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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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 Posted: Sat May 13, 2017 10:46 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| In looking at the wiring looks like 3,4,5 and 6 out of the ECM are the power wires to the injectors. I would think I could test there continunity and make sure the wiring part is good then look at the grounds the same way. |
On these systems....never test continuity on a wire...as a complete unit. It will lie to you almost every time.
Each wire from the ECU to the component has three distinct parts to check...separately FIRST.....and as a unit last.
Pulling the plug from the ECU and putting a VOM probe on each end to test a a unit will cause you problems.
The correct way to test...is to FIRST make sure all of your terminals and crimps are good. This requires inspection and correction...not testing with a VOM.
90% of the equation....is KNOWING that your terminals have a positive mechanical connection by physically checking and correcting them.
1. The connection between your VOM probe and the wire connector needs to be the same quality as what is in the harness.
You need to make test pigtails. Find an old part you can break up like a bad pair of trigger points, an old injector or a bad intake air temp sensor....and pull out a male pin. Either solder or crimp a wire onto the end of it so its a perfect connection.
Clean the pin well. Then crimp it to a butt connector that is an extremely tight fit on the probe of your VOM...like it almost needs to be screwed on...or use a spring loaded terminal block to make a test fixture.
2. The first thing(s) to check on the component end where it plugs into the injector, the trigger points etc.........and you MUST remove the female connector from the plastic plug with a pin-out tool or jewelers screwdriver to check these things....
A. Check the actual tightness and fit of the female connector on the male pin. THE MOST COMMON PROBLEM...is owners or mechanics just wiggling the plastic connector plug in the injector ...and feeling that it has a tight fit and assuming it is a good connection. All that is doing is testing the fit of THE PLASTIC PLUG in the component....and has no real bearing on whether the female connectors inside are a tight fit on the male pin.
In some obscure factory literature on AMP's website back in 1999 I found test reports from AMP....the maker of the terminals....that noted that with as few as 25 plugging and unplugging cycles....along with heat expansion and contraction and corrosion.....the rolled edges of the female connectors lose spring tension and become a loose fit on the male pin, causing intermittent connectivity...and in many cases total loss of connectivity.
If the female connector does not fit tightly on the male pin...take a small pair of needle nose pliers and carefully squeeze the rolled sides of the female terminals to make a tight fit.....or simply crimp new ones on.
B. The next check is to observe if there is any corrosion or tarnish on the connector....there will be resistance and potential connectivity issues intermittently. This is important.
The factory female connectors are usually a silver or dirty gray color. This is tin plated beryllium copper. Over time...tin causes connectivity issues as it oxidizes and turns a dirty or frosty looking gray. You can clean this up with a de-oxidizing cleaner and connectivity electrolyte..... SUPERB STUFF!
http://www.fullcompass.com/prod/025519-Caig-Labs-G5S-6
Likewise...later connectors and many replacement female connectors....are bare copper...which is worse.
Copper...with age.....gets that brownish "patina" like an old penny. That patina....is actually a NON-CONDUCTOR when it gets thick enough. It increases surface connectivity resistance. Of course if you seen green corrosion...its an obvious problem.
Side note: This non-conductive patina that grows on copper by the way...is why by Federal code of regulations, IPC and ASTM standards....critical connectors like aerospace and medical device are only allowed to use PLATED connectors....tin alloys at worst, silver and gold in other locations.
C. Check the crimp area of the wire to the strain relief section on the female connector. These get worked back and forth and crack. If its heavily bent...crimp on a new terminal. If there is bare copper wire showing between the wire insulation and the crimped strain relief of the terminal...crimp on a new terminal.
The component end connectors are now done.
Once all of the above is sorted out.....so you KNOW you have good connectivity at the component end...you move to the ECU plug end.
2. The problem with the ECU plug end is that it is a totally different connector. These little "Y" forks go on each side of the circuit board edge. aside from the tin plating issue mentioned above....and too many plugging and unplugging cycles...they are relatively sheltered so there is rarely any crimping problems unless the harness and plug and ECU have gotten wet.
