Fuel Injector Drawing Air

[James Cornell 10]

I have just sent my yellow top injectors off to injectortune to have them sonic bathed and recalibrated/serviced. They have come back looking like new and the caps, o rings and filters have been changed, in short I am very happy with the service.

 

When I refitted them I applied a small film of oil to the o rings and they seated well and do not leak any fuel. The car is running more smoothly and it is more responsive so a big win there!

 

However injector 1&2 have a distinct hissing sound coming from them and I am not sure whether they are letting be small amount of air through the seals. One other thing that I have noticed is that even after a good run the inlet manifold is considerably cooler (still hot) than it was before, this leads me to believe that the engine is not running mega lean.

 

In short is this normal and I did not notice this noise before because the injectors had never been removed and there was a load of crap in front and behind the seals?

[welshpug 1,661]

Definitely should not be leaking, spray something like brake cleaner or wd40 on the area when its running, of the revs change then theres a leak.

[James Cornell 10]

I tried spraying a small amount of easy start orotund the injector whilst it was ticking over and it did not seem to raise the rpm.

 

The car seems to have a new induction noise which sounds sucky (sorry for the poor description)...weird maybe the car is running as it should Now and I have been used to the sound of it being imbalanced?

[hoodygoodwood 71 3 Cars]

Could the 'hissing' that you can hear be the excess fuel over 3 bar bleeding off at the fuel pressure regulator , or possibly air leaking through the regulator if the diaphragm has perished - you should not be able to 'suck through' it at the black pipe .

[opticaltrigger 52]

That's a good one Miles.I hadn't thought about it from that angle to be honest.

 

O.T.

[James Cornell 10]

I will have a suck tonight but the hissing is coming from the flywheel side of the engine not the regulator side.

 

Also running cooler would normally be a good thing I would imagine but I will have the plugs out to make sure 1&2 aren't considerably whiter than 3&4

[James Cornell 10]

I have made this mistake before, I am counting cylinder 1 as the flywheel and cylinder 4 as the cam belt...I can never remember which way you count them ????

Edited January 13, 2016 by James Cornell

[hoodygoodwood 71 3 Cars]

Did you remove just the fuel rail and injectors because that cuts down on the areas where the fault could be , if you had removed the inlet manifold you might have an air leak caused when refitting it . Does sound a bit like an air leak - could you have dislodged a hose etc .The dreaded oil filler fixing bolt is very close to injector number 4 ( RH ) .

When I had my Goodwood fuel injectors ultrasonically cleaned they came with a printout that showed they were flowing slightly more fuel than before so could run fractionally cooler but would it be enough to notice ? . The fitting instructions warned that the injector ( pintle ? )can stick , so to free it the metal part of the injector body can be tapped with a small spanner .

[James Cornell 10]

When i removed the injectors I just removed the fuel rail and left the inlet manifold alone. The ultrasonic results showed the two of the injectors were 192, one was 196 and one was 198. After the cleaning and replacement parts the flow was an equal 199 on all injectors.

 

Also the spray pattern was ok/fair on all of the injectors and good after so maybe this has cooled the combustion down a bit?

 

Part of me is tempted to remove and reseat the injectors but i am not sure whether this is advisable now that the car has done 60 or so miles