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Meter head flow adjustment question??

All this talk recently about metering heads on a few recent threads got me wanting to check mine for even flow to each cylinder!

I have checked mine first of all by just testing straight from the pipe fittings themselves "WITHOUT" the injector on,,,i turned over car for nearly 30 seconds with the meter plate fully open and results follow...
I have 4 cylinders within 3 percent and 1 cylinder 10 percent out and the other approx 13 percent out.
I believe there is an adjustment screw under the screw head next to each outlet on the meter head,, Can anyone tell me...do you turn each clockwise to increase flow or anti-clockwise??...Just wanted to make sure before i adjust then re-test.

Once i get them all within 2-3 percent i will then test again with my new fuel injectors on!..

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Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 03-09-2009, 02:42 PM
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No can help, but that's a quick way to check things. Did you pour them into a beaker or something to measure the differences?
Old 03-09-2009, 06:39 PM
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Stuart,
Injectors have the biggest effect on balance, hook them up to your fuel lines and check the flow. If one is flowing different, swap injectors on the fuel lines and recheck. It's highly unlikely its the fuel head. Best to get the injectors flow balanced at a injector shop.

Dan
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Old 03-09-2009, 10:08 PM
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930 rocket..yes i poured into measure jug to check however if have bottles sitting on level surface you could also just measure heights if you have them in exact same size bottles.
Dan,i would have thought flow matching the supply to the injectors first would be the way to go then test again with injectors in place,which i will do next...
All thoughts appreciated guys..i have been informed unscrew to increase flow in meter head screws.
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"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 03-10-2009, 01:01 AM
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You're doing it right. Check the head for equal flow and then the injectors.
If the head has been sitting on a shelf for a while thats a good way to check it and rinse it out too.
Then screw on the injectors and check them for equal volume, and clean conical spray pattern.
Old 03-10-2009, 09:26 AM
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Excellent work!

More should do this.

For prospective if you though your AFR was 12.5 at 6000RPM the car would have actually been running with about 4 cylinders at 12/1 AFR, 1 at 13.3 and 1 at 13.8.

Old 03-10-2009, 08:48 PM
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It was a good job you got in there and checked Stu, prevention is better than the cure
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Old 03-11-2009, 01:28 AM
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Quote:
Originally Posted by stup View Post
I have checked mine first of all by just testing straight from the pipe fittings themselves "WITHOUT" the injector on,,,i turned over car for nearly 30 seconds with the meter plate fully open and results follow...
Hey Stup, when you did this, were you doing one line at a time (by simply blocking off the other 5 so no gas would flow out them)? Or all six at once, into their own respective containers?
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Old 03-11-2009, 07:02 AM
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Mark,
I done these tests the best way in my opinion by doing all six cylinder at once!
Hopefully post final results later tonight
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Porsche inspector for Peter Morgan UK
http://www.porscheinspections.com/
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 03-11-2009, 08:51 AM
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After much adjusting i have got the fuel flow from the meter head WITHOUT injectors on to within 5 percent on wide open throttle(meter plate wide open)

Results in first picture.




Below is the next test results with my near new injectors(3000miles) FITTED..

Can new injectors be so unmatched??...Very disapointed in results with injectors in place and i can only imagine they are at fault for the uneven results!!..Also can these mechanical injectors be so far out of spec from each other?



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SP Autobahn www.spautobahn.co.uk
Porsche inspector for Peter Morgan UK
http://www.porscheinspections.com/
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.

Last edited by stup; 03-12-2009 at 09:09 AM..
Old 03-12-2009, 03:28 AM
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I am pretty sure i cannot adjust these injectors and can only try and basically find 6 injectors that will flow similar volumes...

Luckily enough i have an old set which i will give to bosch injector specialist to pick the closest 6 i have out the total 12 off..

Not impressed at all and pretty shocked if this is how far out these are(3000 miles only)

Unless there is something wrong with my results???... it looks like this is the way to go..

P.s If you look at my very first test on number 6,,i then added fuel via the head which resulted good...then i fitted injector and in last pic you can see that number 6 again is very low in flowed volume...so before i added fuel via head this would have been worryingly even more low!!
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SP Autobahn www.spautobahn.co.uk
Porsche inspector for Peter Morgan UK
http://www.porscheinspections.com/
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.

