Dodge Nitro 2.8 CRD, 3.7 V6 and 4.0 V6: The Full Story

The 2.8 CRD is the diesel you actually wanted if you were doing real kilometres. The VM Motori unit, engine code A 428 DOHC, displaces 2768 cc with a 94.0 x 100.0 mm bore and stroke and a 17.5:1 compression ratio. The Bosch EDC16CP31 ECU manages 177 hp and 420 Nm from the factory, which is a solid number for the era. On fuel economy alone this one made a lot of sense for NZ buyers, and quite a few of them are still earning their keep.

The problem is that the VM Motori diesel has a reputation, and it has earned it. These engines do not forgive neglect. When injectors get tired you get hard starting, rough running, and eventually the kind of smoke that gets you noticed at traffic lights. The injector wear is gradual and owners often live with early symptoms far longer than they should because a generic code reader does not tell the full story. We use the wiTECH platform alongside StarSCAN or StarMOBILE to pull live injector data and DPF delta pressure readings, which is the only way to properly understand what is actually happening inside this system.

The DPF is a real conversation piece on these. If the car has been doing mostly short suburban runs, the DPF may never fully regenerate and will eventually block. We diagnose it properly before recommending a course of action, which might be a forced regen, a professional clean, or further investigation if the underlying cause is an injector or sensor fault contributing to incomplete regeneration. There is no point cleaning a DPF if something upstream is causing it to block again in two months.

Comparing this to the petrol variants in the Nitro family: the CRD needs more attention to its fuel system and emissions hardware, but rewards that attention with torque the V6 petrol versions simply cannot match at low revs. If your Nitro is doing highway kilometres, the diesel is the one to have. If it is mostly town work, the petrol options have a simpler maintenance story.

Where the 2.8 CRD is a technically complex diesel that demands proper attention, the 3.7 Powertech V6 takes a simpler approach. It is a 3701 cc SOHC petrol unit with a 93.0 x 91.0 mm bore and stroke and a 9.7:1 compression ratio. The Motorola NGC4 ECU manages a stock 210 hp and 319 Nm. Not spectacular numbers, but honest ones. For a lot of Nitro owners this has been a perfectly reliable daily driver, and that reputation is mostly deserved.

Mostly. Because the 3.7 has a specific Achilles heel that is easy to miss until it becomes expensive: valve seat problems. Dropped or worn valve seats are a recognised issue on this engine, and when the cylinder head gets involved it stops being a small job fast. The good news is that the early warning signs are there if you know what to look for: unusual coolant consumption, a loss of compression on one cylinder, or combustion gases in the cooling system. We catch these early with proper diagnostics rather than waiting for a bigger problem to declare itself.

That timing chain rattle on cold start deserves its own mention. A lot of owners hear it and decide it is just the engine doing its morning stretch. It is not. On the 3.7, chain guide and tensioner wear is a real thing, and oil change discipline matters a lot here. An engine that has been on extended intervals or run with the wrong oil grade will show this faster. The rattle is the engine asking you to take it seriously.

Compared to the 2.8 CRD: the 3.7 has a simpler maintenance checklist day to day, no DPF, no swirl flaps, no glow plugs. But the cylinder head situation means the stakes are higher if you ignore the signs. Compared to the 4.0 V6 above it in the range: the 3.7 gives away 50 hp and some torque, but the fundamental architecture is closely related and many of the suspension and body wear patterns are the same across both petrol variants.

If the 3.7 is the workhorse, the 4.0 is the one that actually feels like it belongs in something called a Nitro. The EGS engine displaces 3952 cc with a 96.0 x 91.0 mm bore and stroke and a 10.3:1 compression ratio, managed by a Motorola NCG4 ECU. Stock output is 260 hp and 359 Nm. In a car this size, that is a meaningful difference over the 3.7 and a completely different character to the diesel.

The 4.0 is genuinely robust when it is looked after, but when service is skipped it develops some very specific complaints. The most common thing we see is a rough idle or misfire, and the culprit is almost always ignition coils and worn spark plugs. These get neglected because the car keeps running, just rougher and rougher, until eventually a misfire code lights up and someone pays attention. Fresh plugs and coils make an immediate difference on a 4.0 that has been on original parts for too long.

Compared to the 3.7: the 4.0 shares the same body, the same platform wear patterns, and the same general suspension story. The difference is in the engine's ignition system demands and the fact that the 4.0 owners seem to push their cars harder, which shows up in how the gearbox fluid gets neglected. Compared to the diesel: the 4.0 is simpler from an emissions hardware perspective, no DPF to worry about, but it drinks more fuel and the tune gains are more modest in percentage terms.

Our Stage 1 tune for the 4.0 takes it from 260 hp and 359 Nm to 280 hp and 390 Nm, gains of 20 hp and 31 Nm. That is enough to notice, particularly in mid range pull where these trucks spend most of their time. Pop and bang maps are also available for those who want a bit more theatre.