Hi I've had issues with my 1990 auto 300zx. Whenever i'm driving at any speed below around 70km/h and take my foot off the accelerator and start to brake the revs go to below 1000. The slower i go, the lower the revs go and it starts revving itself when it gets below 500 to keep the revs up but lately its just been letting itself go to zero and stall which is dangerous when driving. It used to be fine once it had stopped, it would just idle at 800 rpm but lately its been revving itself even when at a stop. It starts up fine, goes to about 1500 for a little bit then idles ok at just under 1000. But if i start driving straight after the engine is turned on on, it's very rough and just pops and bangs so i have to leave it on for a couple of minutes first. I've taken it to Nissan twice and two mechanics but no one can figure out what it is. Nissan were the only people able to get their computers to talk with the engine and the only thing they found was a squashed drivers side exhaust that is leaking a bit but no one thinks that is the main cause of the issue. I have had the Cats, coil pack and spark plugs specifically loooked at and also tried switching my air intake sensors with another 300's. I've sprayed the air intakes with carbon cleaner too and that made it slightly better for about a day then it was back to what it was. also when driving and accelerating up, it gets to about 4000 then wont rev higher unless i ease off and try again as though it hasnt really warmed up enough, it sounds rough and makes a burbling sound. I can't find what the issue is and really don't want to keep spending money on getting it looked at if no one can find what it is. If anyone has any ideas then I'd greatly appreciate it, thanks. Alex
Check the tps. I the tech section there is a how to. If you can get your hands on a diagnostic tool would be even better.
Probably a vac leak... Solution - boost leak test. Fix any leaks. Should cure the issue. Other things to try: Adjust idle (IACV screw), Or replace IACV if faulty. Check TPS, reset ECU (by disconnecting battery for an hour or so) Buying a conzult cable is a good idea. That way u can check for error codes yourself.
Where in Queensland are you? Best to find a local zedder who has consult and a boost leak tester. Sounds like my issues when I first got my zed.
My Z had a problem like this it turned out to be the fuel computer.Too check this you could try the fuel computer bypass.It is in tech section to show you how to do it.Just type in fuel computer bypass in the search in the tech section.:zlove: http://tech.aus300zx.com/
K1NGZ had the same issues recently...... crankangle sensor connector cleaned afm replaced BADZX did some of the things your experiancing, FuelPumpControlUnit turned out to be the culprit....... Neo's zed also suffered the same issues as he stated above. the White zed also had some of the same symptons but it was a vacume hose that was cracked and leaking Kingy
Ah mine's naturally aspirated but I'm going to head to A2Zed at southside, i think they will have the best chance of finding what it is
Right thanks for that, I got the fuel pump replaced and it made it improved the acceleration again but it's getting bad again so the control unit might be the issue like you said, I'm going to take it it to a 300 specialist at southside so hopefully it gets sorted out there
Cheers I've swapped the tps woth another 300, I'll give resetting the ecu a try today, if that doesnt work i'll take it to a 300 specialist
Nissan sorted out the vacuum leaks and said that should fix it but it didnt. It could be the IACV. I took it to an import performance mechanic and he said it was the fuel pump so that got replaced and now it accelerates a bit better but starts shaking and jumping around if im light on the throttle. Also it wont rev above 6 grand before it starts burbling and then it drops to about 4000 and wont go higher. I was thinking of taking it to you guys to have a look at. It would have been my first choice but i was just worried about it not making it the distance. I'll give you a call. Alex
Cheers The idle has been adjusted heaps, the tps has been switched, i'll try the ecu. im assuming thats with the ignition off?
