input needed for no start
 

Hi, I have the infamous no start issue. I have been reading numerous v good threads on what it could be to no avail.

When I re & re'd the rear suspension, I also replaced the fuel pump, DMT relay, O2, head, speed & reference sensors, including a Steve Wong chip. Since this time, I never made note as to which of the two plugs that the speed and reference sensors went into. I do know that the top one is for the head sensor
I does states that if it doesn't start to just reverse them. After doing this it still did not start.

I have no spark whatsoever at the plugs, and I also cannot smell any fuel. On the ECU #1 pin - coil - I get a 12.8 reading. When testing kohms for the speed and reference sensors, at the end of their connectors, I get 9889. When installing the reference sensor, I did glue a 0.8mm thick washer to set the space between it and the flywheel pin.

I have, for the time being, removed Steve's chip, and reinstalled the original one. It is installed correctly according to Steve's instructions. I did this with the thought that it may possibly make it a little easier for the ECU to sync.

The ECU looks as new. Very clean and shiny, and I could not see any cracked solder joints anywhere.

Prior to changing all of the above sensors, the car ran very well. Even after sitting for a long period it would start within just a couple of turns. The cap, rotor etc. only has about 1000 km -60K miles on them. The car has 126,000 km's - 78K miles.

Any and all thoughts will be greatly appreciated...Thanks in advance.

Hmmm?

Okay, so you removed the ref/speed sensor mounting bracket to install the sensors?

Did you try the old DME relay, new one could be bad out of the box.

Also the wiring harness for the CHTS and sensors, did the "click" in to insure a proper seat?

Yes...The connectors are 'snapped' right in. I still though have no way of knowing if they are in the right socket. I wonder if there is a way of finding out which one is the right one? They, as you likely know, are not marked like the sensor cables.

I replaced the new DMT with the old one. When I turned the ignition on I could hear the fuel pump with both of them. Can't say that I noticed that before. After checking things out for sometime, the pump now doesn't go on when I turn the ignition on. I did jump the fuse for the pump -#6 - and it works. I kept it jumped for a moment while I cracked the rear fuel rack plug. It had pressure.

I think that I should take the reference sensor off so as to see, if by chance, that the pin on the fly wheel hasn't been sheared off. I was going to have a look but I put it off as it is such a pig of a thing to get at. Yes, I did have the sensors bracket off as I had removed all of the tin work so as to repaint them.

As I just stated, I somehow have to work out what the correct sockets are for these two sensors before I go any further ay. What do you think?

BTW, I have zip movement on the tach when cranking...Meaning?

Here is a post by a Pelican: http://forums.pelicanparts.com/porsche-911-technical-forum/552276-no-spark-problem-finally-resolved.html

See if you followed all steps.

No Tach means speed sensor is not reading. So we are at the correct culprit, sensors.

On our 3.2s, the fuel pump will not activate until car is on, so not hearing the pump in "ON" position is normal.

With the old DME relay in place, try one more time to swap the sensor connectors.

I think I know what happened, you gaped it 1/8th, right? 0.125 inches = 3.175 MM, that is way too wide.

Should be per the post above and in the Bentley 0.8MM = 0.0315 inches

Wow!...What an excellent write up!.. I wish that I had been able to read this Pelicans thread on my first go around.
I'm going to make up his 'Thinga-ma-jig' tomorrow so that I see if the flywheel still has a pin :( I sure hope that it does. I'll still have to keep looking around to see if I can find out which is the correct sockets for these two sensors.

Jim, what do you think?..It shouldn't harm anything if I were to run 12V down one of the female sockets to find out what # the ECU speed or sensor pin connector is... Would it?

No need, just get an extra long spare wires and hook them up and put the leads of you DVM to see which one is showing a closed loop via continuity tester on audible mode. :-D

Less chance of burning up a wire, these are thin signal wires after all.

Maybe a 9 volt???

Sorry about that...No it was a 8mm washer that I used. I actually ordered it when I purchased the sensors. ( BMW) BTW, having the leads a bit longer is an advantage over the Porsche ones. Crazy eh:confused:...The same sensor for half the price. Just an other little 'RrrrriP' eh.

You do mean 0.8 MM correct?

Yeah, right, BMW cheaper than Porsche, go figure :-)

Correct...0.8mm. Just about as thin as a razor blade.

Your thought of using 9 V's is a much better idea. I even have a new one that I keep as a spare for my multimeter. I'll let you know how I go sometime tomorrow.

Hopefully the flywheel still has a pin:eek:

Jim...Thanks so much for your input...Much appreciated!

Oh my pleasure Brother Michael!

Update...I should have thought about it a bit longer than I did re 'which' female wiring plug is the speed or reference sensor? I just did a simple multimeter continuity test to find out.

