Hey all - gremlins are in my car! I can fix a chevy/holden/ ford blindfolded so my mechanics is generally ok Give me a Z and I am completely stuffed but I have been learning for about five years now - so mechanically I can do a lot but I dont know my way around the Z internals or elecricals still I have a - 92 TT Auto with S2 PTU and nistune fitted The problem: Sudddenly started missfire on cyclinder four. Once when driving it was missfiring - stopped engine - then it started firing - started next time and it started missfiring again???? Hasn't fired since..... Checked TPS - as per manual Checked for air leaks by pressure test - nil leaks at high pressure Checked injectors and flow tested- excellent Check fuel pressure - as per manual on idle and on no vac signal Checked Valve and Compression - both in excellent condition Checked spark plug and coil - excellent spark given off - leaps 4cm onto plenum Noticed that the plug was dry! Leads me to think that the problem is related to the injector electrical connector or back from there I replaced the connector three months ago and it was firing ok since - so it may or may not be related - but it wont be an old bad connector so to speak How do I test the electrical output (with multimeter) on the injector connector as I believe it will be a pulse type of signal - i.e. what settings? If the connection turns out to be fine to the next component - what is the next step ? What other parts are involved in a injector signal missfiring on one cyclinder - can it only be the S2 PTU or is there another part that can cause this ? (thinking of trying another S2 PTU to see if its the problem - is there other components I should try as well that could be causing this besides the PTU if its not connector/wiring related ) I know I am looking a bit ahead at the moment and need to test the signal first in a step by step fault finding process but I am looking at trying to fix this quickly if I can and if I can quickly plug an ST2 PTU in quickly etc then that may help Side note: I notice the timing advances from between 30 to 15 (constant) when I start it and its cold - when it warms up it heads to 15 and is constant - does that sound right? Cheers all :zlove:
Key on, engine running............Set the meter on DCV & backprobe the negative side of the injector connector.
What's the condition of your plugs to the injectors? New? Old? Even if new the wire used ate copper and suffer from a green corrosion and then transfers to the injectors as a white corrosion... This can lead to poor connections and thus misfire, this can be on and off. I found this when I put new plugs on mine, I cut back the wire to a clean section a connected up new wires, solved a lot if issues back then I washed the bay way back when, and found I got a misfire from water stuck in the (old) plugs... That's because of the brittle boot over the wire
If the miss fire is on cylinder 4 and you suspect some electrical component then you can switch out components from one of the other cylinders and see if the miss fire moves to another cylinder.
I will go along with the injector line of investigation, mainly because you said that you had spark and a dry plug after isolating the misfire. Also assuming you have new injector plugs and have swapped spark plugs and coil packs and fault stays on cylinder 4. Measured resistance across unplugged injector 10-14 ohms per FSM. Also listened with a large screw driver for tapping while misfiring, no clicking would mean stuck injector. Using a MM to measure injector voltage can be a bit difficult as the DC square wave is moving quicker then what a basic MM can read, a AC voltage setting may "see" it better with engine running or again not at all "across" the injector. As TSK said you will see constant 12V between either of the injector pins and earth/chassis with ignition off unless your car has been modified or a latter model. One side will be a little lower due to voltage drop across the injector coil. But this approach is less likely to net results with your equipment. IMO the most likely problem will be in the harness, setting up a MM to measure resistance (in a low range if not auto) battery disconnected, ECU unplugged, injector unplugged, securely back pinned at each end of the circuit. Then with someone watching MM start shoving the wiring around a bit from a centimetre behind the connectors all the way through, a special area of interest is where the power feeds are joined up inside the harness at the ECU end. The tech section has some pictures of this that I believe caused another member a lot of problems. http://www.pexcom.com.au/z32cms/e107_plugins/content/content.php?content.332 FFS link stuffed go to Tech Section and search "injector power" Where the power feeds are crimped together may corrode with age, I would not recommend the modification, just using the pictures, if it is a problem after testing, I would probably solder the crimp but hopefully better then the soldering in that article. A larger than average solder iron and a tiny tiny amount of plumbers flux would make it much easier.
