Help needed, power loss issues (1 Viewer)

[JPooley]

G'day crew first post here. Been reading these threads for years and now finally need a hand!
Seen a lot of other people mentioning power loss/ stuttering on their 4.5 petrols.
Couple points are,
Having trouble maintaining speed at 100kph, like it's just dropping out of the rev range it's self.
Between 2-3k there's a flat spot, all noise and no go.
Slowly applying throttle it'll be fine up to 50% any further and it just boggs out unless full throttle is applied and suddenly snaps out of it.
At standstill full throttle range is fine, only when it's under load it's stutters.

Changed most of the vacuum hoses, replaced the TPS, checked dizzy cap, plugs are new, fuel sock and filter are okay, cleaned throttle body, cleaned all sensor connections.

Running out of things to check, any help would be greatly appreciated. Thanks guys!

 

[Malleus]

What year and which transmission?

 

[JPooley]

What year and which transmission?

1995 manual

 

[jpoole]

Still have the catalytic converter(s)? Any chance they are clogged, causing exhaust restriction?

 

[JPooley]

Still have the catalytic converter(s)? Any chance they are clogged, causing exhaust restriction?

Unfortunately not, new 2.5 inch exhaust installed a couple months ago

 

[BILT4ME]

I would look at the temp sensor wiring connectors, as the ECU monitors engine temp to go to open loop and adjust the fuel pump pressure

Second, consider looking at the fuel pump and hoses inside the tank to make sure the little hoses are still.kmtact and don't have holes.

The pump may not be producing the output it needs.

Then look at the fuel pressure regulator (FPR) by checking fuel rail pressures.

 

[JPooley]

I would look at the temp sensor wiring connectors, as the ECU monitors engine temp to go to open loop and adjust the fuel pump pressure

Second, consider looking at the fuel pump and hoses inside the tank to make sure the little hoses are still.kmtact and don't have holes.

The pump may not be producing the output it needs.

Then look at the fuel pressure regulator (FPR) by checking fuel rail pressures.

Will definitely be going over sensors again after most people have pointed to that as a problem. Had a look inside the tank today everything looked okay. Followed the fuel lines to the motor nothing to report on.
Do I need to buy a gauge to be able to check the fuel rail pressure?

 

[Malleus]

Yes. The procedure is in the FSM, which is in the Resources section.

 

[cruiserdan]

Did you look for cracks in the air intake hose?

 

[JPooley]

Yep brought a new one the other day