Injector testing and K-Jet testing.

I recently bought a MK1 1.8 GTI non runner with fuel issues. I don't know the full history of the faults, only what the previous owner told me and he bought it with the same faults so I'm unsure of the whole picture. Apparently the car was running lumpy when the previous owner bought it in 2008. It the stood in his garage until approx. 2010 when he got a mechanic to look at it. The fuel pump, relay and fuel filter were replaced along with spark plugs, ht leads etc. None of this cured the problem so it was parked up until this year when I bought it. I  came to the conclusion that the filler neck had been replaced but the contaminated fuel had been left in the tank which had corroded the tank from the inside out and caused the fuel pump to fail. It also had a lot of fuel in the oil so I changed the oil before starting it. I have now replaced the tank, fuel pump and filter and the car now starts and runs to a degree. It starts fairly well from cold but idles badly and starts running on 3 after a minute or so. Once it starts to warm up it runs like a bag of nails. I have checked the valve timing and set the ignition timing to the best I can given it's current running problem. New plugs have been fitted and it has a good spark so I moved on to the fuel system as I noticed I could see fuel on the piston crowns on cylinders 1 and 3! I have removed the injectors and when I switch on the ignition and injectors 1 and 3 give out a jet of fuel, injector 2 does nothing but injector 4 sprays a nice cone of atomised fuel like I would expect. Injector 2 has a good mount of fuel pressure in the line. 1 and 3 continue to leak for a good time after the fuel pump has stopped. Before I start buying new injectors I wanted to check if the injectors should spray when the fuel pump is running even if the engine is stopped or is there a possible fault in the metering head that could be causing this? Many thanks.

Saulty,
if the fuel pump is running, the injectors will spray if there is enough pressure, i.e. you lift the air flap.

This is one of the tests for injectors and pressure. Have you got the Haynes or Bentley manual for the car - they run through the standard tests for fuelling. I am currently going through something similar, just waiting for a pressure test kit to arrive (thanks Paul C).

If the injectors contine to leak after the pump has stopped this is normally a sign of injector issues. They can be cleaned with an ultrasonic cleaner (haven't tried it myself).

Have you checked the state of the fuel distributor - remove the main pluger and the pressure regulator looking for signs of rust or debris.

Also, have you cleaned out the fuel lines with carb cleaner and an air line?

Search the forum for Rubjohnny's posts on this subject, as he links to a guide on the Mk2 forum.

Good luck!
Lee

LeeO said

Saulty,

If the injectors contine to leak after the pump has stopped this is normally a sign of injector issues.

Leaky injectors can also be the metering head not shutting off properly when the air flap is shut.

Hi, thanks for the replies.

I meant to say in my last post that by swapping injectors to different outlets on the metering head the problems stay with the injector.

LeeO, the fuel lines were cleaned before fitting the new tank etc and I've had the pressure regulator out. Regulator plunger was free of debris although I haven't removed the main plunger yet. I have the Haynes manual and had started some of the test procedures but at the moment I have no gauges etc and a lot of the tests require engine to be idling, which it doesn't do. I can't even check the ignition timing is correct yet.

Can anyone tell me if the injectors are meant to spray when the fuel pump is running? I get a spray when the fuel pump primes itself on powering up the ignition and obviously a spray when the engine is cranking.

The engine starts even with the injectors removed so I've half ruled out the cold start injector being a problem (although it surprised me the first time it did this!).

Thanks.

Matt.

 

Saulty,
if the fuel pump is running but the air flow sensor is at rest, then no fuel should come out of the injectors - as soon as you start cranking, the vacuum/air flow starts which lifts the air flow sensor, then sending fuel pressure down the lines to the injectors.

As yomp said you could also have an issue with the air flow sensor - or indeed the main plunger in the distributor, which could cause fuel to come from the injectors before/after it should.

If you put all 4 injectors into separate bottles, run the fuel pump, and then move the air flow sensor upwards (push from underneath with your fingers) what happens?

It could be you have a combination of issues and have to eliminate each one in turn.

This might be of use as well:
What do I do now? | VW Vortex - Volkswagen Forum

good luck
Lee

Thanks for that Lee, I followed the link you posted and read the bit about adjusting the adjusting the airflap and then, once I had adjusted the mixture screw I lifted the flap to see what happens.

Injector 1 and 3 squirt fuel as long as the pump is running and it cannot be adjusted out. This problem stays with the injector when I swap it to another outlet on the metering head. Injector 3 is far worse than 1 and they squirt several jets rather than a conical mist. This continues when I lift the airflap and they continue to squirt for some time after everything is shut down.
Injector 2 does diddly squat no matter what I do, I have no doubt that this injector has completely failed.
Injector 4 mists slightly on initial powering up of the pump but stops immediately and I get a conical mist which increases as I open the air flap.

