MFI Injectors - Clean or Replace
Moderators: hot66, impmad2000, Barry, Viv_Surby, Derek, Mike Usiskin
MFI Injectors - Clean or Replace
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)
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)
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911T MFI
Gen 2 Boxster
Merc stealth shed
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911T MFI
Gen 2 Boxster
Merc stealth shed
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Re: MFI Injectors - Clean or Replace
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
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
John
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
Re: MFI Injectors - Clean or Replace
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 may well pull the trigger on that under the heading of worth a punt. Are you saying that no ultrasonics are necessary for this?
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911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
Re: MFI Injectors - Clean or Replace
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.g3ngs2 wrote: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 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.
John
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
Re: MFI Injectors - Clean or Replace
what a great tip - thanks for sharing!johnM wrote: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
Dean
1973T Targa MFI 334 met blu- under restoration https://www.ddk-online.com/phpBB2/viewt ... 28&t=67060
1980 924 Turbo, blu/grn tartan - restored
1973T Targa MFI 334 met blu- under restoration https://www.ddk-online.com/phpBB2/viewt ... 28&t=67060
1980 924 Turbo, blu/grn tartan - restored
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- DDK addict
- Posts: 102
- Joined: Wed Nov 20, 2013 9:50 am
- Location: Cookham, Berkshire
Re: MFI Injectors - Clean or Replace
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....
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- DDK 1st, 2nd and 3rd for me!
- Posts: 2114
- Joined: Sat Oct 26, 2013 12:42 am
- Location: Oxfordshire
Re: MFI Injectors - Clean or Replace
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.
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.
Rust Never Sleeps
Re: MFI Injectors - Clean or Replace
I had 6 injectors cleaned and tested here. £15 incl vat per injector
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'72 911E Coupe RHD
'72 911S Coupe RHD
'72 911S Coupe RHD
Re: MFI Injectors - Clean or Replace
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....
Sent from my SM-G950F using Tapatalk
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....
Sent from my SM-G950F using Tapatalk
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
Re: MFI Injectors - Clean or Replace
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
Sent from my SM-G950F using Tapatalk
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
Sent from my SM-G950F using Tapatalk
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
Re: MFI Injectors - Clean or Replace
Are you using the cleaning fluid I suggested in the earlier post?g3ngs2 wrote: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
Sent from my SM-G950F using Tapatalk
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.
John
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
1970 2.2E Coupe.
2004 996 GT3 mkII
2015 Skoda Octavia VRS TSI DSG.
2021 Toyota GR Yaris Circuit Pack
Re: MFI Injectors - Clean or Replace
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
Sent from my SM-G950F using Tapatalk
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
Sent from my SM-G950F using Tapatalk
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------
911T MFI
Gen 2 Boxster
Merc stealth shed
--------------------