The BG - Bezugsmarken geber :) - Reference mark identifier.... or 'giver' - are pins #25 & 26 on the ECU connector. The other female plug is obviously the speed sensor.

As a matter of interest to anyone, if you have the female plug in the position to plug in... (there are 3 pins to each plug)

The top pin is a ground
The center pin is #25
The bottom pin is #26

With this sorted, I will now spend the afternoon trying to find out what the no start issue is... 'Happiness is'... hearing it run again:)

Is the old sensor still intact? If so try it.

We need spark

I found it...At least one if them.
The speed sensor was a whisker tooo close to the flywheel. It's toast. The reference sensor looks OK but I now have to turn the engine over to check on the 'pin'

I don't think that I threw the old ones away?...I'll have to have a look. At least I know what it is eh... Yes ! - 'The Phoenix' will rise from the ashes soon!http://forums.pelicanparts.com/uploa...1464911859.jpg

Nice :D

Heart break hotel
 

Unfortunately, not even an old Phoeinix, nor has anything else risen from the ashes:confused:

I'm back to square one it appears. I have not only gapped (0.8mm 1/2 O.D. washer) and replaced the new replacement speed sensor, but I also just finished taking both them out again to check if they were OK - They were.

I have new speed, reference, head, O2 sensor, including a DME.

I'm back to having no spark or fuel pump. The pump works well when it is jumped from the fuse panel. I even put in a new fuel pump relay.

I have opened up my old and new DME, and when the key is on, or when trying to start it, the points in both of them do not activate. The one thing that is baffling me is that when I jump pins #30 - #87 -#87b, the pump still will not engage.

#30 has 12V. I have done and redone many electrical checks. What am I missing???...

All input is most welcome!!

Let's go back to the ECU. When you put the harness on, did it "CLICK" closed to the harness or just mate together? Take a look at the pins to see if any are smashed or out of alignment.

Due to the plastic on the metal 'lock' side, there really wasn't a click as such but they are definitely seated. It's interesting that you asked about any mashed pins. Due to wondering the same thing, they were the last thing that I checked. I did 'tighten up' a couple of them, but none were so out of position as to impede the harness pins.

Both good questions. Please keep them coming

BTW, do you happen to know why the pump won't go on after 'jumping' the three pins 87-87b and 30? As mentioned, when I manually push the points on the DME relay, the pump does go on but not when jumped.

some news but still a no start
 

I have confirmed that the coil is OK...

I pulled the distributors coil wire, and then plugged it into a new spark plug. I then ran a jumper off of the ignition side of the coil. With the plug close to a ground, I touched/rubbed the ignition wire to the ground and I was glad to see a nice blue 'zap' from the plug.

I still can not get the fuel pump to activate by jumping #87 - 87b and #30 to either of the DME's. One that was working and the new one I had as a spare. If I manually hold the points on either DME's - covers off - the pump will run.

I have 13 V at the female side of #30.

Update...

When grounding #20 on the harness the fuel pump should run but it doesn't.

There is though 12+ volts at #1 on the ECU harness.

At the speed sensor harness there is .9877 ohms ( should be from .6 - 1.6 ohms )
On pins #8 and 27, on the harness, the reading is the same so the new speed sensor is working.

When I manually let the fuel pump run, there was no smell of gas anywhere. When I loosened the fuel plug on the left injection rail there was pressure.

Looks like this is continued here: http://forums.pelicanparts.com/porsche-911-technical-forum/918346-dme-relay-no-can-jump.html

Yes, I am sorry to say but it is. I was actually going to drop you a PM as I have read many of your posts on these matters over the years. They have been very good. .

Being that the DME(s) relay is not working, I guess that I should purchase another one. As mentioned, the original one worked; I have carried this new one in the car as a spare...Would you be able to provide me with any info that you may have regarding why I can not get the pump, and the secondary set of points, to work when jumping the three pins of 87-87b and 30?

Where I am at the moment...

I have 13 V on the #30 female pin of the DME. I have tried both; the one I took off and the new spare that I have. (both covers are of). I can get the pump to run if I manually hold the points for the pump, but I cannot get it to run when jumping #87 -#87b and #30.

When grounding #20 on the harness the fuel pump should run but it doesn't.

There is 12+ volts at #1 on the ECU harness..

At the speed sensor harness there is .9877 ohms ( should be from .600 - 1.600 ohms )
When testing the ohms on pins #25 and #26, on the connector harness, the reading is the same, so the new reference sensor is working. The speed sensor, pins #8 and #27, also had similar reading so it is also OK.

When I manually let the fuel pump run, there was no smell of gas anywhere. When I loosened the fuel plug on the left injection rail there was pressure.

Any idea's?...

*Note - I am moving all info back to this thread..
 

