does anybody knows the resistance of the ignition cable from the ignition coil to the distributor? my right bank was not firing anymore and I checked this cable with a resistance more then 20 giga-ohm. the left side has about 1 mega-ohm. so at the right side I put in a copper wire now with 0 ( zero ) ohm only to test. and it is running fine again. but i think that this wire needs a resistance, but can not find anything in the workshop manual. I also measured all the other 12 wires going to the spark plugs, and they all have between 2,2 and 4,1 kiloohm with the spark plug tubes. thank you for reading and answering
My notes say approximately 700 ohms per foot of wire length--I think that was Steve Magnusson in an older post though not positive. This topic has been discussed frequently here, do a search and I'll bet you can find plenty of data.
before I started this new thread I already searched but have not found anything. may be one of you could put a link in here where to find this older topic? what I have written before was not 100 % right: the engine is running fine up to about 3600 rpm. over this rpm it is missfiring in idle. the gearbox is not completly connected, still waiting for the new gears for the primary gearbox. so I can not testdrive. I tried to get those cables in meter to make by myself. here I have only copper wires with zero ohm. until now I have not found any resistance wires and a new set for 320 € I don´t want to pay.
Dave Helms (scuderia rampante) has Superior ignition wires for the testarossa I believe-I will be looking to replace mine soon. Regards Tr boy
Here was a test done on some major brand spark plug wire manufacturers, all were tested using "1" Ft sections, here are the results......Mark Granatelli 8mm Steel Solid Core Cable - 0.1 ohms MSD 8.5mm Super Conductor - 71.6 ohms Accel 8.8 300+ Ferro-Spiral Race Wire - 166.1 ohms Jacobs Electronics EnergyCore 8.5mm - 178.3 oms Taylor Spiro Pro 8mm Silicone - 301 ohms Mallory Pro Sidewinder 8mm Silicone Suppression Wire - 313 ohms Moroso Blue Maz Spiral Core 8mm - 661 ohms Magnecor KV85 Competiton 2.5mm - 2053 ohms
Yes, if the total impedance of the "coil wire + spark plug wire + extender + spark plug" gets too low this can stress the transistors switching the primary coil current. Are you running the stock MicroPlex ignition system or something aftermarket? If stock, you might be able to get away with using a low resistance coil wire if you use a resistor style spark plug (and keep the stock spark plug wires). Please try describing this again -- "misfiring in idle" and "over this rpm" seem to be incompatible statements.
I have the turbotronic inside from lenz. but this should work for the ignition like the original I have been told. only two additional knock sensors are connected and also the additional injection to this turbotronic. under missfiring in idle I understand that the engine is running without a gear inside because it is still not driveable. under idle I understand all rpm at the engine by the car standing and only the engine running. may be I´m wrong with "my idle" ??? then sorry please for my not so good english. thank you all for the different ohm the wires may have. but I still like to know the ohm from the original ones. so does anyone meassured those or can meassure?
There is always the option to test the wires with a spray/mist of water. Should you be prepared and willing to perform the test, one would have to hold the cables checking for jumping sparks. I'm aware it is not a very debatable issue in light of fierce reactions on another forum. I'd argue it deals with a bad insulation which in all likelihood happens if cables on these cars age. Ich wünsche Sie viel Erfolg das Problem zu klären!
Not going to give you any more information than the stock TR wires are ~700 Ohms/foot as posted before (as this data is how I calculated that ~700 Ohms/foot estimate), but here's the raw data set from when I replaced my TR spark plug wires (and the old ones, that weren't bad , were in the same ballpark): 1-6 coil = 700 Ohms #1 = 1710 Ohms #2 = 1670 Ohms #3 = 1440 Ohms #4 = 1190 Ohms #5 = 1040 Ohms #6 = 870 Ohms 7-12 coil = 690 Ohms #7 = 900 Ohms #8 = 1150 Ohms #9 = 1210 Ohms #10 = 1430 Ohms #11 = 1520 Ohms #12 = 1700 Ohms
thank you very much for those data steve. so as I see it there only have to be a resistance but it is not such a big matter how much resistance? minimum 1,5 k-ohm, max 2.4 k-ohm. sure, the longer the wires the more resistance. so if I would use on each wire an inline 2 kiloohm resistance I think I will get the same result? the problem is that I can not find resistance endless wires to make those wires by myself. and between the coil and the distributor I will put only a nonresistance wire ( copper ).
No, resistance is just the easiest thing to measure -- what can be more important is the total impedance (and if you wanted to go this way it would be better to just use a resistor style spark plug that typically has ~5K Ohm internal resistance). The actual conductor inside the stock TR spark plug wires is a very small diameter metal wire wound in a long spiral so it has both a resistance and an inductance. Are you saying that you can find no company in Deutschland or Europe that makes a "spiral" spark plug wire? Many companies here in the US do, but the most common problem is that the OD of the complete wire is 8mm, instead of 7mm, so they don't fit into the holes on the distributor cap well (or without trimming off some of the insulation).
I found a company in great britain manufacturing those resistant wires. this company is called MADISON WIRE. they make in 7 mm I send already a mail and waiting for an answer. those resistant wires in europe are very hard to get. you get those for nearly each car completly finished, but not on a roll so you could make them by yourself.
I already got an answer from madison wire: just now they don´t have in stock but they produce again in about 4 weeks. the minimum order would be 100 meter. each meter has 2.8 k ohm
Faster would be a set from Dave Helms (AFAIK he can provide bulk that you make or you can send your wires and he can build you a set), or here's another alternative, used set on eBay, he ships worldwide: http://www.ebay.com/itm/Ferrari-Testarossa-ignition-wires-set-ignition-leads-800-miles-new-list-817-/380505102731?hash=item5897df198b&item=380505102731&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr
I was under the impression the less resistance in spark plug wires the better, less resistance equates to a "hotter" spark plug firing. I thought a spark plug wire with 700 ohmns of resistance was an inferior product. Am I wrong in my rationale!?.....Mark
thanks for the ebay link. but to buy those cables , send them over to europe, have to pay shipping, custom and tax here I just can order new ones for 320 euro here. now we will get wintertime here and no hurry to get those cables. so I think of buying new ones or make by myself. also those resistance cables I could use for other cars better than to buy complete cables for those. what means: AFAIK ?
AFAIK - Wiktionary en.wiktionary.org/wiki/AFAIK AFAIK. Definition from Wiktionary, the free dictionary. Jump to: navigation, search ... [edit] Initialism. AFAIK. (Internet slang) as far as I know ... .....Mark
thank you mark for explanation. red head seaker: I once had the same thinking. but this works fine only if you have 1 or 2 cables not near beside of each. but on some high voltage ignition systems there could be problems with inductive interferences. and that problem you can reduce or avoid with resistance cables. on my BB 512 I put in copper cables 2 years ago and have absolutely no problems, even at high rpm. and there is inside the original ignition.
It all depends what you mean by "better". Yes, the spark energy delivered will be very slightly higher with a 0 ohm system (wires + extender + plug), but this can stress the output transistors (if present) driving the coil primary, and the EMI is usually unacceptable for radio use and can drive ECUs (if present and not well shielded) crazy. AFAIK, no modern car uses a 0 Ohm system because of the radio/ECU issue. These spiral wound wires were the performance step forward because they have a much lower resistance than the older carbon-type wires (which are in the tens of thousand Ohms) while still having enough impedance to get around the radio/ECU/blowing up transistors issue. For a super-high compression 1/4 mile drag car, a 0 Ohm system makes sense, but not for a rational road car -- JMO.
