ZD30 tapping sound after EGR blank

Hi Guys,

Got a weird one, I installed an EGR blank plate into the intake side of my ZD30 the other day.

I was very impressed with how the engine ran after installation, much more responsive and smoother. However I noticed under load in 3rd and 4th gear at 2500-3000 RPM a loud tapping sound seemed to be coming from the engine (sounded like a loud tappet-ish noise).

I removed the blank plate and tested again, the noise was gone.

Anyone know what this might be, I'd obviously like to have the plate in to keep the engine clean but the noise was quite concerning.

Cheers in advance.

Could it be "knock"? Perhaps you are under-fueling the engine now with more air available for combustion and it's pre-igniting?

Black_Outlaw said:

Could it be "knock"? Perhaps you are under-fueling the engine now with more air available for combustion and it's pre-igniting?

Click to expand...

It very well could be.

I've searched around on various forums and haven't really seen anyone else having this issue, weird.

I did just do the blanking plate and not the swirl/butterfly mod, I wonder if that makes a difference.

I know the d-22 / 2.5 Litre only needs the egr plate block off no swirl mod but maybe the ZD-30,s do need the swirl mod.

Black_Outlaw said:

Could it be "knock"? Perhaps you are under-fueling the engine now with more air available for combustion and it's pre-igniting?

Click to expand...

no, diesels don't work that way.

someguy360 said:

Hi Guys,

Got a weird one, I installed an EGR blank plate into the intake side of my ZD30 the other day.

I was very impressed with how the engine ran after installation, much more responsive and smoother. However I noticed under load in 3rd and 4th gear at 2500-3000 RPM a loud tapping sound seemed to be coming from the engine (sounded like a loud tappet-ish noise).

I removed the blank plate and tested again, the noise was gone.

Anyone know what this might be, I'd obviously like to have the plate in to keep the engine clean but the noise was quite concerning.

Cheers in advance.

Click to expand...

did you do the butterfly mod?
i would do that first with egr unblocked. then block egr and see if noise returns.
with egr butterfly working but egr blocked you can run into issues with low effective compression which with a worn engine can give combustion problems and more combustion rattle. that could be the tapping noise you hear.

one option is to do the butterfly mod and leave the egr unblocked. this reduces the amount of egr used. there is some thought that the heat from the egr helps with combustion, especially with worn injectors.

swirl mod won't do anything at those rpm's.

Thanks for all the replies guys.

I re-did the blanking plate but did the butterfly mod this time and the noise seems to be gone, not sure if it's a coincidence but i'll take it.

Thanks all