Colin Neal (Kilsyth, VIC)

Hi Allan, I have a turbo diesel, intercooled 4.2L, which I’ve owned for 3 years and do plenty of weekend trips. I’ve done a 2in lift, snorkel, 3in exhaust and fitted a roof rack. I would like to add a winch, 33in tyres, roof console and radio, rear drawer fit-out with a fridge, aftermarket front seats and a turbo upgrade for more grunt.

My problem is, at the moment I have a hesitation that I’m feeling in the rev range of 2200 – 2800 rpm. That’s not to say it’s not happening outside that range, that’s just when I feel it.

It’s most noticeable under load going up hills or overtaking. Four mechanics have not been able to pin-point the problem including Nissan and an injector specialist, they all immediately go to fuel and filter but there’s no change. The car needs to be at running temp for it to happen, winter or summer makes no difference.

I work in the bushfire-affected area of Kinglake and Marysville and do 200km a day up and down hills, so I feel it within 15 minutes of driving. I had the injectors done at 120,000km and I have still had a loss of power and fuel economy.

I believe it came about after towing a heavy boat for several hours, prior to that the Patrol was fine. It is really frustrating and I don’t know what to do next. Your advice would be greatly appreciated as I love my Patrol.

Allan

Well Colin, I think what perhaps you’ll need to do with your vehicle is get it on the dyno with an exhaust gas analyzer. I’d be checking the colour of the smoke it blows at that 2200-2800rpm range, I suspect that it changes colour in that rev range.

I think in your case considering it sounds like you do a bit of towing, you should have an exhaust gas temperature gauge and certainly should have a boost gauge on the turbo, because I think the turbo itself might be for some reason or another fluctuating at that rev range, whether you have an intercooler or not.

I’d also get the tappets adjusted. Adjust them carefully when they are hot and the motor is stopped. I believe that will fix your problem- Thanks Col for writing in.