my testing the injectors on a KR (K jet) 16v

[davidwort 0]

OK, inspired by a thread on the Club GTI forum I've spent today testing the injectors on a KR (K jet) 16v

thought I'd post my pics and info up on here in case anyone here was interested

most important thing, it's playing with vapourised fuel and is very dangerous to do in an enclosed space, I did this outside of the garage and with an extinguisher handy

 

1. remove the battery negative lead

2. you can remove the blue fuel pump relay and jump the main pins for it on the fuseboard to run the pump without turning the ignition on

3. then to run the injectors/pump simply reconnect the battery -ve

4. you need each injector spraying into a bottle, about 500ml capacity each really

5. take the big boot off the top of the metering head and lift the airflow plate to the maximum position, this simulates full throttle max airflow into engine and so full injector pressure

 

 

6 run the pump for 1 minute exactly and compare the amount of fuel delivered by each injector, this compares the relative amount of fuel to each injector from the metering head, should obviously be equal from each injector

7. check out each injector spray pattern to make sure they are spraying fairly neat cones of atomised fuel and not badly uneven 'squirts'

 

 

below are my results:

no. 1 cyl injector

 

no. 2 injector

 

3 and 4

 

inj 4

 

3 and 4 output in 1 in min

 

and the delivery was all remarkably even across the 4 over 1 minute at full airflow plate deflection

 

Couldn't believe the noise it makes, hell of a racket! At that flow rate you'd empty a full tank of fuel in an hour I reckon! lol

As warned, the fuel vapour is v dangerous, even into narrow necked bottles, very glad I did this outside in the fresh air, huge amount of vapour created.

Anyway all seems well, a few odd bits in the spray patterns, but I don't think they are too bad, are new injectors perfect spray cones? I didn't think even they were?

Very tempting to do a wideband lambda and gauge, looks like it could be extremely useful even if not going fully EFI on the engine - this idea for K-jet is credited to the chaps on Club GTI, very nice work and great info gained on the Air/Fuel Ratio over the full rev range, clearly shows the limit of K-jet fuelling at high revs.

I'm going to bung some injector cleaner through the tank anyway, hopefully that can only help.

Next job is to check out a ropey fuel sender in the tank :)

 

Edit: 24/11/09 I now have the official VW test procedures/info for the whole injection system, pressures WUR resistances etc.

here's a taster:

 

ISV should measure 3.5 to 4.5 ohms across terminals

warm up regulator resistance (it has an internal heating element) should be 20-26 ohms

to check control pressure of fuel from warm up regulator you need the appropriate unions and a fuel pressure test gauge, but after 2.5 to 3 mins control pressure should increase to 3.4 to 3.8 bar

it should be about 1.7 bar on a cold engine with 20 degree ambient temp

ecu temp sensor (small ones on side of head) should read 2,500 ohms at 0 deg C dropping to 100 Ohms by the time the engine is fully warm

injector delivery rates should be:

at idle, after 20ml delivery for one injector, the others should be within 2.5ml

at full throttle after 80ml of delivery, the others should be within 8ml

idle CO should be about 1% +/- 0.5%, modified engines tend to be set nearer 2 at idle, with the WUR adjusted to provide more fuel at full throttle

[Yandards 0]

Fairly standard procedure regardless of injector system but very good information.

 

Few extras to add to the test though:

 

Full throttle fuel injector check:

 

You will need to mark up 80ml points on the containers first, then operate at full throttle until one injector reaches the 80ml mark, max variation between injectors is 8ml.

 

After shut off of the fuel supply observe the fuel injectors for drips for 2 minutes, there should be none.

 

Idle fuel injector check:

 

Little harder this one but it is much more relevant to spray pattern, unfortunately the procedure refers to a specialist VAG tool that sits over the air flow sensor, best bet is to try to set it up so that all four injectors are flowing but at no where near full throttle.

 

You are looking for a fuel quantity of 20ml this time and once again shut off once the first injector 'wins' max variation is 2.5ml.

 

Look at the spray pattern is should be good cone shape, if not blip the plate to full throttle and try again.

 

You are allowed to swap over the injectors (largest to smallest) if the variation is too large and repeat the test.

 

If you have swapped the injectors over and the same injector still gives too high/low a reading then it needs to be changed.

 

If you have swapped the injectors over the the variation still occurs at the same cylinder then the injector fuel line is damaged or the metering head is defective.

 

I think the low flow rate test is more useful than the full throttle one especially when it comes to the quality of the fuel spray cone, it shoulld take quite a while to get the 20ml required at low throttle positions and we spend more time driving around off full throttle than on it (execpt Kev anyway :))