Group Purchase: Copper Contact Distributor caps - join here

[BenF]

Just following on from an earlier thread:

http://www.imoc.co.uk/forums/viewtopic.php?t=578

I'm compiling a list of people who are definitely on for the Group Purchase.

At the moment it looks like we should have 10+ which would make the price of a modified cap, rotor and dust deal around £65 give or take a few quid.

To join the GP, please email me at [email protected] and I'll mail you back.

The Group Purchase will close on Friday 14th, and proceed with the people who have confirmed interest then.

I'll also post a list here of the people who have joined the GP.

Cheers,

Ben.

(edit - added closing date)

[BenF]

I'll update this post with the list of people confirmed as being on the GP

Those who have confirmed to date:

Stu Wilson (Rev2 T)
Dean Philpott (Rev2T)
James Cook (?Rev2T?)
Ian Page Rev2T

To be confirmed :

Stu Wilson
Dudeone
V8killer
Bry
steve
Graeme Shaw
Terry
Chumbaside

[gmtc]

I got one in the last GP about 8 months ago (still like new as my car has done about 500miles since!). Ben does a great job.

[JJ]

Ben,

I have some concerns about this. By no way am I trying to put people off this, just want to ensure theres no come backs for you on this.

These copper contacts caps... definitely the way forward and excellent in terms of transferring the spark across the electrode and reliability - no excessive corrosion to the electrodes, however on a recent test done on a friends car which had one fitted ( not sure if its one of yours that your talking about ) the electrodes area is wider than that of the toyota cap.

My concern lies in setting up the base timing on particularly the turbo cars. With the electrodes being wider, the ESA ( electronic spark advance ) mechanism on the stock ecu is allowed to "wander" a lot more.

What does this mean.... even with the distributer keeled right over to fully retard the ignition, I could not get it any further back than 16-18 degrees BTDC.

Where the distributer is on a "normal capped" setup, 10 degrees maybe visable, however fitting the Copper cap, the base time has adjusted to some 25+ degrees.

Whilst this isn't so much an issue on idle, what I've found is it causes problems when boosting. This "wandering" of the ignition advance is all computer controlled, but given the ability to wander more is effectively almost turning the distributer completely in the direction of fully advancing it... idles fine, responce is superb, but on high boosting, if the ecu gets it wrong and retarding doesn't take place, it will blow the knock sensor. The stock map has set ignition points based on the base timing of the ignition set by the distributer.

I had a friend constantly bugging me why his car was running so crap on performance... it was so responsive, yet on boost was backing off and bucking. Its blew a toyota knock sensor, so I checked the ignition timing... 25-28 degrees... so adjusted to to the best i could get it.... 18 degrees BTDC.

Stuck a Gm knock sensor on and a week later... again... blown knock sensor. I've never known one of these GM ones to blow yet ! Had to get to the bottom of this and lowered the boost and changed the knock sensor out again. Looked at it up and down.

Now this car does have a HKS fuel computer on it too and wasn't sure of the specs ( maybe cams fitted too ) - this evidently will add even more ignition the the current map !!... when i checked the timing, I thought maybe the intake cam had jumped a tooth .. nope... I resorted to full ignition swap out, then found the copper contact cap fitted.

When refitted, started the engine and the ignition was fully retarded.. where I left the distributer... and it was something like 3 degrees ! Moved the distributer to a sensible 10-12 degrees ignition base timing and it all started looking normal again with the postition of the distributer was nominal.

So theres my concern, not directly copper caps themselves, but the knock sensors it'll go through if people change them out and not check their igntion timing at the same time.

Don't get me wrong, I can't tie this copper cap to the same brush, its looks to be a blueprint cap with modified copper electrodes that have a far wider area than stock. If these are the caps that your talking about, suggest a modification to shave off some of the copper material as this as I have experienced creates post fitting effects to the purchase.

Over and out

[V8Killer]

John,

very good point made. I've always wondered about the contact patch area myself, but have never really thought that deep into it. On the one that Ben F done for me last time i think the contact patch was approximately probably about 2-3mm bigger.

