of is that trailing can cause temps to be a bit hotter... maybe do what you were thinking and pull a few degrees due to the higher compression.

Ken

Definitely the alternator. I haven't adjusted the pot yet, I'll definitely try that before doing the ecu mod, along with moving the power wires. All wires are new, except the cas wires.

Again, what is a ferrite choke?

If the timing being backed off doesn't help the trailing I'll try some different plugs, I doubt the eng is stock ports, don't know for sure though cause it's a jspec that the customer supplied and I haven't opened it. I do know it's making far more power than expected for 8psi, and it came with a hybrid turbo and ngk 105's so who knows. Haven't dyno'd it yet though, need to sort this stuff out first. Thanks again guys hopefully I'll have time to work on it over the next couple days.

Have you ever looked on say, a USB cable, or some other cable meant to hook to the computer, and seen that cylinder shaped "thing" around the wires? That's a ferrite choke.

All of the things you want to try sound reasonable to me.

Ken

If you have noise on the +12v line,I've read of people using a car stereo noise filter added just before the MS with some success.Might want to consider that also.

^ It's in the mega manual as well. I probably have one in a box somewhere. I used to be a stereo nut, had 6 tens in my 2nd gen. Now I have an expensive head unit that's not even connected to any speakers. It's just there to fill the hole.lol.

I'll let you guys know, thanks.

Well, I pulled alot of timing on the trailing and it still knocked. Also the car is making huge increases in power when I advance the timing at the cas. It's as if the displayed values for timing on the laptop are false. Is it possible that I have a setting wrong some where? When I rev the car and watch the timing with a timing light it doesn't seem to advance like it should. Runs beautiful and pulls like hell with the timing advanced at the cas and the trailing disconnected. Tried adjusting the pots and it seems to have done the trick however when you start the car in the morning it some times needs a jump even though it's cranking well. Starter noise maybe?

Is this on a custom harness or one of the Zeal harnesses?

The best thing you can do to ensure good timing is set the timing to -5 using the fixed angle setting. Then use a timing light to make sure that the timing is where it should be at idle. Then rev it up a bit to make sure timing stays put. If it moves a degree or two, you can use the spark latency setting to make it stay put.

If it moves more than that, chances are you have the Ne wires on the CAS backwards, or, if it's not one of the Zeal units, you have the jumpers for the VR conditioner inside wired with TSEL to VROUT instead of VROUTINV. Having the zero-crossing pot not all the way counter clockwise can cause this too.

Incorrect settings in software can also cause this.

Also, have you tried reversing the two trailing plug wires? I believe one guy on the forum, whose name I can't remember had them backwards, and then when he switched them the right way, the knock went away.

Ken

Funny, I never thought of switching the trailing around. There in the stock position right now. It's a custom harness, thanks I'll try these and get back to you.

Brent

If they're in the stock position, they should be fine. I can't think of any reason why they'd fire backwards, unless maybe there is an incorrect setting.

If you post your msq, I'll take a look at it when I get a chance, and try to see if I can find anything that could cause your problem.

Ken

I'll try to post the msq tomorrow. I switched the trailing around and it got way worse. As it should. Also we're having trouble starting the car without a boost now. The battery is huge and it's turning more than fast enough to start with a stock ecu. We're going to install a new starter in the next couple days.

What is it doing when it won't start? You might want to adjust the sensor gap a bit in the CAS.

This thing's driving me nuts. It's not getting a signal from the cas then you boost it and it picks it up right away. I even tried the cas that runs my car daily and nothing. I'll try adjust the sensor gap when the customer brings the car by again.