Meter head flow adjustment question??

[mark houghton]

[QUOTE=JFairman;4539234]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.QUOTE]

yeah, I remember that post. Seems pretty straighforward. I would love to do the same to my injectors but shudder at the thought of trying to access the injectors on the drivers side. Almost as bad as trying to get the sparkplugs out on that side.

[mark houghton]

Uhh....sorry for the additional post, but one question regarding "matching injectors". Is that just a simple term for getting your hands on a couple dozen injectors, cleaning them all as described, and flow tesing/pattern testing to get down to the 6 that are the closest? There is no means that I know of to affect adjustments to the injectors themselves.

[JFairman]

"I would love to do the same to my injectors but shudder at the thought of trying to access the injectors on the drivers side. Almost as bad as trying to get the sparkplugs out on that side."

With the intercooler, aircleaner, rubber intake hose elbow and blow off valve removed it's not hard to get at everything.

The origonal toolkits flexable sparkplug socket tool is the easist to use, and safest tool for removing and installing the sparkplugs on a 911.

You'll probably get a temporary sore back but what else is new...

[mark houghton]

Originally Posted by JFairman

You'll probably get a temporary sore back but what else is new...

We old folks have permanently sore backs anyway! Last time I did the plugs the motor was out...how nice can that be. The time before....not so nice. Thanks for the tip of removing the rubber elbow. Just one more piece to remove, but I can see where it would help a lot.
Now I guess I'll have to dive in and do the injectors, and check the plugs while I'm in there. Just so happens that I've already got the intercooler and aircleaner off as I complete installation of my LC-1 and Leaskified WUR.

[stup]

You guessed correctly,,that is the other test i have done earlier today,been back flushing my injectors,,Holding out pintle with wire etc and flushing through meth spirits with air pressure,,,seen a few small particles come out..will have to fit/test now and will post results..

To be honest every job in our cars is a bit of nightmare due to access etc but once you spend several hundred hours under that engine lid you do eventually get used to all aches/pains etc afterwards

[JFairman]

ibuprofen and beer works for the back pain..

[lite75]

try switching the injectors to another line and retest, this should tell you if it's the injectors.

[stup]

Ok,,with the help of Alan L who has completed similar tests,

It seems that the only way to accurately test flow from each cylinder is with removing electrical plug on meter head so that you dont have to crank over engine to deliver fuel or in the 964 turbo because there is no plug to disconnect i had to jump contacts in fuel pump relay and now my pumps will run without turning engine over!

It appears when you crank over engine the starter draws voltage from the fuel pumps which in turn will give you varied results to each injector,,learning all the time here!

So now i have got my flow from injectors pretty matched now however whilst i am in there can anybody tell me what the min/max volume from each injector should be at WOT (meter plate fully open)..??? .....for example 50-100ml per 30 secs??

[cole930]

Stu,

I've looked at numerous cis publications and there is no mention of specific flow volumes. It is simply stated that flow is measured by operating injectors into individual calibrated beakers and comparing volumes to determine equal flow from all injectors.





Cole

[stup]

Thanks all for input!!

Here is conclusions for testing on my 1992 3.3 turbo which may help others in future!

You can only acheive accurate results with jumping the relay for the fuel pumps so you are flowing fuel from head/injectors at full pressure.. cranking over engine to pump through fuel is not accurate because i think the starter drains power from the pumps!

There is only 1 relay i found to jump for my model..(i believe the 930 has 2 relays)

Control pressure circuit flow rate spec for 964 3.3 is 160 to 240 ml per min
I tested and acheived 220ml,,,so all ok there!

At wide open meter plate with injectors FITTED my car flowed between 120ml-124ml per 30 seconds(tested twice and results the same both times)..approx all within 3% at WOT

At approx 25% open meter plate every injector flowed the exact same on all 6 cylinders..

So thats me very happy with results with only any small variance been shown when run at WOT for 30 seconds,If this was tested for 15 seconds obviously 3% when then become much less however testing at longer time at WOT will give you more accurate results!

Final results!


I purchased small scales to measure volume...(empty bottle = 20 grams,e.g 142-20=122grams...1 ml = 1 gram)

[JFairman]

Regarding the 6 little 3mm allen head differential pressure spring tension adjusters under the button head covers on the fuel head you mentioned in another post...
Which way did you turn them to increase fuel flow from the corresponding injector line and what is your system pressure?
I'm guessing you turned them clockwise to increase flow because from looking at cross section diagrams it looks like that would increase spring tension on the spring loaded differential pressure valves under each injection line port opening them up a little in the process.

thanks,
Jim

[JBL930]

With a 930 you don't need to jump any relays, you just unplug the lead from the back of the fuel head/metering plate area, turn the ignition on and the pumps run.

Good to know you've got it sorted Stu, do you think it was within spec before you started with the tests or did it need adjustment?

[stup]

You turn the 3mm allen key screws clockwise to increase flow!...Anti clockwise=reduce.

I checked control pressure flow rate and this was 220ml per 1 minute(line into wur,with pumps running only)
Test values are 160-240ml per 1 minute.

[stup]

Correct about 930's Jonathan although on 964 turbo there is no plug connected only the socket where is should be fitted as it is on 930.

To be perfectly honest i am not 100 % sure how far it was out previously because i tested first by cranking over engine(I read somewhere within 10% is standard spec,,cant confirm though)however on a modified car running more boost etc it is better being more accurate and at least i now know mine is near perfect and can now tune AFR more confidently

[JBL930]

[cole930]

Stu,

Well done, excellent information for all of us.


A BIG THANK YOU !!!!!!!

[911st]

So cool!

Matched injector flow is so inportant to not blowing a motor and for running AFR's that make for the most power.

[911st]

Do not blow up you car!

Ok, there is a post of a guy setting his car on fire. Engine fire...

We are probably ok doing the fuel quantity tests as long as the plugs are hooked up. However, it might make sense to kill the ignition system when doing this test.

How would we best do that? Pull the small wires off the coil?

[911nut]

Originally Posted by JFairman

Regarding the 6 little 3mm allen head differential pressure spring tension adjusters under the button head covers on the fuel head you mentioned in another post...

How tight are those little devils on? I could only get a 9/64" allen wrench to fit them and felt like I needed to put a pipe on the wrench to break one loose. I stopped before I screwed something up.
Anyone?

[NathanUK]

Originally Posted by 911st

We are probably ok doing the fuel quantity tests as long as the plugs are hooked up. However, it might make sense to kill the ignition system when doing this test.

How would we best do that? Pull the small wires off the coil?

How about unplugging the CDI?