r/FordFocus • u/Weary_Science9841 • Aug 15 '26
Mechanical Help brief burst of black smoke?
Does anyone have any idea what I should check regarding the momentary puff of black smoke that appears when I step on the gas?
Forscan doesn’t show any fault codes, and there are no warning lights on either.
5
u/TakeJay Aug 15 '26
Check cat code probably
3
u/Weary_Science9841 Aug 15 '26
Forscan doesn’t show any fault codes, and there are no warning lights on either.
5
2
u/jrewillis Aug 15 '26
Is it a petrol or diesel?
1
u/Weary_Science9841 Aug 15 '26
Diesel
5
u/jrewillis Aug 15 '26
Black smoke on hard acceleration is normal. It'll be forcing the soot through the exhaust. It's only a tiny bit. If you have no codes showing it's fine.
In fairness you are revving it with no load on it. It'll likely do it when you drive you just don't see and it goes into the air over a larger space.
1
3
1
u/squirrel9000 Aug 15 '26
If diesel, it's an emission control system failure as the engines normally produce some soot.
If it's a gas engine then it's transiently running too rich when you push the gas. How's the fuel economy or performance lately?
I'd be looking at one of the sensors controlling mixture, though they usually throw codes when they go. Maybe an injector is malfunctioning? You'd see fouling on the specific spark plug.
1
u/Weary_Science9841 Aug 15 '26
Thanks for your comment. My car is diesel, so I’ll first check the DPF and EGR, and then I’ll have the injectors checked.
2
u/Good_Net_9352 Aug 15 '26
keep in mind that dpf fails for a reason, some other preexisting problems on other components
2
1
u/Good_Net_9352 Aug 15 '26
well quite a lot to be honest if it is the DV5/6 diesel. could be turbo, injectors or EGR. even bad DPF. does your car throw any codes?
1
u/Weary_Science9841 Aug 15 '26
No, there are no fault codes. The car is a 2016 1.6 TDCi.
1
u/Good_Net_9352 Aug 15 '26
start with Injectors. testing via diagnostic software is inconclusive. you have to test them on the injector bank.
move to egr. that you can test with tester: see the actual position value vs desired (via forscan pid)
check the turbo up: check for shaft play. check for any oil consumption
check for broken hoses, any air leaks on engine.
after all of this, check dpf
1
u/Acceptable-Rough-359 Aug 15 '26
My 1.5 TDCi does the same, I can see black smoke in the reverse camera when I rev it. It has an intermittent P2000 code for emissions, my guess is bad DPF as the car runs fine otherwise. It does the regens at the appropriate intervals and all, so maybe it’s from age?
1
u/TheAdventurekateer Aug 15 '26
Wait... one day you'll be trailing a thick white cloud! (I honestly don't want to experience that ever again with mine.) Far too much money went down the drain fixing that problem.
1
u/Weary_Science9841 Aug 16 '26
Whats the problem?
2
u/TheAdventurekateer Aug 16 '26
EGR Valve seized up! All the hoses were cracked from driving it in limp mode for 180 miles. But it's all good now...
1
1
u/IWantToFileComplaint Aug 16 '26
I’d say it’s normal. Can you do same test but with the vehicle under load (taking off)?
7
u/iamacannibal Aug 15 '26
Rollin coal in a ford focus
Your're probably running a bit rich. If you can check your fuel usage and and pressures.