Toby85

Hi, So I'm at my wits end and hate my trusty old steed! It's my daily, family owned since new, 211,000 miles (still on the original clutch) 2004 UK GT coupe, however, ongoing issues are ruining it! The issues I'm having are a bouncing Rev counter and an intermittent rough running - related or not I don't know. The car sounds deeper, kind of like the timing is retarded or something, and splutters/bogs on wide throttle openings, but this intermittently clears and runs/sounds great! I've noticed that when I drop the clutch and let the revs drop they drop down to about 700rpm before jumping back up to about 1200rpm and slowly falling back to idle (always idles a touch high at 760rpm) as I'd expect. Oddly, if I let the car slow whilst in gear, ie use engine braking, it almost always starts with this rough running but if I avoid this it can run fine for whole journeys. Only code I get is an occasional p0300 which comes and goes. I'm not sure it is misfiring, sounds too smooth and unplugging each cool makes a marked difference. i have obd scanning facilities and the only interesting thing is the timing which at idle (760rpm) is at 7 degrees. I've tried coil packs, spark plugs, injectors. Any midlands specialists fancy a look?! Thanks in advance, Toby

Hi, Thanks. See here; http://www.350z-uk.com/topic/85790-intermittent-p0300-not-a-misfire/ Kind of at a loss now but with house move I can't afford to guess with my money and I don't know who to trust locally that I could afford to find the problem!

Hi, Bit of an ask of someone local-ish here! I'm trying to get to the bottom of a long standing intermittent P0300 and get the feeling it's either of the above now. However, I'm loathed to throw the money at the car if it doesn't fix it - getting too expensive and frustrating! So, if anyone has any of the above is there any chance I could try them? I'd leave you with the cash while I try the part as not to rip you off of course. If anyone can help please let me know! Thanks in advance Toby

Thanks for the response. I'm not convinced about the cat but I will, when I have time, have a look. The exhaust won't come apart without a fight I know that! Where abouts are you based? Thanks again

Evening All, I have been having a hugely frustrating problem with my Z for some time now and have been trying to resolve it when i can in between family / house purchase / work etc. I posted on here about it quite a while ago and got a lot of help which i have been working my way through but am back for more! What i'm getting is a car that sometimes appears to run fine, without fault, but other times the exhaust note changes and my MIL lamp starts blinking/comes on solid. It doesnt misfire (pulling each coil pack makes an obvious difference), but i am getting the code P0300 and occasionally P0420. The exhaust sometimes sounds normal but can become quieter, almost silent above about 1750rpm, and other times become much bassier - sounds as if some cylinders (potentially one bank) is firing differently, maybe cam or ignition timing? If i put my foot down when the exhaust sounds like this it bogs down and splutters. Other things i've noticed are that the rev counter bounces/jumps (never moves smoothly, always in pulses) and also when i dip the clutch, the revs drop too far momentarily before they jump back up to around 1200rpm and slowly settle back to idle. Does this reliably regardless of situation but never stalls. Throttle response also seems needlessly aggressive/snatchy on very light throttle openings from coasting. I've tried injectors, coil packs, spark plugs, cleaned throttle body, cleaned cam and crank position sensors, cleaned MAF, cleaned every electrical connection and earth in sight, tried an extra earth, compression tested all cylinders and monitored live parameters whilst driving (comparing between when it runs ok and when it isnt running right) - nothing seems to change. Things i haven't tried but suspect - IPDM, CPS, Lambda/s. I did look at the iPDM and it looked ok aside from some corrosion on one relay (ignition). I swapped this with another relay - nothing changed. Car is standard, HIGH miles (in excess of 200k), has good compression (over 165lb on all cylinders) and is always quick and reliable to start. Economy seems unaffected and part throttle, even when misbehaving, is fine despite the change in exhaust tone. Remains totally driveable and reliable returning over 30mpg when driven carefully on the work commute. Sorry for the long post - but - HELP!! It does my head in! I'm in the midlands so if anyone local has a stock of spares or an unused car they dont mind me trying parts from i'd appreciate it hugely! Thanks in advance, Toby

Cheers! Yeah I'm really glad it's running sweet. I only just got the car as a project and this was the real underlying 'problem' with the car, amongst plenty of other niggles. Almost all sorted now and just flew through the mot without an advisory! Just goes to show that with regular servicing mileage seemingly can have marginal wear on the car! It's been family owned since new by 1 owner who used it to commute on the M25, then once yearly got it MOT'd, serviced and washed by Nissan - and that was it! Was a little battle scarred when I picked it up but shows very little for it now it's had a little TLC and pampering! Only jobs left are sat nav blank (another thread in here), clicky rear axle/s (to be sorted soon), gearbox oil change (although seems fine) and potentially a wheel bearing starting to grind a little!

Ok, this issue is resolved - thought I'd update the thread to help others having this infuriating code! So, after paying for coil packs and injectors which did nothing and after much fruitless investigation it turned out to be something hugely simple - a dirty connection. Summary; Symptoms - general rough running but reliable starting and no stalling. Bogged down under heavier throttle. No obvious miss from a single cylinder. Intermittently flashing engine management light, sometimes going in to limp home mode. Diagnosis - error code P0300 only. Solution - cleaned electrical connections using flushing action with electrical cleaner. Ended up being one of these three; - Variable valve timing control solenoids - both connections filthy - Multiplug connections from battery positive terminal (no idea what for) - showing signs of corrosion I started the car after these and it was like a different car. Night and day! To anyone else having these issues - start here before anywhere else!