Inspect for green corrosion. Clean it with Deoxit spray as listed above.
Check that the gap between the forks are all the same thickness. At a glance you can see if any "Y" forks are wider or narrower. I take a small plastic pick and very slightly bend one side of each fork just a little to make the gap maybe .010" narrower so they are tighter on the circuit board edge and they are all equal.
3. The biggest, biggest problem.....is that your wires are 40 years old. They have cracks in the insulation....issues with fraying etc....that may be in the harness sheath and you might never be able to see.
So...to finally test all of this with the VOM.....the very best way....once you have all of your corrected female terminals back in the plastic plugs....is to take your male pin pigtail.....insert it in each female connector one wire at a time......
Then on the ECU end....take the pin out tool or jewelers screwdriver...and remove the corresponding "Y" terminal from the ECU plug....one at a time.
While you have it out...you can actually clean and close the gaps on them easier......but for the pigtail for the VOM on this end.....I use a small alligator clip (Radio shack or the hobby store. At the hobby store you want the gator clips that are used to connect to model rocket igniters)....and clamp the alligator clip onto the crimped portion of the "Y" fork and not on the Y section itself.
Now you have the VOM securely connected to both ends of the wires...hands free.
Set the VOM to continuity with an audible beep...so its a contact beep when you have it connected.....and flex the wire harness all along its length with your hands between ECU and the component end....listening for the audible beep to stop. This signals a break in the wire.
Then switch the VOM to resistance and check the resistance. They should all be "0".
Put each wire back in the ECU plug before removing another.
The checking and cleaning takes about an hour. There are only 23 wires in the system.
The individual wire testing takes about 30 minutes. Ray |
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crodog1
Samba Member
Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Sat May 13, 2017 4:15 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| Wow, that is a great deal of good information. I could not find the connector cleaner locally so I did order some. When I get it I will start looking at the connectors the way you explained and we can go from there. I am hoping I will find something that will fix the issues with the 1 and 2 cylinders not working. I have a renewed hope that with your great iformation I will find the problem. Thx again for all your information. gary |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sat May 13, 2017 5:47 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| Wow, that is a great deal of good information. I could not find the connector cleaner locally so I did order some. When I get it I will start looking at the connectors the way you explained and we can go from there. I am hoping I will find something that will fix the issues with the 1 and 2 cylinders not working. I have a renewed hope that with your great iformation I will find the problem. Thx again for all your information. gary |
You know.....for about $200 in parts.....including factory style ratcheting crimpers that are useful for every crimped connection in your car.....you can build a brand new harness. 
Ray |
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crodog1
Samba Member
Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Sat May 13, 2017 6:56 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| May come to that but I am on a mission now. Wish me luck. With the information you have given me I fell I will come out on top. Thx again. I will post what I find. Thx Gary |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sat May 13, 2017 7:48 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| May come to that but I am on a mission now. Wish me luck. With the information you have given me I fell I will come out on top. Thx again. I will post what I find. Thx Gary |
You will either come out on top or find out why not! 
Ray |
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crodog1
Samba Member
Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Sun May 21, 2017 9:56 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| Need some help. I took off the wires at the injectors and took them out of the plastic holder they were in BUT know I don't know which on goes on the lift or the right pin of the injector. Does it matter? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Mon May 22, 2017 2:07 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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....as I noted....remove one wire at a time.
It should not matter as they are a simple solenoid. An electromagnet.
But....every diagram I have seen shows the + wire on the right hand side when looking at the injector from the fuel rail end. The + wires lead to the ECU....#'s 3, 4, 5, and 6. The others lead directly to ground.
Ray |
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crodog1
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Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Mon May 22, 2017 6:32 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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Thx Ray,
I have learned my lesson. One wire at a time.
