Gio

Changed the fuel filter and replaced the air box hose clamp. For me, that's quite adventurous :D I can understand using a cable tie as a quick fix but why leave the broken hose clamp in place?

The JeffTT method worked fine. Careful as the filter itself is full of petrol (no, really :) ) so be prepared for a bit of spillage and have something ready you can drain the old filter into. An old towel tucked under the filter before you start catches the drips as you remove the hoses. The clamps can be unscrewed quite a way to get them pushed back over the flange on the filter pipes. I found it easier to disconnect the engine side one, then loosen the battery side one and loosen the filter clamp to remove the filter (bit of screwdriver leverage on the hose while wobbling the filter) rather then disconnect the battery side one before removing the filter as it says in the how-to. I noticed the old filter had a bent pipe. This, and the cable-tied air hose and the borked MAF grille makes me think someone's been a bit cack-handed. Not going there again (don't worry, nobody on here, just local garage).

Got it, thanks.

That's the bit I'm being a bit dense about - what to do after the engine has stalled. Does this mean use the ignition key to try to start the motor (in which case, why won't it just start?) or something else?

Thanks - I see the manual says to crank it a few times after using that function. Which sort of implies needing to remove the fuel pump fuse in case it re-pressurises the system. The ConZult button is this one: Ah, that makes sense, thanks. Haha - as the TTZ page says Thanks guys.

And from me too :happybday:

Happy birthday to the forum IT :sorcerer: :)

I found this how-to http://www.ttzd.com/tech/fuelfiltertech.html ConZult has a fuel pressure release button - if I use that, do I need to do the remove fuse / crank engine to release fuel pressure as in the how-to, or will using the ConZult fuel pressure release be enough? Thanks.

Better get a green card and international driving permit.

PS if anyone wants the dud MAF to experiment on - or the unused O-ring - just pm me. Cheers.

Replaced the MAF - my first "proper" job on a Zed in 20 years haha. Only lost a 10mm socket somewhere, though. Hope the Zedgods let me off with that as I'm going somewhere tonight and don't want to push my luck by appearing cocky.

Today I changed the MAF and, short answer, she now starts and idles and the stumble has gone. It might be this whole thing was a MAF on the way out. Many things learnt thanks to the help on this thread. 2 things stand out for me on MAF: the test isn’t unplug the MAF sensor while the engine’s running. The test is stop the engine, unplug the MAF and see if it will start / idle. If I’d done that days ago, could have spotted dodgy MAF earlier! the voltage on the new MAF seems in the same range (more stable) as on the dodgy one at idle before it failed completely. So it looks like voltage isn’t the only diagnostic for a MAF on the way out. First start up after replacing MAF [video=youtube_share;0PbLyQUg5aE] After 20 min test drive [video=youtube_share;T29CXcxmPr0] I still need to do a full ConZult and check against JeffTT’s figures to be on the safe side. But you can see the AAC is a lot better than it was. Thanks to Joely P for pointing me in the right direction for airbox stuff. Might even replace my own air filters next time… Had some trouble fitting the O-ring before I noticed the new MAF already came with one fitted d'oh. Old and new MAFs. Someone’s clearly been a bit heavy with levering the hose off – and I wonder if debris from that might have damaged the MAF. New Bosch 13091 O2 sensors to be fitted next week. Also proper NGK PFR6B-11 Given this is the first time I’ve ever taken a spanner to my Z for anything mechanical, I’m somewhat relieved the only casualty is a 10mm socket somewhere down on the engine tray where I can’t see it. Thanks to you all for your help and advice – wouldn’t have had the courage otherwise.

$248 ex works https://www.z1motorsports.com/intake-mas-and-hoses/nissan/new-oem-300zx-mass-air-flow-sensor-meter-mas-maf-p-1752.html

Well, before the MAF died https://www.300zx.co.uk/forums/showthread.php?190301-Intermittent-rough-idling-next-diagnostic-steps&p=1989513&viewfull=1#post1989513 the next steps were to follow the rest of your advice. Got plugs, fuel filter. O2 Sensors on their way. From CAS sensor variation, timing instability, Simon thinks the ECU is constantly trying to compensate for something. One possible cause is a dirty injector or 2. Now the last time that happened to me (the blue S3 NA), the ECU revved high at idle to compensate for the dud injector I had. So that's not the case here. However, if we eliminate the things in your advice and it's still not right, then it might be injectors - so I was doing some desk research to be forewarned and have something lined up if needed. But look what arrived yesterday and is now the first job to see what happens.

