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Light Tapping Sound

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nodrogs

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N. Ireland
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Honda Accord 2.2
Does anyone else get a light tapping noise from their i-CTDII, 2nd gear about 1500-1700 rpm? It sounds like it might be noisy injectors. Timing chain and manifold were done at 65k (now on 94k), and oil is changed every 6k with 0W-30. Oil level is spot on. Doesn't do it when revved and doesn't do it all the time. I think its at its worse when has been sitting for a while but not fully cooled.
 
hond's stance :

10) Fault
Increased combustion noise which can be heard at light load around 2000 rpm. (Diesel models only)
Fix
This is due to the changing fuel injection parameters at this speed. The fuel system uses "pilot injection" as a means of softening diesel knock noise. The pilot injection is a small injection before the main injection but due to the standard limitations of the fuel injection and electronic control system it is not possible to use pilot injection during all speed and load conditions. The increase in noise, which is present on all diesel engines, is when the pilot injection is switched off. This is a characteristic that some customers may notice more than other based on their individual driving style i.e. throttle position, gear choice etc. but should not be considered a defect.
 
Top info bud... is there a set level that the pilot injection takes place - or is it ECU dependant?
 
Thats excellent info there Adam, thanks very much. Is there any reason why this has become more noticable recently?
 
without searching further i caunt realy explain in specific terms but i will try to elaborate shortly i a way that isnt an essay and everyone can understand lol
 
older dieslel engines used to inject fuel into a chamber at the side of the main combustion chamber due to the fuel pumps relaively low preasure. this caused the tell tale diesel knock we all know and hate as fuel started to combust outside the main combustion chamber hense the knock. think tractors and your preaty close. modern common rail diesels AKA the I-CTDI inject directly above the piston due to the higher preasures achievable and controlability via quciker responding injectors and ecu's. the pilot injection softens the knock as a small ammount of fuel is injected before the main injection. the pilot injection starts to combust as the main injection begins, therefore reducing the force one main injection would produce. at certain speeds and loads it will not be possible for the injector to work fast enough and to gain full power only a main injection is possible. the introduction of piezo christal injectors has improved the possible injection times even further hense the further reductiion in noise on the I-DTEC.
 
ive got to be on my game anyway as i am in the uk skills final this thursday and friday. never know......by the end of the week i may be top young technition in the uk?
 
beefy_634 said:
ive got to be on my game anyway as i am in the uk skills final this thursday and friday. never know......by the end of the week i may be top young technition in the uk?
Click to expand...

What do they class as young Adam?
 
young as in under 24 and has been in the trade for no longer than 4 years. the top 3 people out of the honda regonal got into the final 6, which say a hell of a lot about how good honda training is! there was 10 regenal finals i believe and only 3 people out of the other nine regenals got to the final. each regenal heat would have had up to 10 competitiors. dont forget Mark our other apprentice came first in the honda heat and i came third! so good luck to mark and hopefully a HH 1 2 lol
Mark and me still have a lot to learn but we have the right structure in place at HH and the attitude and hunger to better ourselves. ime allready at diagnosic level and am currently aiming towards master tech, ime competing at a skills final and loving working with honda. things are looking good!
 
the lad who came seccond in last years final was in my class yeh. wasnt gatwick, sumware in derby
 
his names stuart prince. he didnt get selected to reprisent the uk, its on the web sumware. anyway cheers cj, ile let everyone know how we both get on
 
So that is what that soft (only on light throttle at around 1800 revs tapping is) Ive driven pretty much every thing diesel in my time but never heard this noise before so was a bit worried, I'm a happy lad now :) Thanks very much Adam
 
Adam and CJ thanks for the info spot on response very informative.

Adam - good luck and best wishes in competition going forward
 
Hi

Am i right in thinking that this is normal on a 7th gen diesel then. I have had my car for over 2 years and i have been trying to figure this knock out which has been explained above. Could others respond for confirmation? Thanks
smile.gif
 
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