I need to speak to a guy about borrowing a pressure test kit but I have ordered some 2 new injectors anyway to see what happens and I'll probably order 2 more once I've tried them.

Going back to that link, I found another forum where a guy says the injectors should spray while the pump is running which is why it's called a  continuous injection system! That's the trouble with the internet/Google is you get a lot of conflicting information!

Thanks for your help, I'll let you know how I get on.

Matt.

Sounds like you are on the way to fixing it. I double-checked the Bentley manual, and when the airflow sensor is at rest there should be no fuel from the injectors.
Lee

Thanks Lee, I think I need to get myself a Bentley manual!

Matt,
there is a download link for the Bentley in this thread:

http://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=technical%2Fbodywork-fittings-and_2%2Fpower-hood#post_1527638

Thanks Lee, that's a great help. I owe you one!

sounds like the metering head is fubar if some injectors spray even without the flap lifted and some wont spray no matter what. if its had rust and/or water in the fuel system then this is the likely cause as they are very fine tolerance inside

i would start by making sure tank is fully clean, neck has no rust or holes then replace metering head, wur, 5th injector and injectors, remove the fuel pump & accumulator to clean them out and blast all the fuel lines thru to ensure they are clear. if any rust/water got to the metering head it'll have played havoc with the rest of the system also.

for the injectors you can get new merc brass ones off ebay if its a tintop gti, direct swap. then its a case of shop for good spare parts for the rest of the system

this thread is worth a look too, check all the kjet basics over and ignore the 16v specific parts
http://www.vwgolfmk2.co.uk/forum/viewtopic.php?f=37&t=25972

Hi John, thanks for the reply. I'm clinging to the hope that the metering head is ok at the moment as the issues with the injectors stay with the injectors when I swap them about. I have since fitted two new injectors and they both spray a cone now. I have ordered two more, hopefully I'll have them tomorrow!

Tried to start it with 3 good injectors and it fired up for a few seconds and then died. I t would stay running if I had my foot on the accelerator but it was running as rich as hell!

I've gone through the list and followed the test procedures for the wur, 5th injector, thermoswitch and idle air valve. Big progress was made, wur tests ok, 5th injector sprays nicely and thermoswitch works. Idle air valve has a voltage so I removed the pipe from the air valve to the inlet manifold. The engine then fired up straight away with no accelerator but idled at around 2500 rpm. I found I could control this by restricting how much air was allowed into the inlet manifold and kept it running until the engine warmed up. It's still running rich and I tweaked the mixture screw anti-clockwise until it ticked over with the hole blanked fully. I didn't go much further than that as I still have one bad injector and it's also my birthday today so I'm now have a beer!

I have removed the idle air valve and looked through it, all I can see is a small slot. If I turn the disc inside with a probe I can get a hole to show on the disc. Can anyone tell me what I should see when the idle air valve is cold? I am assuming the large hole should line up and as it warms up the disc moves round until it's just the slot!

Many thanks.

Matt.

Sounds liek good progress

never looked inside one I'm afraid, but it should have a large hole for air to go thru cold, and gradually get smaller when hot. I assumed it was just like a gate which gradually closed tbh

Thanks for the help and advice so far, I've had quite a few jobs to do on my golf so it's been a slow progress but we are getting there. I have some updates to my diagnostics:

Dizzy cap, rotor arm and HT  leads replaced (it had the wrong type of HT lead fitted!)
Checked the valve timing again.
All four injectors replaced.
Another new fuel filter (safety precaution given the amount of work that has been done and the history of the car!)
New air filter.
Removed the WUR and cleaned out including the gauzes.
Removed the AAV, stuck it in the freezer overnight, stuck it on 12v and all seems to move ok! Some research online shows that mine is probably open enough given the air temperature.
Checked the metering plate for adjustment.
Cleaned all fuel lines again.
Checked the FD, removed plunger and pressure regulator.
Checked the 5th injector.
Carried out compression test and all cylinders, all 175-180 PSI.
Annoyed my neighbours while trying find about a 100 million intake leaks.
Bought some bits off eBay and made a cheapish K-Jet pressure tester! These are the results:
Air temp approx. 12C
System pressure - 5.2 bar.
Cold start with WUR and AAV disconnected - 1.1 bar. Engine idling at about 1500 RPM
After a few minutes with WUR and AAV reconnected max pressure is 3.6 bar.
Turned off engine and the pressure dropped to 2.8 bar after about 5 minutes but held at 2.8 bar for over 15 minutes, now at 2.6 bar after more than 30 minutes.

