Ignition timing 5.0 SC

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gilps
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Ignition timing 5.0 SC

Post by gilps »

Would appreciate some basic info on ignition timing the car is a Tvr 5.0 with rotrex supercharger about 6psi of boost.

If you could confirm the standard dizzy I believe it's 16deg mechanical advance and 10 deg vacuum advance.

So with 12 deg static 16deg mechanical and 10 vacuum the max advance is 38 deg

So light cruise say 70mph at 2.5k rpm what advance should I be getting

Full throttle acceleration what advance should I be getting?

The main reason for asking is I had an Omex fitted and then set up by a specialist and to be honest I'm not happy with it at all. At the moment at light cruise I'm getting between 29 and 32 total advance.

Hard acceleration I'm getting between 20 and 24 total.

If I reconnect the dizzy I get much better performance and probably better fuel economy on cruise.

Would really appreciate any help or advice on this
Chris [/img]



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Post by DaveEFI »

If you have the spec for the original dizzy, you can draw out a graph and compare the results into your Omex ignition table. Your tuning guy probably concentrated on getting maximum power. Tuning for decent economy etc takes a lot longer.

There's probably far more info on tuning available for MegaSquirt. You could read that - the principles will be the same.
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Post by gilps »

Many thanks will have a look

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Post by gilps »

Image

This is the ignition graph I have on the car. The thing that's confusing me (I have a lot to learn) is that when I installed the Omex (as instructed by the supplier and Tuner) I was told that I didn't need a MAP sensor as my boost was less than 1 bar. So instead of Map and TPS it uses MAF and TPS to set the load.

I will be getting it on another RR soon to see just whats happening but would appreciate your input

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Post by stevieturbo »

A screenshot can only give very limited information.

But that load table is indicated in pressure, ie kpa, and if that is the table in its entirety does look silly for a boosted application, because it has no load values for any boosted sites.

But you seem to be saying there may not actually be a map sensor in use ? Which again would be silly...and make that table look silly.

So really...more info needed about the install.

And there could be other correction tables in use, so a photo of just one, isnt enough info.

Again it all comes down to the actual install. Verify 100% what sensors are in use, and how they are calibrated etc.
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Post by DaveEFI »

It would seem odd to not use MAP to advance the ignition, if economy matters? But then I've no real experience of using MAF.
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Post by stevieturbo »

DaveEFI wrote:It would seem odd to not use MAP to advance the ignition, if economy matters? But then I've no real experience of using MAF.
It would be very odd to use MAF too for a standalone ecu of any kind....does the car even have an airflow meter ?

And what design is it ?

MAP would be the easiest and most sensible option.
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Post by Darkspeed »

If its an OMEX 200 it is very limited in what it can do anyway. And is only TPS / MAP Looking at the avaialble options do you have the OMEX 2 bar (absolute) MAP fitted?
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Post by DaveEFI »

Think you can use MAF with MS3. Not that I've tried it. Speed density is by far the easiest for home tuning.
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Post by gilps »

Thanks guys

The inputs are as follows MAF, TPS, Air intake Temp, Coolant temp, and a trigger wheel on the crank.

The MAF is obviously not doing what it was supposed to do so I have a 2 bar MAP sensor on order and will fit that and get rid of the MAF input. Then off for mapping again hopefully this time it will be better.
Fuel economy wasn't really an issue I just want it set up properly so everything works as it should.
Thanks for help guys

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Post by stevieturbo »

Using the MAF input, if it is a regular 0-5v signal should work just fine if tuned correctly.

MAP is just easier to follow though.

Easy is good !

So I wouldnt necessarily blame using MAF as one of the load parameters, but if timing isnt doing what you believe it should be doing, that's totally down to whoever set it all up.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Post by Darkspeed »

The Omex 200 is ignition only - I take it the MAF is connected to the separate fuel controller or am I on the wrong page with the Omex 200 ignition map you posted. So the Omex 200 was just fitted with the standard atmosperic 1bar absolute MAP when mapped?
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Post by stevieturbo »

MAP, MAF, TPS...doesnt really matter.

An analogue voltage input based on load is just that, a simple analogue voltage.

Whether the software goes to 1 bar, 2 bar, 3 bar again doesnt really matter. Of course it is good practise for the numbers to be correct, but they dont have to be if there are some strange limitations within the software.

They all just relate to a voltage.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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Post by DaveEFI »

Darkspeed wrote:If its an OMEX 200 it is very limited in what it can do anyway. And is only TPS / MAP Looking at the avaialble options do you have the OMEX 2 bar (absolute) MAP fitted?
Just been reading up on it. An odd choice for a V8 since you still need the dizzy.

And no mention of being able to use a MAF sensor.
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Post by stevieturbo »

DaveEFI wrote:
Darkspeed wrote:If its an OMEX 200 it is very limited in what it can do anyway. And is only TPS / MAP Looking at the avaialble options do you have the OMEX 2 bar (absolute) MAP fitted?
Just been reading up on it. An odd choice for a V8 since you still need the dizzy.

And no mention of being able to use a MAF sensor.
It's a choice that was probably available at the time. It gives you good control over ignition for minimal install/effort.

Not really an odd choice.

People still use ecu's to control everything and retain a dizzy, some for strange reasons, some for visuals so the car appears standard or original.

And as said, whether MAF, MAP, TPS, whatever, doesnt really matter as it will just be an analogue voltage.

What the user does with it is all that really matters.
9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0

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