I personally haven't had any issues with it though.

Muhsin

[SimonPearse]

Ben,

I have some concerns about this. By no way am I trying to put people off this, just want to ensure theres no come backs for you on this.

These copper contacts caps... definitely the way forward and excellent in terms of transferring the spark across the electrode and reliability - no excessive corrosion to the electrodes, however on a recent test done on a friends car which had one fitted ( not sure if its one of yours that your talking about ) the electrodes area is wider than that of the toyota cap.

My concern lies in setting up the base timing on particularly the turbo cars. With the electrodes being wider, the ESA ( electronic spark advance ) mechanism on the stock ecu is allowed to "wander" a lot more.

What does this mean.... even with the distributer keeled right over to fully retard the ignition, I could not get it any further back than 16-18 degrees BTDC.

Where the distributer is on a "normal capped" setup, 10 degrees maybe visable, however fitting the Copper cap, the base time has adjusted to some 25+ degrees.

Whilst this isn't so much an issue on idle, what I've found is it causes problems when boosting. This "wandering" of the ignition advance is all computer controlled, but given the ability to wander more is effectively almost turning the distributer completely in the direction of fully advancing it... idles fine, responce is superb, but on high boosting, if the ecu gets it wrong and retarding doesn't take place, it will blow the knock sensor. The stock map has set ignition points based on the base timing of the ignition set by the distributer.

I had a friend constantly bugging me why his car was running so crap on performance... it was so responsive, yet on boost was backing off and bucking. Its blew a toyota knock sensor, so I checked the ignition timing... 25-28 degrees... so adjusted to to the best i could get it.... 18 degrees BTDC.

Stuck a Gm knock sensor on and a week later... again... blown knock sensor. I've never known one of these GM ones to blow yet ! Had to get to the bottom of this and lowered the boost and changed the knock sensor out again. Looked at it up and down.

Now this car does have a HKS fuel computer on it too and wasn't sure of the specs ( maybe cams fitted too ) - this evidently will add even more ignition the the current map !!... when i checked the timing, I thought maybe the intake cam had jumped a tooth .. nope... I resorted to full ignition swap out, then found the copper contact cap fitted.

When refitted, started the engine and the ignition was fully retarded.. where I left the distributer... and it was something like 3 degrees ! Moved the distributer to a sensible 10-12 degrees ignition base timing and it all started looking normal again with the postition of the distributer was nominal.

So theres my concern, not directly copper caps themselves, but the knock sensors it'll go through if people change them out and not check their igntion timing at the same time.

Don't get me wrong, I can't tie this copper cap to the same brush, its looks to be a blueprint cap with modified copper electrodes that have a far wider area than stock. If these are the caps that your talking about, suggest a modification to shave off some of the copper material as this as I have experienced creates post fitting effects to the purchase.

Over and out

surely the distributor cap has no role in setting the timing?
I have not looked inside the distributor, but I assume that timing signals are picked up from a hall effect or optical sensor which detects tha angular position of the central shaft wrt the distributor body. The rotor arm and cap only function to route the spark to the required cylinder.
I have not realy looked into the mr2 ignition system, but that is the usual meathod....
If the relative position of the rotor contact and cap contact was important then the timing would float as differing atmospheric conditions influence how far the spark will jump, and the spark will surely jump from the arm to the cap!

[JJ]

surely the distributor cap has no role in setting the timing?

Simon, I totally agree with what you've said, I didn't post to condemn the cap, I posted it to advise people if they did go down this route and was experiencing flatspots on hardboost, to watch out for the ignition timing changes.

Most people with evidently buy a cap, buy plugs and simply bolt them in their previous positions.

This had my head scratching too !! The distributer does have a pretty standard a 24 tooth pickup.. but its used to calculate the crank position too, but as you say... the ecu can fire the plugs during different conditions.... but fitting this CC cap, its more prone to advancing the base timing for some reason... and the reasons only to be blamed at the cap.

Didn't see it retarding at all .... but I guess the toyota system will advance it as far as possible when not on load and thus optimal firing / combustion.