Then engine starts from cold within a second without any throttle but it idles at around 1500 RPM. If I rev the engine it will slow the idle but sometimes stall. If it stalls it will start right away with no throttle. The idle is slightly lumpy from cold start right through to warm up and sounds like it's missing or running on 3 most of the time. If you rev it whether hot or cold it will nearly staal, or somestimes stall but always starts quite easily.

It does smell quite fumey, not sure if it should. I know it's old and we forget what cars used to smell like but should they smell much?
Not done quantative tests yet but hopefully will do those later this week.

I'm starting to fear the worst about the FD though. If anyone has any tips or thoughts on my findings they are gratefully received.

Thanks.
Matt.


 

All those pressures look good. It could be running a bit rich - hence the smell. If you take out one of the spark plugs, what colour are the deposits (only a rough guide  - black is rich, pale brown is lean)? Hopefully when you do the quantity test it will confirm if the FD is OK or not.

Thanks Lee, the spark plugs are fairly black so it's running rich but as I have only had it running on my drive and not actually driven it on the road yet I would have expected them to be sooty anyway. I will hopefully get it outside tomorrow and try and adjust the mixture a bit though.

I have now done a quantity test on the system with some varying results! Spray pattern on all injectors is good.

The first test I carried out gave the following results:
Cyl 1 110ml
Cyl 2 75ml
Cyl 3 50 ml
Cyl 4 115 ml.

I swapped injector 1 with injector 2 and swapped injector 3 with injector 4 and got the following results.
Cyl 1 120ml
Cyl 2 80ml
Cyl 3 90ml
Cyl 4 100ml

As the injectors are new I didn't expect a change but I did so I swapped them all back to their original positions and got this:
Cyl 1 105
Cyl 2 75
Cyl 3 100
Cyl 4 105.

I assumed I had some dirt or gummed fuel in the FD and, as I put some injector cleaner in the tank a couple of weeks ago I assumed it was started to clean the system out so I carried out a few more in the hope that cyl2 would improve. I didn't seem to but as all the tests I was doing were with the sensor plate fully open I decided to do some tests with various sensor plate positions!

Plate open enough to squirt fuel:
Cyl 1 95ml
Cyl 2 100ml
Cyl 3 80ml
Cyl 4 80ml

Plate position varied throughout test.
All 4 cylinders got 100ml

Plate position fully open:

Cyl 1 100ml
Cyl 2 80ml
Cyl 3 95ml
Cyl 4 100ml

I assume from these results that my FD is faulty but look forward to any comments or suggestions.

Thanks.
Matt.
 

Those results do look a bit all over the place! If the injectors are new it can only be the hoses or the FD. If it was blocked hoses I would expect the affected cylinder to always read low. The last two tests are only just outside acceptable. Maybe once you have run it a bit and got more cleaner through the FD, it will improve?

Thanks again Lee, I have an FD off an early 1.6GTI which I was assured was working so I've installed that one for now and checked the quants. They are much more balanced and within tolerance so I'm tempted to leave it on until I've got the car road legal and can drive it properly. I'm not sure of the implications of this and trawling the net has not given me a definitive yes or no answer but can anyone advise on any potential problems that might arise by fitting a 1.6 FD?

Anyway, with the new FD fitted the car fires into life from cold straight away and runs smoother than with the old FD but it does idle at about 1500 RPM when cold and slows down as the engine warms to about 900-1000 RPM. Moving it about on the drive etc the car is a lot smoother than before but once it reaches normal running temperature it seems to suddenly run rich and puffs black smoke and smells very fumy, far more fumy than when it's cold. It also did this with the old FD!

My questions are:
Is the 1.6 FD ok on a 1.8?
Should it idle at around 1500rpm when cold?
Could the WUR be faulty causing the sudden rich running when the engine reaches normal running temperature?

Hopefully someone can help me with these issues!

Many thanks.
Matt.

it should start at 900-1000 rpm and stay there all thru the warm up process, it may just be you need to now get the co and base idle reset with all the changes you have made. check the ignition timing while you're there also

with the metering head ithe 1.6 ones supposedly deliver more fuel so this could well be where the issue is. if you match it to a 1.6 WUR this might help though as they are also different.

ideally you should get the right metering head for the 1.8 since thats what its designed for

Thanks John. Do you know if a mk2 1.8FD will fit? The number on my actual FD is 0438100100. I take it any FD with that number will be the same. I've noticed mk2's have a different air box number but the metering head number and the FD number are the same as mine.