I've been having trouble with spark blowout in a boosted application that went undetected as a problem with tuning for quite a while, until it became problematic enough for me to finally identify its presence. In the process of working to resolve it I learned quite a bit that I did not know through researching the solution.
Rather than go into detail about my experience I'll just get to the point of the modification since few are having to address spark blowout in a boosted application here. Since my stock coils were old and I had no history on them, I decided to replace them with a high voltage set of MSD coils for a DIS ignition system. The reason some who purchase performance coils say they didn't notice a difference is because a stock to mildly modified engine does not need a high output ignition coil and regardless of the coil output rating, it is only going to deliver as much energy as needed to jump the plug gap. Some do notice a more stable idle but then again that questions the condition of the OE equipment. Perhaps you can gain a little efficiency by installing an HO coil on a stock engine and widening the plug gap.
I approached this problem knowing Accel coils were considered poor performers by the overwhelming majority of reviews I read about them and even saw a brand new set still in their boxes on ebay that had to be relisted before they finally sold for $60 for the trio. That's almost as much as a single dual post GM Accel coil costs to give you an idea of how much they are avoided. Mean while during the same auction a set of used MSD dual post coils like the ones pictured here sold for over $80.
If you go with a multi supercoil upgrade try to get them all from the same batch if possible. Note that not one of the 3 coils I purchased is identical which means either a change in production run, location, or in this case production date. Despite MSD having a much better reputation for their coils in this application I was not impressed with this discovery.
To the point, since the ignition coil basically steps up voltage, theoretically the more voltage you put into the primary winding the more potential voltage you get out of the secondary winding up to a point. With that being said, I checked my voltage at the harness and found 11.2 volts with ignition on and 12.2 volts at the battery so obviously there's a bit of resistance going on and room for improvement.
I removed the power supply terminal from a bad module that I had on hand, and exposed the terminals from it.
I then soldered the appropriate wires from a stock Fiero fuel pump relay and harness, using the backup power wire that would normally go to the oil sending unit in the event of a relay failure for backup, to serve the same purpose in this application, so that if the relay fails the module will be powered by the harness B+. The harness plugs into the female plug taken from the bad module and soldered to the relay, and an extra plug that fits in the module is soldered to the output wires from the relay to be plugged into the module so the system can easily be returned to stock.
Be mindful of your wiring according to the OE wiring diagram, the plug at the module should actually have B+ supplied to terminal A (as it appears in my diagram only, terminal B is in the "A" location on the module plug), my arrangement was crossed due to the diagram I was looking at. Connecting the module up to power in reverse polarity will severely reduce the performance of the ignition system.
Ignore the bypass circuit, it will prevent the relay and motor from shutting off in this arrangement
Now all I have to do is put it in the car and test it. Not sure it will make any difference but I'll be happier knowing that I'll have at least 12 volts at the coils instead of 11.2 volts and that makes it worth it for me.
[This message has been edited by Joseph Upson (edited 03-26-2013).]
Got the harness installed and tested, below is a picture of the voltage at the coil with the car running, very nice. I would be in denial if I didn't say the car seemed to idle better after a drive and I did notice a slight change in tone of the motor once it was engaged but I can't say it was because of the increased voltage at the coil and here is why; The first stopping point was the gas station where I turned the car off, at least I thought I did. The motor decelled as if it were about to shut off but suddenly picked up and kept idling. Pulling the relay shut it down and I knew I had to go back and look at my arrangement.
Next stop was the gym where once the ignition was turned off there was a delay but the motor decelled and picked up again then shut off. I thought maybe the whole incident was because the relay was sticking and finally loosened up except the engine light was on, and the radio was still going signifying power was coming from somewhere other than the start switch. I had considered it earlier but didn't think about it as long as I should in order to realize that once the relay was activated the circuit would become self sustaining through the bypass and in order for the circuit to work with the backup arrangement I have there would also need to be a second relay to cut the power from the battery using a different B+ source. In other words, I cut the backup wire and it worked fine with the car shutting off with key off. So, the change in idle when the relay was plugged in may have changed the fueling as a result of the boost in voltage to a circuit that was 1 volt lower than battery voltage with the key off and suddenly seeing at least 1 or more volts increase once the relay was plugged in since that circuit also turns the ECM on
The next modification will be to attach a sufficient heat sink to the bottom of my relocated module as despite no longer being exposed to heat rising up from the exh manifold in the stock location over the valve cover, it now has extra heat from receiving the full voltage from the system although the lower resistance in the primaries of the MSD coils may offset it. I stuck my hand beneath the module mount bracket after shutting the car off and it was very hot, too hot to maintain contact and considering it's about 35 deg outside it has to get much hotter during the Summer.
[This message has been edited by Joseph Upson (edited 02-11-2013).]
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02:00 PM
2.5 Member
Posts: 43225 From: Southern MN Registered: May 2007
All made in China, possibly different years though, Snake, Monkey, Rabbit ...
