C18NZ too slow.

[Johnwik35404]

poor acceleration in higher gears than 1,2 feels like towing a car when you press the throttle
gets worse when engine gets warm
Changed fuel pump, fuel filter, injector, tps, o2 sensor, map sensor, spark plugs & ht leads.
no change in acceleration

[Cavalier342]

Have you checked the distributor cap, take it off and look inside, the contact terminals inside tend to wear out quite often, also the terminals inside the round housings where the HT leads plug into the distributor cap, check inside for any heavy corrosion (light blue in colour).

If it's worse when the engine is hot, it could indicate a vacuum leak somewhere, either in the air inlet hoses or inlet manifold gasket, have you checked the EGR valve too, it could need a clean.

Is the transmission manual or automatic?

[Robsey]

Have you checked all the vacuum pipes.?
Especially the plastic elbows.
They crack or snap for fun.
Also, does the car start easily both cold and warm.?
If it is a vacuum or induction issue, my original C18NZ used to get very sooted up plugs, and be a bugger to start when warm.

Other than that, you did not mention the distributor or the rotor arm.
A dirty rotor / distributor would struggle to pass sparking voltage, and more so when warm.

On an extreme note, have you noticed a drop in coolant level?
My C18NZ did not like enthusiastic driving, and so would blow a gasket.
Although that said, it is a piece of cake to replace.

Before the sluggishness, had anything changed or been done to the car.?

Timing belt change perhaps... it could be one tooth out on the belt, and that would be enough to make it feel under-powered.

[3cav3]

Clutching at straws it's not something stupid like brakes sticking on? Many years ago my Volvo V70 suddenly lost power and even absolutely flat out all I could get was 60. It didn't pull to either side, but when I stopped for diesel I noticed in the dark that the front n/s brake disc was glowing red. It turns out the caliper on that wheel had siezed. Felt like it wasn't firring on 2 cylinders, it had gone that sluggish.

[Johnwik35404]

I found out timing belt was a tooth off due to loose belt tensioner.
thanks for your advices

[Robsey]

Thankfully it is an 8 valve engine,
So no harm can come from the belt slipping or breaking.
(It is a non-interference engine).

Be sure that the tensioner is now set on the correct marker.
"V" groove for a new belt.
"I" line 4mm to the left for a used belt.

viewtopic.php?f=70&t=4047

[Mk3alan]

I had a silencer pass all it's internal sound absorbing material (looked like wire wool) down the exit pipe causing huge restriction - it just wouldn't go, in fact by time I had cut the box open to investigate I don't know how it ran at all!

Alan

[Cavalier342]

Ye, I was going to suggest a blocked exhaust system as well, as old original muffler boxes tend to get clogged like an old smoker's lungs.

[cavalier1990]

Ye, I was going to suggest a blocked exhaust system as well, as old original muffler boxes tend to get clogged like an old smoker's lungs.

Had this on my folks old hyundai lantra, there is a big hill coming out of Inverness on the A9, I had foot flat to the floor just to get up it!