D40 Power Loss (6Speed manual 4x4) - SOLVED

[Mrluver22]

Hi mates need some advice! I've been noticing when driving my Nav and the Air Conditioning is turned on there's a bit of power loss. While driving with the AC on and I switch it off there's an instant power gain! Is there anything I can do to reduce/eliminate this? Also when the AC is turned on shifting gears isn't as smooth as when the AC is turned off( no matter how light you are on the clutch pedal ) .

 

[doc]

Sounds very weird. My aircon makes no noticeable difference to the performance of my D40 (also 6 speed manual).

 

[Mrluver22]

Honestly it feels like compression braking once I come off the throttle in any gear and the AC is turn on.

 

[happy john]

The compressor does use 4hp whilst in use but it should not be greatly noticeable i can detect the slightest bit in mine when i turn it on don't forget also your engine fan robbs your donk of about 10hp.

 

[user 10312]

Sounds like something is a miss. Be interesting to see how easily the A/C compressor turns over with no belt on and the A/C on. A difficult to experiment to set up as you would need the engine running.
Perhaps pop the bonnet with the engine running and and get someone to turn the A/C on and off, have a look and listen more closely. Noisy belt, excessive noise from bearings....

6sp manual here and I can barely pic the difference. Probably can pick it easier under light throttle cruise than any acceleration.

 

[joe2006]

Although mine is auto, I notice no difference whatsoever.

 

[Mrluver22]

Tappet I just tried and there's a bit of squeaking from the belts for about 2-3 seconds when the AC is switched on. No bearing noise tho.

 

[user 10312]

Hmm, that sounds fairly normal. Mines give a bit chirp on start-up sometimes.

Dunno, hopefully someone will come along with some better diagnosing ideas than me. In the mean time I wouldn't use the A/C.

 

[Old.Tony]

First thing I'd ask is if the aircon is working as expected. Is the air actually chilling?

Second thing is does the car accelerate normally (without the aircon on)? Is that a perceptive "normal" (having been affected by the lack of performance for some time) or does the car still provide the same fuel economy and haul up the hills like it used to? I'm wondering this, because 4HP (AC) plus 10HP (fan) = 14HP and out of 126kW (171HP) 14HP is only a small amount, but if you're running at like 60%, 14HP is a much bigger slice of the pie. Not sure this is where it really is though, because of the "engine braking" issue.

Now that makes me wonder what on earth is happening. For it to feel like it's engine braking you're talking about a significant loading on the engine.

There is ONE figure I'd like to get from your ECU - engine load at idle with the AC off & on. This will be quite telling about the load of the AC - the ECU will make adjustments on the fuelling so that it idles at the correct level. At idle, you should see your fuel rail pressure sitting around the 4,000psi mark (give or take a couple of hundred PSI). I don't know what the manual's default engine load should be, my auto's is about 8%, but you should be using around 1.8 litres per hour at idle (give or take .1 litres per hour).

Got an OBD adapter & Android phone?

 

[doc]

This figure thats being thrown around for the engine fan - allegedly having a parasitic drain of 10hp. You do realise that it's a clutched fan, yeah? Once the revs build, the clutch starts to disengage progressively until its basically freewheeling.

In the old days of fixed fans, maybe. But I have to say - I'm dubious at best.

 

[Mrluver22]

Reply to Old.Tony , the air conditioning works great as the day I bought my Nav from the nissan dealer. Acceleration without the AC turned on has dropped a bit and the fuel economy has dropped too even tho I'm servicing every 5000 km. For the idle pressure I'll have to get back the info onto you. Thanks for the info guys hopefully I can solve this issue because it's frustrating.

 

[kevvyp]

Ever since i bought my D40 (107000k) i have had rough idle issues and A/C issues, when i engage the a/c i have symptoms similar to yours, it has a strange FLAT SPOT for want of a better word when i move off and when changing gears, also a noticeable power loss, on the weekend i put half a can of EGR cleaner thru her and what a difference, idle has improved, acceleration is a LOT smoother and no more A/C problems, i used this cleaner http://www.jlmlubricants.com/en/products/diesel/diesel-air-intake-egr-cleaner worked a treat in mine.

Kev

 

[Mrluver22]

Thanks mate but my D40 didn't come with an EGR system !I did the manual fuel pump reset (via the accelerator pedal and ignition) and it cleared the power loss issue I was having.