Interesting. I guess theres some made in China stuff everywhere.
I found this quote frmo MSD in another forum, hope its not too off topic:
"MSD was developed and born in El Paso 40 years ago. We have grown to encompass over 150,000 square feet of space to design, test, manufacture, and support our components. We have engine dynos, chassis dynos, CNC equipment, an EDM machine to cut molds, wave solder machines, surface mount pick and place equipment, and more tools and capabilities to aid us in MANUFACTURING the best ignition components available. We are comprised of just under 300 employees – with the average seniority of 12 years! No other manufacturer can even come close to that kind of commitment from its employees.
Every 7-Series, 8-Series, Pro Mag and most 6-Series Ignitions are designed, built, tested, and supported in the USA. We say ‘most’ on our 6-Series because there are two models that do incorporate a half populated PCB from overseas. In El Paso, we populate the rest of the raw and power components, assemble it, test, burn it in and package it.
Yes, some coils, such as the Blaster 2, are made overseas. One reason is there are no oil filled canister style coil manufacturers in the United States. All MSD coils are made to our specifications and thoroughly tested. Also, the coils for the Pro Mag 12s and 44s, the HVC line of coils and our multiple spark LS coils are all made in the United States.
One area that we offer caution, especially when purchasing used or through the internet, is with Distributors. MSD designed the Pro-Billet distributor and now you are seeing complete copies of our distributors coming from overseas. Even name-brand competitors are selling distributors that are copied from the original MSD design – some even with our part numbers! The distributor issue has become a predicament for MSD as we still get the tech calls, the upset customers, and even some returns of these off-shore duplicate distributors.
We could go on with other products in our line such as the 8.5mm Super Conductor, APS Starters, Crank Triggers (all made in the USA), but want to keep it short. It is important to mention our budget based line, Street Fire. This is line offers several distributors, easily identified with cast housings, as a budget based brand. The distributors are produced in China, however it took over a year to get a product that we were confident in. We put them under a different brand to clearly set the two designs apart. For the record, there is also a Street Fire CD ignition and spark plug wires as well – both made in the USA.
Face it, anything having to do with electronics is a tough business to be in with hundreds of raw material components, and it’s nearly impossible to build a product out of 100% USA components. You can be assured that if you do have an MSD coil that is made in China or in the United States, we will stand by its performance and provide you with the same support as any other MSD products." http://www.yellowbullet.com....php?t=275621&page=6
I'm not too worried about the coils since they have a 1yr warranty on them and I expect them to malfunction before that if there's a problem. If it's made in China my curiosity would be with who's insuring quality control and quality parts. Once these coils are assembled that's it, there's not much to inspect. I like the coil that looks the most like the OE coil on the bottom. With most electronics parts as evidenced by my Digikey catalog there is a grade/durability rating like for example, the resistance to high temps which is very important in an ignition system.
Finally got around to relocating the ignition module and coils. I used a 3/16" square base for more capacity and attached a heat sink to finish this project. I may add a small fan to top it off.
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10:17 PM
woodyhere Member
Posts: 399 From: prior lake, MN USA Registered: Aug 2011
I'm not familiar with multi coil set ups. I have done a lot of reasearch and developement on GM HEI single coild systems. Do the coils each get a 12 volt positive wire like the HEI single coils get? Does the module perform the same switching function as in a HEI V8 distributor module? If the systems are similar then I know why your module is generating so much heat. The heat sink is a great approach. If your module triggers the coils, I have a different way of approaching the voltage issue.
Originally posted by woodyhere: I'm not familiar with multi coil set ups. I have done a lot of reasearch and developement on GM HEI single coild systems. Do the coils each get a 12 volt positive wire like the HEI single coils get? Does the module perform the same switching function as in a HEI V8 distributor module? If the systems are similar then I know why your module is generating so much heat. The heat sink is a great approach. If your module triggers the coils, I have a different way of approaching the voltage issue.
Yes, as for the concern with the heat, it's because of the turbo and the extremely hot Summers in Florida and Georgia along with long exposure times in traffic. I hot wired the system to insure maximum voltage potential after measuring as much as 1 volt difference between the harness B+ and the battery and because of spark blowout which I discovered needs more current (which the smaller plug gap provides) instead of more voltage. The smaller plug gap generates more heat in the ignition components so the effort to keep things cool is a wise one.
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11:13 PM
Mar 24th, 2013
Englishrafe Member
Posts: 153 From: Lorient, FRANCE Registered: May 2008
You can't get special "turbo" application sparkplugs? The ones with the fine pointed electrodes. I have a little experience with turbo charged Renault 5s and my high static comp ratio Trans Am motor , and these were the only plugs that stood up to the increased pressures without misfiring.
Originally posted by Englishrafe: You can't get special "turbo" application sparkplugs? The ones with the fine pointed electrodes. I have a little experience with turbo charged Renault 5s and my high static comp ratio Trans Am motor , and these were the only plugs that stood up to the increased pressures without misfiring.
