Nissan Terrano 2.7 rough idle and bad economy

[Flyingkiwi]

Hi guys,

So I have a 96 Nissan Terrano with TD27T engine. It idles rough all the time at around 650 RPM, unless I select the HEAT switch and then it idles at around 1100 RPM until it gets up to temp and the heat function automatically turns off. When under braking and decelerating with the heat function on, it idles rough until the truck rocks backward on its suspension when it is stopped fully, and the RPM comes back up again. This happens in drive or neutral.

Also I'm getting approx 420 Kms per 60 liters tank of diesel, which is rubbish for a diesel in my book.

I have blocked off the EGR valve and it hasn't seemed to help the idle except the turbo is a bit more responsive.

Any help would be much appreciated. Injectors? Fuel Pump? PCV valve? ECU?

Thanks!

[MihiT]

Always with automatics I suspect the box/ clutch first!
Check the fluid for a start.
Resetting the ECU/ TCU and letting it relearn may help.

Other than that, if injectors haven't been done, do them. If you crack the feed lines while it's running, and one cylinder doesn't make a difference, you will have found the fault.

The heat thing also points to thermostat issues, so a rad flush (this will also improve trans cooling) is on your to-do list.

Basically do any maintenance that should have been done, and if the issue persists you have a genuine problem!

[Flyingkiwi]

Ok I'll get the injectors looked at then. Is there a way of doing the ECU relearn myself or does it need to be a mechanic with a special gizmo? The heat function is nothing to do with the radiator, it's a preheat of some sort which helps it idle better in cold conditions, whethers it's glow plugs or something in the air intake I'm not sure.

[MihiT]

Ok I'll get the injectors looked at then. Is there a way of doing the ECU relearn myself or does it need to be a mechanic with a special gizmo? The heat function is nothing to do with the radiator, it's a preheat of some sort which helps it idle better in cold conditions, whethers it's glow plugs or something in the air intake I'm not sure.

That would be beyond me then! So this is pure guesswork:
If it increases the idle that would suggest that it's putting more diesel in. (Advancing the timing) if THAT is causing issues then i'd be looking to the injector pump, which unfortunately is big $$.

A set of reco injectors shouldn't be too steep. I paid about $400 for 6, so I'd guess about $280 for your 4, then you know they're right. By the time you've taken, or paid, to get them out, you may aswell put good ones back in.

You should be able to reset all your computers by leaving the battery disconnected overnight. In saying that, if it does have an OBD plug, it could pay to have it checked for any error codes before you do.

[Crash bandicoot]

Check the inlet hose between the airbox and turbo for splits take it off and turn it up side down and stretch it