Gary |
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crodog1
Samba Member
Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Wed Jun 07, 2017 3:40 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| Ok Now What? I have tested the wires and connectors for the ECM to the injectors and their grounds and have found all the wires to be good. I have replaced the two injectors on cyl 1 and 2 but still when the engine runs I get no fuel coming out of the injectors. So do I have a bad ECM? Not sure where to go from here! |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Wed Jun 07, 2017 8:43 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| Ok Now What? I have tested the wires and connectors for the ECM to the injectors and their grounds and have found all the wires to be good. I have replaced the two injectors on cyl 1 and 2 but still when the engine runs I get no fuel coming out of the injectors. So do I have a bad ECM? Not sure where to go from here! |
Meaning.....you get no fuel from ALL of the injectors....or just two? And which two? 1 and 2?.......these are not on the same circuit.....so that would mean that both injectikn channels would be bad.
And if that were the case.....the other two injectors would not inject.
How are you judging that the injectors are not spraying?
Also a quick test that both sets of injectors are CAPABLE of spraying and have connectivity.....is to pull all four injectors out. Lay their tips on clean, dry paper towels. Disconnect the positive wire to the coil and insulate it (no sparks).....bump the key to the first step about three times to buzz the pump and charge the system.
Then with the key on but engine off......open the throttle all the way. All four injectors should blip about 10 times. You will see it on the paper towels.
If two injectors on the same side of the engine operate......that means that both injection channels are firing....so its not the ECU.
Did you pull the connectors from the trigger points plug and flean and adjust those as well?
Also....what is your fuel pressure?
This still sounds like a wiring issue. This can happen from a very high resistance wire in the harness with cracked insulation. It reads fine for resistance and continuity at rest....but under load its high resistance. Ray |
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crodog1
Samba Member
Joined: April 29, 2017
Posts: 44
Location: Wisconsin
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| Posted: Wed Jun 07, 2017 3:28 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| It will run on 3 and 4, not very well but it will run. I have nothing on 1 and 2 (left 2 cylinders when you are facing the front of the car) I have cleaned and checked the grounds, have removed the connectors from the white blocks at the injectors, have cleaned and adj the trigger points too. I am at a loss. gary I will do the spray test this wkend and let you know what I come up with. |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Wed Jun 07, 2017 4:18 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| It will run on 3 and 4, not very well but it will run. I have nothing on 1 and 2 (left 2 cylinders when you are facing the front of the car) I have cleaned and checked the grounds, have removed the connectors from the white blocks at the injectors, have cleaned and adj the trigger points too. I am at a loss. gary I will do the spray test this wkend and let you know what I come up with. |
You have a broken or shorted wire somewhere. As i noted......neither injectors 1 and 2....together.....or injectors 3 or 4....together.....are on the same circuit.
If 3 and 4 are working.....that means that both injector channels in the ECU are operating and you are getting output from the ECU.
The only thing that injectors 1 and 2 have in common with each other......is their ground wires.
What you might also check.....is to take the volt meter and set it to continuity ......clip the black probe end to the engine case .....and with the red probe.....test each connector in each injector plug.
You should only find one of them in each plug going to ground. And......the two ground wires....one from each injector plug.....should be crimped together at the female connector where it attaches to the lug on the case centerline.
If you find more than one wire in each plug going to ground or any cross connects between the positive connector and either one of the negative connectors....you have a broken wire in the harness.
Also.....as I noted/asked.....how are you "judging" that 3 and 4 are injecting.....but 1 and 2 are not?
Are you doing this by disconnecting injector plugs? That is not a great way to test for this.
Because the injectors fire in pairs....instead of sequentially........in reality there is only one cylinder of the four that has nearly "perfect" injection timing with reference to when the intake valve is open. The other three range from one injecting for about half of a valve open event to two injecting against closed intake valves at some point in the cycle.
This runs for the most part....two ports wet and two ports largely dry. This is only significant at idle.....as once you get above about 1500 rpm its all happening so fast its not an issue.
But.....when testing at idle for injector operation.....just pulling the injector plugs can give some odd results. A better way is to pull the ignition wires off one by one.
Also....check very carefully for vacuum leaks at the joint between the intake runners and head....and the boots between the runner and center plenun.
If you have significant vacuum leaks on one set of runners......this can make the test of pulling an injector plug enough more strange.
