Aftermarket ECU setup questions (Haltech + 205gti)

PeterT

Member
1000+ Posts
Properly tuned, it will be fine. Can you add a cam sensor? Then you can make it sequential and enjoy the low down torque.
 

angru

Member
Yep. I planned to run as sequential. Going off the jenvey website though and most stuff I’d seen online, had thought for the size and performance of the motor that 38-40mm would be perfect and 45 a bit big.
 

DjB8V

New member
I'm running a Si coil pack, which is wasted spark correct? Can some one explain wasted spark. I've tried Googling, but it was info overload.

I was debating about adding in a cam sensor just because I have the facilty within the ECU to run one, but after re-reading this thread, I don't see a need to.

I am looking at setting up a clutch switch using a TPS and digital pulsed input. Has anyone had any experience with a clucth switch on a 205?
 

AlexB

New member
Assuming firing order 1,3,4,2 when Cylinder 1 is at TDC of its compression stroke and ready to be ignited, cylinder 4 is also at TDC but is between its exhaust and intake strokes and no compression as valves are open. Same goes for cyl 2 and 3.
Think of the coil as double endd so it fires two spark plugs at the same time, for cylinder 1 the spark will ignite the compressed fuel/air mix but in cylinder 4 nothing happens, hence the term 'wasted spark'.
Your Si coil pack contains two double ended coils.
 

GRAHAM WALLIS

Member
1000+ Posts
The Si/405 SRi wasted spark system is the best that I've seen. Totally reliable and effective. The 306 XSi/ S2 Mi16 individual coil packs on the plugs is the worst by far, very unreliable. Later direct to plug coils seem OK.
 

PeterT

Member
1000+ Posts
The Si wasted spark setup is indeed reliable and you should run with that. Adding the cam sensor does allow direct fire on the ignition, but is unnecessary in your application. More importantly, the cam sensor allows sequential fuel injection which will improve low-mid range torque and response. Thus:

fuel - sequential
ignition - wasted spark
 

DjB8V

New member
Assuming firing order 1,3,4,2 when Cylinder 1 is at TDC of its compression stroke and ready to be ignited, cylinder 4 is also at TDC but is between its exhaust and intake strokes and no compression as valves are open. Same goes for cyl 2 and 3.
Think of the coil as double endd so it fires two spark plugs at the same time, for cylinder 1 the spark will ignite the compressed fuel/air mix but in cylinder 4 nothing happens, hence the term 'wasted spark'.
Your Si coil pack contains two double ended coils.

Perfect !!! Makes perfect sense, thanks.
 

DjB8V

New member
The Si/405 SRi wasted spark system is the best that I've seen. Totally reliable and effective. The 306 XSi/ S2 Mi16 individual coil packs on the plugs is the worst by far, very unreliable. Later direct to plug coils seem OK.

Good to know. I'm all about reliability.
 

DjB8V

New member
The Si wasted spark setup is indeed reliable and you should run with that. Adding the cam sensor does allow direct fire on the ignition, but is unnecessary in your application. More importantly, the cam sensor allows sequential fuel injection which will improve low-mid range torque and response. Thus:

fuel - sequential
ignition - wasted spark

This is more great info. Based on this, I will look into adding a cam sensor for seqential injection. But as you stated, I'll keep the wasted spark ignition.
 

DjB8V

New member
Cam sensors. There aren't any 8v XU9s that have a factor cam sensor, correct me if I'm wrong. But I did find this -

Hall effect pickup distributor conversion

Being that I'm running a coil pack, if the above pickup fits, could I use the original distributor as the cam sensor and mount the coil somewhere else?

Is this stupid? Is there a better way?

Cheers.
 

PeterT

Member
1000+ Posts
That means you'd have a dizzy, which you're trying to avoid by using the Si coil pack. I was wondering what your plan was for a cam sensor.

One solution, although somewhat ugly, is to mount a hall effect sensor in the cam cover, aligned with a cam lobe. When the top of the lobe comes near it, it will trigger. I'd experiment with a bare head, cam and cam cover before committing.
 

DjB8V

New member
That means you'd have a dizzy, which you're trying to avoid by using the Si coil pack. I was wondering what your plan was for a cam sensor.

One solution, although somewhat ugly, is to mount a hall effect sensor in the cam cover, aligned with a cam lobe. When the top of the lobe comes near it, it will trigger. I'd experiment with a bare head, cam and cam cover before committing.

I did consider the sensor through the cam cover idea too. Would a hall effect sensor survive direct exposure to an oily cam?

As for the dizzy plan, the plan would be to use the dizzy as a reference for the cam only. The block the Si coil pack is mounted to. Is it necessary to run the coil pack? Can it be mounted elsewhere?

Adding a cam sensor is looking to be a lot more complex than I thought.
 

GRAHAM WALLIS

Member
1000+ Posts
I did consider the sensor through the cam cover idea too. Would a hall effect sensor survive direct exposure to an oily cam?

As for the dizzy plan, the plan would be to use the dizzy as a reference for the cam only. The block the Si coil pack is mounted to. Is it necessary to run the coil pack? Can it be mounted elsewhere?

Adding a cam sensor is looking to be a lot more complex than I thought.
Don't bother to start with, only a minimal advantage, just get it going with the CAS.
 

R1173

New member
No need to drill and tap the Jenvey throttle bodies for vacuum. They already have take of points in them. Jenvey also sell a kit to combine all ports into 1 for your map sensor. Check out the Jenvey web site it explains it all. By direct from Jenvey, the Australian supplier is extremely unreliable. Don't ask me how I know, a very unpleasant experience.
 

GRAHAM WALLIS

Member
1000+ Posts
No need to drill and tap the Jenvey throttle bodies for vacuum. They already have take of points in them. Jenvey also sell a kit to combine all ports into 1 for your map sensor. Check out the Jenvey web site it explains it all. By direct from Jenvey, the Australian supplier is extremely unreliable. Don't ask me how I know, a very unpleasant experience.
Mine didn't and the previous owner used the idle bleed holes. Wouldn't idle and not enough vacuum range, only used half the map. I organised proper ports and an EFI Hardware 4 to 1.
 

R1173

New member
Graham, yes you are right. It does use the idle bleed holes but you need to use the proper jenvey inserts to go in the bleed holes. And that goes partial to my point about the Australian supplier. Part of my issue was that he didn't install the right parts. One conversation with Jenvey direct and the sorted my issue very quickly.
 

DjB8V

New member
Are these holes you're talking about?

I thought I had the vacuum signal issue sorted and I was going to tap and screw some fittings in. The holes I'm pointing at are in two runner only. My understanding is that you need a signal from every runner.
 

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