Last edited by stup; 03-12-2009 at 04:51 AM..
Old 03-12-2009, 04:47 AM
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Stu,

I don't want to bust anyones bubble here or cause conflict but I think you have to do a complete system approach to tuning a CIS. This includes fuel pumps, filters, accumulator, fuel head, lines, and injectors. I believe matched injectors are the key to a good end result but you also must have fuel pumps that are delivering consistent,even, and, required pressure a filter thats clean and unobstructed and an accumulator that holds the correct pressure.

This is a continuous pressure system and checking flow at individual open lines is not going to tell you a lot. Cap 5 lines while pressure checking the 6 th. You want to check the system pressure at each line not the flow. If you have the correct, stable pressure to the fuel head, your pumps, filter, and accumulator are ok. If pressure at the end of the fuel distribution lines is even the fuel head is good. By definition the fuel pressure at the end of each line should be very nearly the same. Then most importantly the injectors. Each injector should be checked for opening pressure, flow, spray pattern and sealing. When looking at the fuel distributor and injectors it is nearly imposable to check these without a flow bench. This is best left to a Bosch service center or shops that specialize in servicing fuel injections.

I felt bad for you when you saw the final results of your hard work, but you need to cut yourself some slack here, you do not have the equipment to do this and very few of us would. Your intent is pure you just need to buy several thousand dollars worth of equipment or send some of it out.

I am no expert here, I'm just a dumb old fart that shares a common bond with all who love these old sleds.

Cole
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Last edited by cole930; 03-12-2009 at 06:38 AM..
Old 03-12-2009, 06:34 AM
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--930's have a reputation for burning pistons. Many have wanted to blam this on the design of the intake manifold because it dose not test for even flows on a flow bench. Under boost I suspect this is not as big a deal. However, CIS is sensitive to varnishing and needs to be clean to work properly. If we had carbs, we could have probably had them partially or fully rebuilt every 5 to 10 years. However, with CIS we seem to think that is not necessary or they are above that. My bet is it is the head that is responsible for a high percentage of the failures.

Look at the numbers I calculated based on one injector being 10% less and another 13% less. If you though your AFR was 12.5 at 6000RPM the car would have actually been running with about 4 cylinders at 12/1 AFR and the weak cylinders at 13.3 and 13.8. That will cost someone a cylinder or two on the track quickly. This is why we typically want to run a litter richer mix than the EFI guys do. For a little insurance.



I would think the procedure might be:

Test with injectors in place for quantity and watch to see if all have a spray pattern.

If any do not spray, send injectors out for cleaning and balancing.

Retest in place. Adjust as necessary.

If unable to get them balanced attempt to run professional fuel injector cleaner through head.

If still not matched, send head out for rebuild.

Retest rebuilt head in place.

Old 03-12-2009, 06:53 AM
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This was just a check before a finalised some AFR tuning,,car appeared to be running great before!

All tests performed on ALL 6 cylinders at one time to try replicate engine running as normal on wide open throttle.

I would have thought the pressure to each cylinder fuel line is correct now after i adjusted meter head to produce very similar volumes when measured without the injectors fitted.

I appreciate what your saying about sending injectors to specialist to confirm my last results,,I was just very surprised to see a variation in volumes once i hooked up my injectors to each fuel line then tested the same way..i.e 6 cylinders at once at wide open throttle.

I will proceed with testing and will use specialists to confirm my tests!!..I must have spent hundreds and hundreds of hours now upgrading and working on this car,including a complete engine rebuild etc etc and believe its not the time to throw the towel in as of yet..

Unfortunatley in the UK we have not many specialists here,,only some who claim..

I have had many people travel several hundred miles to have me work on their cars due to the lack of knowledge over here!

As said before i will use a specialist to confirm my test with their proper test rig but i was very surprised to see 6 injectors produce such a varied result at each cylinder considering the injectors are nearly new!!

P.S no conflict!!,,we all post on this forum to try help each other
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SP Autobahn www.spautobahn.co.uk
Porsche inspector for Peter Morgan UK
http://www.porscheinspections.com/
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.