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Let's try to get some clarifications on record here:

DME: Is the large box with silver metal cover under the driver's seat and is also called ECU or control module or similar. It is the electronic brain that "listens" to the sensors and delivers fuel and spark signals.

DME relay: is the black small box. It's a double-stage relay (or two relays with some common connections) that serves two purposes.

DME relay stage 1 is where a portion of Term#15 is controlled. This is the branch that is powered when the ignition is in RUN or START. This stage turns on and then powers the injectors and the ICV and the DME itself when you turn the key. It also provides power to the positive side of the coil of relay's 2nd stage.

DME relay stage 2 of the DME relay could also be called fuel pump relay since it serves exactly that function. It is controlled by the DME and when it is turned on it powers the fuel pump and the O2 sensor heater.

Term#30 on the DME relay socket is a direct connection to the battery positive terminal without fuse. So this should always be +12V.

Pin 20 of the DME harness needs turn the 2nd stage of the DME relay on only when the key is in RUN position. If that doesn't work the DME relay or the harness is damaged or the ignition switch isn't working. Could also be an alarm issue if equipped.

Pin 18 and pin 35 are connected internally inside the DME harness. The wires are spliced together inside. If you are absolutely sure you have counted the pins correctly this would suggest the DME harness is damaged. A very unlikely but not impossible scenario.

The resistance readings are 800 - 1600 Ohm or 0.8 - 1.6kOhm. Same difference but let's keep the units correct if someone else reads this in the future.

Let me ask you this: When you turn the key to RUN you should see (if the cover is off) and hear the DME relay click. This is the first stage turning on. At the same time you should confirm that the ICV on the back on the engine is vibrating. That tells you that the DME is getting power and the first stage of the DME relay is working. If not check the ignition switch or any factory-alarm or after-market alarm unit.

And last but not least why are you starting this new thread instead of continuing the previous version here input needed for no start. Maybe more efficient to keep everything in the same.

Good luck,
Ingo
__________________
'74 Targa 3.6 (not stock ) - '01 C4 (almost stock) - '00 ML430 (stock)

I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs
Porsche "Hammer" or Porsche PST2 - I can help!!
How about a NoBadDays DualChip for 964 or '95 993

Hi ...I just read your post on my new thread.

I understand what who are stating in how the replay works in conjunction with the ECU aka DME. Thanks for the info. For clarification, there is no power on #35. I should then open up the wiring harness that enters the 'box' - Correct?

Update - Correction... No power on #18 or #35 on connector pins.

No, there is no 'click' at the relay when I turn the key on. I have the covers off both of the DME's, and the points do not move. I also took the ICV off and cleaned it with carb cleaner. It did rattle when I shook it before I did so. It appears though to rattle a little easier now. I assume that there is no vibration due to having no power.

BTW, the alarm was disconnected many years ago and the ignition switch is about two years old. There are no other aftermarket items running off of the ignition switch. I do have an aftermarket amp which runs through original the radio head. I use my iphone for my tunes and it is plugged directly into the amp. I do have a separate on-off switch for the amp which is for the iPhone.

Again, any thoughts on why the DME relay won't work when jumped?

In the morning I'll open up the harness to the ECU to see if a wire is broken or whatever.
__________________

OK, if the DME relay stage 1 doesn't switch when you turn the ignition to ON check if you see power at pin 86 in the DME socket. Measure against pin 85 (GND) in the socket and against a metal surface. If the later works you are missing ground. If neither works your issue is at the ignition switch or alarm module or wiring. If both work and the relay doesn't click audibly when in the socket it's bad.

Cheers,
Ingo

Hope
 

I just rechecked the pins, and pin#1 has 12V+
While there, I quickly took the cover off of the connector, and all seems to be OK within it, including about 3" into the harness. I'm also going check into the wires at the DME relay.

Thanks so much Ingo!.. I'll give everything you suggested a go in the morning.

As a first detail: It is important to be precise when discussing a technical subject. If you create confusion by using incorrect terminology you will get incorrect imprecise responses.
Above you say "DME". I can infer that you actually mean "DME Relay". There is a huge difference. DME is "Digital Motor Electronics", ie the computer and it is expensive and complicated. "DME Relay" is a switch that turns on the fuel and part of the DME. It is inexpensive and rather simple.
Be precise. [disengage pulpit]

-----------------------------
Back to the task at hand.
The issue you mention above needs to be resolved before you go any farther. If jumping the DME relay doesn't fire up the fuel pump it is an obvious failure and you can't test anything else until it is resolved. You must be able to turn on the fuel from that connector otherwise you will never get it to run.

