Engine starts but does not rev up

never ever let any NISSAN engine CAM belt fail
or bend the valves over in the heads, or worse.
gee the engine is listed and maker as the only cars made that all their engines are INTERFERENCE engines.
5 engines used that year world wide, here they all are.

2.0 L VG20ET V6 Turbo (200Z, 200ZG, 200ZS)
2.0 L RB20DET I6 Turbo (200ZR)
3.0 L VG30E V6 (300ZX)
3.0 L VG30ET V6 Turbo (300ZX Turbo)<<<< bingo i guess.
3.0 L VG30DE V6 (300ZR)

this is normal. for high performance engines
to run 2 cams and huge valves and super high CR compression ratio's and lost of extra power (say from old push rod engines)
the Pistons, chase the exh valves closed super close.
this gains huge power, this act. (cam timing did)
so are interference.
but no engine told or country, told.
so no exact answers are possible. lacking that, or USA VIN if is USA>
in some countries they de-tune and engine for marketing reasons.
or what ever. IDK.

what a shop does is not crank it more and bend it more.
we do a BY HAND cylinder leak down test. or just inspect the cam timing using just EYEBALLS.
the manual for the car SM says do not move crank with cams not timed. clear as day. ever read a SM service manual?
page 1 , on timing belt page states this../

All 1984-88 Nissan Z and ZX engines are equipped with timing belts. Since these engines are of an "interference type'' design, if the timing belt breaks, the valves may contact the piston heads and cause extensive engine damage. Therefore, regular timing belt inspection and replacement is very important.!!!! oops <ignored this?
60k to 100k miles they fail, use Gates belts to run 100k.
MILES. if not in USA covert that to KMeters>
better engines are chain drive cams and not mix/belt/chain.
some cams need cam locks to do it.

cam wheels are at 11am left and 1pm right
and crank is very odd this. engine



belt tension is 22lbs (top center) RTM read the manual carefully

Probably a warped head and or valves.

if your valves are bent ,then i take it your timing belt has snapped .which means your camshaft can not turn ., so you can not get a spark at the plugs.if it was the old distributor you would have been able to check the coil with a spark plug tester the trouble is with a coil pack it is controlled by both sensors and your ECU but due to the camshaft not turning so your camshaft position sensor can not tell the ECU to fire the coil pack.

bent valves / sticky valves / tight valves. sounds like heads off to repair Did you rev it hard ?

Yes -- the motor is identified as an interference engine and that means in the event of belt failure there will be damaged valves from hitting the pistons. IT is a matter of removing the head and replacing the bent valves . There should be not other damage to the engine . The job in an accredited shop will be around $1000 dollars which should include valves -head gasket kit-new belt- idlers -hydraulic tensioner and cam and crank seals and labour

The valves will be bent and you will need a head job done. The time to do the job outside head reconditioning would be around 4 hours labour and the parts will include valves, head gasket kit, timing belt, adjuster pulley, and if the job is done properly crankshaft and cam shaft seals as oil is the main cause of belt failure.

The sequence of engine started normally, then the rpm dropped, followed by the bad noise is not a good sign.

The "bad noise" could be nasty, as in $$$$$ , and unrelated to the change of spark plug wires.

I'll bet the engine turns over but won't start, of maybe it fires a few times and stops. If this is the case, DO NOT keep trying to start the engine. It won't and you will do more damage trying.

What I suspect is that the main cam belt has slipped a few teeth, commonly because one of the idler bearings has jammed. What then happens is that the pistons hit the valves and bend them.

The diagnosis is done as follows (by your local garage as I doubt you have the skill or inclination):

a) remove the belts, main pulley and 3 front covers from the engine
b) remove the cam belt and inspect the idler pulleys for damage and wear.
c) realign the cams and belt correctly, and see if the engine will start. It may, but will run rough or won't start at all.
d) do a compression test on all cylinders. There should be about 150 psi in each one. You will almost certainly find one or both banks of cylinders have 50-80 psi or so, which indicates bent valves.

The fix for this requires that the heads be removed and the bent valves replaced. Taking the engine out is BY FAR the easiest way to do this, as doing it in place is extremely difficult. Getting the engine out is pretty simple once the radiator and AC condensor are removed. There's no need to remove the transmission.

In fact, if the valves are bent, its usually cheaper to get a complete running engine from a wrecker than repairing yours.

Your 98 likely has the FJ25 DOHC engine, but it could be the FJ25 SOHC. Make sure your garage gets the right one, and replaces the idler bearings, water pump and cam belt before they put it back in.

Here at my repair shop have never had to replace a cylinder head, due to timing belt failure, just replace bent valve's and machine head.

hi from uk the cambelt timing marks for accent 1.3/1.5 petrol are as follows= the cam cog has a hole drilling between the outer toothed and the central securing bolt this hole at TDC number 1 cyl is at top central and lines up with a V cut in the cyl head at rear of cog ? the crank cog at TDC number 1 cyl is a pop mark on both the cog and on thefront face of engine quite noticable ! these line up and are at approx 12 -30 pm when viewed fit new belt from crankcog in anticlockwise ie crank then cam then tensioner HOWEVER! if you are considering just replacing belt and tensioner ? be warned this engine is an interferance engine that is to say if belt fails whilst driving there may/will most probably be damage to the valves (bent) due to contact with pistons so would advise caution and suggest compression test all cyls after fitting new belt and tensioner and before rebuild completely once valves have bent they will not contact pistons again but you will have serious missfire/s and probably back fire up inlet manifold coupled with failing to start if engine is high milage ? consider removal of cyl head and check? de coke and replace damaged or best all valves then engine will have improved performance and more milesin future hope this helps

Hi this sounds very messy if somebody has made a mess of things the only way to check it out is to get it to a reputable garage and get it checked over ,did you have the head pressure tested as a common fault with these cars is internal cracking of the head which can often look like a head gasket failure the only solution then is a complete new head good luck with this