Those of you with your old cap kicking about, feel free to try it, get the timing light out and watch the changes in the timing position.

[SimonPearse]

surely the distributor cap has no role in setting the timing?

Simon, I totally agree with what you've said, I didn't post to condemn the cap, I posted it to advise people if they did go down this route and was experiencing flatspots on hardboost, to watch out for the ignition timing changes.

Most people with evidently buy a cap, buy plugs and simply bolt them in their previous positions.

This had my head scratching too !! The distributer does have a pretty standard a 24 tooth pickup.. but its used to calculate the crank position too, but as you say... the ecu can fire the plugs during different conditions.... but fitting this CC cap, its more prone to advancing the base timing for some reason... and the reasons only to be blamed at the cap.

Didn't see it retarding at all .... but I guess the toyota system will advance it as far as possible when not on load and thus optimal firing / combustion.

Those of you with your old cap kicking about, feel free to try it, get the timing light out and watch the changes in the timing position.

I'm not trying to be argumentative, If you have measured/seen a change in timing just by changing the cap then fair enough, but I cant realy see how the cap can affect the timing even if the contacts were (within reason) the 'wrong' size, or in the wrong position.
Perhaps someone who is more knowledgable can enlighten me?

[paul port]

The ignition timing is taken from the pickup in the distributor body. This is not moved at all when changing the cap.

If the cap is not one of Bens... it's going to be one of mine (I did make a couple of blueprint ones on request) The copper contacts are always larger than the stock contact.

I have to say that there is no way I can see the size of the contact affecting the cars timing - If it were true then it could only mean one thing, that the ECU tries to advance/retard as far as it can until the spark can no longer jump from arm to cap electrode.

Take a look at the rotor arm, the contact is that wide for a reason. The reason is to allow the spark to easily jump the gap at the ECU's max advance / retard. If it were any smaller, there would be the possibility of the spark failing to jump at both extremes giving a missfire. To be honest, I think the wider the better - more area for the spark to jump to - one only needs look at the scorch mark on a copper electrode to see the area used.

Did you remember to short the two pins in the check connector when adjusting timing? apologies if it's kinda stating the obvious - but it's well worth mentioning.

Paul

[BenF]

Ben,

I have some concerns about this. By no way am I trying to put people off this, just want to ensure theres no come backs for you on this.

JJ, No problem - happy to chat about any concerns.

These copper contacts caps... definitely the way forward and excellent in terms of transferring the spark across the electrode and reliability - no excessive corrosion to the electrodes, however on a recent test done on a friends car which had one fitted ( not sure if its one of yours that your talking about ) the electrodes area is wider than that of the toyota cap.

Yep, they're usually slightly wider, just my about 1mm each side or so.

My concern lies in setting up the base timing on particularly the turbo cars. With the electrodes being wider, the ESA ( electronic spark advance ) mechanism on the stock ecu is allowed to "wander" a lot more.

The ECU picks up the timing from sensors in the distributor mechanism - it (to me) looks like it uses Hall Effect sensors and a toothed wheel behind the rotor to pick up the details of the cam timing.

Also - the standard rotor arm is a wide 'T' shaped so the spark can jump across from any part of the T to the contact. All the slightly wider copper contact means is the spark has a larger area to potentially spark across. The area of the contact is much smaller than the end of the 'T' on the rotor arm, and so is insignificant compaired to that.

What does this mean.... even with the distributer keeled right over to fully retard the ignition, I could not get it any further back than 16-18 degrees BTDC.

This doesn't sound right to me. With the copper contact cap on, and the te1 and e1 diagnostics pins linked you can adjust the timing to your heart's content.

Where the distributer is on a "normal capped" setup, 10 degrees maybe visable, however fitting the Copper cap, the base time has adjusted to some 25+ degrees.

<snip>

There's no way fitting a new cap can change the timing.

The only way you can do that is by rotating the whole assembly. It is possible to change the base timing only by advancing the timing by rotating the whole distributor assembly clockwise.

If the 2 14mm bolts doing this on your friends car it is possible they could come loose and do this.

