turbovr6

one thing not mentiones in this saga is AMPERAGE. ok so you have 12v going to the injectors, but what about amperage??? I don't recall what the FD specs are, but amperage is an important factor here. I realized here today that by jumping the 2 grounds together you are creating less resistance, AND more amperage flowing through the injectors. Just because the injector ohm's out ok, does'nt mean its all good. If it's all gummed up inside, or some debris is stuck in there, it would take alot more amperage to get that sucker to open up.

rxrotary2_7

AND you are completing a circut.... from what i know, the PFC does not have individual injector drivers.

i wish i had this problem beofore so i could tell you, but i havent. i would check as Jeff said, to see what duty the injectors are when they are tied together as i would be very interested in this as well...

rxrotary2_7

9 times out of ten it is something so stupid. i always step away for a day or two and then go have at it. another thing, not knockign you, but dont be so sure of yourself. if you have hacked up this harness to any degree, have someone else recheck it for you. i am the same way and cant believe i screwed somethign up so i overlook it. are you sure you are using that multimeter right?? in ALL cases? have someone else check the harness.

another thing i know always works is to try different parts. i know this has been mentioned, but i will just reiterate the point. always swap onto/from a known runnign car to see if the problem is still there. simple process of elimination. and do not think that because it worked before, it still works. stranger things have happened. hell we are now on MARS for christ sake! LOL

93 R1

No. I was saying that:



If the sensor is plugged in it is giving a certain resistance value to the computer depending on temp. Thats how temp sensors work. If you unplug the sensor or cut off the connector it *may* cause problems. If the computer doesn't see the resistance in the circuit it doesn't like it. I was saying to add a resistor to the circuit or put the senors back on.



But Jay said that it doesn't matter. The PFC doesn't care about the temp sensor so this means nothing

turbovr6

yeah, apparently the pfc was designed for us "car hackers" with the stock ECU if the omp is bad, or unplugged, the ECU goes into safe mode. The PFC does not care. On my car the OMP and fuel temp are disconnected and everything works fine, you will notice on the PFC diagnostic screen that the respective sensors have a solid dot indicationg they are not working, but thats about it

9BASE3

So, in theory (If there is not individual injector drivers) what I did would work? I'm not happy with a jerry rigged car, but I'm just curious if it would actually be a fix. On that note, I'm hoping to put the harness back in tomorrow and put the manifold back on and see what happens. I've used 2 seperate multimeters, and put my PFC in another car and it worked fine. I'll take the harness to the shop and have a few of the guys do some tests. Thanks for the idea! Anyway, I'll keep you guys posted as I work on it some more.. I really never have time so I just pick on it when I can.. I'll let you guys know what the injector values are once I get it all back together..

tampaFD

so rxrotary you mean the pfc goes to batch fire instead of sequential injection? are you sure? the stock system has i have 1 good stock primary and 1 that leaks if you want to try they are in the mail tomorow if you say so. the fuel temp sensor is realy for hot start stuff on a stock ecu.

jeff48920

".... from what i know, the PFC does not have individual injector drivers."





No disrespect but, this does not make sense to me.



As best as I can tell injectors are not simple on-off valves even though fuel injection systems are based on simple on-off circuitry. If the application of a ground causes an electromagnetic field to move the pintle across its range of motion, and duty cycle is the percentage of time the pintle is in an open position, then the longer the ground is pulsed, the father the pintle is moved towards its full open position. If this is true and you apply a permanent ground, the duty cycle of the injector is going to be 100%. If the PFC simply provided a common ground it would have no way to control the opening and closing of the pintles and if the injectors required common permanent grounds, then there is no reason to route the ground through separate ECU circuitry. I also think that there is no fuel injection equivalent of "waste spark". The continuous injection of fuel at 100% duty cycle would result in a too rich condition in very short order.



Therefore, I suggest that although the car runs with a common ground applied, that is not an acceptable fix.



OK so now that that is out of the way, I also admit I am too dumb to figure out a solution. I will keep working on this.



Good Luck

Jeff

rxrotary2_7

i understand "how" an injector works, what i dont (and obviously none of us here do) understand is WHY it works when the grounds are *jumped* together...

what i was getting at and now that i look at his diagram again is that the two injectors would complete a circut IF the grounds past the jumper were broken somewhere. something along these lines...





would the ecu complete the circut and fire them? this is where the individual drivers came into play in my mind... dont know if it is right or not, but i was just throwing it out there. that is also why i said that the he should find out the duty (like you said, and like i said you said) of the injector to see if they are at 100% or not....

best of luck figuring this out. i am to stupid to also.

jeff48920

Actually I think the drawing is wrong, but your explanation is right to a point.

The drawing should show one wire from each injector going to a common lead that is fed + voltage by the main relay. The second wire (Ground) from each injector should have a direct path to its own junction in the ECU. The jumper wire exists between the ground wires leading from the injectors to the ecu.





I would normally absolutely agree that either the wiring post junction or one or the other of the connectors had a fault, however, Justin assures us that, when hooked up to a noid light, the unit functions correctly without the jumper which would indicate to me that no fault exists either in the wiring or connector.



Damn no wonder Justin's head hurts.