Hello,
I'm trying to work out how to wire in the MegaSquirt on the Porka and the coil has me confused.
Am I right in thinking that a standard 12V coil is fed permanent +12V then grounded every time you want a spark?
Its just that the Porka has a 12V coil but its fed through resistance wires I assume to drop the voltage. If I bin the resistance wires, will it get upset?
Cheers
Rich
TFALC Ignition system wiring - Porky EFI
TFALC Ignition system wiring - Porky EFI
1994 Lotus Esprit S4 - Work in progress
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
It was common on older cars to have a coil that really didn't want to be run at 12v but rather via a load resistor. There are a number of reasons for this (a) you could bypass the resistor during cranking to get a bigger spark (battery voltage drops to ~10v while cranking), (b) the resistor helps snub the inductive spike that happens when you interrupt the current flow to create a spark.
If it's designed to run with a resistor, you should leave it in there - the resistor won't cause any problems for your mega-squirt.
One side of your coil should be connected to an ignition switched supply, via the load resistor if that's what was already fitted.
The other side should be connected to the coil switching output on the mega-squirt.
The MS will take that signal low for a brief period (to energise the coil), then release it (to cause a spark).
Removing the load resistor, if there is one, will likely result in great sparks for a while and then a dead coil afterwards.
You can test the setup by taking a lead from the -ve side of the coil and touching it to earth briefly, then release; when you release, you should get a spark on the HT side (use a spark plug resting on the block and connected to the dizzy center lead to test this).
Cheers
Robin
If it's designed to run with a resistor, you should leave it in there - the resistor won't cause any problems for your mega-squirt.
One side of your coil should be connected to an ignition switched supply, via the load resistor if that's what was already fitted.
The other side should be connected to the coil switching output on the mega-squirt.
The MS will take that signal low for a brief period (to energise the coil), then release it (to cause a spark).
Removing the load resistor, if there is one, will likely result in great sparks for a while and then a dead coil afterwards.
You can test the setup by taking a lead from the -ve side of the coil and touching it to earth briefly, then release; when you release, you should get a spark on the HT side (use a spark plug resting on the block and connected to the dizzy center lead to test this).
Cheers
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
Nice one cheers guys!
I did a bit more research and it looks like I can leave the +ve side of the coil alone which means the resistor wires function as Porsche intended.
I have got the under bonnet wiring sorted out and I have the pig tail wired up now I just need to introduce them to one another...
I did a bit more research and it looks like I can leave the +ve side of the coil alone which means the resistor wires function as Porsche intended.
I have got the under bonnet wiring sorted out and I have the pig tail wired up now I just need to introduce them to one another...
1994 Lotus Esprit S4 - Work in progress
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
There is an option for wideband lambda, I'm just too tight to buy one! I have a narrow band one. There is a guy who hires them out for tuning.
The fuelling is basically going to be set up as a best guess, there is a function on the software for a default map, allegedly its pretty good for the '24.
If I can bully it into running I'll book a session at the local rolling road for a decent setup
The fuelling is basically going to be set up as a best guess, there is a function on the software for a default map, allegedly its pretty good for the '24.
If I can bully it into running I'll book a session at the local rolling road for a decent setup
1994 Lotus Esprit S4 - Work in progress
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
ive been reading about this project. good work so far!
can i suggest you invest in a Zeitronix wideband meter. i run one on the GTti. and do all my mapping on the road with this meter. the dash mount gauge is ok at idle but its really necessary to log it on the laptop. it also takes in inputs for boost/vac, TPS, EGT and a user defined input. it really is worth a look!
its great that you can hire one, but it can be a very useful diagnostic and is great when you want to iron out a flat spot or play with accelleration enrichment etc. and also coming up to winter its nice to be able to set up a cold start enrichment or hot start enleanment..... youl wish you still had one when you hand the hired one back!!