Out messing with the car again last night. Seems the nav unit isn't being 'told' to switch on with the ignition - where should I be looking? The screen switches on but nav doesn't. If you hold the eject button the disc will eject and unit stay on, displaying nissan, for around 10 seconds before switching off again!

When my uncle owned the car it worked fine - he bought the car new in 2004, and it's an original with the remote. I don't think it's the disc due to the way it behaves - the moment I release the eject button the screen goes blank! Ditching the sat nav will again involve money buying a cubby which I wouldn't use - so it's get it working or leave it dead!

Hi, Ok, an odd one and I can't find any info about the issue online! I have an '04 uk GT with factory fitted birdview nav. However, the nav will only display a blank screen - that is, until I hold the eject button. Of course, this is useless. 1 - I can't drive like this, and 2 - even if I could, as I'm pressing eject, there is no disc in the nav so it just shows the nissan logo. Anyone experienced or heard of this before?! I know people will just tell me to replace the nav with an aftermarket but this costs money I'm trying to save and if it's not repairable then I'll just leave it be for now. Thanks for any advice given! Regards, Toby

Sorry which is the best wireless dongle? There's loads on eBay, are they all compatible with most App Store apps? I'm just looking at a cheap £13 elm327 black wifi plug in dongle, there's loads of apps on the App Store I will try!

Ok, cheers. What adaptor are you using? Maybe a cable would be better than wifi for stability? Do any if the adaptor a work universally with any of the apps? Cheers

Hi, Does anybody use one of these cheap wifi iPhone compatible OBD scanners and find it genuinely useful for monitoring live data? I'm still trying to resolve a p0300 code with no luck and being able to see love data such as O2 readings, fuel trims etc would be really useful. Any advice? Thanks in advance, Toby

So yesterdayi took off and cleaned up both am position sensors and the crank position sensor which has now thrown the code 0345 - it still runs as before but with this new code so I must have disturbed something. I'm loathed really to keep throwing money at random sensors - I might just give it to a local specialist and let them investigate

I have noticed that the rev counter seems to pulse slightly when the revs rise or fall rather than move smoothly as I'd expect, it's not jumping above or below where you'd expect but just doesn't move smoothly - like I said, just moves in little pulses

Not the injectors either. At a complete loss now!

Just an update - I got hold of a spare good cool and swapped it across all cylinders - made no difference. Checked all earths and cleaned, also added more - no difference. Couldn't find any vac leaks. Am now at the stage of changing injectors - I've got 3 good ones and I'm swapping 1 bank at a time. They don't look the same as the originals but I've read they are all the same specs, just the manufacturer varies. I'll update tomorrow with any findings! Fingers crossed...

It's a UK car, early GT. Plugs are new, next is coil pack going cylinder to cylinder to find the issue (hopefully)! I'll clean all the connectors while I'm there and also clean the earths. Cheers, Toby

I'm in the process of obtaining a replacement coil pack to start. I haven't yet had a thorough check of the inlet tract for leaks but will do. Are there disposable gaskets sealing the plenum/TB/inlet manifold or are they reusable? Spark plug bores are bone dry and the removed plugs looked very healthy, a nice pale brown light coating. I guess it takes a while to remove the injectors so trying to isolate the problem would be a nightmare - guess it would be easier to replace the whole set?! Thanks Sam, Toby

Keyser - thanks, I will make all given advice a priority! I'll update with progress. Regards, Toby

Oh, and no idea of fuel trims - sorry!

How odd, but very useful information! Wonder why that is?! All were fluctuating fine anyway so looks like this is ok, one more ruled out! Thanks!

Plugs are spanking new, made no difference! Just had a fresh full service. Good shout on earth straps - where are they on the Z? Any idea which bank of cylinders is in fault from the O2 readings above? I have no software - a mechanics friend brought his diags gear over! So you can isolate the problem to each cylinder? How does it work that out? I'm based in West Midlands, near Burton on trent. Thanks Toby

Hi, I've recently been having problems with my '04 350Z GT, running slightly off and throwing the engine management light on. The fault was found to be code P0300 - random misfire. Next I ran a compression test - results as follows; 1 - 165 2 - 170 3 - 160 4 - 175 5 - 170 6 - 170 So, although there is a 15psi difference between cylinders, I don't believe this is enough to cause a real concern - engine is 207,000 miles used! I next compared the way my car sounded to the way a good Z sounded, and it just sounded a little off - not a misfire, just not quite silly like it should be. When disconnecting the coil packs one at a time, it made an obvious difference. Next we plugged it in to a diagnostic reader and the only thing we found off was a lambda reading. The results were as follows (obviously these were fluctuating slightly); 02 1B1 - 0.295 02 2B1 - 0.290 02 1B2 - 0.590 02 2B2 - 0.330 So, obviously one lambda is showing a huge variation, I imagine a rich mixture due to a cylinder not firing but it could also be a faulty lambda? Also, which lambda is this? If anyone could offer any advice on what to look at next I'd really appreciate it - I'd imagine either an injector, coil pack starting to degrade or faulty lambda. Thanks in advance for any advice offered! Regards, Toby

Ok, compression test done (dry and the results are all within spec (just) at 160 lowest and 175 highest, which I'm sure won't be throwing the random misfire 0300 error. I also unplugged one coil at a time whilst running and each made an obvious misfire so it doesn't even seem to be misfiring to me! So confused.