My Z has always been hard to start when cold. It needs assistance of the accelerator pedal to keep the idle up for a few seconds, then is fine. The other day, I started it without my foot on the pedal. It started, but the idle was very erratic & after a few seconds it stalled. I haven't been able to get it to start since then. I checked there was spark with one of the plugs, that was ok. After trying to crank over the engine a numerous amount of times, I pulled all the plugs to check if any where wet. A couple were, so I left them out & let any fuel in the cylinders to evaporate. This morning I reinstalled the spark plugs & tried starting. Still no luck and the engine is turning over fairly slowly. I pulled out one of the spark plugs that was visibly wet last time, but it is bone dry. I recently installed larger injectors (back to front) which I rotated while in the rail. I know at least one person thinks I have pinched the lower injector o-ring. This may be the case, but I have driven the Z a lot since the plenum pull and it has been perfect. Smooth idle, boosting fine etc... The problem of starting when cold was an issue before the plenum pull, but normally if it did stall, I was able to start it again. This time she isn't even nearly starting. Any ideas/advice would be appreciated
Fuel pump priming? FPCU bypass done already? Fuel pressure ok? Does it smell like its flooding at all?
doesn't bigger injectors need a tune from the get go to match the pressure needed and all that jazz before it will run properly? But you did say it was running fine after that.. hmmm engine turning over slowly sounds like a battery issue, not having enough charge to turn over. Getting the full 12v and/or 13.5 when running?
Yep, can hear fuel pump prime when I turn the key. Haven't checked fuel pressure yet, trying to get my hands on a gauge. Josh, I had a modified Eprom to swap over when I installed the larger injectors. For the record, I hooked datascan up and no faults.
Yup. Gotta change the injector latency and K value to match the injector size... If you have upped the fuel pressure tho, its a possibility the pump could have died... Checked fuel reg? Did it smell like it was flooding?
recheck all plugs you undid on the PP... may have been in enough to work for a bit but not clipped in and thus fell out... PTU, TPS, CAS, Idle control thingy at the back of the plenum all your bad boys that would effect it, unplug and replug again... plus the voltage on ur batt when you start it.
My bet is you have cut a lower injector o'ring or 2. They do not always leak straight away, I have had them do several hundred kays and then leak all of a sudden. Before pulling the injectors, check to confirm you have spark on all cylinders. Charge the battery or swap it for another, crank the engine several times. If an injector o'ring is cut, the plug will be very wet. I also like to use new plugs when trouble shooting, you can easily see if that cylinder is firing by the plug colour, it is hard to tell with used plugs.
jeeze sim... seems like your SHELL be RIGHT attitude has bitten u in your ass !!! as stated u need 2 pressure test and find your fuel leak DUDE.. fix it properly man... one bad fuel leak and you can kiss your whole z good bye in a nice fireball....
Can't check for spark, as I'm working solo. I think I will pull the plenum again & order in some new lower o-rings. Fingers crossed this will fix the issue. I went down to Repco yesterday to get some copper spark plugs to help with trouble shooting... But they were useless & said they only had iridium or platinum :bash:
Repco are fricken dushbags :bash: If the problem was there PRIOR to the plenum pull then obviously it may have nothing to do with the plenum pull. With the engine cold (will be cause you can't start it ) hook up Datascan & check what temperature the coolant temp sensor is reading. This needs to be pretty accurate or you will have trouble especially when cold. While you have Datascan on there check the battery voltage, anything less than 11volts with the key on not cranking & your battery is no good to start the car (voltage is just a guess you might get away with a little less). Hook up a fuel pressure gauge to the fuel system, crank the engine to ensure the pump has primed it, turn the key off and watch the gauge - if pressure drops quickly you have a leak. The fuel pressure will bleed off over a period of time but it shouldn't fall away quickly (five minutes or so would be normal at a guess). I've seen this exact same problem three or four time before, battery & bad temp sensor was the root cause every time. If you pull the plenum to check your injector orings you can pressurise the rail & simply look in to the cylinder ports to check for fuel leaking. Actually you could do it with the plenum on using a pressure gauge just isolate the rails from the rest of the system and pressurise it etc, easy as no need to pull plenum unless you do have a leak.
Battery is showing 12v, CTS was displaying 13, no error codes. Time to start pulling the plenum again... YIPPEE haha
Thanks, Martin Another question: The thin black film that covers one side of the intake gasket, what is that for? Is it to stick to the plenum so it doesn't move when installing, or more to it than that? The gasket itself is less than a week old & in perfect condition, so I'd like to reuse it if the black film isn't necessary.
Update: It isn't leaking lower injector o-rings. They have been replaced & new copper spark plugs installed... still same issue. Engine turns over, but won't fire. Code 55. Need to check each cylinder is getting spark still (can't do it alone). Also need to try and get my hands on a fuel pressure gauge.
Also check the AFM. If you have an oil filled pod filter the fine wire in the AFM can get covered in oil and blow. If the engine ran erratically this may have damaged the wire also. This will stop the engine from starting - I know from experience.
To check that just unplug it. Will start without it but won't rev over 2500RPM and will sound a bit rough.
Hey mate. You can check for spark solo if you haven't found a helper yet. Using 10AMP wire and a simple on/off switch in the middle of it, run it from the positive terminal down to the starter solonoid. You can trigger ignition from the engine bay while your working. It's how I do it anyway. It may be worth checking your timing as well if everything else is ruled out. something may have broken and jumped your teeth on the crank sprocket...
when you said fluctuating idle was experienced at a cold start before the non-starting problem it made a light bulb switch on in my head... I've had a little bit of hesitation and fluctuating idle on some of my cold starts too, and after having a good listen to my engine with my ear over the motor i think i have pinned it down to the Idle air valve at the back of the plenum sticking a bit, it sounds like that anyway. So as someone has also mentioned this might be something worth checking out. maybe try starting with the throttle slightly open the whole time? might confirm or disprove that theory...