Ray |
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crodog1
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Posts: 44
Location: Wisconsin
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| Posted: Sun Jun 11, 2017 11:29 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| ok here is what happened. I took the injectors out and put them on some clean paper towels, unplugged the ignition coil and turned the engine over. I got spray on all 4 injectors. I put them back in and started it up but when I pull the spark plug wires on the left bank (1 & 2 ) it makes no difference. I have replaced the plug wires and plugs with new. I have checked the compression in each of the 2 cylinders but they are still not firing. I am not sure what to try next. I did put a fuel pressure gauge on the fuel rail and I am running about 40 psi. A little high but I don't think that would keep the 2 cylinders from firing. I am at a loss. |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Jun 11, 2017 12:33 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| ok here is what happened. I took the injectors out and put them on some clean paper towels, unplugged the ignition coil and turned the engine over. I got spray on all 4 injectors. I put them back in and started it up but when I pull the spark plug wires on the left bank (1 & 2 ) it makes no difference. I have replaced the plug wires and plugs with new. I have checked the compression in each of the 2 cylinders but they are still not firing. I am not sure what to try next. I did put a fuel pressure gauge on the fuel rail and I am running about 40 psi. A little high but I don't think that would keep the 2 cylinders from firing. I am at a loss. |
40 psi is not just a LITTLE high. Its far, far, far too high.
That right there can cause this problem...or a problem... because
1. The D-jet injector CANNOT under any circumstance be run over 35 psi. This is because they have low tension springs to go with their low impedance.
This causes them to not be able to re-seat and seal after they open. They will be a constant leak source.
2. The angle that is ground on the pintle is set for a specific spray pattern at a specific pressure rating. When the pressure goes above about 35 psi...and along with not re-sealing....the injector spray pattern reverts to a STREAM...instead of a spray pattern.
So....since every 1 psi of increase is approximately 3.57% increase in fuel volume...AND you have constant leaking...AND you have lousey atomization....you are from just the pressure setting alone...running a minimum of 43% too much fuel...probably more.
That high of a level of fueling can make for almost total non-ignition. If these two cylinders are two of the ones with open intake valve overlap....this alone can basically short out the plugs. No spark. Flooded on two cylinders.
So....you replaced the injectors #1 and #2...with the ones you just bought right? Chances are these may also not have the same spring pressure and are acting worse than the ones on 3 and 4.
There is a reason why the system SAYS it needs 28 psi....and not just PRESSURE. The injectors require a specific range of pressure by design.
The factory setting is 28 psi. These injectors can safely only run to about 32 psi. I say safely...because unless you are using a QUALITY gauge of at least an "A" classification (which is a class 1 in Europe) and a max range of about 40-50 psi...you can be off by more than that margin.
On a common class B gauge (class 2.5 Euro) you can easily be a +/- of 1.2 psi in the middle of the gauge on a 60 psi gauge...which is a spread of 2.4 psi....and on a class C or D gauge (class 4 Euro)...the most common water pressure gauge you buy at Home depot...will be a whopping +/- 3% in class C and +/- 5% in class D....in the middle of the scale.
So on a 60 psi class C gauge you can be off by +/- 3 psi. So just having a crappy gauge can put you over the safety limit of the injector when you are pushing upwards to 32 psi.
http://winters.com/engineering/gauge-accuracy/
Rig your fuel pump up to the battery direct so the pump runs constant with the ignition off. You just need two long wires with female connectors on the end. make sure you mind the polarity at the fuel pump. Its marked.
With the gauge connected and the pump running....set your pressure with the 10mm adjusting screw on the fuel pressure regulator...to 28 psi.