if you can get a decent base map thats ideal, if you cant, its fairly straight forward to write a tune from scratch. timing is easy to throw in but hard to do right (you really need a dyno to see where you can advance the timing until the torque starts to flatten off) there are always gains to be had doing the timing on a dyno but the fuel is pretty simple but again some engines might produce good power at 12.5:1 and others are better at 13.4:1. its easy to tune to a number though. it can be safe but it may not be at optimum power.
lol if the yanks can run a max adv of 34 deg on their engines then the compression ratio must surely be pretty low. that should help you when you write your tune as theres less chance of getting detantaion.
i can see what you're saying about leaving the ign in limp mode and tuning the fuel. but be careful, or you could burn the exhaust valves at high RPM.
have you read Dave Walkers book on engine management and carburettor setup and tuning? it gives some good info
can i suggest you invest in a Zeitronix wideband meter. i run one on the GTti. and do all my mapping on the road with this meter. the dash mount gauge is ok at idle but its really necessary to log it on the laptop. it also takes in inputs for boost/vac, TPS, EGT and a user defined input. it really is worth a look!
its great that you can hire one, but it can be a very useful diagnostic and is great when you want to iron out a flat spot or play with accelleration enrichment etc. and also coming up to winter its nice to be able to set up a cold start enrichment or hot start enleanment..... youl wish you still had one when you hand the hired one back!!
if you can get a decent base map thats ideal, if you cant, its fairly straight forward to write a tune from scratch. timing is easy to throw in but hard to do right (you really need a dyno to see where you can advance the timing until the torque starts to flatten off) there are always gains to be had doing the timing on a dyno but the fuel is pretty simple but again some engines might produce good power at 12.5:1 and others are better at 13.4:1. its easy to tune to a number though. it can be safe but it may not be at optimum power.
lol if the yanks can run a max adv of 34 deg on their engines then the compression ratio must surely be pretty low. that should help you when you write your tune as theres less chance of getting detantaion.
i can see what you're saying about leaving the ign in limp mode and tuning the fuel. but be careful, or you could burn the exhaust valves at high RPM.
have you read Dave Walkers book on engine management and carburettor setup and tuning? it gives some good info
Wow, top reply!
I need to get it all fitted first! The plan was to get it started on the limp mode, so that it can be started. That will enable the idle map to be sorted out. I have a spare set of vlaves if it all goes wrong... Another engine will be under £100 too...
That will prove all my mods are working correctly then I can worry about the VE details!!
Work to do...
I'm off this weekend so I'm hoping to have the EDIS in and all the wiring done.
I need to get it all fitted first! The plan was to get it started on the limp mode, so that it can be started. That will enable the idle map to be sorted out. I have a spare set of vlaves if it all goes wrong... Another engine will be under £100 too...
That will prove all my mods are working correctly then I can worry about the VE details!!
Work to do...
I'm off this weekend so I'm hoping to have the EDIS in and all the wiring done.
1994 Lotus Esprit S4 - Work in progress
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
ye thats a good plan. although you would be as well just bunging in 10degBTDC ramping up to about 25 BTDC by the time you get to about 3-3.5K to get you running. if the engine feels flat or like its holding back then give it some more advance and then look at a 3d curve to smoothen it out.
if you find its hunting at idle. then you can play around with the numbers a bit closer.
if the AFRs are around 13.5-14.7:1 at normal engine temp idle then you can decide where it is to idle
say its 800rpm you would want to run about 10deg and wind the air bypass screw down until the speed is where you want it. this will give a solid idle.
you can retard the timing at the faster RPM sites sharply after the 800deg this will stop it climbing up. and at the sites lower than 800deg you can have a sharp advance to pick the speed up and hold it at the speed you want it.
it sounds complicated but the earlier you get playing with a tune you can pick it up fairly simple.
disable everything like AIV idle valves, closed loop, accel enrichment etc, just work from your VE maps until its running sweet THEN you can start to tweek with the extra settings.
if you find its hunting at idle. then you can play around with the numbers a bit closer.
if the AFRs are around 13.5-14.7:1 at normal engine temp idle then you can decide where it is to idle
say its 800rpm you would want to run about 10deg and wind the air bypass screw down until the speed is where you want it. this will give a solid idle.
you can retard the timing at the faster RPM sites sharply after the 800deg this will stop it climbing up. and at the sites lower than 800deg you can have a sharp advance to pick the speed up and hold it at the speed you want it.
it sounds complicated but the earlier you get playing with a tune you can pick it up fairly simple.
disable everything like AIV idle valves, closed loop, accel enrichment etc, just work from your VE maps until its running sweet THEN you can start to tweek with the extra settings.
