Can pre in ignition be mapped out?

[td163]

Hi guys,

Long story short I am chasing a very annoying tapping/rattle noise it is very annoying to me so up to yet I have replaced the crank pulley and after this did not help I replaced all the injectors with the 076 version today which supposedly stops this noise but it has not helped at all.

The noise can be quite loud under full load and you can hear it anyware from setting off up to 3.2 where it goes. As soon as the accelerator is pressed even the slightest bit it can be heard and stops soon as it's released. It's confusing me quite alot as I really expected these injectors to stop this as many have said. :/

Can pre ignition be removed when having a map done? Also is it safe to disable it?

Thanks guys.....

[Poodle]

It probably can be removed, but it increases efficiency so do you really want to for the sake of a bit of noise? Buying second-hand injectors is always a risk, i'd recommend going for refurbished myself, mine got rid of the noise, gained some mpg and possibly solved my cutting out problems.

[td163]

It depends on how much efficency but if it wasn't too bad I'd do it honestly ....from research I was under the belief the pre ignition was put on to quieten the engine down by 3db and to make it more emmisions friendly.

The injectors I got had only 90k on them and being the 076's I thought I'd have been OK as people are reporting 180k on those with no Rattle.

Although just been for a 30 mile drive and once the engine is to full operating temp the Rattle is quieter but still quite noticeable under light acceleration and low rpm.

[Poodle]

Yeah, that too, it effectively primes the combustion chamber to provide a more gradual, complete and efficient burn. In all honesty i think the best thing you can do to help it is add sound deadening under the bonnet.

[Uberderv]

You have probably bought some faulty injectors. The problem is that you can't test the injectors before buying them. If you were to do a leak off test you might see if its only one at fault or you could listen to each injector using a small tube on the body.

[Ruan]

Trust me - you don't want the pre-injection mapped out! You thought it was loud before, it'll sound like a transit van when cold without it - it's the pre-injection that quietens down the main injection.

[td163]

OK ok I'll drop that idea then lol. I am going to try this two stroke in the tank of diesel see if that helps and if that doesn't cry

Can anyone tell me that trick with the screwdriver on the injectors to find the noisy one? Where on the injector do I put the screw driver? Do I press on or not? Etc etc

[Uberderv]

You can use a tube, imagine its like a doctors stethoscope. You just put it where you want to listen, in this case the injector body.

[td163]

I don't think I've got any tube... Plenty of screw drivers though would that work?

[Uberderv]

Yes lol, just the vibrations from engine will be transfered up the driver to your noggin if you hold it too close. It will still work though

[Poodle]

Screwdrivers will work fine, you might struggle to interpret what you're hearing though. Put it as low down on the injector as you can without the shaft of the driver toucing anything else.

[td163]

Thanks for humoring the diesel newbie lol.

[pro_steve]

I could probably figure out how to turn it off, but I wouldn't want to, the whole purpose of it is to make it quieter, fit a set of low mileage injectors instead, I'm sure that will make it run nicer.