Just wanting some guidance on some interesting phenomena.

I have a 1JZGTE (inline 6, twin turbo) powered Soarer running 650cc high impedance Sard injectors. Factory items are high impedance 380cc. I purchased the replacement injectors new; they would have travelled perhaps 10000km in my car.

For a while now, I've heard this rapid ticking noise, most notable on idle, coming from the area of the fuel rail. I wasn't sure whether what I was hearing was cam shims that needed doing, or a dodgy injector(s). At no stage have I had duty cycles >70%, or an engine that's running lean on the dyno. I can't hear the noise once the engine's revving; not sure whether that means it's truly subsided or merely inaudible.

Today, for fun, I tried messing about with the PFC injector compensation (i.e. % & lag) on a per-injector basis, to see whether I might be able to precipitate anything.

The results, interestingly, were that the compensation value (be it % size, or lag time) seemed to matter only when it applied to injector #1. The engine ran noticeably rougher and literally dripped petrol when I adjusted for positive lag time, and any negative lag time caused the idle to hunt like crazy, as has happened before when I've deliberately induced a lean idle to check AFRs.

I could input any compensation value or lag time into any of the other injector rows, and there was no perceptible change to the idle.

My questions, therefore are :-

a) Is this behaviour peculiar to the PFCs injector management, or is it significant ? What I'm getting at is, of course, whether this is an a posteriori test that demonstrates a dead/dying injector on #1 cylinder, causing that ticking noise, or, conversely, demonstrates that the *other* injectors are cactus because the compensation values seem to make no difference to them?

b) Would a confirmatory test be to unplug each injector and corresponding spark plug and see whether the ticking noise vanishes when the injector's unplugged ? Is this necessary given the behaviour above ?

c) If it is injector based, what exactly does the ticking noise represent - (imminent) electrical failure, or mechanical failure ? If mechanical, does it indicate that the pintle is failing to be actuated completely ? Or that there is a mechanical obstruction (one that might lend itself to either detergent based injector cleaner additive, or removal and ultrasonic cleansing of the injectors) ? If it's electrical, what if anything can I do to isolate the problem and fix it ?

I'm trying to avoid having to pull the injectors or replace them, but am willing to do both as needs dictate.

Thanks for any advice or suggestions.

 

Unless the PFC is quirky, I would think something is going bad with the #1 injector or it's driver.

Watson, I suggest that the evidence suggests that you do the next most logical test! Doh Holmes, what is that?

It is a binary test. Swap positions with another injector to verify if the problem switches with the #1 injector or stays with the #1 position.

 

Chuck, thanks for the advice; that was going to be my next step.

What are some common "something(s)" that you're referring to?

I ask because any Watson worth his salt would want to try and divine a diagnosis at a time other than autopsy, to continue your analogy

 

When I use a direct diagnostic connector and wiring to test fire (open) an injector, I can hear it click. That verifies that it is opening but not that it is closing all the way. It would have to be taken out and placed in a test holder with pressurised fluid or air to check for leaking. And, sent to an injector shop for flow testing.

I never heard my injectors click when the engine is runnnig on my RX7. Stock or mod, maybe my engine is just too noisy?

What would cause more noise (clicking) than the others. Maybe if something inside was worn, the pental is sloppy and is hitting harder, or the spring is weaker.

I can seperately change lag and it will affect the injector and idle, but then we only have two. You have 6, so changing only one would have less affect on idle.

I would presume that your PFC would treat each injector identically, so if changing one has more affect than the other 5, something is wrong with that injector, it's wiring, or driver within the PFC.

 

Actually...I have a question as well, this clicking, coudlit be knock that you hear at Idel? my FD is acting up lately. I think one of my 850cc is stuck open, becasie even when I change lag to -20 I cant even get it bellow 12.5 afr, where as a week ago I could get it to about 14.5 at that range at idel. Now oddly enough My engine had flooded before this started happening. At the time I wasnt sure why my engine was flooding. I had also noticed that the wires to my IGniton amp box woudl make the idel hunt about 100-50 rpm...SO i rewired it for nice tihgt connection. It now longer hunts when touched. But the idel still hunts and runs hella rich now. Keep in mind I use 850s in the primary. I had them cleaned before I dropped em in, coudl it be one of them is stuck open? anyway to check if it is the Injectors without pulling them out completely? Or coudl this be a ignition system probelm.

 

Just a follow up to this ... I removed all 6 injectors, which was a massive, unadulterated PITA, but really very worth it. Dropped in 6 new Sards, and lo and behold - rock solid idle (there was this really annoying misfire, that I'd been chasing as an electrical problem for literally months ...), normal PFC behaviour, *immediate* starting (hot or cold, without needing to play around with Cranking Inj settings !), and just a general impression of overall smoothness that's been missing for a long time.

I'm going to get them flow tested at some stage soon, but I think that one or more was either stuck open, leaking around its seals, or generally unhappy.

At this point I'm delighted It's been an expensive exercise though