Last edited by stup; 03-12-2009 at 07:23 AM..
Old 03-12-2009, 07:15 AM
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Isn't this all about flowing identical volumes through each injector? Without the injectors in place, you had matched volume...until you installed the injectors. Wouldn't that suggest that the injectors themselves are either partially obstructed or not opening to the same degree? And wouldn't it make sense then to run your balancing act once again with each injector in place and isolated, while adjusting the volume delivery for each at the fuel head until each delivers the same amount of fuel? In other words, adjust to make up for the differences in the injectors.
My logic is probably too simplistic and most likely faulted, but it seems pretty straight forward to me. You may be able to match volumes, but who knows what the spray patterns will look like (anything from fine atomization to a pencil stream of fuel!).
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Old 03-12-2009, 07:33 AM
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It should be as straight forward as you say!

I would prefer and would have thought setting up the head firstly is best thats why i tweeked head to suit even flow first,,,I would prefer checking injectors before tweeking head again.

I am pretty sure it is down to injectors and will complete another test to confirm!
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"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 03-12-2009, 08:02 AM
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All I can say is thank FCUK you checked!! I was in your place Stu not long ago, without your knowledge, you know where it got me! Think happy thoughts

Correct my logic here:- Send your injectors to an injection specialist, i know a VERY good guy in my neck of the woods Stu if you want an address. He will check, clean, match them and send them back. Hook them back up to your fuel lines and redo your test, adjust at the fuel head as necessary until you get the amount of fuel the same across all 6. I would do the test at part throttle, test again at half throttle, and again at full throttle, if they are all the same across all throttle positions then happy days.


Different subject, you also need to establish what your system pressure is, it must have been really low originally as you were out of fuel really early. Get that checked, and shimmed up to around 95psi or so.
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Old 03-12-2009, 08:05 AM
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To be honest Jonathan with you reminding me several times about your experiences it is what started my testing,,so thanks to you on that one.

One more test tonight and if all still not correct i will send away 12 injectors to find a matching 6..I think i have one bosch specialists not too far away up here that has checked injectors for me in the past however if you could PM me a link or number also that would be appreciated also!...More and more specialists only test electronic injectors nowadays you find!

Posting this thread also hopefully will only make people more aware of what potentially could be out of spec on their car leading to potential damage!
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SP Autobahn www.spautobahn.co.uk
Porsche inspector for Peter Morgan UK
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"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.

Last edited by stup; 03-12-2009 at 08:58 AM..
Old 03-12-2009, 08:55 AM
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I thought i'd give the bloke a quick call before i blurted his name out, he looks after my diesel vans when they have injection issues. He said he has moved completely into doing diesel stuff now, and has not got the equipment anymore to properly test your style injectors. Sorry for the false hope

Stick with it though Stu, when it's sorted it will give you peace of mind
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Old 03-12-2009, 09:37 AM
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Try the injectors on different lines then retest, and...

There's a post somewhere here with pictures where someone tied the pintle open on the end of the CIS injectors with fine strands of copper wire, then after soaking them a while in techron injector cleaner or something similar put a piece of fuel line with some techron inside over the pintle end and then back washed them with 120psi air pressure.

I did the same to mine last summer but I never did the fuel volume test you've done here, but plan to in the future.
I did the copper wire and backwashing job by sitting down, and while holding the injector between my knees (thats the uncomfortable part) I used hemostat tweezers to lightly grap the pintle and pull it outward from the injector body with one hand just far enough to wrap the 2" long fine strand of copper wire around the pintle shaft which holds it open after releasing the tweezers.

Then I soaked all 6 injectors with the pintle facing upwards for about 2 weeks in a glass jar filled with techron injector cleaner. Taking the jar and shaking it gently every couple days to agitate the techron inside the injector tube bodies and dislodge any air bubbles that may be inside.
After several days I started noticing some little dirt specks in the bottom of the jar that came from the inside of the injectors.

I've read here that there is a fine screen fuel filter somewhere inside each injector tube and hopefully soaking them like that and then backwashing them by blasting air pressure and techron through them in reverse while holding the pintle open with finecopper wire cleans out the inside of the injectors.

After removing the wire the pintle seats back in place and you can check the spray pattern by inserting a tight fitting plastic straw from a full can of carb cleaner or brake cleaner into the end of the injector and spraying the solvent through.
The pressure in the can is usually enough to open the injectors and you should see a conical spray pattern.
Carefully warming the can of spray solvent in the sun will increase the pressure if it is not enough to open the injectors to spray.

This is not going to be as good as a professional injector serviceing but if you don't want to spend a ton of money doing it it's worth a try.
Old 03-12-2009, 09:38 AM
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