Bouncing idle

[phihac0123]

Hi i recently bought a Z32 1990 twin turbo and when the car is on idle the RPM bounce well it depends sometime it bounce around 500RPM to 2000RPM and other time it bounce around 1500RPM to 2000RPM and when i am on the road and it the gas full blast i get some engine hesitation i know it could be my TPS but i am not sure about it so i need some help

[evildky]

I would suspect a vac leak, first step si to check the ecu for codes, might want to verify the TB's are sync'd and closing all the way, won't hurt to calibrate the tps and clean the iacv.

[phihac0123]

Will do thanks alot

[BallZee32]

when did you buy the car? and how many miles?
does it do it all the time? or cold starts? hesitation at WOT could be dirty/improperly gapped plugs

[phihac0123]

I bought the car about a week ago and the car as 158000KM (sorry for the KM but i am from Canada) and it bounce specialy when the engine is cold but it does it also when the engine is at operating temperature, sometime its stabilise but it will idle at 2000RPM

[DCaff300ZX]

I would suspect a vac leak, first step si to check the ecu for codes, might want to verify the TB's are sync'd and closing all the way, won't hurt to calibrate the tps and clean the iacv.

This.
LOTS of personal experience between the two of us, get back if the above fails and also for further questions dealing with what we both know you probably will find...

[phihac0123]

What should i expect to find? and i did check all of my 6 spark plug today and i am pretty sure that was what causing the hesitation i think its still the original one that nissan put in so yeah they have done there time after 158000km on them i will order new one tomorow and i know there is a specific type of NGK spark plug i should use and if i am correct i think its the NGK PFR6B-11B

[DCaff300ZX]

First off if as you suggest the plugs are that old, they may well be a big part of your issue so do replace them of course, and your part number looks correct and especially if pulled from a Z32 source.
Then, if problems persist you will need to go hunting for continuity with various connections and be sure ALL maintenance is up to date, both at once actually for best results. Your 1990 has old style injectors which have various failure issues due to age, corrosion of connectors and electrolysis due to the ethanol in today's gas. Corrosion can be a major issue under the hood depending upon your locale, maintenance level and usage pattern...to much to go into now without being led there by issues.

Maintenance is your Z32 friend, Do as evildky suggested and also download the fsm from here for tests and troubleshooting help, and ask away with any other specific questions or problems that come up!

[phihac0123]

Thanks alot guys you have been so much helpfull does the more recent style of injector works if i swap my old ones for newer more recent one and if i got more question ill ask away hahaha but thanks alot

[DCaff300ZX]

For best results, if you are not a DIY car guy, find a reputable Z32 mechanic in your area and let him at it- he will know what to look for and to do, and be able to let you know what you are facing with your car. Listing your location in your profile helps others possibly advise you on local things, BTW.
If not, you need to begin a crash course of learning through the online service manual you can download here, and reading the various stickies and such here and elsewhere dealing with the myriad of problems that come with a 23+ year old car. The Z32 is hard to work on and the TT the worst of the two, parts are a bit expensive and hard to find and a good Z32 mechanic the hardest yet to find, so there you go...you are ready to begin your Z32 journey!