Here's a question (well two questions):
(1) What sort of advance do you think a 1.8 K-series VVC engine has when running right at the top end (7,200RPM), full throttle, obviously.
(2) How long do you think the coil is energised for each spark (wasted spark system).
The reason I ask is that I am building a "power limiter" which is like a rev limiter, but it holds power steady above a certain engine speed by retarding the ignition according to a 2D map (WOT is a given in this scenario).
I'm trying to figure out a baseline "map" to pre-program it with to hold the power constant at 170 above 6,900 RPM (the engine makes 170@6,900 in current tune and climbs to 177 at 7,200, running on standard ECU).
Cheers,
Robin
P.S. I was guessing it might have as much as 40 degrees advance and that dropping it off by 10 degrees at 7,200 (linear slope between 6,900 and 7,200) would probably do.
P.P.S. I was assuming the coil pulse width would be no more than about 5ms per spark.
(1) What sort of advance do you think a 1.8 K-series VVC engine has when running right at the top end (7,200RPM), full throttle, obviously.
(2) How long do you think the coil is energised for each spark (wasted spark system).
The reason I ask is that I am building a "power limiter" which is like a rev limiter, but it holds power steady above a certain engine speed by retarding the ignition according to a 2D map (WOT is a given in this scenario).
I'm trying to figure out a baseline "map" to pre-program it with to hold the power constant at 170 above 6,900 RPM (the engine makes 170@6,900 in current tune and climbs to 177 at 7,200, running on standard ECU).
Cheers,
Robin
P.S. I was guessing it might have as much as 40 degrees advance and that dropping it off by 10 degrees at 7,200 (linear slope between 6,900 and 7,200) would probably do.
P.P.S. I was assuming the coil pulse width would be no more than about 5ms per spark.
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
thats an interesting project.
why would you not just adjust the base map to give retarded timing to flatten off the power curve?
the coil charge time will be specific to the coil and coil driver that is being used. i think my denso ignitor is about 3.5mS
i am new to rover Ks and dont know.
also 40deg adv is quite a lot. thats pretty aggressive for a production car or are you running an aftermarket ECU? but it certainly could be as much as 40. i just dont know to be honest and im not affraid to admit it
why would you not just adjust the base map to give retarded timing to flatten off the power curve?
the coil charge time will be specific to the coil and coil driver that is being used. i think my denso ignitor is about 3.5mS
i am new to rover Ks and dont know.
also 40deg adv is quite a lot. thats pretty aggressive for a production car or are you running an aftermarket ECU? but it certainly could be as much as 40. i just dont know to be honest and im not affraid to admit it
Project is for a guy that has tuned the head (more gas flow) but kept stock ECU, thus he cannot remap it.
He has to limit to 170 for Class A regs in LOTRDC next year and doesn't want to splurge 700+ on a new ECU plus the hassle of mapping it (which is quite a big job for a VVC engine).
I was thinking worst case would be 40deg ... reason is that my plan is to attack this using a shared open drain circuit, so the ECU starts the coil charging off in the normal way and if my box wants to retard it, it turns on a second FET to keep the coil drive clamped low even after the ECU releases its own drive. Then when the box-o-tricks decides it has retarded the ignition long enough, it releases its own FET and the coil sparks as normal.
Problem is, that retarding for 40 degrees (I assume 40 adv worst case and that spark at TDC must produce way less power than spark at proper point) equates to a delay of (40/360)*(7000/60) = 13ms. This means the coil is switched on for 3-4 times longer than it would normally be - now I think this won't be an issue (in the old days, think how long coils were energised for on the idle with a points system) - but you never know!
