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Quote:
Originally Posted by Srwilliams View Post
Bazaar:

You know I never checked the DME relay because since the car was running great before I powder coated I assume that the DME relay was good. But I am a little confused. I thought the relay next to the DME (brain) was the fuel relay and if it was no good your fuel pump would not have power to work. Since my fuel pump is powered and spraying its butt off I assumed that the relay was good. Could that DME relay prevent the spark that I am missing. Here, I am trying to educate myself
There are 2 sets of contacts inside the DME relay. One set for the fuel pump which evidently works. The second set of contact supplies the injectors and DME computer (ECM) which also works because the injectors are getting power. So the problem is not the DME relay. You can try to change it just to try. It does not hurt to have a spare anyway.

You can do one more check to see if the DME computer (ECM) is getting power at terminals 18 and 35. If it is getting power, then ECM is suspect.
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Old 05-08-2013, 06:12 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
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Quote:
Originally Posted by bazar01 View Post
There are 2 sets of contacts inside the DME relay. One set for the fuel pump which evidently works. The second set of contact supplies the injectors and DME computer (ECM) which also works because the injectors are getting power. So the problem is not the DME relay. You can try to change it just to try. It does not hurt to have a spare anyway.

You can do one more check to see if the DME computer (ECM) is getting power at terminals 18 and 35. If it is getting power, then ECM is suspect.
Bazar:

I will do the test on the power to the ECM tomorrow. But I am just curious. I know I am having problems with the injectors not spraying. Perhaps that is the ECM injector board. But I tested the ECM at prongs 1&19 and got a pulsation to the coil. So, even if I am having problems with the ECM, it appears to be putting out a pulse to the coil. My problem is that the coil is not reading the pulse from the ECM signal and distributing it to the distributor for a spark. Could fault from the ECM come into play under that scenario
Old 05-08-2013, 06:22 PM
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From what I've read, you didn't drop the engine. ? There is a pin on the flywheel the the sensors need. Just a thought, read this thread. Sorta sounds like your problem. 86 won't start after new flywheel? no injector or coil pulse.
Old 05-08-2013, 07:54 PM
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Quote:
Originally Posted by Srwilliams View Post
Doyle:

You read correct. the pulse is going to the coil, but there is no output of the pulse from there. There are two wires to the coil. When the car is off they both read negative and when the car is on they both read positive (or vice versa). Doesn't the fact that these wires are reading positive and alternatively negative mean that they are good. What do you mean by a possible bad coil wire---could you direct me?
I assume by your comment: """""5. Sully sent me a diagram of the readout of the DME. I went to the interior of the car and checked the output of the DME (brain) to the coil (Pins 1&19). The brain was sending out a pulse to the coil as the diagram said it should. HOWEVER, the pulse that is sent by the brain is not being read by the coil and then sent to the distributor (hence no spark).""""" that you mean the coil input signal is seen at the primary, yet the secondary has no output (that is, the coil output signal is not there (AT the coil output, that is). One could test the coil's output (and it's associated cable connection TO the distributor) through simple spark testing of the feed wire to Distributor from the coil. Of course, one has to gauge the spark "qualities" (as to health), but you get the drift, I'm sure.

As well, there exists some resistance measurements/specs within the Bentley that will give you a static resistive read of both primary and secondary coil condition. Of course, sometimes, when heat is expended, things change: still, a good check.

Best!

Doyle
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Old 05-08-2013, 08:09 PM
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The ground is was referring to at the battery is the neg. battery cable. It is grounded to the right. Of the battery. Pull battery out and you will see it.
Old 05-08-2013, 08:19 PM
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I have questions highlighted in green. Can you answer them pls.?

Quote:
Originally Posted by Srwilliams View Post

1. First, pulled the injector plug as y'all instructed and put a voltage meter on the right prong. Surprisingly, I was getting 12 volts on all of the injectors with car turned on.

2. Went to left prong of each injector and was getting ground signal on each injector with car off. Did you pull out the ECM connector when you did this?

3. As yall instructed I then moved to test all of my ground points. Found the one behind the fuel filter on the drivers side wall of engine and it was properly grounded, as well as the ground strap on the front of the intake manifold (hope that is what it is called---But trust me I found that strap that you guys posted for me). One poster said on his 87 he had a ground point at the negative side of the battery (8 inches long). On my 87 Carerra, 3.2, I could not find that front ground wire.) Me and a friend mechanic looked all over by the battery---could'nt find.

3. Here is where the problems kick in. Although I was getting 12 volts to the injector, they still were not pulsing. I got noid lights as you guys instructed and I and the mechanic put them on the injectors---no pulsing.

