Rough idle

[krauser]

G'day all, I've been a long time lurker here and have really appreciated the good advice I've picked up - from the outside temp sensor install to the YD25 timing chain replacement. Here's a little problem I'm hoping the brains trust can help me with:
2007 STX,auto diesel with 101,000 kms on the clock. Bought new, always serviced at the local dealer, never had a problem.
Was getting it ready for a trip to Condobolin recently and became concerned by a rough idle - start up, select reverse and release the brake and it would idle out of the garage feeling like the tyres were flat-spotted. I took a bit more notice after this and found that as you pulled up to the traffic lights, this same lumpiness would occur, until the car stopped. Release the brake and let it idle forward and the lumpiness happens again.
It was nearly due for a service, so decided to get the service done and get the lumpy idle checked at the same time. Dealership found nothing on the diagnostics, but found lots of shit in the fuel tank, so remove and flush, new fuel filter and vacuum control valve and it was marginally better. They said that No.1 injector was showing a pressure variation around 1400rpm, possibly from the dirty fuel, so advised some injector cleaner and take it for a good run, which we did, 3000+ kms to Condo and back!
I run a scan gauge (another good tip from here!) and fuel economy seemed no worse (we were pretty loaded and had stuff on the roofrack). The lumpiness almost went away, but on our return to Brisvegas, it's as bad as ever. I started it up this morning and thought engine was going to jump off the mounts!
Dealership said before I left that they had a set of spare injectors that they used for diagnosis, but it seems to me that they'll just keep replacing stuff till they find an answer, rather than any diagnosis. At $120/hr, that gets a bit exxy!
Obviously, I'm open to suggestions for self diagnosis, and I've read quite a few threads on here regarding similar idle problems, but I'm also hoping for recommendations for a good diesel specialist, preferably with YD25 experience, on the north side of Brisbane. Any suggestions?
Thanks in advance,
Peter.

 

[jonney]

maybe the Injectors need a proper clean , any mechanic with the injector clean unit will be able to clean your injectors , forget that $120 per hour crap. phone around certain mechaical workshops in your area and ask if they have the injector clean unit . sounds like this could be your problem as the injector clean worked for a short time but they need a proper clean now.

 

[bods]

Maybe give this a try first... Should be the same procedure for the d40 http://www.navara.asia/showthread.php?goto=newpost&t=27063

 

[TigerST]

Welcome and agree with BODs

 

[Old.Tony]

Welcome - four years to the first post. Must be a record in there somewhere!

I agree with Bods too. Give it a purge.

While you're fiddling, pop the SCV off the fuel pump and give it a clean (petrol, paint brush & allow to dry).

Did you use an aftermarket fuel filter? That would be it right there. Inner seal doesn't make great contact and under suction there's just enough gap to let the car suck air in.

 

[krauser]

Thanks for the advice, fellas. Yeah, been lurking for four years, but cars aren't really my thing, especially these new fangled diesel ones, so I couldn't really contribute much.
Fuel filter is a genuine one, so that should eliminate that possibility. Will investigate a purge or an injector clean. Anyone got a good mechanic? Shall report back when I get it fixed!

 

[krauser]

Fixed $$$$

Had a chat with Michael at Diesel Specialists at Virginia in Brisbane. The dealership's diagnosis of a dodgy No.1 injector was correct - ended up replacing all 4 injectors, high pressure pipes, seals etc for less than the dealership quoted just to supply the injectors. It now idles smoothly, comes off the idle cleanly and drives like it should. Pissed off that the injectors had trouble at 100K, though!