Resistors for 48# Siemens?
11-20-2008, 02:29 PM
#31
Drifting
Thread Starter
well I have a STOCK DME, with a vitesse maf chip/board in it. I believe I have a KLR authority chip.
What's the consensus? Do I run the resistors or not? I need to know asap...
What's the consensus? Do I run the resistors or not? I need to know asap...
11-21-2008, 01:08 AM
#33
Nordschleife Master
Vitesse provided resistors with the injectors i bought from them, so i am using them. There are many old threads about people saying the DME gets pretty darn hot (due to the injector driver) when not using stock impedance injectors. I dont think i came across any threads stating they had problems with the car using resistors inline..except for that one where someone who will remain anonymous used spade connectors 
.
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11-21-2008, 01:13 AM
#34
Drifting
Thread Starter
whats up with using spade connectors?
I mean, I obviousbly plan to solder mine in, but just wondering. What happened?
And yes, I figure John knows what he's doing, but I want to be 100% confident in my decision.
I mean, I obviousbly plan to solder mine in, but just wondering. What happened?
And yes, I figure John knows what he's doing, but I want to be 100% confident in my decision.
11-21-2008, 02:32 AM
#35
Drifting
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I have seen problems and blown DME's without resistors however as Jon stated, I have yet to see any issues or damage caused from properly installed resistors. I have been using the exact same ones I sent you for years. I got 4 of them and only used 2. My first injectors were Python 83lbs which I used for 3 years. Last year I switched to Siemens 86lb injectors when one of the Pythons sprung a leak.
11-21-2008, 03:52 AM
#36
Rennlist Member
Yes, in stock form they all fire at the same time twice per cycle. Sometimes I forget how unstock my "stock" DME is. I really don't see how that changes the calculation though since there is still 2 injector drivers. The wires are split at the DME and is why you would use two resistors, one on each wire. If it wasn't split you'd use one resistor or you could use 4 smaller resistor with one on each injector but that's a bad place to put them. The values would equal out to the same if using the correct resistors. Wattage has alot to do with as well. The voltage drop is minimal and should effect most injectors. Some do need to be "kicked" a little harder with can be done by the DME software and chip tuning.
I generally agree that running series resistors is the 'safe' thing to do if there are concerns, but stand by my calculations. The voltage drop across a 1 ohm resistor running 2.4 ohm injectors is not minimal ! It's nearly 5 v (see earlier schematic).
However if the engine appears to run fine with resistors then so be it !
11-21-2008, 05:38 PM
#37
Mikeyoman,
I think I see one thing wrong with your schematic: it shows the resistors on the wrong side of the circuit. 12v is delivered to the injectors and the function of the injector driver in the DME is to switch to ground. The resistors are the last thing in the circuit that the driver sees (pretty sure this is correct). Does this make a difference in your calculations? I don't know.
One other bit of information for thought: when a 944 is hard to start, a troubleshooting technique is to unplug one of the injectors as a test for high fuel pressure. The theory behind this is that too high fuel pressure will cause the injectors to not fire and cause circuit impedance to go high (like high resistance). Unplugging one can lower total circuit impedance and can cause the injectors to overcome the high fuel pressure and allow the engine to start. So if your in-line resistors are of too high a value then you could have performance issues. That said I have run 1 ohm resistors with my 55 lb/hr injectors for years with zero problems.
I think I see one thing wrong with your schematic: it shows the resistors on the wrong side of the circuit. 12v is delivered to the injectors and the function of the injector driver in the DME is to switch to ground. The resistors are the last thing in the circuit that the driver sees (pretty sure this is correct). Does this make a difference in your calculations? I don't know.
One other bit of information for thought: when a 944 is hard to start, a troubleshooting technique is to unplug one of the injectors as a test for high fuel pressure. The theory behind this is that too high fuel pressure will cause the injectors to not fire and cause circuit impedance to go high (like high resistance). Unplugging one can lower total circuit impedance and can cause the injectors to overcome the high fuel pressure and allow the engine to start. So if your in-line resistors are of too high a value then you could have performance issues. That said I have run 1 ohm resistors with my 55 lb/hr injectors for years with zero problems.
11-21-2008, 05:42 PM
#38
Race Car
FYI I have ran my car with 2.4 ohm injectors w/o resistors for quite some time now.
I believe the are also being worked pretty had due to them being smaller
my .02
I believe the are also being worked pretty had due to them being smaller
my .02
11-21-2008, 10:21 PM
#39
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What exactly are the consequences of running resistors? The consequences of not using them is a possible blown DME, I have yet to see anything damaged from using them.
11-22-2008, 04:14 AM
#41
Race Car
pretty hard
I guess I should say that these are out of my S/C car and are the 36# ford units. I swapped them b/c of a problem with the stockers.
These supply all the fueling up to 15 psi and then my supplemental kicks in. Even then though, I have to believe they are running at High IDC
I guess I should say that these are out of my S/C car and are the 36# ford units. I swapped them b/c of a problem with the stockers.
These supply all the fueling up to 15 psi and then my supplemental kicks in. Even then though, I have to believe they are running at High IDC
11-22-2008, 12:56 PM
#42
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Oh wow, I just saw this thread and I apologize for the confusion.
When I bought the injectors from Lindsey Racing they said I wouldn't need any resistors for street duty. So in other words, unless I was on the track or something, where it would see full load for extended periods of time, then it should be okay.
However, after speaking with John from Vitesse Racing, when I ordered the MAF conversion kit, he recommended some resistors to be safe.
He sent me two and if I can find them I'll send em to you if you want. Sorry about that, I completely forgot he sent those to me. I had that kit sitting around for a long time once I stopped working on my 951 so I didn't even think about that.
When I bought the injectors from Lindsey Racing they said I wouldn't need any resistors for street duty. So in other words, unless I was on the track or something, where it would see full load for extended periods of time, then it should be okay.
However, after speaking with John from Vitesse Racing, when I ordered the MAF conversion kit, he recommended some resistors to be safe.
He sent me two and if I can find them I'll send em to you if you want. Sorry about that, I completely forgot he sent those to me. I had that kit sitting around for a long time once I stopped working on my 951 so I didn't even think about that.
11-22-2008, 02:09 PM
#45
Drifting
Thread Starter
o, ok. I just saw LR, then read conversion kit and interpreted it all wrong. Its ok, I dont think I'm going to run resistors. I HAVE some, but after talking to some buddies in the area, they've told me they dont run resistors and their cars have been doing fine for years and they even see track duty.
I am curious, my kits used isn't it? The protube looks all and used (not to mention red paint inside it), the maf sensor is dirty, the injectors MAY have been used. Its hard to tell. I mean, the harness is new looking...but that's about it. Did you buy it brand new yourself, from vitesse?
I am curious, my kits used isn't it? The protube looks all and used (not to mention red paint inside it), the maf sensor is dirty, the injectors MAY have been used. Its hard to tell. I mean, the harness is new looking...but that's about it. Did you buy it brand new yourself, from vitesse?