Big power loss with AC on ?

[gxr]

I have just noticed that I loose most of the power/acceleration as soon as I turn my AC on !??
TB45E 2001 GU.
Now before I go on a wild goose chase to try to figure out where the problem is and bearing in mind that I do not have access to CONSULT, could one of you learned gents please tell me where to start looking, unless of course, you know exactly what it is:D

Thank you in advance

[boggy2006]

there's usually some power loss when the aircon kicks in at it will take a couple of kW or so, but should only be slightly noticeable on a 4.5 engine. How much power are you using, does it still accelerate or is it undriveable? Does the aircon work ok? If so, the compressor shouldn't be seized up (not heard of this happening anyway). Maybe try taking the belt off and turning it by hand. Is the battery charged up ok (so the alternator is not also fully loaded when the aircon fan comes on)
Otherwise could be the ECU sending the wrong fueling message to the engine. ie. usually it raises the idle a bit when aircon kicks in, but if there's a fault maybe it's reducing the fuel or something. Sorry I can't be more specific. Maybe check the engine diagnostics codes (on a GQ it's be bridging 2 pins on the diagnostics connector, not sure about a GU).

[gxr]

Thanks Boggy,
Im talking about a big power loss like Im suddenly towing a 5 ton trailer! It still accelerates but very very slowly , with the pedal to the floor and RPM at about 4500 it would take about a minute to reach 80Km/hr , gear shifts ( Automatic) at about the right speeds.
AC runs fine and is not seized up and turns normally, Idle speed does come up a bit when I switch the AC on so no problem there. My instincts tell me it could be one of many sensors acting up so I will have to go through them one by one on the weekend or find someone with a Consult. My local Nissan dealer has no clue on Patrols, so not much help.
Also another thing I did notice lately is a noticeable loss of power going uphill especially when the engine is hot so that may be another indicator of a sensor malfunction, which one exactly , remains to be seen !
Anyway will post my findings after the weekend.

[YNOT]

It could be the oxygen sensor in the exhaust.

Tony

[gxr]

Thanks Tony,
Ill check that first, I know where it is located, but have no experience taking it off or even what it looks like !
Is it an item I can clean up with a spray of some sort or is it one of these that just dies when its time is up?

[YNOT]

You could try cleaning it in vinegar but I wouldn't bother, just replace it.

Do a search on here for "reading and erasing fault codes" and have a go at reading your engine fault codes, it might give you a clue where to start looking. Some sensors may not log a fault code even though they are faulty so the codes are only a guide.

Tony

[gxr]

Gee whiz! Live and learn ! I spent ....well Im embarrassed to say considerable time trying to locate the oxygen sensor on my TB45E MIDDLE EAST version which as it turns out......does not have an oxygen sensor:clownredpuff:
One less thing to worry about:icon_victory:

[gxr]

Decided to change air and fuel filters for starters, not really convinced they are the problem but they probably need changing anyway.

[Bigrig]

Trial and error can be frustrating mate, but you'll no doubt find the problem - all the best with it.

[gxr]

As you said ,Trial and Error is usually accompanied by rather abusive expletives !
So I dropped by the Nissan service center to pick up the new filters and thought I would pick the head mechanic's brains about my problem and he suggested I change my A/T fluid! Ok, why not, it is kind of overdue according to the maintenance schedule. But of course I want to do it myself as Nissan would probably ask for an arm and a leg. So Im off to consult my manual to see how I can drain the converter since ill be using Shell Donix dexron 3 TG instead of the D-matic that came with the GU and which is unavailable here!
Let you know how it goes.

[YNOT]

There is no easy way to drain the converter.

Tony

[gxr]

so what is the hard way and what happens if i dont drain it all and just replace whatever I can drain?