Then reconnect your pump plug and lets try this again. Ray |
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crodog1
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Posts: 44
Location: Wisconsin
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| Posted: Sun Jun 11, 2017 12:43 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| OK, I will try that. I am a little confused though. Why does the right bank ( 3 & 4 ) work all the time? I understand what you are saying about the fuel pressure but why is it not affecting 3 & 4? I will try adjusting the fuel pressure down to 28 psi. I will let you know how I make out. thx for your input and advise. Gary |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Jun 11, 2017 3:14 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
| OK, I will try that. I am a little confused though. Why does the right bank ( 3 & 4 ) work all the time? I understand what you are saying about the fuel pressure but why is it not affecting 3 & 4? I will try adjusting the fuel pressure down to 28 psi. I will let you know how I make out. thx for your input and advise. Gary |
Do you understand the inkection timing issue here? This is not sequential injection. Only one iniector fires on a fully open intake valve cycle. The other three fire anywhere from partially open to fully closed. This leaves under normal circumstances.....two ports that run very wet at idle with poor-er atomization ....and one runs partially dry and one runs fully dry.
Thats at NORMAL running. With massive injection overpressure....mixed with this timimg issue.....you can have two cylinders still not rumning so rich that they will not ignite.
Also....as I alluded to.....just disabling a cylinder and comparing it to another does not mean that the cylinder is not firing. It may just be running so poorly that you cannot tell when compared with one that is firing fully.
Also make sure your ignition timing is as close as possible when starting out at least witj a test light until you can set it,with a strobe. If you are grossly out of time.....this also affects injection timing....as the factory timimg must be set exact because the injection trigger points are slaved to distributor position.
Also....did you replace the distributor cap and rotor? Ray |
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crodog1
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Posts: 44
Location: Wisconsin
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| Posted: Sun Jun 11, 2017 4:40 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| OK got it. I will try to lower the fuel pressure to 28psi and keep my fingers crossed. Thx for all your help. I sure would like to get it running right. |
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crodog1
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Posts: 44
Location: Wisconsin
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| Posted: Sat Jun 17, 2017 6:42 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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It never seems to end. I tried to lower the fuel pressure at the fuel regulator but did not have any luck. I am not able to get it down under the 40 psi. I checked the fuel pressure coming from the pump and found it to be about 90psi. I had a new regulator so I put it on but got the same thing. Any ideas?
Hard to believe I have 2 bad fuel regulators. Thx gary |
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crodog1
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Posts: 44
Location: Wisconsin
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| Posted: Sat Jun 17, 2017 7:26 pm Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| Maybe I need an electric fuel pump that only puts out, lets say, 40 to 45 psi. Then maybe my pressure regulator will be able to adjust it down. ? Maybe. ? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Jun 18, 2017 6:57 am Post subject: Re: 1973 Porsche 914 1.7 D-Jet |
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| crodog1 wrote: |
It never seems to end. I tried to lower the fuel pressure at the fuel regulator but did not have any luck. I am not able to get it down under the 40 psi. I checked the fuel pressure coming from the pump and found it to be about 90psi. I had a new regulator so I put it on but got the same thing. Any ideas?
Hard to believe I have 2 bad fuel regulators. Thx gary |
Slow down.
1. How are you testing pressure....and with what?
2. How are you testing the pressure "at the pump"......there is NO provision for that. Fuel pressure tested exactly at the EXIT of the pump....should be very little different if any....tjan pressure at the injectors.
3. What fuel pump are you using? The stock pump should have 3 hose connections. They are labeled....IIRC.... "S" for suction, "D" for discharge and "R" for return.
4. How is your fuel regulator plumbed? Have you followed the return line from the back of the regulator....all the way to the fuel tank looking for kinks, crimps and restrictions?
5. Is the fuel flowing the correct direction through the engine? The fuel should come from the cylinders 1 and 2 side.....flow to the cold start injector and then to cylinders 3 and 4 and then ENTER the fuel pressure regulator from the side.....flowing out the back.
Pressure is checked from the barb on the fuel line between cylinders #3 and 4. There is no way to check it "at the pump".
Please tell me you are NOT deadheading the pump to the pressure gauge at its outlet. That can blow all the seals in pump....or if the pump is old can cause the bypass valve to start to leak.
If you cannot adjust the fuel pressure regulator.....and the regulator is kjown to be good.....you generally either have a restriction on the return line or your gauge is suspect. Ray |
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