One Injector Possibly Not Firing?

[75coupe]

Car was running fine, then decided to finally coat the caps on top of the injectors, put them all back, new stainless bolts and now black caps and its running rough.

ive narrowed it down to no6, as when removing injector plugs one by one its only one that does not kill or affect the rough idle, it has 11.72v to the plug.

How do i check the injector is firing?

Why would it now not be working after a simple take cap off paint replace bolts and reassemble?

I did at the same time take off cas and timing belt cover to paint exposed vct end as it now shows through the rb26 timing cover, but this idle is way rougher than just the cas being a smidge out and changing the cas position makes little to no dif, i had marked the cas up before removing its always been marked as it gets removed occasionally for various things...

Any help appreciated

[Dose Pipe Sutututu]

sounds there's an issue with the plug? wouldn't make sense other wise..

also put a multimeter on the injector and test the resistance - see if it's similar to other ones.

[Plattsy]

or just whip em all out on the rail and crank the engine. see if fuel comes out

[Blackkers]

only thing I can think of would be the plug. or if you can, apply an external 12v to + and 0v to - and listen for it ticking

[75coupe]

Hmmm ok they are all good suggestions except for the second one, ill see how it goes with some more testing.

Thx

[rondofj]

To test if its the plug, just swap injectors to the next plug? That'll confirm it.

[75coupe]

Ofcourse thats an easy test, why didnt i think of that, doh

[75coupe]

Ok ive confirmed its not the injectors, swapped a couple around and still same issue.

Checked plugs, one was sooty the other was wet, changed plugs, still same issue,

Thought perhaps painting the vct end of the cam has done something, loosened four small bolts on front of vct and had a look tightened them back up car is running much better but still a bit rough.

So, what do people think has happened, painting the vct has caused it to not work correctly.

I did notice the exhaust sounded weird when running rough and atmo bov noise sounded different now that i loosened the bolts on vct and tightened them again sound is back to normal beside it still running rough..

[89CAL]

What do you mean you've painted the VCT end of the cam?

[Ben C34]

I assume you have have a clear cover.

Did you reset the timing properly once you took the cover off to paint the vct?

[75coupe]

Ive got rb26 cam and timing belt covers, i cut a hole in the timing belt cover to allow the vct intake cam end to poke thru, since ive be dressing up the engine bay ive pajnted case and now the intake cam end, which is the vct actuator (not sure what to call that), so i painted the part that pikes thru the 26 timing belt cover for cosmetics, but it seems in doing that it may of created this prob.

Ive only noticed it as i painted it around the dame period as painting the caps on the injectors, it doesnt get driven much..

So when ive loosen and retighten the four bolts on the the end of the intake came, vct end part it has made a difference to the rough idle..

Hence why i thinking painting it has interfered with its operation, are the four bolts on the the end of the intake cam (vct) needing to be to torqued to a specific number or are you not supposed to loosen and retighten them at all...

This is something ive not done previously so im shooting in the dark here...

Your help is much appreciated...

[portaz]

When you say you coated the injector caps do you mean you painted the plastic electrical connections ?

[75coupe]

No, just the metal caps that hold the injectors in and get bolted down to the fuel rail.

[iruvyouskyrine]

Pics of engine bay, specifically cam gears, cam covers and VCT actuator please.

[MJTru]

Yes I agree with above^^^^^

Please send photo of engine bay. do you think you might have painted a contact for one of the injector power supply. Next did you remove the vtc timing sprocket to paint it. ??:huh:

[75coupe]

[portaz]

Looking at it I doubt that's the issue but as it only happened after you painted it must be, all I would do is grind the paint off under the bolt heads just incase it's some weird earthing issue and change back to mild steel bolts instead of stainless . I had an issue like this years ago with an audi and it's hard to accept sometimes but the issue wasn't there before so you have to start again unfortunately

[89CAL]

I'm using stainless bolts on my side feed injector caps, no issues at all

As for the VCT actuator which you have painted, It shouldn't really effect the performance of the car at all wether you painted it on the car or off. By the looks of it you painted it off the car, but I could be wrong. That bit there is all mechanical, the only problem you could have would be oil leaking from the front cover.

Seems odd that Something happened when you played with that cover. Maybe there is a problem with the VCT somewhere, maybe in the solenoid or wiring. Have you tried unplugging the VCT and seeing how the car runs? I get the feeling you might have already mentioned that you have done this but just in case

What ECU are you running/whens the last time it was tuned?

[75coupe]

I starting to think its an electrical issue, what is the vct plug?

[75coupe]

Or which is the vct plug i should say