CDTI power drop over 300RPM
 

I recently bought a cdti to save it from the scrapyard and while fixing MOT failures ( brake pads, discs, handbrake, rear jacking point and number plate lights) I also fitted a new air filter, viton O rings, silicone intercooler hose from Jules, cleaned the EGR and intake manifold, oil and filter and fitted the correct fan with new brushes. It's now passed it's MOT and pulls well up to 3000 RPM then it struggles to rev any more. Is this normal for a diesel? I've had the 1.8 and still have my ZT190 so can't really compare it with the others.

Could be a dodgy MAF sensor.

I don't know if it's related but there is a smell of the exhaust inside although It doesn't sound like the exhaust is blowing

I rarely take my CDT over 3,000RPM, I will get more acceleration by changing up with the same throttle opening. Pressing harder on the pedal above 3,000 doesn't do much except use more fuel and make more noise. 3,000 rpm in top gear equates to 90mph.

Roughly 180,000 miles, I replaced the old intercooler pipe with a new one, I also cleaned the EGR and inlet manifold, there was about 10mm of coke in it.

That's what I was asking really, is this a normal response or is there something wrong with that's causing this.

The longer stroke, heavier crank and flywheel of the diesel engine in general tends to give it these characteristics. I have had many older diesels, the free-est revving being the 2003 Audi 1.9TDI, but even that was unrewarding above around 3,300 rpm. My CDT is the standard 115 bhp. Once it's through its MoT, I intend to have it remapped for more power and efficiency - watch this space.

No it is not normal, mine is an auto, and will happily rev to the red line whilst in sport mode (it is not a pleasant experience to me, as I consider myself mechanically sympathetic, so rarely use the sport mode).

^^^^^^^^^ this would be my first port of call. Try unplugging the MAF, and see if this improves the response, and if it does, then a replacement (Bosch only, do not be tempted with cheaper alternatives - BMW M5 V10 uses the same insert and is normally quite a bit cheaper, carefully swap between the housings)

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The longer stroke, heavier crank and flywheel of the diesel engine in general tends to give it these characteristics. I have had many older diesels, the free-est revving being the 2003 Audi 1.9TDI, but even that was unrewarding above around 3,300 rpm. My CDT is the standard 115 bhp. Once it's through its MoT, I intend to have it remapped for more power and efficiency - watch this space.


That's something I was considering but I wanted to know the car is working as good as it can before getting a remap. I'll be interested to hear how you get on.