Hi, I have a 300zx 1992 model (Twin Turbo) which needs help. The story goes: about 6 months ago my zed started behaving weird, i was driving it back from the shops and the oil pressure gauge was all over the place and it would not stay running... i.e. I would start it and then take off and the minute you took the foot off the accelerator (change gear, brake, etc) it would stall. I also found out the waterpump was stuffed (again) so i took the Zed to a "reputable" Zed specialist in Brisbane. who replaced the waterpump and "fixed" the problem but 1 week later after it driving pretty good it started to stall and not idle without the help of my foot on the accelerator. Also the mechanic checked for fault codes but there was none and it was fine.... This car has also been through 6 waterpumps in the time i have had it... 3 years. 2 per year.... not to bad? Can anyone guide me to what might be wrong or happening here? I miss my Zed....
Your water pump problem is most likely an aftermarket pump being installed. There has been countless occurances where a non genuine pump fails in a matter of 6 months to 3 years. In regards to idle there is only a couple of things that will make it do that and fault codes won't show it. First most likely culprit is the throttle position sensor terminals may need cleaning and retension the pins on the plug (the small black one). This will also need to bew checked with datascan to ensure it measures .44 volts when closed and that the closed TPS signal is actually coming on. The other possibility is the AAC and FICD plugs located on the rear passenger side of the plenum (yellow and blue plugs). These will need the same treatment. Electrical connectors are the most common cause of engine malfunction in the Zed these days.
Fairly common on Zeds. and Possibly the IAA unit, try pulling it apart and cleaning as per the tech section.. That is very unusual, im guessing they were not genuine Nissan water pumps? The Nissan ones are usually pretty good, only reason they usually fail is old age or if the belt is adjusted too tightly.
Definately something dodgy going on there, water pumps should last years. I've never had one fail on me yet. Ive known of people to still have their ORIGINAL waterpump that is 15 years old still ticking along. The oil pressure acting dodgy is not good either, unless the gauge or sender is faulty which is probably a good place to start and then of course the oil pump itself. Does the oil light come on? As for the idling problem, my guess would be a big leak somewhere. Check all the couplers/connections etc...
Id get your mechanic to stop tightening your belts so bloody tight, to much pressure from the belts will bugger the bearing in them, but for your main issue im not sure,checked for damage to the sump? , just an idea Have fun figuring it out buddy
To note: After i got it fixed recently... the oil pressure gauge stays on the lowest of the normal range. But still doesnt idle...
One of the first things I'd be doing in your shoes is changing your "reputable Zed specialist". Six waterpumps in 3 years is unacceptable. A problem like this should have been solved long ago. Whether it's the pumps being fitted, or the belt tension or whatever.... it should have been cured by now. Your "new" Zed specialist should also be able to solve your idle problem using something like 'ConZult'. It's possibly due to TPS connections, TPS setting, AAC (the thing near the battery) setting, a vacuum leak, or a faulty AFM. The oil pressure variation I would bet is due to a loose connector on the pressure sensor or on the back of the gauge itself, or perhaps even a discontinuous wiring problem (which would be a bugger to fix)... the Nissan setup seems to either work or not work, but seldom shows variable pressures. Give your girl the TLC she deserves!
as mentioned there are countless causes of idle problems. we could go through each one and charge someone a fortune to fix it. or we can point out the tech article and let them have an attempt at fixing it for free. this is the approach we use for these kinds of "annoying" problems. how is the water pump going, we replaced it with the genuine article, still holding together?
Failing Water Pump In regards to the failing water pump, other things to check are that the pulley's and fan are all spinning true (no wobble), replace or service the fan coupling and look for anything that may take the fan + coupling out of balance.
How have they been failing?? If they have sprung leaks and have had to be replaced. I recon I know why. In my NA I had a very slow coolant leak which meant that I often had to top it up with coolant. What this meant was the coolant level was usually quite low. The car was still fine temp wize. Over 5000 klms. The lowish coolant level made the pump cavitate quite a lot. what this did was scour the pump insides so much that the Alloy just ate itself away through the housing till small pin holes appeared. I put in 2 in 10,000 klms till I fixed the under plenum hoses where the leak was. I suspect this may be the reason your's has died so often. Do you add coolant everytime you take the cap off ?? How much??
