Fuel Injector issues

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Fuel Injector issues

Postby Joose on Sun May 20, 2012 1:12 pm

Hi all,

Okay, so about a week ago when I tried to start my car, it really struggled to start and when it finally did, it sounded like it was running on only 2 cylinders and dumped about half a liter of fuel out of the exhaust and massive amounts of unburnt fuel in the exhaust gasses. Needless to say, this was bad :cry: I have been investigating and have traced to problem to the ECU (XMS4A) which is earthing two of the injectors permanently! This is causing massive amounts of fuel to be dumped into the cylinders (cylinder 1 and 4 were literally flooded and big globs of fuel went flying out of the spark plug holes when I ran the motor on the starter with the plugs out and the injectors disconnected - BIG GLOBS, not just mist or vapour!)

It seems that pin #2 on the 8-pin injection plug is constantly earthed (I traced it back through the harness to the ECU and the wiring and injectors are fine, its the ECU thats the source of the earth). Pin #3 (or is it #7? the switched ground for the other 2 injectors) is not doing this, and it has a big healthy resistance to earth (like 1800 or 18000 ohms, dont remember) but pin #2 has virtually no resistance to earth.

What does this mean? Is my ECU buggered? Could it be software related? Not sure how this could have happened because the car was running fine on all 4 cylinders until this happened :?
Building: 4AGE 20v Locost SA
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Re: Fuel Injector issues

Postby andredp on Tue May 22, 2012 3:19 pm

Howdi

If you are 100% sure the earth is via the XMS4, then either the map went corrupt causing it to keep one injector output open, or the circuitry in the unit went faulty. Just check the resistances in the wiring with all the injectors as well as the plug into the management system disconnected, to make sure. Let me know.
Andre'
Racing: Locost Racer - Rocam with plastic intake manifold ;)
Upgrading: Luego Locost SA - ex 4AGE 20V - soon to be x2 on KWs
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Re: Fuel Injector issues

Postby Joose on Tue May 22, 2012 3:40 pm

andredp wrote:Howdi

If you are 100% sure the earth is via the XMS4, then either the map went corrupt causing it to keep one injector output open, or the circuitry in the unit went faulty. Just check the resistances in the wiring with all the injectors as well as the plug into the management system disconnected, to make sure. Let me know.


Hi Andre,

I see that injector 1 and 4 are wired to one input and 3 and 2 to the other. if I stick the prongs of the multimeter into the ECU plug (i.e. into the female ECU plug, not the male harness plug) I see no resitance (0.02 omhs) on the output for injector 1 and 4 and a big number (18000 odd I think) on the output to 3 and 2. This is with the other prong stuck into the earth pin on the female ECU plug. I also checked the wiring between the ECU and injectors (very little resitance - good connection). I suspect it may be the map thats corrupt then because my laptop is really not happy with this PP software. When I tried to plug the laptop into the ecu when the engine was running, it briefly displayed data, but then came up with an error message saying the XMS4 cannot be found when I revved it. If its just idling or if the engine is off, It doesnt do that, and the connection seems fine. Also, that red value of -16384 is back it seems..

Anyway, I basically need to figure out if I should take it for a dyno as is and hope that it can be fixed there, or if the ECU needs replacing. Have you ever had a problem where the ECU "died" in this way? Do Injector outputs on ECU's malfunction like this, or is it most likely a map issue?
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Re: Fuel Injector issues

Postby andredp on Wed May 23, 2012 6:58 am

Hi

Ok, definitely sounds like either the map is corrupt or the unit got damaged. I'll mail you some options.
Andre'
Racing: Locost Racer - Rocam with plastic intake manifold ;)
Upgrading: Luego Locost SA - ex 4AGE 20V - soon to be x2 on KWs
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Re: Fuel Injector issues

Postby Joose on Fri Aug 31, 2012 7:26 pm

Okay, so it turns out it my car is broken.. again :evil: it ran well for a glorious 50 meters up my driveway, and then when I came to start it this morning to take it to Langlaagte, it was again running on only two cylinders... frak. I think that there is a problem with one of the injectors shorting and thus blowing the ECU/Injector drivers. It never seems to happen at perfect power when the car is there, but that could be because the car doesnt move around or up and down on the dyno like it does when I drive it up my driveway. So my next question is:

Does anyone have a source for blacktop fuel injectors? Where can I buy replacements? I dont want to go to the agents because they will charge the price of a new engine for a set of 4!
Building: 4AGE 20v Locost SA
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Re: Fuel Injector issues

Postby 200sxrb25 on Fri Oct 12, 2012 8:58 pm

I got 2 intakes, i do not know if it is black or silver top :oops:
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Re: Fuel Injector issues

Postby kalfiekind on Thu Oct 18, 2012 12:13 am

Have you tried swapping the injectors around? This should cause the problem to shift if the injector is guilty.
Don't have injectors though.
Finally getting to start planning a build.
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