Hissing Plug Hole

[flez1966]

Hit a problem...

Guy comes with car failed mot high emission (hydro carbons) but fairly average if a little high co2

car is running mostly on 4 cylinders but more often as not on 3 when at idle.

filters changed, injector cleaner, oil changed etc...

I told him we should change plugs as par for corse and if one is duff it would cause the high readins and missing.

New plugs no change...

But...........

Plug hole one, with plug out, was hissing... for 20 minutes + !

Sounded like it had puncture, after 20 minutes I cant see it being oil pressure, I unscrewed rad cap, so not water, cant be crankcase pressure, and i removed oil cap. cant be exhaust pressure....

Still a hissing of leaking pressure, from inside the cylinder......

So i gave up and fitted the plug.

Still missing, running on 3 occasionly 4 etc.

I think its an injector, anyone want to say I'm barking up the wrong tree or would you also be looking at tearing the injectors out?

its a 2.0 v v t i about 8 year s old i think he's gone home in a sulky mood lol.

[Jamesbelfast]

Obviously the poor CO readings is down to unburnt fuel entering the exhaust and you have been able to trace it to a cylinder misfire.

What colour was the spark plug removed from the misfiring cylinder?

It's possible a leaking injector could be the cause of the hissing. There will be residual pressure in the injection system for some time after shut-down so try releasing the fuel pressure and see if the hissing stops.

It would also be prudent to carry out a compression test in case the hissing is due to escaping coolant or gases - in fact it could be due to residual coolant evaporating inside the hot cylinder. Releasing the coolant pressure cap doesn't mean coolant can't continue to escape.

A chemical sniff test of the coolant may also reveal if the coolant is contaminated with combustion gases.

If it were me my next step would be a compression test - no point in faffing around with injectors when a compression test is quick and cheap.

[flez1966]

If it were me my next step would be a compression test - no point in faffing around with injectors when a compression test is quick and cheap.

I dont have a compression tester that can get down to the hole, how easy is it to release fuel line pressure?

Are the injectors 'in the airstream' above the inlet valve, because if it is a leaky injector hissing then i guess I was lucky that the inlet valve was open for it to be heard above ambient outside noise.

The coolent looks clear and fine and has not had to be topped up since last service app.

I could not even see the injectors, I guess there under the plastic inlet manifold?

I dont have a manual to hand for this engine is one available online?

[Jamesbelfast]

Hit a problem...

Guy comes with car failed mot high emission (hydro carbons) but fairly average if a little high co2............

Am I correct in assuming you are a mechanic or garage??:)

[flez1966]

Hit a problem...

Guy comes with car failed mot high emission (hydro carbons) but fairly average if a little high co2............

Am I correct in assuming you are a mechanic or garage??:)

Home hobby mechanic of 25 yrs experience on petrols and diesels, although have worked in a garage as auto electrician, I'm very old school taught but know my way around electronics on them also.

In all my years I've never heard a plug hole hiss like this, for such a long time, and to be so constant.

What annoyed me was the injectors were not easy to reach or even see, and I dont know the /correct procedure to relieve fuel line pressure on thi s model, I could have done many non-correct methods, but that would not be the right course of action etc

[Thermal]

My bet is on the injector.

You didn't specify the engine type, but chances are that the injectors are under the plastic cover on top of the engine.

Can you smell petrol from the hissing plug hole?

I would have the injector(s) tested.

Be carefull when opening fuel lines!

There is a very high pressure in them and you risk being sprayed.

Actually, this is a specialist job and certain parts of the fuel line connectors may not be used twice!

[flez1966]

My bet is on the injector.

You didn't specify the engine type, but chances are that the injectors are under the plastic cover on top of the engine.

Can you smell petrol from the hissing plug hole?

I would have the injector(s) tested.

Be carefull when opening fuel lines!

There is a very high pressure in them and you risk being sprayed.

Actually, this is a specialist job and certain parts of the fuel line connectors may not be used twice!

Thanks I put what i thought i knew about the engine type in th e1st post but after googling for images I can say its very much like this engine..

EXCEPT our hissing sid has got TWO oxygen sensor on the front manifold and that picture as nonoe, that may be relevent...

We have the same plug packs above the plugs, but the inlet manifold is plastic and goes downwards.

and it says on the side of the car 2.0vvti.

I tried to video the hissing ewith my phone but the phone has noise cancellation so has filtered the hiss, but you can at least see then engine

yLBOuMYG4Es

YOutube

So, 'how' do i release fuel rail pressure ????

And yes the plug hole did have a tiny smell of hot fuel vapour

I have looked through these forums and I cant find one image of a guy with his engine on the wifes best dinner table while she is at bingo, its not like the usual citroen/ford forum.....

Dont any of you lot ever get dirty fingernails lol

Is there any pictorial guides to fuel system de-pressurizing etc or at least a vague desciption of a valve/tap to release it with?

If the info i have learned in my many hours of googling this evening is thats its a spark ignited diesel engine, so i guess only way to release prssure is to the crack open the ends of the injector pipes like on a diesel?

[Thermal]

Hi,

You really need to be specific on the engine type.

Toyota used many different engine types through the years, and they are all different.

The D-4 in 1AZ-FSE stands for Direct injection, not Diesel.

Here's a link to an interesting file.

It's not complete, but it contains a lot of interesting drawings etc.