Infinity Exhausts https://www.infinity-exhausts.co.uk/show_gal?rp=gals&r=3&gox=Nissan replied to my email and they said: Given the above recommendations, sounds good.

:clover::clover::clover::D

I might need new injectors. When I had a different idle issue in 2010, I got a set of 6 Deatschwerks remanufactured from ConceptZ at $365 for 6 $61 each. These are still available at $529 / $88. SO I had a look round and there are others down to around $62 for AUD remanufactured. Then I looked on Ebay and found https://www.ebay.co.uk/itm/6x-NISSAN-300ZX-FAIRLADY-INFINITY-J30-MAXIMA-SENTRA-26lb-270cc-FUEL-INJECTORS/222825765310?fits=Plat_Gen%3AZ32&hash=item33e17359be:g:40IAAOSwOn1aeGPN which claim to be new JECS for £89 for all 6! If something looks cheap, it often is - has anyone had any experience with these? Cheers

Prompted by this post, I fired off a few enquires. The first to get back was Longlife in Basingstoke https://www.longlife.co.uk/Longlife-Basingstoke who have quoted £799 inc VAT and fitting for cat back s/s. If I get anymore replies, I'll post here.

Me too. I like AndrewG's but it's $1,200 ex US in my config. I noticed this lot https://www.ebay.co.uk/itm/Nissan-Custom-Built-Stainless-Steel-Exhaust-Rear-Dual-System-2012NZX-DS-59874025/152696441574?fits=Model%3A300+ZX&hash=item238d6acae6:g:EXAAAOSwGYVW~l03 on Ebay - cheap but do we know anyone who's used them?

I think I'm going to have the same need soon-ish. There's a lot less choice out there now, isn't there. Couple of years ago I went to these guys https://profusionexhausts.com/ and they quoted about £1,400 for a fabricated one. That RTec one looks a lot better value!

Looks like the MAF is now u/s as of yesterday. Thanks to Joely P, I summoned the courage to approach the Z with a socket. (I am now short of a 10mm socket and extension as I dropped it into the engine bay – which is why I should never be allowed anywhere near an engine bay). Apologies to Jimmer and DJ Party Favor as I misunderstood their suggestions on MAF test. I’ve done that now and it will start and idle with the MAF unplugged. It will start but then die with the MAF connected. MAF connected: start then die. MAF unconnected, idles: The error codes also point to this. I cleared them and restarted to check and Code 12 Mass Air Flow Sensor reappeared. I’ve waved WD40 at the connector and plugged / unplugged a few times to clean. No change. I take it the arrowed brown bit on the harness doesn’t disconnect from the arrowed black bit? That’ll be a dead MAF, I take it (unless a harness issue somewhere). I wonder if that was the cause all along: MAF sensor on the way out, causes idle issues, then fails completely. I guess the only way to test that is replace the MAF sensor and look again. Start with MAF connected: [video=youtube_share;LvLa42LUiS4] Start without MAF connected: [video=youtube_share;-bxaXdlhr7k] Other things I noticed were cable ties instead of fixing the hose clamp, some missing bolts and worn grommets on the nose panel – also cracked scuttle where the RAC replaced the battery. Humph. Just more things on the list which every Z owner knows only too well! Thanks to everyone who's helped - if I get there in the end, it will only be thanks to you.

Yep, Captain Stock, that's me :) Thanks for that guide. So the MAF is bolted to the airbox cover- follow that guide until the airbox cover removal, then unbolt the MAF from the cover - is that right? I just checked and have now got Code 12 Air Flow Sensor which I've never had before. Oh well...

Is there a how to replace MAF guide anywhere? I've tried search here, Twinturbo.net and the Aus forum but haven't found one. Yesterday, she ran worse than ever (OK the day before apart from the idle) and wouldn't go over 40. MAF voltage appeared to be 0.010V so it or the connector on the way out, I guess. Being useless at tech, I daren't try anything without a guide! Thanks.

:D as I read through your advice and look stuff up, I found you replaced the IACV on my previous (blue NA S3) Z in 2008! Cheers

Jeff, that's really helpful, thanks. I'll go through this in detail with Simon when I've had a chance to read thoroughly. In the mean time, you say afm issue and afm being wide open - do you mean the IACV / AAV? Many thanks - Mike