2.5 crd 2002 idling rough when hot - possible causes?
#11
08-18-2014, 05:17 PM
Vmaxxer has illustrated one of the characteristics of clogged injectors, a VERY long high-speed run in the order of hundreds of miles is probably as good as actual injector cleaner, the throughput of diesel in the injectors is much heavier than normal, and the pulsing frequency is much higher due to the high speed of motorway/highway driving. The clogging shows up when the throughput is at its minimum as when idling.
I can tell you with BP "ultimate" cleaner-diesel that it costs 40pence extra per gallonUK as of my calculation about 2years ago.
Unclogging the injectors will make a significant improvement in MPG, one of the reasons to keep a permanent eye on fuel consumption. Example:-- My daughter has a 1.9ltr. diesel Vauxhall Vectra-matic which was doing around town about 25mpgUK. After a long trip from Yorkshire to Wales, it's now almost 30mpgUK on the same local motoring here in Leeds.
Leedsman.
I can tell you with BP "ultimate" cleaner-diesel that it costs 40pence extra per gallonUK as of my calculation about 2years ago.
Unclogging the injectors will make a significant improvement in MPG, one of the reasons to keep a permanent eye on fuel consumption. Example:-- My daughter has a 1.9ltr. diesel Vauxhall Vectra-matic which was doing around town about 25mpgUK. After a long trip from Yorkshire to Wales, it's now almost 30mpgUK on the same local motoring here in Leeds.
Leedsman.
Our cars and speed limits in the UK usually mean we will never reach peak torque RPM, we tend to do 99% of our driving in the 2,000-4,000 RPM range, most around town-ers and school run-ers never get to 2000RPM with their light throttle loads. Its not so difficult even in the 2.8 automatic to 'blow cobwebs' out. Take an already warm car onto a quiet trading estate on a Sunday, lock it in 2nd and give it 15-30 minutes at 4000RPM, it will boogar your MPG average but will cough some cacka up !
A caveat emptor doctrine applies to the above advice, and yes check all levels before and after and watch the gauges like a hawk.
#12
08-18-2014, 05:28 PM
So lots of coincidences. On Sunday I added some Bardahl and the engine idles much better now although it's still a bit constipated...! Tomorrow, or the day after, I'll receive a vacuum pump/gauge so I can test the EGR valve. I already suspect the EGR solenoid. Additive based cleaning definitely helps, but I would like a long term solution. Will keep you all posted...! Regards, kkc.
#14
08-18-2014, 06:45 PM
I used the Wynns on my Mercedes petrol 2.3E, on my CRD 2.5 I used some Injector cleaner which stated it was especially developed for CRD diesels, but I be damned if I can remember which brand it was 
#16
08-19-2014, 01:52 PM
I tried redex for diesel engines in my fuel, it didn't make a difference it was grumpy as hell when idling at the traffic lights and loss of power when accelerating off. after 20 minutes of driving the engine just smoothes out and is back to normal again. I have just ran it round the block a few times and pulled up on the road and it was grumpy again when idle, however, after about a minute and a half the idle smoothed out and was normal again. could this be the EGR valve ? as I have read it stops functioning after 60 seconds of idle.
#17
08-19-2014, 02:26 PM
update..... looking closely at the fuel injectors on the top of the engine there is a puddle of diesel and one of the injectors and the supply line that attaches itself to it is wet with diesel. think I may have found my problem. what do you guys think ?
#19
08-19-2014, 05:23 PM
Update: I measured the vacuum going into the solenoid today and this came to 22in HG. So this checks out ok.
The solenoid itself tested ok for continuity so I assume it's ok. I did not test for any current from the relay into the solenoid.
I also manually forced a vacuum into the EGR valve in steps up to 22in Hg and the idling did not improve or get worse. On top of this the applied vacuum was lost after a few mins, indicating a leaky diaphragm. Does this last observation mean that the EGR needs replacing i.e. no point in cleaning? Thx, kkc.
The solenoid itself tested ok for continuity so I assume it's ok. I did not test for any current from the relay into the solenoid.
I also manually forced a vacuum into the EGR valve in steps up to 22in Hg and the idling did not improve or get worse. On top of this the applied vacuum was lost after a few mins, indicating a leaky diaphragm. Does this last observation mean that the EGR needs replacing i.e. no point in cleaning? Thx, kkc.