Petrol Fuel Injectors

pikey · Unread post by **pikey** » 07 Jun 2004, 18:25

Have an issue with number 3 cylinder not firing. Checked ignition which is fine, sparking well. I have taken rocker cover off and viewed that everything looks in good order. Removed plug and started (do not have compression tester), sounded like a tank with no exhaust but engine ticked over exactly the same as when plug is in. Looked to me like there was pressure but did not want to loose end of thumb in process.
Decided it may be a fuel issue, however I have limited knowledge of fuel injection.Removed fuel rail and swapped number 4 with number 3.
Have not started up yet, awaiting spilt fuel to evaporate then will test.
Am I following the correct path? Does the tank noise with the sparking plug sound about right ?
94 20i 8v xantia

AndersDK · Unread post by **AndersDK** » 07 Jun 2004, 20:06

You seem to know what to do, to trace the problem [;)]
A cylinder building up pressure, will be noisy. Also the open injector hole will emit resonance noise from exhaust, as the exhaust valve opens.
It's rare to see an injector fail completely, often they simply seep out fuel constantly, but you never know.
- now - if the problem moves to cylinder 4, you have your faulty injector.
If the fault is persistent on cylinder 3, you have an electric problem for the injector drive feed.
Note that one side of the injector coil is (must be) a constant +12V feed (engine running), the other side is an earth pulse provided by the ECU.
The injector coil may simply be disrupted, or the wiring is faulty for injector 3.

pikey · Unread post by **pikey** » 07 Jun 2004, 20:37

Thanks,
great info about the negative switching !!!
I,ll have a look tonignt.

wheeler · Unread post by **wheeler** » 08 Jun 2004, 00:28

what about a resistance check of the resistors ? check each one (with the wiring disconected from it) if one of the injectors has failed electrically then you may well get one of them with an odd resistance from the others.

Unread post by **alan s** » 08 Jun 2004, 03:13

This may be worth a read.
http://www.autospeed.com/cms/A_2119/article.html
Alan S

pikey · Unread post by **pikey** » 08 Jun 2004, 15:12

Thanks for your replies,
Started up last night and number 3 is still down, so not injector issue, checked voltage on digital volt meter and I had a no voltage reading on injectors when the ignition turned (fuel pressurized) an any injectors. checked across connector terminals and between each terminal and the -ve battery connection but no reading. checked meter on battery and was ok. Should I only see voltage when the engine is running?
So it looks like I am down to either valves/piston or ecu.
Any ideas would be great!!!!

Unread post by **alan s** » 08 Jun 2004, 16:10

Further to the above link I posted, from personal experience you will possibly find that the pins are pushing the sockets back inside the plugs on that injector and as a result you're not getting the power through. It's such a simple solution that most won't/can't believe that's all it is.
Alan S

pikey · Unread post by **pikey** » 09 Jun 2004, 15:39

checked voltage on injectors last night.
all seem to switch upto 8v on my digital volt meter between ecu case and both pins.Reseated ecu connector (looked in good condition.
time to have a serious look at compression.

pikey · Unread post by **pikey** » 10 Jun 2004, 15:27

right, checked compression last night and is follows.
1=185 psi
2=90 psi
3=90 psi
4=190psi
I am pretty sure the head gasket has blown between 2 and 3. Can anyone confirm this suspicion ????
oil does not have any water trace.
Also is hermitite red a good idea when replacing the head gasket?
jeff

Unread post by **alan s** » 10 Jun 2004, 15:41

<font color="red"><font size="4">Off with his head!!!!!</font id="size4"></font id="red">
Alan S [}:)]

Unread post by **philhoward** » 11 Jun 2004, 20:55

It's a 99% chance that the head gasket has gone with those readings; failing that you've two sets of valve gear playing up at the same time. Either was it's as alans says.
Hermatite red? NOOOOOO! You shouldn't need anything on modern head gaskets, as they have an impregnated goop built in to them. On older engines than the Xantia lump (old minis, fords, etc) i used a very thin smear of Hylomar Blue sometimes on the HG; usually on inlet manfiold gaskets and thermostat gaskets etc. If it's good enough for Rolls Royce, its good enough for me.