You should try and stick away from soldering on vehicle wiring looms, it's best to use SS connectors or there are alloy ones that won't corrode. Solder joints can either change the resistance (bad) along the wire (if) the two wires being connected are not physically touching each other, (twisting the two then soldering may/can solve this. The other issue is the solder joint can still corrode with a white type of corrosion, also the other issue is the joint may not be a solid solder joint and could break! I don't know of any proffessionally built, purpose race car or aircraft with soldering of two wires together due to these risks. Just sayin
I hear ya and in general agree with you. But I would not hesitate to do what I suggested as the wires are crimped together and the contact surfaces have corroded. By using a tiny tiny amount of plumbers flux the surfaces will be rejuvenated and with quality soldering sealing the joint from air. Quality soldering is the prerequisite, not as pictured in the tech sections switched power article. NOT LIKE THIS !
Update on situation NEWS UPDATE Tested the injector connector and all is fine - the connector is working - as stated previously all connections are new and I soldered them correctly (not like that brickies labourer job - lol) This brings me back to the only thing left - The injector playing up (as brisz suggests as well) being the only cause left (given it has spark and fuel pressure and compression and valves working correctly) I originally discounted this as a possible cause as the injectors are less than 500k since AAA (Arvin) serviced them / flow tested them etc etc for me. The injectors were fitted correctly with all new parts (I confirmed concentric circles by micrometer after I installed them to ensure the seals were fitted correctly - cause if they are not fitted correctly in all three seals - they will be closer to one side than another). There are no fuel or air leaks at the injector site confirming correct seating. I installed new fuel filters/ fuel regulator and replaced all the fuel lines at the time so the fuel should be clean, not to mention that I dont run it under half a tank at any time ( to make sure debris isnt picked up in the pump) I took care to make sure the pintles werent hit or touched when installing them etc etc so I am really at a loss as to how or why the injector would start to play up after only 480k since the install. I have started testing to confirm its the injector for sure and so I took out the camshaft position sensor (FOR THE FIRST TIME EVER - HINT I'M A NEWBEE AT THIS PARTICULAR TEST) as per the manual and turned it 360 - each 1/6 of a turn getting a click as per the manual with no click missing in between. Problem is I cannot tell where the clicks are coming from! They all actually appear to be coming from around the Fuel Pressure Damper!!!! - WTF??? I was under the impression that each click would come from each injector?? I thought my hearing might be getting a bit old so I put my finger on each injector to see if I could feel anything when turning it but I cant feel any clicks at any of the injectors - (even though five are obviously working - lol) I thought the click was supposed to be at each injector - it makes sense that damper gets a vibration shunt from each injector firing though anyway. If I get a click each 1/6 then can I assume the injectors are all fine anyway even if I cant feel each injector firing? Can dirt/ varnish buildup caught in a injector nozzle or can the injectors fail mechanically as well and still click? What should I do from here? Am I testing the camshaft position sensor right and does this sound right?? The manual says each injector should sound and I figured I would be able to hear each one (maybe its my hearing after all - I will get some "ears help" to confirm this in the meantime). Is the clicking 1/6 turn irrelevant and the object that you have to feel /hear each injector regardless of a click each 1/6 turn??? Or does the click each 1/6 mean its all working regardless of where I think the sound is coming from?Shouldnt I be able to feel a vibration click by putting my finger on each injector cap? I am hoping I dont have to do a plenum pull at 480k for a newly reconditioned injector! I am thinking of getting some suburu upper engine cleaner and suburu fuel injector cleaner (heard some good stories about using this stuff - aka seafoam in the U.S.) even though I dont normally believe in using anything but fuel oil and water coolant - then giving it a gentle highway run in the hope that this can cure it and save the plenum pull - what do you think What would be your next step from here? Thoughts /opinions?? Thanks all for the input so far - I remember each persons help and good things go around in a circle in my world Cheers all :zlove: P.S. Who's car had that f....... birds nest soldering job - f......! :rofl:
