Help: Injector readings - what do they mean?

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

All good except my 120 had an injector at 3.3 and didn't cold knock, blow white smoke or rattle like a tin of marbles.

[rob_macca67 Avid PP Poster! Find all posts View Profile Close rob_macca67]

Just went down to visit the local toyota dealership to chat with them as to what the recommended limits are that ALL Toyota Dealerships should be quoting..... They proceeded to show me their database and it stated +/-5 for Euro-4 Injectors. The Head Mechanic said the older Euro-3 style injectors were +/-3 but the new ones are definitely +/-5.
He went onto explain that when one cyl is high the corresponding other one would mostly be reading low (ie: 1 & 4cyls; 2 & 3cyls).
We then got onto the under bonnet fuel filters and how toyota don't change them until the light comes on. The mechanic said if the vehicle was his that he would change his every 20,000kms and not wait until the light comes on..... mainly due to the quality of our fuels here in aust.....

I had my injector feedback values checked and they came back all within the tolerance that toyota quoted with the highest (#4) being -2.5. I've always tried and run BP fuel when it's available; I run a 2micron AUX fuel Filter + a Fuel additive so I've done all I can do to protect the engine/injectors. The car runs sweet and the engine is nice a quiet with none of the rattles that people have heard..... So. for me, I'll just keep an eye on it and will request a injector FB reading every so often when they need the vehicle for the overnight major servicing.....

[timforward89 Lurker Find all posts View Profile Close timforward89]

Hey Sydneydude,

Not sure if i read this wrong but you stated the engine would knock under load, by the looks of it all testing was done at 0 KM/H. I would personally get the car in the same conditions that causes the knock and analyse those results. Sine there is no load on the engine significantly less fuel will be injected, providing inaccurate readings of what is actually going on. By reading the printouts the maximum engine load factor you applied while conducting these tests is a mear 30.3%.

In terms of the negative and positve on each injector, this is normal. Because each injectors will have a slightly different internal friction on the valve, a setting is provided from factory to deliver what is called "Metered Flow", meaning they will distort the injection time ever so slightly to acount for these differences in fricton, therfore each injector will inject the same volume of fuel.

The "Injector feedback value" is how the ECM determines if an injector is excessively worn. As the solenoid on each injector de-energises (after completing injection) an internal spring will return the valve spool. This movement of the de-energised valve spool creates a magnetic field which then collapses as the spool closes/stops movement. As the field is collapsed current is induced, now a current has been supplied to the ECM from the injector. The time in which the ECM de-energises the injector, to the time the ECM recieves a backfeed of current is measured. Using calculations and spec limits set by factory, the ECM can now determine if the injector is worn because a worn injector spool will close faster than a new one(because there is less friction)

In saying all that, i would test the car under those conditions that cause the knock and be looking at desired fuel rail pressure, actual fuel rail pressure and look at temperature differnces from fuel from supply to fuel return. Currently you have about 40 degree increase in temp on all charts, see if this changes when load up the engine and increase the pressure and flow rate of your high pressure pump. High fuel rail retrurn temps usually indicate rail leakage, misfunctioning reliefs and worsely, high pressure fuel pump failure. I would also be comparing results with Toyota specs not people opinions on what they should be (no offence).

Hope this helps your understanding a little better, Tim

[120D4D Avid PP Poster! Find all posts View Profile Close 120D4D]

Bloody hell Tim - that is one impressive first post!

[timforward89 Lurker Find all posts View Profile Close timforward89]

Cheers 120D4D,

Sydneydude,

No worries at all mate didn't really solve much, i just feel you can still check a few parameters to check before condemning an injector.

You say only when it's cold it knocks, this isn't the typical diesel knock that most diesel engines get at start up?

If not, and dont quote me on this coz i cant find a cut away of a 1kd-ftv engine anywhere on the net, so I cant see the layout of seals. Apparently the copper seal between the injector and head fails, causing cylinder gases to run up the side of the injector and subsequently failing an o-ring that seals the top the injector from engine oil. as it read, engine oil would then run into the cylinder overnight and cause that knock at start up.

Now this should also cause blue smoke out the exhaust(if burning engine oil) and white smoke if overfuelling.