Cheers,
Robin
He has to limit to 170 for Class A regs in LOTRDC next year and doesn't want to splurge 700+ on a new ECU plus the hassle of mapping it (which is quite a big job for a VVC engine).
I was thinking worst case would be 40deg ... reason is that my plan is to attack this using a shared open drain circuit, so the ECU starts the coil charging off in the normal way and if my box wants to retard it, it turns on a second FET to keep the coil drive clamped low even after the ECU releases its own drive. Then when the box-o-tricks decides it has retarded the ignition long enough, it releases its own FET and the coil sparks as normal.
Problem is, that retarding for 40 degrees (I assume 40 adv worst case and that spark at TDC must produce way less power than spark at proper point) equates to a delay of (40/360)*(7000/60) = 13ms. This means the coil is switched on for 3-4 times longer than it would normally be - now I think this won't be an issue (in the old days, think how long coils were energised for on the idle with a points system) - but you never know!
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
Robin,
I'm just about keeping up with the tech...
I can't think it will hurt the packs in the short term, I would think you will shorten the life of the pack a bit but how long will it really be retarded for?
What would the duty cycle be?
Rich
I'm just about keeping up with the tech...
I can't think it will hurt the packs in the short term, I would think you will shorten the life of the pack a bit but how long will it really be retarded for?
What would the duty cycle be?
Rich
1994 Lotus Esprit S4 - Work in progress
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
1980 Porsche 924 Turbo - Funky Interior Spec
2004 Smart Roadster Coupe - Hers
ah ok now i understand why you would want such a thing, the problem is i dont know if i follow entirely what you're suggesting.
are you saying that the ECU says spark NOW! but your FET keeps it switched off for a pre-determined time (which equates to X deg retard being the difference between the actual ECU mapped advance and your preferred timing point at the given RPM) at which point your second FET triggers the spark and outputs a separate 5V square wave to the ignitor?
or are you hoping the "fire" pulse from the ECU has a duration long enough to spark when you actually want it to (which is x mS after its meant to fire to give 40deg adv)?
i dont know where you are getting this extra time that the coil is energised for as its the ignitor that is energised as apposed to the coil. if you energise it for too long, the coil will be ok but the ignitors can over heat and fail/mis-fire.
i really am not aware with the coil pack arrangement on the K as i havent even looked at it yet so i cant be sure.
this is a long shot but sureley there would be a piggy back ECU or even a power commander from a motorbike that would be ideal for intercepting the pulswidth and modulating the values to make them user-defined?
that way the stock ECU can control the fuel and the VVC and the piggy back can concentrate on the spark? im sure you could pick one up for about £100 and it would be mappable (so to speak) on a laptop
let me know if im following you or if ive got the wrong end of the stick completely
are you saying that the ECU says spark NOW! but your FET keeps it switched off for a pre-determined time (which equates to X deg retard being the difference between the actual ECU mapped advance and your preferred timing point at the given RPM) at which point your second FET triggers the spark and outputs a separate 5V square wave to the ignitor?
or are you hoping the "fire" pulse from the ECU has a duration long enough to spark when you actually want it to (which is x mS after its meant to fire to give 40deg adv)?
i dont know where you are getting this extra time that the coil is energised for as its the ignitor that is energised as apposed to the coil. if you energise it for too long, the coil will be ok but the ignitors can over heat and fail/mis-fire.
i really am not aware with the coil pack arrangement on the K as i havent even looked at it yet so i cant be sure.
this is a long shot but sureley there would be a piggy back ECU or even a power commander from a motorbike that would be ideal for intercepting the pulswidth and modulating the values to make them user-defined?
that way the stock ECU can control the fuel and the VVC and the piggy back can concentrate on the spark? im sure you could pick one up for about £100 and it would be mappable (so to speak) on a laptop
let me know if im following you or if ive got the wrong end of the stick completely