Dripping injectors

Hi everyone

The search to improve my cold starting issue goes on, having been sugested by many at the AGM that it may be dripping injectors…

I finaly got to checking my injectors (91 GTI rivage DX engine) and followed the excellent guide on the forum.

After struggling to get the little felows out, the results were as follows:-

• On starting the fuel pump, all gave a short splutter then stopped…

• on lifting the feul meetering flap - all gave then pretty much equal spread of spray pattern.

• All incresed and decreased the spray / volume as the fuel metering flap was lifted or lowered.

• After a short while all produced 100cc all within a fraction of each other - seriously, all within a couple of %.

• However for the next 10 minutes, 1 and 4 dripped 5/7 times and 2 and 4 dripped 2/3 times respectively.

• After breaking for lunch of at least and hour…. upon return - all are still wet the touch with No 4 still has a dew drop and clear evidence that it has been dripping for the last hour.  

Is this levelling of dripping that may casue my cold start issues and might cleaning them ultrasonically address the issue?

Other that the cold start problem, the engine has been running well.

I can have them cleaned fairly cheaply as opposed to buying new - They of course have the top hat and therfore will, I presume be the more expensive ones. or is no 4 the bad boy?

your considered thoughts please.

regards

rivage5 said

• However for the next 10 minutes, 1 and 4 dripped 5/7 times and 2 and 4 dripped 2/3 times respectively.

• After breaking for lunch of at least and hour…. upon return - all are still wet the touch with No 4 still has a dew drop and clear evidence that it has been dripping for the last hour.

According to the Bentley Service Manual (factory VW manual here in the States), with the airflow sensor plate in its resting position and the fuel pump running, the injectors should not drip; if any of them do, they are faulty.  Try having them cleaned first; if you have it done by a professional, that person should also measure the opening pressure of each injector; if any fail that test, they should be replaced.  From the manual: "[The injector] should open at 3.0 to 4.1 bar (44 to 59 psi).  Any injector which opens or leaks at a lower pressure or has an uneven spray pattern should be replaced."

Also, I'm not sure if the DX has one, but if it has a cold-start valve (aka 5th injector), test it as well to make sure it's functioning as it should.

Ultrasonic cleaning of this type of mechanical injector rarely improves them, the problem is that they could really do with being run in reverse to clean any muck out, which is not possible.

You need to invest in a new set of injectors. Regardless of shroud there are two types, the difference is the thread size, you almost certainly will have the fine thread being a later car, they are the dearer of the two !
Renew the o rings at the same time.
I would also change the oil ASAP as petrol thins the oil and acts as a cutting agent causing increased bore and ring wear.

Gents - sincere thanks for your replies.

You have confirmed my thoughts.  I will have them cleaned using the ultrasonic method.  but, I was intrigued by the chap in the US on Cabby info site that blasted them trough with a proprietry cleaner to seemingly good results.

I suspect ultimately I will be buying new - presumably Crazyquiff is the cheapest overhere? - How much are the later type in the USA + shipping tp uk (part number on the injectors is 0437 502 043)?

Working through the CIS system for faults - when would be the right time to test the fuel pressure? I still suspect the WUR is tired its not perfect until fully warm.

regards?

they shouldn't spurt when the fuel pump primes, and they shouldn't drip AT ALL. so there's your problem

new brass ones are available on ebay, not half as cheap as they used to be though! i read somewhere that if the k-jet injectors drip then thats it, they're buggered. something to do with how the internals are put together iirc

Thanks Rubjonny

Since my last post I have been looking on fleabay at the brass ones - There are only a copuple of things putting me off at the moment:-

1 The tread size - its a finer thread on my car apparently - a lot for sale seem to have the coarse thread.

2 Mine has the silver top hats - if the new ones don't come with them, presumably I would need to transfer mine across?

Thanks for your reply though - You have confirmed my thoughts that I need new.

Regards

The ones I got from Crazy with fine threads came with the top hats on.

Not really sure what the top hats do though, I have heard people say that they have not noticed any difference with them not fitted

You can change to the course thread ones but then you need a set of flex hoses as well :-(

doh! 2 choices, either buy the finer thread ones or change to earlier mk1 fuel hoses with the coarse threads.

the top hats are for the injector air shrouding system, which doesnt really do a great deal really. its not like later MK1 & MK2 GTIs have a ton more power than the early ones because of it

I ran the brass ones on my 16v when it was in my mk2, then switched to shrouded ones when the engine went in my cabrio and noticed no difference whatsoever.

(i traded the complete mk2 k-jet system for an abf management system when the engien came out is all, i didnt change it for any performance reasons)

I told you it was leaking injectors!

Replace them, and get new rubber o rings from GSF £2.something

If your feeling in the mood you should also replace the inserts that the sit in on the back of the head…

A huge thanks to all who contributed and gave their views on this problem of poor starting when cold.

You may recall the symptons were poor starting when cold as if it was flooded, giving rough idle and a strong smell of fuel - obviously not right and not doing the car any good.

Having tested my existing set of injectors - I followed your advice and replaced the injectors. Times being hard - I took a punt on some 2nd hand ones of Fleabay and managed to get a set with the right thread (mine are the fine thread expensve ones). If they also proved to be duff - I was going to try and have one set cleaned and check the results.

However, I tested them before installation (as per the link in the technical section) and they gave a good jet pattern and importantly did not drip!

I have had them installed for a couple of weeks now and the results are amazing (ok - so a car starts big deal, but it really brassed me off not starting properly). The car now starts hot or cold every time without touching the throttle and settles and idles smoothly - A quick wur, wur and bang it starts. Out on the road - the engine sings round to the red line smoothly.

A massive thanks once again  - Lee_dub, rubjonny, lhasadreams, Kamz and PNErivage for your help.    :clap:

Regards

Glad you sorted it mate :-)

I had a similar problem on mine, I solved it temporarily by disconnecting the 5th injector, as seeing as it was overfuelled already due to the leaking injector, and the aditional fuel was flooding the engine. it solved my cold starting problems, while I sorted out a set of new injectors.