Stuck a Gm knock sensor on and a week later... again... blown knock sensor. I've never known one of these GM ones to blow yet ! Had to get to the bottom of this and lowered the boost and changed the knock sensor out again. Looked at it up and down.

Now this car does have a HKS fuel computer on it too and wasn't sure of the specs ( maybe cams fitted too ) - this evidently will add even more ignition the the current map !!... when i checked the timing, I thought maybe the intake cam had jumped a tooth .. nope... I resorted to full ignition swap out, then found the copper contact cap fitted.

One other thought - I'm not familiar with the HKS fuel computer - but other 'chips' such as the Unichip work by first dialing in big advances in base timing, and then amending the inputs to the ECU causing it to retard the timing back to something sensible.

Sounds like the det problem was caused by other mods I'm afraid - I've never seen this problem on my '2, having fitted various copper contact caps and I'm very very fussy when it comes to TLC for my car

When refitted, started the engine and the ignition was fully retarded.. where I left the distributer... and it was something like 3 degrees ! Moved the distributer to a sensible 10-12 degrees ignition base timing and it all started looking normal again with the postition of the distributer was nominal.

So theres my concern, not directly copper caps themselves, but the knock sensors it'll go through if people change them out and not check their igntion timing at the same time.

Don't get me wrong, I can't tie this copper cap to the same brush, its looks to be a blueprint cap with modified copper electrodes that have a far wider area than stock. If these are the caps that your talking about, suggest a modification to shave off some of the copper material as this as I have experienced creates post fitting effects to the purchase.

Over and out

heh - comes back to my original point. The Dizzy cap actually doesn't do anything to help the ECU determine the timing. This is done by sensors in the base of the distributor, which aren't affected by the cap.

When the ECU decides to fire the ignitor and get a spark and where all the rotor arms and copper contacts is just a happy accident as far as the ECU is concerned. Remember, the rotor isn't 'charged' and ready to spark at all times -the ECU deliberately fires a spark at what it decides is the right interval - so the size of the contacts really doesn't factor in

HTH !

[JJ]

Okay, my engrish is not that good ! I totally agree with you all and I understand how the igntion system works on these cars very well... yes a wider electrode means less for the spark to jump, I understand all the theories behind it, I'm just relaying my experience ... has anyone else checked the ignition timing before and after the cap change - I only went down this route because of the car blowing knock sensors. I know technically it shouldn't affect it one bit, but I rack my brains ( what little I have ! ) why it moved around - hence the post. Again, possiblity of this HKS diggery doo in the boot causing problems with angry ignition settings.

TE1 and E1 .... whats that !!!

that the ECU tries to advance/retard as far as it can until the spark can no longer jump from arm to cap electrode.

This is what I'm kinda getting at... thanks ! The ignition map wouldn't allow this to happen.... so any ideas whats causing this if this is the case ?

Thanks.

[stevecordiner]

Mines had a copper dissy on for over a year or so and I dont think there has been any issues with knock sensors or the timing being set

[paul port]

TE1 and E1 .... whats that !!!

For the benefit of everyone else...
The ECU adjusts it's ignition timing dynamically.
When you want to adjust the Base ignition timing, you need to tell the ECU to stop fiddling with the timing! and to leave it at base.
You do this by connecting TE1 and E1 in the check connector with a paper clip or length of wire.

If you don't do this, the timing will continue to wander all over the place whilst you try to adjust it.

Paul


PS, on the main subject - I would seriously expect the ECU max Advance / Retard is limited by an ECU software function - not what is physically possible with the dizzy cap electrodes! Seriously, in automotive electronics you don't leave things to chance.

[Stu Wilson]

Well,after all that techno sniping ,I'm still having one

[JJ]

Well,after all that techno sniping

Cheeky !

[BenF]

JJ,

No worries. I've got a standard cap and a modified one to hand here - if I get a mo this weekend I'll swap between them and see what happens to the timing when the TE1 and E1 pins aren't linked on mine, when the engine is fully warm.

I don't expect there to be any difference, but I'll double check as you've got me curious now