Why does my Nissan 300ZX run rough or die at stop signs?

Short answer: Start with a compression test. On one 1990 300ZX with a used engine, a second test showed zero compression on one whole bank; the intake cam on that side had sheared its key, so the valves weren't being opened at the right time. On a rebuilt 1986, members said compression of 100–140 psi was far too low (around 190 psi is normal) and that a bad idle air control valve can also drag idle down until it stalls.

Symptom: The engine runs, but badly, with one bank of cylinders not contributing and wet plugs on that side. Or it chokes and stalls at stop signs, or shuts off soon after starting, and won't hold a steady idle.

What to check first

1. Run a compression test on every cylinder, and repeat it if results look odd.
2. If one bank reads zero, check the cam timing and cam keys before replacing sensors or the computer.
3. Compare readings to spec (members said roughly 190 psi for the 1986 engine).
4. Clean or test the idle air control valve (it sets idle speed).
5. Read the plugs: wet plugs on one side point to that bank, and sooty plugs point to a rich mixture.

Likely causes

1. Sheared cam key or timing problem. Found on the 1990 car with zero compression on one bank.
2. Low compression from worn or poorly rebuilt engine. Members' view of the 1986 engine.
3. Faulty idle air control valve. Can make a weak engine stall at idle.
4. Leaking or sticking injectors. Suggested for wet plugs on one bank.

What it usually costs

No owner posted prices. A compression test is cheap; cam or engine work is a major cost.

Is it safe to keep driving?

An engine that stalls at stops or runs on one bank isn't reliable in traffic, and continuing to run a mistimed engine can bend valves. Verify with a mechanic.

DIY or shop?

DIY for compression tests and idle valve cleaning if you have tools. Cam timing and engine work are shop jobs for most owners.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists these recalls touching this area of the Nissan 300ZX: 95I006000 (1984-1989 model years, fuel system, gasoline). Check your VIN at nhtsa.gov/recalls. If your car is part of this recall, the dealer fixes it for free.
• In plain words: NHTSA lists this as a safety improvement campaign for 1984–1989 cars, covering fuel injectors and hoses that can leak. It isn't the same as a recall, but it's worth asking a Nissan dealer whether it was done on your car.
• NHTSA complaints: 44 keyword-matched complaints for Nissan 300ZX 1984–1996 (of 296 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-26; keywords: stall, dies, idle, rough, misfire, compression, injector, fuel leak). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Nissan 300ZX not running properly on Car Talk, an owner put a used engine in a non-turbo 1990 300ZX. It ran with only the driver's side firing, despite swapping the computer, sensors and coils. Members suggested firing order, cam sensor triggering and injectors flooding that bank. A second compression test showed all zeros on the passenger side, and with the timing belt off the owner found the passenger intake cam had sheared its key.
• In 1986 Nissan 300ZX - Looking for help with engine on Car Talk, an owner with a rebuilt engine said the car began choking at stop signs and shutting off soon after starting; plugs were sooty and compression was 130–140 psi with one cylinder at 100. Members said a bad idle air control valve could drag the idle down, but that compression is way too low on all cylinders (around 190 psi is normal) and to question the rebuild.

Quick tip

Both owners swapped plenty of parts before the compression gauge told the real story. Test first. It's the cheapest tool in the box.

Vehicle focus: 1984–1996 Nissan 300ZX (3.0L V6, non-turbo and turbo).

Safety / mechanic note

Stalling at stops can leave you stranded in traffic. Verify with a mechanic.