isuzu 1999 problem

[markbaker05]

hi, i have a 1999 bighorn, big mistake if u ask me,, but anyway,,
had a few probs 6 months ago, they tried everything, new ecu , sensors, new injectors, injector loom,, sumthing finily fixed it,,
anyway i have a similar problem,
i have a quierey, i can trace the wires form the injector loom back to the ecu, all of them except 1 (red back line), which is the common feed wire to the injectors, is this a positive or negitive feed wire and doed it even go to the ecu, and if possitive how many volts goes though it, and input would be much apreciated, thanks mark

[Rotazuk]

It will go back to the efi relay probably . Should be 12v ( or batt voltage give or take ) on there . The ECU wants an earth to fire the injector and the positive is a common feed .

Thats on most efi systems that I have come a cross anyway , also black/red is a positive wire marking in most jap wiring .

[Crash bandicoot]

the injectors share a common positive, same with independent ignition coil systems.

it is the negative that is controlled by the ecu.

on independent coil systems the ecu also controls the firing of the spark plugs this way.

it is done this way to protect the ecu rather then having high pulses of current running through the ecu.

[markbaker05]

hmm , good info thanks, and i agree,,, so for there to be a problem with the common injector wire one would asume that all injectors would be suffering? maybe? or can injectors hqave different tollerances ,,,,, ... and one would asume there probily is no problem with ecu being all that its doing is providind negitive feeds,,, ... what voltage should be going though the common feed wire ?? thanks

[markbaker05]

where do you find the efi relay,, and could you just jimmy 12 volts to the common feed wire and c what hapens or is that sumething u just wouldnt do,,,

[markbaker05]

had a women look( as my women wouyld say) in black box thing behind batery in engine bay , found big red fuse thing blown, 50 amp ,,, sits in a row of four big fuses,,, between abs and ecm labeled fuses,, only repersented by chinesse writing,, removed and shorted terminals out with a standard 10 amp fuse which made no noticable difference(10 amp fuse did not blow),,,,, also checked red black common injector wire and tested at 2.3 volts to 2.6 volts as motor was running,, hope this info may help , thanks

[Rotazuk]

Whats the thing doing , running like crap , not starting , using too much fuel ?

Chris

[markbaker05]

starts ok,,, feels like its running on 3 cylinders,,, laking power, wont reve out out 3500 rpm when in gear but will reve to 4000 when in nuteral, u can here the bad missing sound, ocasiononly it almost sounds and feels like it all ok again but that is short lived after u rev the motor again, fuel consumption is ok, water ok, oil ok, oil and water is not mixing,,,, compression is 1-460 2-450 3-460 4-410 mayb as simple as that ,, i dont no,suposibly 410 should still be ok,,, unless its a head gasket and compression from no 3 is leaking into no 4,,, i dont no,,,,,,

[badnuz]

what motor is it? the 4JX1 are prone to shitting the loom and one of the fuel senders ( i think its a sender, cant quite remeber) but you can get a whole new loom from holden for about 3 hundy from memory... has something to do with the leaking fuel or something shorting the loom.....

will double check my facts tomorrow, but we have had a few of them thru work.... very common

[markbaker05]

its a 4jx1 , the loom are deffinitly a problem, they leak oil back though the loom quite often and cause probs,,, ive replaced the injectors and loom 6 months ago,prety sure thats whats fixed it the first time,, so when it all went wrong again i just got a second hand set of injectors and a new loom and put them in,, didnt fix it this time,,

i changed a blown fuse in the black box area behind battery with a 60 amp which blu out as well ,,

any idear what that curcuit mite b 4 , labeled f15, located between abs and ecm labeled fuses

[markbaker05]

is a compression of 410 enough to work?

[sibainmud]

is a compression of 410 enough to work?

Being a diesel Marine engineer, I have always used this rule of thumb........10% vairience between the highest and the lowest is acceptable. Yours is just a bit outside this but should go fine, will just idle a little rough.

[badnuz]

its a 4jx1 , the loom are deffinitly a problem, they leak oil back though the loom quite often and cause probs,,, ive replaced the injectors and loom 6 months ago,prety sure thats whats fixed it the first time,, so when it all went wrong again i just got a second hand set of injectors and a new loom and put them in,, didnt fix it this time,,

ah, yes, oil.... did you replace the leaking oil sender???

[markbaker05]

no, but it was replaced 6 months ago,,, thats tghe 1 on the common rail for the injectors a