I think it was an American brickie, funny that its in a tech section as a how too. :rofl: Get a length of garden hose, jump the fence at night and shorten the neighbours it will be like old times. Or get a large screw driver and place the tip on the injector cap and your ear to the handle. Or hose and use like a stethoscope. Problem is that you dont know if it is misfiring, doing it with the engine running and misfiring would be the go. You have said that the misfire was intermittent, so if you hear the injector clicking and decide its OK when its not you could end up chasing your tail. Or make this:
Hey Brisz I have a stethoscope - so I will try that - lol Its not intermittent par se, rather it worked for 470klms than it didnt for 5k, then it did for 2k and now it doesnt and hasnt for about 4k. No go since. so the clicking at the injector tells me what? - that the injector is spraying or that its working electrically or mechanicallly but maybe not spraying? i.e. what does the clicking mean its doing and can it still be faulty even if it clicks? Its obviously not firing still (just before pulling out the cam sensor it was still not firing) thats why I am testing this right now, so motor running wont help me so much, but rather just make it more difficult to hear I guess What do you think would be wrong with the injector - as an offhand gambling guess - based on everything mentioned? I bet if i pour some petrol in the spark plug hole it will fire for a short time - (I plan to do that soon). Cheers
If you think it is one injector (and everything else connected to it is OK) have you switched it out to another cylinder?
Pouring petrol in the plug hole is a little risky, I see where you are going but too much and it could end in tears, I have never done that on a VG so will leave it to someone that has played with fire to advise you. Im hoping you hear nothing from the injector, if you have checked resistance across the injector and its within range, it may be stuck shut, this is still on the back of a dry sparkplug. An injector could still make a noise but still be faulty but I would expect that to be on the side of poor spray pattern, which should give you a wet plug I would imagine. If there is no clicking like the others it is coming out I would say. From what you are saying about the mode of failure I am going electrical as above, but you have decided to chase hardware so I am answering you the best I can. Even with the motor running and misfiring give the injector and coil pack leads to cylinder 4 a good wiggle and near ECU also, you would be looking for a change in idle/misfire.
Tend to agree, don't pour petrol in the cylinder, it won't prove anything. On the technical side.......... Did you check the injector voltage with the multimeter? A "noid light" can be used to check if there is a signal sent to the injector. You should be able to hear the injectors 'Click" quite clearly with a stethescope.
Is the Noid light the only way to test it properly ? Hey Guys East Coast Z- Yeh I checked the injector lead with the multimeter and it came up with 12 volts negative and positive on both leads, given it came up with 12v even though its a pulse signal can I assume its working as it must be a strong signal to send 12v even though its a pulsed pattern? Or do I need still need the noid light to confirm it? Brisz - I was only going to use a small amount of fuel such as a quarter of a teaspoon, to me that would tell me if its the injector connector or the injector straight away - I will defer on this given you are both advising not to do it though. I am about to recheck the clicking with my trusty stethoscope - will let you all know how it goes Brisz I think its still injector related - I actually changed the coil/ spark plug with my spares and it is still missfiring - I hear you on the ECU but I havent done that yet based on the injector connector showing voltage on both leads and it working before (been a long time since the ECU was touched). Given its dry - this would mean the injector is not opening at all to me David - ????? I dont understand - changing injectors means plenum pull? Why I would change injector positions then put the plenum back together only to find that the injector is faulty then plenum pull again? After doing a plenum pull wouldnt I would be better off just having no4 injector flowtested at Arvins - putting the plenum back on knowing its working. Have I misunderstood what you are saying or am I missing something altogether there? All - I will see how the click recheck goes with the stethoscope in the meantime Cheers to all you guys for the advice/ help so far!
The multimeter test confirms that the power is provided to the injector, so you can eliminate that as a problem. A noid light will flash similar to a timing light if the circuitry is working properly, used as a quick check only. Analysing the waveform with a scope will determine the state of the fuel injector.