You need to trace the wire back to the fuel pump.
- I would first check and see it you have continuity to the fuse block. The least likely of failure is the wiring harness from the DME relay to the fuse block so let's rule it out first.
- Also check the continuity from the DME relay plug to ground. If that has continuity then the harness is shorted and is a serious hazard. (Very unlikely but you are there so check it.)
- Check the fuse block, it's connections, and the fuses are a common failure. Check where the wires terminate, the screws, and the holes where the fuses rest in the blades. They must be clean to carry current and of course they need to have continuity.
- Check the wiring from the fuse block to the fuel pump. (Actually you have already done this when you jumped the fuel pump but if someone reads this it should be complete...)

Weird question: When you jumped the DME relay connector did you connect to the mirror of the diagram on the bottom of the relay? (It would be a normal type of mistake...)

------------------
The fuel pump is not supposed to turn on when you turn the key. If the fuel pump comes on by just turning the key to the run position then something is wrong. (You could conceivably get a car to run this way but it would still be wrong.)
The DME relay is there so the DME can control the fuel pump. If the DME isn't running the motor the fuel should be off.

OK... I still have no power on the DME relay pin #86.

I took the heater, etc out to recheck the alarm module. It's harness connector was unplugged and of both the plug(s) and the module were taped over and secure.

I have removed the back of the ignition, and all of the main -red- wires have 13 V.

With the cover off of the DME female relay, all of the wires were in excellent shape. Again, power only on pin #30. I did ground #85 as suggested, but it appears that the ground is OK as it didn't change the no power on relay pin #86.

I removed all of the top and bottom screws on the fuse bar and cleaned them up with some sand paper. I did the same to the three fuses in the engine compartment.

I peeled back the wiring harness on both the DME relay and the ECU/DME, and they also are 'as new'.

What is there to try next, or is there? :confused:

Being that the ignition switch is only two years old, it turns the starter, including things activates the fans, radio, electric windows etc -all work...I consider it not to be the problem.

The coil checks out, as do both the speed and reference sensors. The issue seems to be that of not having any power other than #30 on the relay, including the fuel pump does not work on a jump of #30 & #87b.

It appears that I better get BCAA in here to tow it to a shop.

Slow Down!

There are so many conflicting (improbable) test results my head is spinning.

Main one ---- fuel pump runs when you push down the wiper but not when you jumper the DME relay and no power when you jumper the DME relay.

Correct...The car ran well and it is in v good condition throughout. It has always been garaged, and is only licensed from May 1st - Nov. 1st. What I am saying is that there is no corrosion anywhere on the car. The electrical harnesses are all in excellent condition,

Whatever has happened, happened after I changed all of the sensors, DME relay, and a SW chip. I can read schismatics and have rebuilt engines...This issue has truly got me baffled big time. Thanks for your interest.

Fully agree. You need to solve one issue at a time. First, you need to understand why the 1st stage of the DME relay doesn't turn on. I had posted a simple set of tests where you check for power from the ignition switch. Without that nothing else matters. Don't open harness to the DME as that is downstream from your issue

You're both right...
 

I must find out why there is no power at pin #86. I know that it is the key to opening up the other side of the relay, fuel injection etc.

Being that it is switched, would you happen to know what the pin # on the ignition switch is? I know from having the relay apart, that it should be one of the four red wires on the ign. switch.

Thanks for your patience in advance

The alarm module usually INTERRUPTS the wire from the ignition to the relay's stage 1. Unless you have a jumper installed a car without alarm module will not start. Just saying....

Wow so my post on the other thread (regarding this issue) may have been a bit premature. Looks like lots of awesome interest and support on this thread. Keep digging Horse you'll figure it out.

Unfortunately I still have no power on pin #86 on the relay. From what I understand is that pin #86 on the relay is controlled by the alarm unit which is output pin 87a.

Just making an edit.. re 87b being part of the alarm. I have read that it is the black wire that connects directly to bus 15 at the unfused side of the turn signal/back up light fuse. In the 'Run' position it has 12 V.

Now 'IF' the relay has a malfunctioning factory alarm, how do I check to see if is 'malfunctioning?

There is still no power on fuse #7 but there is 12 V on #8...I understand that these two are the 'Run + Start' positions which is also #15 on the ignition switch...Is this correct?


What is new, is that by jumping #30 and #86 it will power the fuel pump. #86 is a thicker red wire with a greenie-gold stripe. On the fuse block it is #7. I ran a continuity test on it and it is OK.

Question: How can I check if the fault is in the ignition switch? I said that it was two years old but I see that it is now four years old, but with very few starts, relative to a daily driver.

The switch or the alarm seems to be the only things that I can narrow it down to.


Input please...Thanks

I pulled the heater etc., out of the way to get at the alarm module again. The main plug, consisting of four separate pins, is disconnected but the two pin, 2 wires, are still plugged in. They are the horn wires. One red and the other is red/white.They are still hooked up on the bus block...I tried starting it with them unplugged but it never made a difference.