D22 fuel pressure problem

Hi guys, New d22 owner here.
4 months ago I purchased a 2010 d22 2.5crd with 70,000ks
Unfortunately 1 month later I had to replace the timing chains, and if that didn't hurt enough now im having a real problem with the fuel pressure.
When the car is cold the idle is very up and down. only when cold though.
im not noticing any power loss but I am getting bad fuel economy. (500ks from full tank)
Brand new genuine fuel filter.
Cars not blowing any smoke.
Every diesel mech I take it too all have very different expensive opinions.
What we do know is there are no codes being thrown however with it plugged into the computer it is showing the fuel rail pressure is fluctuating between 26-32.
Has anybody else ever experienced symptoms like this?
the car seems to drive fine once warm
Thank you for any help. much appreciated.
Matt

Also i have reset the coputer after fuel filter change. I did purchase a genuine filter from nissan. However i didnt get that extra seal that everyone talks about. Could this be causing this issue?

Could be the missing o ring, other common faults are the "suction control valve" and the fuel rail pressure relief valve. There's a few threads on both with the SCV being the most common.

I also have a very irregular idle when cold (d40 tho).but its dissapears when warm to a point.their are a few high flow/updated scv getting around...some users say they cause a irregular idle also...could it be that yhe scv is having problems actually limiting the fuel flow at idle?

It's not just Navaras that have suction control valve problems either.
http://www.npoc.co.uk/forum/nissan-primera-p12-fuel-pressure-problems_topic44222.html
http://www.npoc.co.uk/forum/nissan-primera-p12-lack-of-power_topic44275_page1.html

The new scv i was looking at fits all denso vehicles...triton navara...few others.

What i was also going to say was most parts that fail in reguards to fuel arnt even nissan made parts!!

I have the same problem when cold and found that after I did a diesel purg it stopped for a while. I also noticed that with the air con on it is less noticeable due to the slightly higher revs. I have all the o rings on the filter also and it doesn't help. I just hit the heat switch now for a few minutes.
Cheers.

Diesel purge made mine a bit better..but not somthing i really worry about.starts and runs fine...never stalls just hunts a little

This morning mine did stall whilst idiling but as soon as i drive it its fine. Ive just installed the oring but still not confident that is the problem. Im definetely thinking towards the scv.

When changing scv does it need to be programed? Or is it as simple as out with the old and in with the new?

Wouldn't hurt to reset the ecu, but they don't need programing.

Awsome thanks heaps. Might replace it and hopefully that gets my problem soughted so i can finally start enjoying this car.

You could try cleaning it first. Seems to be more of an issue on d40s than d22s, but people have cleaned them with good results.

Ok, do you have any recommendations on how to clean it once ive removed it?

Nope hahahah. I'll see if I can find the thread lol

Still trying to find it... I wonder if old_tony knows where it is, or what's involved in cleaning it...

A straight dose of liqimoly ďiesel purge while its still fitted...remove the scv and reffit it 180° around.will be a hour or so job but its worth a go before you replace it. The liqimoly brand cleaner is probs the safest and strongest internal stripper you will easly find.get a full can and pull the fuel hose off and run the engine on that alone untill the can is empty...4BYFOR and Rustynav did a good write up on it somwhere here

Where is the scv located.

I believe its located at the back of the fuel pump