My case is trial and error. The narrow tip irridium plugs OE and after market NGK TR6s are a no, no for boost in my engine. So far the best performing plugs have been the Bosch Copper plus plugs as they would go to 10 psi on .030 gap before blowing out and at .022 so far I haven't had a problem. I'm checking out the AC Delco plugs that were used in the Turbo Grand Prix now to see if they'll work as a backup option. From what I've read to this point copper plugs are the way to go with misfire problems related to boost pressure and that's what has worked the best to this point.
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06:44 AM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
Great idea on the voltage boost, but not so great execution. It looks like you tied the relay into the oil pressure switch. With it wired up that way, the ignition system will now receive power whenever the engine oil pressure is above 4 PSI. That's why you couldn't turn off the engine with the ignition key. It looks like you also may be back-feeding extra voltage into the fuel injectors.
Instead of tying into the oil pressure switch, tie into an "ignition key on" power source.
I would actually suggest using the power wire from your ignition module to activate your booster relay. Just send that wire to your relay instead of the module. And have power fed to the module from the relay (via the alternator). No piggy-backs. No back-feeding power into other circuits. Just discreet power directly from the alternator to the ignition.
[This message has been edited by Blacktree (edited 03-24-2013).]
Originally posted by Blacktree: Great idea on the voltage boost, but not so great execution. It looks like you tied the relay into the oil pressure switch. With it wired up that way, the ignition system will now receive power whenever the engine oil pressure is above 4 PSI. That's why you couldn't turn off the engine with the ignition key.
Instead of tying into the oil pressure switch, tie into an "ignition key on" power source. Or you could tie into the A terminal of your fuel pump relay (green / white wire).
The oil pressure circuit is not involved. I simply overlooked the B+ loop I made that turned it into self powering via the alternator once the ignition key was turned to the on position and before the motor is cranked. I mentioned that mistake and cut the loop which solved the problem. I used a pump relay for the extra wire, not the pump circuit.
[This message has been edited by Joseph Upson (edited 03-24-2013).]
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12:57 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
Sorry, your description was confusing. And the drawing didn't help.
Bound to happen when you don't read closely.
quote
Originally posted by Joseph Upson:
I then soldered the appropriate wires from a stock Fiero fuel pump relay and harness, using the backup power wire that would normally go to the oil sending unit in the event of a relay failure for backup, to serve the same purpose in this application, so that if the relay fails the module will be powered by the harness B+. The harness plugs into the female plug taken from the bad module and soldered to the relay, and an extra plug that fits in the module is soldered to the output wires from the relay to be plugged into the module so the system can easily be returned to stock.
Be mindful of your wiring according to the OE wiring diagram, the plug at the module should actually have B+ supplied to terminal A (as it appears in my diagram only, that's terminal "B" on the module), my arrangement was crossed due to the diagram I was looking at. Connecting the module up to power in reverse polarity will severely reduce the performance of the ignition system.
Ignore the bypass circuit, it will prevent the relay and motor from shutting off in this arrangement
Now all I have to do is put it in the car and test it. Not sure it will make any difference but I'll be happier knowing that I'll have at least 12 volts at the coils instead of 11.2 volts and that makes it worth it for me.
I'll go back at some point hopefully and post a better diagram. Some times in a rush we miss things.
[This message has been edited by Joseph Upson (edited 03-26-2013).]
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01:36 PM
Mar 26th, 2013
woodyhere Member
Posts: 399 From: prior lake, MN USA Registered: Aug 2011
Most of the modules (GM) I have worked with have a voltage limit of 20 volts. The older ones on the 4 cyl Fiero have a lower rating. I have been working on a voltage boost module. It will sence the voltage imput variations and smooth them out. The output voltage can be set and stays constant. Using stand winding ratio coils and putting 17 volts in the system should give a boost current high enough (150%) to open the gap on the plugs and still have enough voltage to jump the gap and enough amperage to make a nice fat spark. What are yuour thoughts?
Most of the modules (GM) I have worked with have a voltage limit of 20 volts. The older ones on the 4 cyl Fiero have a lower rating. I have been working on a voltage boost module. It will sence the voltage imput variations and smooth them out. The output voltage can be set and stays constant. Using stand winding ratio coils and putting 17 volts in the system should give a boost current high enough (150%) to open the gap on the plugs and still have enough voltage to jump the gap and enough amperage to make a nice fat spark. What are yuour thoughts?
Woody
That would be great except for one concern, the continuous high voltage supply to the module assembly when it is not necessary and the heat generated as a result that may drastically shorten the life of the components. Perhaps using a boost sensitive switch that activates a 5 wire relay to move between system voltage and the higher voltage would do the trick.
At the moment I have my intercooler water pumps wired that way instead of having them run continuously.
I recall smelling my radio components start to burn when my alternator voltage climbed up near 17 volts as it was failing so the heat build up theory is definitely a concern.
[This message has been edited by Joseph Upson (edited 03-26-2013).]