I was thinking a good way to test the integrity of both seals would be disconnect all injector wiring harness; and leave them disconnected. Remove the rocker cover and get a second person to crank the engine. Watch and listen for the cylinder gases escaping from that top injector seals, maybe slowly drizzle clean engine oil over each injector to diagnose the failed pot. but honestly i think you will hear it, like a puffing sound from the failed pot. Just remember, the injectors' wiring has been disconnected so this will more than likely generate a fault code, so make sure have a scanner handy to reset the codes or risk derating the engine.

Don't forget to readjust the engine oil level after putting it all back together.

[ToeEdge Junior Member Find all posts View Profile Close ToeEdge]

I've just checked my values with Techstream as I have noticed mine getting the "cold knock" for the past several weeks.
Cold -
Cylinder 1: 2.3
Cylinder 2: -1.6
Cylinder 3: -3.0
Cylinder 4: 1.5

Hot -
Cylinder 1: 0.1
Cylinder 2: -1.0
Cylinder 3: -0.8
Cylinder 4: 1.2

Those cold figures look pretty bad. Question I have is why is injector 4 seemingly stable?

[Foxy48 Member Find all posts View Profile Close Foxy48]

Hi ,My shortie is about to go in for the 80k and the cold start. I do have a rattle but I thought it was my air box but I have eliminated that . It is only when cold and I put her into reverse under brake coming out of the carshed and then when driving off . For a little while it would disappear when hot but now it seems to be all the time .Please don't tell me it is an injector I'm only a lowly pensioner but I have a feeling I will have to bite the bullet .BTW what program are you guys using to get these readings through the port? Cheers Foxy

[120D4D Avid PP Poster! Find all posts View Profile Close 120D4D]

Cross your fingers Foxy, it might be an engine mount only.

the mounts are not cheap to replace either but at least you can put up with it and keep on trucking!

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Foxy where are you? May be able to point you to someone who can help you out.

[Anth120playdo Banned Find all posts View Profile Close Anth120playdo]

Don't take risks, just put new injectors in.
Genuine only. Make sure they are new new new.

[Foxy48 Member Find all posts View Profile Close Foxy48]

Hi people, thank you for answering my call, I live in a little country town called Lobethal in SA. I'm about 50k's out of Adelaide. I was an ex dairy farmer and a Vietnam vet, Cheers Foxy
120D4D, Mate, I have got everything crossed and then some, I do hope your right
Mjrandom, Thank you for your help ,it would be appreciated

[Foxy48 Member Find all posts View Profile Close Foxy48]

#############,sorry I forgot ,Yes It rattles first thing when cold and when I put her into reverse so I'm praying your right Cheers foxy

[120D4D Avid PP Poster! Find all posts View Profile Close 120D4D]

Well as possibly Baileys most recent Pradopoint client I thought I'd provide some (very) early feedback. - Probably stating the obvious but Matt and Luke at BDG were a real help - thanks Matt for the time you took over the phone & via PM.

I was directed to Southern Fuel Injection (SA) and they were fantastic to deal with - I really miss good old fashioned service!! I have my prado back, better than new and under budget!

I knew I was onto a good thing when I spoke to Matt and being referred to an experienced injector mechanic in SA meant I was in safe hands!

For those looking at less than ideal injector feedbacks - dont want for the grenade, ring Baileys and they'll point you in the right direction...

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

And you got the new spindle coated DLC ones, lucky bugger. Should see you right for many years to come.

Cheers Andrew

[iantz Avid PP Poster! Find all posts View Profile Close iantz]

Well as possibly Baileys most recent Pradopoint client I thought I'd provide some (very) early feedback. - Probably stating the obvious but Matt and Luke at BDG were a real help - thanks Matt for the time you took over the phone & via PM.

I was directed to Southern Fuel Injection (SA) and they were fantastic to deal with - I really miss good old fashioned service!! I have my prado back, better than new and under budget!

I knew I was onto a good thing when I spoke to Matt and being referred to an experienced injector mechanic in SA meant I was in safe hands!

For those looking at less than ideal injector feedbacks - dont want for the grenade, ring Baileys and they'll point you in the right direction...

When we did the snorkels at Gramps I heard your rattle after you started the car. Didn't want to say anything! Glad you have rectified the issue!