Idle speed decrease after long run

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Graham996
Posts: 18
Joined: 15 May 2020, 19:16
x 1

Idle speed decrease after long run

Post by Graham996 »

Hi everyone

My wife just got back from a long run in the 3008 and the idle speed has dropped to 740 rpm which is very lumpy but smooths out as soon as you touch the throttle. She also reported that it seems to lose power when going up hill (about 20 miles into the journey) after this she drove it very gently for fear of breaking down. Before this journey I checked the car and it was ticking over at 820rpm and was running very smoothly with plenty of power. I cannot detect any problem after the car has cooled down. It has done this a few times now and I am unsure of what is wrong as there are no fault codes.

Some background to the recent history which involved changing a fuel injector is detailed in the following post and I wonder if the two are connected.
viewtopic.php?t=65304

If anybody could offer any advice it will be much appreciated.

Graham996
Posts: 18
Joined: 15 May 2020, 19:16
x 1

Re: Idle speed decrease after long run

Post by Graham996 »

I have had some time to reflect on this.....

If all is good when its cold and warm, could it be that as the engine becomes hot the seal on one of the injectors starts to fail because of thermal expansion effects which leads to a reduction in compression and consequently power, and I guess the idle speed drops off a little as well. Is there anything I can read off the live data via the OBD port to prove this point?
I think I am looking at stripping it down again and I guess the above would be proved if I saw soot or diesel around the injector. As I write this I think I can recall smelling diesel in the engine bay which is possibly stronger than it ought to be.

Sunday looks like a challenging day

Graham996
Posts: 18
Joined: 15 May 2020, 19:16
x 1

Re: Idle speed decrease after long run

Post by Graham996 »

Just watched an interesting video.
I didn't use an injector seat cutter for re-seating the injector although to be honest neither of the injectors I removed were leaking or had any deposits on the seats that I could see, the ports were also clean and dry.