today the car was running sounding very rough, so i did a conzult. no errors and everything looked right.

 

balance test showed revs drop by about 50rpm on clyinder one and 400 to 500 rpm on the other five

 

to me this reads that cylinder one is working slightly but not fully. am i right??

 

recently i had a new front bumper fitted and they forgot to refit the splash gaurd over the cone air filter, the car started running ruff the day after i washed it (and i have a vented nose pannel) so i was blaming it on water sucked in the air filter into the cylinder. however there is no sign of water in the engine

 

what else should i check?

i had asumed it was not an electrical problem due to the asumed fact that the cylinder is working a bit rather than not at all

sounds similar to mine when the injector was on it´s way out...not totaly shot, but dying. Maybe check the resistance across the injectors to rule that one out.You should get a reading between 10 an 14 ohm

 

:)

make sure the filter is completely dry and give the maf a good clean. if this doesnt work then check coilpacks, plugs and injectors :)

check for,

functioning coilpacks swap over etc

plug

is the injector clicking? if so ohm the injector from memory should be 12 to 14 ohms(check that )

stick teh maf in the airing cupboard overnight, its likly either a bad injector or spark or a bad connection to either process of elimination.

today the car was running sounding very rough, so i did a conzult. no errors and everything looked right.

 

balance test showed revs drop by about 50rpm on clyinder one and 400 to 500 rpm on the other fiveto me this reads that cylinder one is working slightly but not fully. am i right??

 

recently i had a new front bumper fitted and they forgot to refit the splash gaurd over the cone air filter, the car started running ruff the day after i washed it (and i have a vented nose pannel) so i was blaming it on water sucked in the air filter into the cylinder. however there is no sign of water in the engine

 

what else should i check?

i had asumed it was not an electrical problem due to the asumed fact that the cylinder is working a bit rather than not at all

as long as the 6 pots drop by a simalar range then it seems normal on the drop test mate

dont sound to good ... sucked water and cylinder 5 can have caught the water and bent some thing mechanical but again i can be wrong i dont think that much water will cause any damage and about cyl one i wont worry ... get cyl five sorted first :D

dont sound to good ... sucked water and cylinder 5 can have caught the water and bent some thing mechanical but again i can be wrong i dont think that much water will cause any damage and about cyl one i wont worry ... get cyl five sorted first :D

 

That amount of Water wouldn't bend anything, but with a wet filter and water vapour being sucked onto the MAF sensor it would be giving false readings. even if they are in range, it might be so varied that the ECU is trying to compensate a lot and getting very confusing signals.

 

Take the filter off and dry it out, take the MAF off and give it a clean with carb cleaner then put that with the Air filter in a warm dry location. then refit then run the test again.

well,

 

everything is now dry,

swapped coil packs round - confirmed its not that

found loose connection on PTU - turns out that just created extra faults

so still down on cylinder one

fairly sure now its the injector

any one got a TT injector spare i can try?

what is the going rate for second hand injectors?

how much is a new one? is it 300zx specific or a standard part?

have you don the screwdriver test and ohmed the injector? not sure if your aware but injector removal is a pita becuse the plenum is in the way. if the injector is bad you will get the wrong ohmage. a quick listen with a screwdriver will often tell you if its working or not. place a long screwdriver on the injector top whilst the engine is tuirning over and listen through the body they should click and make teh same sort of clicking, as above the injector should be reading around 12-14ohms

using the dremel method changing the injector is sooooo easy

 

if it does turn out to be an injector

 

:)

It could be a coil pack breaking down under load. Try a spare one of those first and swap it around to see if the problem goes away.

have you don the screwdriver test and ohmed the injector? not sure if your aware but injector removal is a pita becuse the plenum is in the way. if the injector is bad you will get the wrong ohmage. a quick listen with a screwdriver will often tell you if its working or not. place a long screwdriver on the injector top whilst the engine is tuirning over and listen through the body they should click and make teh same sort of clicking, as above the injector should be reading around 12-14ohms

 

A good first step but dont forget all that you are testing is the solenoid is in good order & working. The solenoid could be physically broken from the needle in the injector or the injector clogged so it is not injecting properly or at all!

Can the injectors be cleaned, i.e. in a sonic bath etc?

so lots of progress, but still not working properly

 

still not got a working cylinder one :(

 

 

thanks to everyone for the advice (especially Jefftt and Jamie) now i'm after some more help before i give up and buy a 370z

 

i've fixed the intermittent cylinders 4 and 5 by cleaning all the green gunk of all the injector plugs and sockets (except no 6 that i couldnt get too) and pushing the plug firmly into the PTU. however still no cylinder one

 

i measured injector one and no resistance so bought a second hand one and replaced it

 

i checked the cylinder has no water in it and the maf and air filter are dry

 

i swapped coilpacks one and 3 and the fault stayed with cylinder one

 

i replaced the spark plug on cylinder one.

 

i checked the main plug is in the ecu firmly

 

i listened to the injectors with a screwdriver and injectors 2 to 6 give a clear sharp click, injector 1 gives a mufled indistinct nock. therefore i deduce injector 1 is not firing and assuming i've not been sold a duff one( it reads 12 ohms) i think i need to start testing the wiring loom

 

as i understand it the injecctors are fed straight from the ECU?

do both wires come from the ECU?

if so why two wires?

does anyone have a diagram/picture of which pins of the ECU ?

what sort of signal do the injectors get? (i am asuming a 12v low current pulse)

would i see anything using a multimeter, or do i need an osilascope, or is there a correct tool for the job?

 

while i'm checking the wiring loom:

i believe the coil packs are fed from the PTU?

why 3 wires?

do all 3 come from PTU?

what do the 3 wires do?

what is the correct test tool here?

 

thanks again to anyone who can shed some light / encourage me back to looking at it

Not necessarily the answer you need, but info here on the injector wiring at the ecu end http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.332

 

diagram http://300zx.co.uk/cgi-bin/manual.cgi?list=efec&dir=&config=&refresh=&direction=forward&scale=0&cycle=off&slide=118&design=default&total=190

 

http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.401

it may well be the injector connector itself, is the top rubber boot damaged? they get badly corroded as you know, but somethimes the corrosion inside is just too much. you should be able to test the injector loom with a multimeter. with some patience. if it is that then its a case of buying a new connector for a few quid and pigtailing it into the existing loom.

Not necessarily the answer you need,........

 

cheers, your like some human google bot 300zx indexing service

 

the coilpack diagram was spot on and a few pages later i found the injector diagram :)

 

now i know what to do next, just need the rain to stop

 

 

also got a couple of injector conectors on order as i broke one. no idea how your meant to get them off intact

you will struggle if there are old, but you need to pop the metal clip out a bit, or completely, but they tend to fly off never to be seen again, once off, re-fit the clip then they just push on and 'click', hth...

My advice to you is to energise the injector with some wire across your battery,have the plug out and look down the hole.you should see fuel spraying into the cylinder,that will eliminate the injector bud,if you want to test the electrics i can lend you a noid light which plugs into the loom and flashes with the ecu signal.It really is prolly quite simple.