4. Went to check for spark. No spark or fire at the distributor.

5. Checked coil. With engine off, got negative on both wires and postiive on both wires when the engine is on (this may be reversed but you get the idea. Power was going to the coil, as well as ground. But coil was not sending pulse to the distributor to cause arc, fire, or spark (one of them is correct). Everything completely dead at distributor. We pulled a spark plug and put it in the ignition wire that goes either from the coil to the distributor or to the coil and nothing (mechanic did this test so I am ignorant here)

5. Sully sent me a diagram of the readout of the DME. I went to the interior of the car and checked the output of the DME (brain) to the coil (Pins 1&19). The brain was sending out a pulse to the coil as the diagram said it should. HOWEVER, the pulse that is sent by the brain is not being read by the coil and then sent to the distributor (hence no spark). What type of meter did you use to check the pulse at pin 1 and ground pin 19? Did you actually see a high and low voltage signal?
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Old 05-09-2013, 02:33 AM
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Bazaar:

In answering two your two specific questions.

1. No i did not disconnect the ECM (brain on the inside of the car) from the ECM harness when i checked the ground on each left injector prong.

2. When I checked pins 1 & 19 I used a voltage meter. the mechanic who was reading the meter said it was pulsing. I did not see it, and I really do not know if he knew how to actually read the meter. I simply went off of his word.

Could you share with me your suspicions that prompted your questions because i am truly stumped
Old 05-09-2013, 07:14 AM
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Quote:
Originally Posted by Srwilliams View Post
Bazaar:

In answering two your two specific questions.

1. No i did not disconnect the ECM (brain on the inside of the car) from the ECM harness when i checked the ground on each left injector prong.

2. When I checked pins 1 & 19 I used a voltage meter. the mechanic who was reading the meter said it was pulsing. I did not see it, and I really do not know if he knew how to actually read the meter. I simply went off of his word.

Could you share with me your suspicions that prompted your questions because i am truly stumped
1. The reason I asked if the ECM was still connected was because with the ohmmeter probe on the ground pin of the injector plug and the other ohmmeter probe to the nearest ground point in the intake manifold, that just indicated that the injector plug has a connection to the ECM ground circuit. A better way is to test continuity directly from a disconnected injector plug to a disconnected ECM plug so you can tell if there is a disconnect someplace in the firewall connector.
2. It is really hard to see the pulsing on a digital meter display. A scope meter will be best. With your test, you really cannot say the ECM is providing the ground pulse to the ignition coil.
The ignition coil pulse signal is a series of fast 12V and 0V switching signal. 12V saturates the ignition coil primary coil and zero volt causes a collapse in EMF on the primary coil to induce the high voltage spark on the secondary high voltage coil. The high voltage gives the spark plug the high voltage arcing.

Are you going to send out your ECM for testng? You can just wait until you get the ECM back to confirm your ECM is good, then troubleshoot further.
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Old 05-09-2013, 08:15 AM
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Quote:
Originally Posted by bazar01 View Post
1. The reason I asked if the ECM was still connected was because with the ohmmeter probe on the ground pin of the injector plug and the other ohmmeter probe to the nearest ground point in the intake manifold, that just indicated that the injector plug has a connection to the ECM ground circuit. A better way is to test continuity directly from a disconnected injector plug to a disconnected ECM plug so you can tell if there is a disconnect someplace in the firewall connector.
2. It is really hard to see the pulsing on a digital meter display. A scope meter will be best. With your test, you really cannot say the ECM is providing the ground pulse to the ignition coil.
The ignition coil pulse signal is a series of fast 12V and 0V switching signal. 12V saturates the ignition coil primary coil and zero volt causes a collapse in EMF on the primary coil to induce the high voltage spark on the secondary high voltage coil. The high voltage gives the spark plug the high voltage arcing.

Are you going to send out your ECM for testng? You can just wait until you get the ECM back to confirm your ECM is good, then troubleshoot further.
Bazaar:

I am going to send out the Brain now. I will get it back and then troubleshoot from there. Thanks so much for you and everyone else's patience and guidance.
Old 05-09-2013, 08:32 AM
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Quote:
Originally Posted by Srwilliams View Post
Bazaar:

I am going to send out the Brain now. I will get it back and then troubleshoot from there. Thanks so much for you and everyone else's patience and guidance.
Good luck.

Here are the diagrams for the fuel injectors and spark ignition. This will help.


Injectors:


Ignition:


Let me know if you need the complete file in pdf.
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Old 05-09-2013, 11:32 AM
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Just to give a little information on the coil, the black wire is a 12V source when the key is in the run or start position to the coil +15 terminal. The green wire goes from the coil '-' connection back to the DME, which makes the connection to one of the brown ground wires connected to the intake runner to trigger the spark. There is no signal on the green wire, just a series of intermittant ground connections to trigger the spark. It works like a set of electronic points opening and closing the ground connection.
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Old 05-09-2013, 12:14 PM
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Quote:
Originally Posted by E Sully View Post
Just to give a little information on the coil, the black wire is a 12V source when the key is in the run or start position to the coil +15 terminal. The green wire goes from the coil '-' connection back to the DME, which makes the connection to one of the brown ground wires connected to the intake runner to trigger the spark. There is no signal on the green wire, just a series of intermittant ground connections to trigger the spark. It works like a set of electronic points opening and closing the ground connection.
I respectfully disagree that the green wire makes a connection to one of the brown ground wires connected to the intake runner to trigger the spark.

