MFI Injectors - Clean or Replace

[g3ngs2]

So - as of a couple of days ago the injectors are out of my 73T. They came out without a fight which was appreciated (as was the on average sub 10% leak down!)

The injectors are of unknown age and no paper on them came with the car so the options in front of me are 1) Find someone somewhere with the right kit to give them a clean 2) Close my eyes, remove a decimal point in my mind and buy new.

For anyone who has been at the same cross roads - which did you do when weighing up the relative thoughts of
Version 1 - Time, the inevitable law of sod that you may need to replace a couple of them over
Version 2 - The pure unadulterated incomparable and immediate joy of new injectors (not that I've ever experienced this but it sounds like fun - and it would have to be a feck load to part with 600 quid)

[johnM]

I have had quite a lot of success cleaning injectors. I have used a injector tester like this.

https://www.vevor.co.uk/injector-nozzle ... gKVsfD_BwE

For less than the price of a single injector you can clean all of them.

I have used Wynn's petrol injector cleaner, pumped the fluid through the injector, let it soak for a day or two then give it another good go with the tester pumping more cleaner through them. Seems to work well. You are looking for a clean crack off at about 212 psi with a good spray pattern, no dribbles.

https://www.carparts4less.co.uk/p/wynns ... gI-e_D_BwE

Kind Regards

[g3ngs2]

John - thank you so much for the quick reply that looks really interesting and very under the price of a single injector.

I may well pull the trigger on that under the heading of worth a punt. Are you saying that no ultrasonics are necessary for this?

[johnM]

John - thank you so much for the quick reply that looks really interesting and very under the price of a single injector.

I may well pull the trigger on that under the heading of worth a punt. Are you saying that no ultrasonics are necessary for this?

I've not used an ultrasonic bath myself, but I'm sure they would help. I think the key is to get neat cleaning fluid into, and flowing through, the injector which an ultrasonic bath wont do.

I had an injector fail, engine dropped onto 5 cylinders. I took the injector out and put it on the tester and fluid just flowed straight out of the nozzle with zero back pressure. I gave it a sharp crack with a small hammer and then fired a load of cleaner through it via the test rig, and its been fine since. It had stuck open most likely due to gummy fuel being left in the injector.

[deano]

I have had quite a lot of success cleaning injectors. I have used a injector tester like this.

https://www.vevor.co.uk/injector-nozzle ... gKVsfD_BwE

what a great tip - thanks for sharing!

[christaylorsound]

My local garage cleaned my SC's injectors with something like this, then charged me more than I could have bought the machine for! With a suitable adaptor and a injector tester/pulse tool (which I have) you could probably do later EFI injectors too.... Thinking now.... New tool....

[BILLY BEAN]

If you decide to retain the injectors they ought to be tested for flow and spray pattern.
I have been down both routes: clean, test and reinstall on my 70 car and new on the ST replica.
Note that even if you purchase new injectors they are worth testing for spray pattern I had a duff one that was returned to the retailer.

[72911E]

I had 6 injectors cleaned and tested here. £15 incl vat per injector

[g3ngs2]

Thanks all, very useful info

Heading down the cleaning route and see what happens. (Hopefully the law of sod will be kind on needing new... but you know how that goes....).

Getting close now....as of this afternoon....

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[g3ngs2]

So I got my tester and initially thought oh good 5/6 are OK, chirp at the right point and they all sprayed the same way.

6 wasn't really doing anything much other than spraying a star shaped bunch of jets on the first pump

But then I went to try and find how a new injector behaved...

https://youtu.be/nmkiBz65Wjs

Admittedly for a Merc but still Bosch MFI and aiming for 250 psi ...Nevertheless out of the five what I thought good ones, only one behaved like the new injector at the start of this video. (The other injectors he tested were all good examples of what bad looked like and none of mine were that bad)

So it sort of feels like if you're going to buy five new, you may as well buy six

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[johnM]

So I got my tester and initially thought oh good 5/6 are OK, chirp at the right point and they all sprayed the same way.

6 wasn't really doing anything much other than spraying a star shaped bunch of jets on the first pump

But then I went to try and find how a new injector behaved...

https://youtu.be/nmkiBz65Wjs

Admittedly for a Merc but still Bosch MFI and aiming for 250 psi ...Nevertheless out of the five what I thought good ones, only one behaved like the new injector at the start of this video. (The other injectors he tested were all good examples of what bad looked like and none of mine were that bad)

So it sort of feels like if you're going to buy five new, you may as well buy six

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Are you using the cleaning fluid I suggested in the earlier post?

If so leave it in the injector for a day or two and then rattle a load of fluid through them using the injector tester to flush any wax or dirt out of the injector.

Then have another go to see if they improve.

[g3ngs2]

Yup... Let them bathe for two and a bit days.

Then flushed them, the one good one got "good good", the other four improved throughout the morning with flushing, another bit of a bath, then some more flushing. During that is when they started to behave without needing some hard pumping.

If I had two more hands I'd video how they behaved, but with one on the handle and the other to catch the output in a bottle I was all out.

Had I not seen how a new one behaved I may well have thought that'll do for 5... but I can't unsee it now

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