UNRAR the downloaded file and enjoy.

http://www.mediafire.com/?gw1wm4kq2vj

[flez1966]

Toyota used many different engine types through the years, and they are all different.

The D-4 in 1AZ-FSE stands for Direct injection, not Diesel.

Thanks for the file, looks liake it has a few bits that will be useful

No its not a diesel, its a petrol, but I cant fid leads going to the injectors or even see them, so after typing '2.0 vvti injector'' into google i found some pictures of injectors, went to those pages, and then found its mechanically injected ???

I know VW did this with an engine and even a porsche had one like that, but i thought electrical injection replaced all the cogs and springs you get in sewing machines...

Any-how, the original question is still unanswered, how does one remove fuel pressure form the injectors if they are the mechanical type so i can see if this stops the hissing and proves the injector to be leaky?

[Thermal]

... how does one remove fuel pressure...

There are several ways to relieve the fuel pressure.

The simplest might be to remove the fuel pump fuse (ref. Users guide for location), and let the engine run until it stalls because of fuel starvation.

Other methods require vacuum equipment, which you may not have laying around.

Then remove the negative Battery lead, before proceeding to any fuel system component.

To locate the injectors, you have to know the engine type.

In the above RAR archive, there is a file called "fuel.pdf".

In fuel.pdf, there is an exploded view per engine type.

Hint:

If you remove more than 1 injector at the same time, make sure to mark/label them.

They must go back into the cylinder where they came from, or else the ECU has to be re-programmed.

That goes for new injectors as well.

[flez1966]

... how does one remove fuel pressure...

Hint:

If you remove more than 1 injector at the same time, make sure to mark/label them.

They must go back into the cylinder where they came from, or else the ECU has to be re-programmed.

That goes for new injectors as well.

All very good info i should of thought about fuel pump fues....Doh, on mine there a release lol.

Ahh I saw something in another thread about injectors being specific, no doubt it makes them cheaper to produce and let the ecu know the fuel rate per injector and compensate on the fly, then try to manufacture them all to exact flow rates and have to throw/recycle the failures

Do they do the same with the coil packs?

When he gets time to pop back i'll remove theplug from the offending cylinder make sure we still have a hiss, then put plug back in and pull the fuse, see if we have hissing after its ran dry.

I hope under those conditions its not a case of the pressure drops low enough to not open the valve, but still has enough for a hiss, to be sure I'll get him to come when he has a bit more time so it can stand for a while to see if it stops after say 30+minutes etc

[Thermal]

As far as I know, Toyota uses a special "Fuel tester" device to adjust the fuel rate per injector, which then stores that data in the ECU.

No 2 injectors are identical, therefore it's so important to label them after removal/cleaning.

Beside that, dealers have the so called "Toyota Intelligent Tester" (TIT) equipment, with which they can monitor and adjust almost anything in a Toyota you can think of.

These cars are getting so complicated, that it severely limits the number of DIY jobs, without the required Special Service Tools (SST's) and TIT.

That may be a reason why Toyota owners generally have clean finger nails, another being reliability.

(** knocking on wood **)

[flez1966]

That may be a reason why Toyota owners generally have clean finger nails, another being reliability.

(** knocking on wood **)

Ha Ha yeah, I live at the other end of the spectrum my personnel cars a citroen....

Although there getting so computerised now the same things the problem, no diagnostic software, so you cant change anything...

I know mine is very very computerised but its distributed, one ECU per job and quite often its a copy of something else or works the same as something else so substitution or rebuilding is possible if you can weild a soldering iron..

I've become quite amazed at how so many so called car manufactures dont manufacture most of the cars there sell, the just buy bits from parts suppliers and then put a body Shell round it and call it there own..

Look at any main car on the road and it will have a ZF gear box, Bosch ABS, someone else's cabin heater..

I call my car a citroen, its a PRV engine (peugeot renault volvo build), Lucas brakes, Bosch ABS, Bendix got a hand in, ZF made the awful gearbox, Webasto made my sunroof......

The hubs for the wheels were 8 years later used again by volvo before ford put them on the vans, and when my map sensor dies I just take one from a GM astra....

BUT...

Thats all digressing....

The owner has had a comp test and all cylinders within limits and of each other so no cracks or leaks, but one plug, not on the hissing cylinder, was very sooty compared to the other new ones, the other guy looking at this now has replaced or is replacing that plug pack, I wish him good luck because it could be that, and I hope for him it is!

I do know on some cars plug packs are un-relaible so its a good bet. personally, I'd have cleaned the plug back up, and /swapped plug packs around to see if the sooty'ness moved with it as 'free' confirmation, he drives it everyday etc its a taxi so would have only taken a shift at work to see and cost nothing.

[Thermal]

Spark plugs...

Some engine types are indeed very sensitive to the correct spark plug type.

The Vvt engine type concerned here may be one of those, since its electronics may be able to switch between lean-burn and "normal" modes frequently, to achieve its claimed economy.

That requires the correct spark plug, in order to survive in those changing environments.

However, that's an entirely different subject and doesn't explain the hissing.

Let us know when you find out what caused it.

[flez1966]

Spark plugs...

However, that's an entirely different subject and doesn't explain the hissing.

Let us know when you find out what caused it.

if the plug pack works i doubt anything will be done for the hissing.......

will update when i know more