Misfire, then non-starter this morning -- HELP!

[prj]

They will just pull off together with the fuel rail.
The only thing you will have to overcome is friction of the o-rings against the inlet manifold.
Also, when re-fitting the rail, put some oil on each of the injector o-rings, it will be much easier to re-fit that way and you will avoid damaging the o-rings.

[ericd]

The connector for the haul sender is the plug at the front of your engine that is fixed to a small bracket on your inlet manifold.

If you remove the coil pack and your plugs, put your plugs into the coil boots and then crank it over you will see if they are all sparking correctly.

As Brian states the hall sender plug is right at the front of the engine, near vacuum hose and bracket, another thing worth mentioning , when myself & others experienced hall sender failure, and subsequently more turns to start, keep an eye on the battery strength , sometimes although it would merrily spin the engine over , sometimes you'd get a vag-com code hidden away indicating something like insufficient voltage, I'm sure i stuck something in here years ago about it and the code it would sometimes generate, so keep the battery as charged as you can when you're trying to get it going...

[UrS4boy]

Fuel pump and Crank Position Pin info

Reading through this thread, it is entirely possible that the misfire was because of a dodgy Fuel pump that has now completely packed it in. Suggest that you remove the fuel rail and injectors (as previously suggested) and place the injectors (still attached to the rail) into five containers (small plastic water bottles?) one per injectors. Then have somebody attempt to start the engine while you observe the injectors. No fuel would indicate either dead fuel pump or missing crank position pin (they do fall off the flywheel sometimes).

Here is some AAN fuel pump info that you can adapt to your situation (note the internal hyperlinks):

http://forums.quattroworld.com/s4s6/msgs/22623.phtml

Here is some crank position pin info.

http://forums.quattroworld.com/s4s6/msgs/51259.phtml

[Bowlerwell]

Thanks guys. I'll try measuring fuel flow ASAP.
Thanks again for all your help.

Sent from my HTC Desire using Tapatalk

[Bowlerwell]

Update.

Ok, so I have a spark, so the sensors must be fine. In any case, I have bought a new set of F5DP0Rs, just not sure how old the current ones are... they're fairly black.

I removed the fuel rail (fuel everywhere now, so looks like there was residual pressure) and inserted the injectors, then pointed the end one into a cup and connected it electrically (all the other injectors in the rail, but not connected electrically). I cranked maybe 6-7 times before the battery died, and got 1 spurt from the injector.
Does this sound about right, some time to build up pressure, then a spurt before the battery died?

I'm starting to think maybe it's not the fuel pump.
Perhaps the engine is just flooded since I only ran it for 20secs on Saturday? Plausible?

[prj]

I cranked maybe 6-7 times before the battery died, and got 1 spurt from the injector.
Does this sound about right, some time to build up pressure, then a spurt before the battery died?

No, it does not sound right at all.

[Bowlerwell]

Then what should I expect?
I'll have the battery on charge tonight and retry tomorrow.

[prj]

It should pretty much start squirting fuel from each injector in firing order almost right away.
If it is barely squirting after 6-7 revolutions hm... well, you can try to crank it more and see if you start to get a nice spray at each injector.

But your issue sounds like fuel pump, if you have spark and it is not squirting fuel properly.
Although then I don't see how you have a misfire in only some of the cylinders.

[Bowlerwell]

Thanks Dimitri.
I'm gonna get the injectors cleaned anyway.
Could it be that 2 injectors are more gunked up than the others, and a failing fuel pump caused those cylinders to fail first?

I'll also run a fuel pump flow test.

Also, can anyone explain to me the procedure, and best place to insert a fuel pressure meter?

[UrS4boy]

...I removed the fuel rail (fuel everywhere now, so looks like there was residual pressure) and inserted the injectors, then pointed the end one into a cup and connected it electrically (all the other injectors in the rail, but not connected electrically). I cranked maybe 6-7 times before the battery died, and got 1 spurt from the injector. I'm starting to think maybe it's not the fuel pump. Perhaps the engine is just flooded since I only ran it for 20secs on Saturday? Plausible?

Ummm...sounds like you didn't remove the fuel rail as I had suggested, i.e. as one unit, injectors and hoses attached (electrical connectors temporaryily detached). Should not have had to spill any fuel that way. And then once out, put each intact injector into a suitable container (small water bottle) and connect the electrical connectors. THEN try cranking the engine while somebody watches the spray coming out of the injectors.

The way to clear a flooded engine (with a good battery), is to put the throttle pedal to to floorboard while cranking the engine. This opens up the flow of air into the engine to help purge the excess fuel from the cylinders. I guess people who have grown up on fuel injection and not carburetors never learn (or have to learn) this trick.

[Bowlerwell]

Ummm...sounds like you didn't remove the fuel rail as I had suggested, i.e. as one unit, injectors and hoses attached (electrical connectors temporaryily detached).

I attempted to remove it this way Dave... but it didn't work...
With some wiggling around to ease the injectors out of the head, it finaly gave: but left 2 injectors in the rail, and 3 in the head. I then had to remove the 3 individually and re-insert them into the rail.

Will re-test with charged battery when I can.

Thanks again!!!

[Bowlerwell]

Ok, I have charged my battery and re-checked the injector firing.
I have pools of fuel in each container, and I think they were firing in the correct order.

[Knight Rider S4]

Hi John


Two things I would check as mentioned the hall sender but lambda sensor would be a good bet here as if this is knackered it will cause back firing , unsteady tick over and failure to start in some cause , I had this with my old red avant

If you have a POS failing they usually work better when cold heat makes them fail ,
Injector fault might be there but this would not stop the car from starting , I have seen them run on 3 cylinders


Cheers

Steve

[Bowlerwell]

Thanks Steve.
I have spark and the injectors are firing, so the hall sender should be fine.

Yep, it could be a lambda. Especially if you have seen these symptoms before on a bad lambda!

I thought about POS, but it was Cyl 2 & 4 misfiring, so that's mean both POSs broken. THen when it failed to start, I assumed it wasn't POS since it's unlikely they all broke simultaneously. (I now know i'm getting spark on coil pack 1 anyway)

I'm gonna get the injectors serviced, put in new spark plugs, and maybe a new lambda too.

JB

[prj]

Uhm, forget the lambda.
That won't cause it not to start.

You can just disconnect the signal wire and it will just not be used...

And yeah, it sounds like your engine is flooded for some reason. Put everything back together and crank it with the throttle pressed to the floor. It should start after a while.