Strange idle issue and other bits

[ZXJ]

Hello everyone, I've finally joined to get some much needed answers.

Regarding the idle issue, when idling, I have a high idle at around 2k, however, when I tap on the throttle it brings it down to 1k, I have to do this most of the time when sat at traffic or maneuvering so the car isn't screaming when it's near stationary, any suggestions on what it could be? I bought a host of parts, - both coolant and temp sensor, throttle position sensor, thermostat (car takes ages to warm up..?) after scouring many threads and post, I bought the bits, however they're not fitted yet.

Most idle threads were related to low idle and stalling, not much on high idle and tapping the throttle to get it down hence I started the thread, could it be the iacv? Is anyone familiar with having to tap the throttle to bring the idle back down?

there is a like an occasional thumping noise can be heard through the exhausts, sounds like it's coughing - misfiring?

I've recently purchased it, its a 1990 300zx TT manual, I absolutely love the car however the idle issue is bugging me, the engine appears bone stock, looks like half of its imported life was spent off road, its dusty, spider webby under under the bonnet, most of the parts look untouched and unmodified.

She also reeks of exhaust/fuel when the windows are down, could be running rich.

I wanted a car that would make me get my toolbox out again, I don't think Ive found a more perfect car that fits this critera..

Thanks all

[nissanfreak12]

Ohm test your injectors, they need to be between 10-14 ohms. if its at 14.2, they are bad. That will cause the thumping in the exhaust especially in the early style injectors. Start reading up on them.

Also need to check for boost leaks, if its big enough, it will cause what you are doing with the idle. Bad injectors will do it, all together will do it. Check for corrosion on all the connectors. If there is green corrosion, that will also cause a ton of issues.

BTW, welcome!

[ZXJ]

Thank you for the suggestions NissanFreak, the injectors are something on the list the thumping or popping feels are getting on my nerves, though today, I changed my coolant and temp sensors, and also throttle positioning sensor and also did a reset (unplug for 30scs and plugged back in the sensor whilst on idle) this seemed to have done the trick with the massive revs, Ive also lowered my idle at the IACV so far so good, I thought the car would drop so low it would stall but now I'm sitting around 850rpm idle, no leaks from what I could see, though I've a set of hoses to come and to be replaced, if anything I should believe the idle would be very low and nearly stalling if a leak were to be.

Ohm test your injectors, they need to be between 10-14 ohms. if its at 14.2, they are bad. That will cause the thumping in the exhaust especially in the early style injectors. Start reading up on them.

Also need to check for boost leaks, if its big enough, it will cause what you are doing with the idle. Bad injectors will do it, all together will do it. Check for corrosion on all the connectors. If there is green corrosion, that will also cause a ton of issues.

BTW, welcome!