Ignition timing drift?

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
andytat
Posts: 21
Joined: Tue Feb 12, 2019 4:08 pm
ECU Model: S80 Pro
Firmware Version: 80.11

Ignition timing drift?

Post by andytat »

I have a strange problem and need help.
We are tuning a slightly modified Porsche 3.2 Carrera,
The spec is :

DTA S80 Pro ECU
3.4l Mahle cyls and pistons.
993 Intake manifold
SSI exhaust system
964 lightweight flywheel and clutch with 60-2 teeth
Bosch oil and air temp sensors
Marrelli MAP sensor
Magnetic cam sensor ( inside distributor)
Bosch 1 227 022 008 ignition module
Bosch blue coil
The ignition is fired through the std distributor.
The engine starts and runs well but as we were mapping it using a dyno
dynamics rolling road something strange was happening.

The engine was not happy at all reving beyond 4,500rpm (either under load or not)
While investigating what was happening we double checked the ignition timing with a timing light to compare it with the DTA settings.
At 2,000rpm the figures are the same at 24 degrees
at 4,000rpm the DTA reading is around 30 degrees and the timing light shows 44 to 47 degrees btdc

One of the first things we did was to disable sequential injection and we also disconnected the cam sensor completely to eliminate this

We have been scratching our heads all afternoon with this problem, all compensation tables are set to zero and I was wondering if the ignition module could cause this problem, although I have used these bosh 008 modules many times with Autronic and Motec ECUs with no issues.

Any help or advice is most appreciated.

Cheers

Andy
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Ignition timing drift?

Post by stevieturbo »

What sort of timing light ?

Is this wasted spark ?

Why are you using an ignition module ? DTA can drive an inductive coil/coils directly. An additional module isnt really needed ( and if used, ecu must be set accordingly )

At idle,

Baseline timing ( ie missing tooth position ) with timing set to 0 deg, and a TDC pointer.

Then lift timing to 10deg and again, check with a non dialback light
Then 20deg and see what it reads.

IF it reads double with a wasted spark setup that is pretty normal. But either way you would see that pattern with the above test.

If you are spark per cylinder or coil/dizzy and proper sequential ignition, then yes the timing on screen should be reflected accurately at the timing light.

Are there any crank/cam errors ?
andytat
Posts: 21
Joined: Tue Feb 12, 2019 4:08 pm
ECU Model: S80 Pro
Firmware Version: 80.11

Re: Ignition timing drift?

Post by andytat »

Thanks for the reply Stevie.

2 different timing lights, mine which is Snap on
Dan, the tuners, which I forget the make but is a high quality light.
Both exactly the same readings

Not wasted spark.

Using an ignition module because I wasn't aware the ECU can run a single coil with
a dizzy

There are no crank signal errors at all, the crank sensor pattern is perfect. We'll try your suggestions re timing checks in the morning and see what happens.

Cheers.

Andy
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Ignition timing drift?

Post by Rob Stevens »

Sounds like the ignition module is adding ignition advance somehow? you could test the theory by getting the DTA to advance to just 24 deg at 4000 rpm and I suspect that you will see 35 degrees at the engine.
But as stevei says may as well ditch the ignition module, or keep it and just map the engine to whatever it wants, which will probably be 24 degrees (on the DTA) everywhere.

Personally I'd go for 6 x CoP's as there must be loads available for this engine, unless it's a a period look you are going for?
andytat
Posts: 21
Joined: Tue Feb 12, 2019 4:08 pm
ECU Model: S80 Pro
Firmware Version: 80.11

Re: Ignition timing drift?

Post by andytat »

Thanks Rob.

I was thinking the same re the ignition module.
Being a bit tight I didn't really want the extra cost and work
of going COP.
I am going to try a new ignition Module this morning and see
what happens.
I'll keep you posted.

Cheers.

Andy
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Ignition timing drift?

Post by stevieturbo »

Dump the ignition module, it's just another item to give trouble that is not needed.

And do you have external amps checked in general engine settings ?

What sort of crank trigger is it ? Polarity of sensor definitely correct ?

And yes, COP, CNP or even a wasted 6 tower coil pack would make a lot of sense.

the checks I said mainly related to a wasted spark setup...but with a dizzy they dont really apply.

But even with a dialback light, it is worth verifying timing using only the crank pulley markings at with 0deg on the light. Removes any risk of timing light issues, but again with a dizzy and single coil, there should not be any issues with the light.
andytat
Posts: 21
Joined: Tue Feb 12, 2019 4:08 pm
ECU Model: S80 Pro
Firmware Version: 80.11

Re: Ignition timing drift?

Post by andytat »

Thanks for the help guys.

I ditched the ignition module this morning and all was well!
totally stable ignition all the way and tuning was a breeze.

Cheers.

Andy
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Ignition timing drift?

Post by Rob Stevens »

Glad you are sorted :)
And you forgot to tell us how much power you got and what the expectations were.
andytat
Posts: 21
Joined: Tue Feb 12, 2019 4:08 pm
ECU Model: S80 Pro
Firmware Version: 80.11

Re: Ignition timing drift?

Post by andytat »

Well, we noticed a bit of an issue when running above 4,000 rpm on the rollers.
The engine was starting to lightly misfire, as if a soft cut rev limit was cutting in.
We played around with the basic settings and found by increasing the coil on time
it would rev higher before the same thing happened. We raised the coil on time to
3,500 and it was happier to 6,000rpm but still missing slightly above that.
The max power we got was close to 240bhp, I was hoping for 250-260 but I decided to wait until the car was fully built so that I could test it properly on the road and see how it went.
Yesterday I took it out for it's fist proper drive of about 15 miles and it felt great but wouldn't pull to the rev limit (6,800 rpm) as it was missing above 5,500 rpm. I stopped for a cup of tea and then drove it again for 10 miles. Almost as soon as I started driving it wouldn't accept full throttle above 4,000rpm and after 5 miles it was getting worse. I stopped again for 10 minutes to chat with a mate and when I started it it was having difficulty reving above 2,500 - 3,000rpm so I drove it home, scratched my head a bit and started to wonder if the coil could be faulty (it's a blue bosch coil running a distributor) I fitted a spare coil this morning and the engine seemed to start a bit better so I took it for a short test drive. It didn't want to take any throttle above 3,500rpm so I raised the coil on time to 4,500 which improved it but it still isn't right, you can't give it full gas over 5,000rpm as it misfires and occasionally backfires. It tells you in the software not to raise the coil on time above 3000 unless there is a good reason!
What do you guys think? I have checked the resistance of the rotor arm and plug leads as well as all of the compensations to see if they could be having any effect but can't find anything, so I really need some help chaps.
Cheers.
Andy
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Ignition timing drift?

Post by stevieturbo »

A single coil to drive all cylinders will need to be able to fire with a very short dwell time.

Convert to COP or CNP, or a coil pack.

IMO even 3000us is high for a single coil application.
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