The DME ignition driver circuit provides the grounding to achieve the zero volt pulse. The grounding is internal to the DME circuitry. The DME itself which is located inside the cabin has it's own grounding point and does not need the grounding point in the intake runner.
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Old 05-09-2013, 12:49 PM
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Srwilliams, I hope this doesn't confuse you.
I realize this is somewhat off track, but I enjoy learning from others also.
I respectfully will agree with you, you are the Engineer and I am the Electrician. I have not had the training in electronics you have and over simplified the ground connection. While not a direct connection, it just seems to me that internal grounds seem to come from the external ground wires on the intake runner. Most of the ground connections seem common from what I can make out of the diagram, aside from the bridge connection for the California emissions ground.


Also, a note on the coil from the manual for Srwilliams. Testing of the coil should not be with leads on the meter across the coil (+)15 and(-). They also seem concerned with how the terminations are made on the coil.


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Old 05-09-2013, 02:22 PM
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Sully:

No problem. I am in the background smiling as I pick up little tidbits of scrape information that falls to the side during the exchanges of two heavyweights---Bazar and Sully.

In truth, I am learning a lot from the debates and meetings of the minds that the two of you come to. Also, it lets all of the rest of us neophites and DIY people know the level of knowledge we need to reach to be able to effectively work on our cars. I am so impressed by the knowledge that people like Bazar and Sully have, as well as their ability to break matters down on the base level so people on my level can understand. they never once have talked over my head in trying to assist me
Old 05-09-2013, 03:03 PM
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Spoke with a VERY knowing Porsche guy today and he was quite concerned (with all of the disconnects) that the sensor connections didn't get swapped on the reconnect, as this would give you the indications you are experiencing. Hopefully, you've already put that suggestion to bed.

Best!

Doyle
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Old 05-09-2013, 03:20 PM
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Hey y'all, i take no offense in constructive disagreements. I just wanted to make sure the information on this thread is correct and will be useful to anybody down the road.

This board is all about helping and learning from each other. We all love to work on our pcars.
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Old 05-09-2013, 04:10 PM
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Quote:
Originally Posted by dshepp806 View Post
Spoke with a VERY knowing Porsche guy today and he was quite concerned (with all of the disconnects) that the sensor connections didn't get swapped on the reconnect, as this would give you the indications you are experiencing. Hopefully, you've already put that suggestion to bed.

Best!

Doyle

Doyle:

Both me and a knowledgeable porsche enthusiast covered the sensor possibility (mis-swap) several times. In fact that is the first troubleshooting we did.

But I really want to thank you for the level of your concern of my predicament that you consulted with your own resources. For you to go to that extent to assist me really speaks to your level of concern and consideration.

Thanks so much
Old 05-10-2013, 03:42 AM
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My apologies, SRWilliams. I've just now read the entire thread and obviously missed your reference,...so, onward (with the sensors having already been checked).

Best,

Doyle
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Old 05-10-2013, 09:40 AM
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Lightbulb Injectors not spraying - solved

was this O.P. ever solved?
- a report would be useful,

in any case, i am posting this possible solution so that a future comrade who stumbles here via google will have a decent clue about a possible solution

i had a similar problem as of 3 days ago; (5 days before that i drove it over 600 miles with no problems)

'89 3.2 ... suddenly just began running like on half cyls after a mile (like fuel starvation, then would pick up momentarily, .... then died completely & no start -

i went thru testing most of the "usual" suspects starting with the DME Relay; then the Test Plan ( the Relay is good - the pump works per spec ign on & crank, , it has good spark, no NOID indication, swapped DME/ECU, etc);

it does start & run on starting fluid;

- starting on the circuit tests suggested in this thread, & my enlarged factory wiring diagrams in hand, i discovered no 12V at the injectors, and no continuity from Pin 87 of the DME Relay socket to the injectors - so i apparently had an open in the harness

today, i discovered that the injector harness 6-pole plug had simply come undone - it just vibrated loose
(to paraphrase rusnak "that is weird")

- obviously had to be working its way loose for a long while - (spirited driving on rough mountain roads a possible contributor, but the wiring loom was securely bolted to the manifiold per oem just 2" or so from the plug )

p.s. - this thread has lot's of good troubleshooting info i've not seen in many others

O.P.
QUOTE=Srwilliams;7427450] in fault checking my no-start issue I have traced it down to my injectors not spraying.
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Last edited by larrym; 08-31-2017 at 07:42 PM.. Reason: solved - updated
Old 08-29-2017, 03:17 PM
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solved - see above edited post
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Old 08-31-2017, 07:44 PM
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