superpilot27

problem:
While driving my stock 1987 Carrera targa, the ignition quit. No sputter, no cough, just dead.

story:
I was doing about 45mph on sunny dry day when it quit and immediately pushed clutch in, tried all starting techniques (key, clutch out) and coasted through 3 green lights and about a mile into a safe parking lot. A nice save swerving powerless in tough traffic all the way parked. That is the good news. Now the bad.

troubleshooting:
1. jumped DME Relay to confirm that the fuel pump is working, the ignition is not.
2. tested, no spark at plug, cap, or coil
3. checked bentley manual, test for coil shows no power at coil
4. checked ref sensor speed sensor and both check out same ohms 1-2 and infinity 2-3 and 1-3
5. checked all fuses, my car May 1987 does not have an ignition fuse in the fuse box

<B>background:</B>
last year I replaced DME relay, computer, cap, rotor, coil and both ref sensor and speed sensor.

need:
ideas.
has anyone had this happen?
I need to figure out how to troubleshoot/jumper thee ignition switch or wiring to the ignition switch, or maybe there is a sweet magical poschephile fix?

rusnak

do you have an aftermarket alarm? It could be that. It could also be the dme relay. If you have to jumper the fuel pump for it to work, I'd first swap out your dme relay to see if that's it. Always carry a spare.

Here's a post that I lifted from Ingo (aka "Ischmitz") on Pelicanparts.com tech forum. His posts regarding no-start issues and the Bosch DME, are so helpful and concise that his name should become a google search term.

Here it is:

(quotes added)
"First, make sure the DME is getting power and is running with the ignition ON. Simply put a hand onto the ICV (little silver can on the intake) with the ignition switched to ON. You should feel it vibrating with about 80Hz. If not you need to check why you don't have power to the DME. (Alarm unit, fuses, wiring, etc) If all checks out maybe the DME is faulty (unlikely)

Next, while you crank feel the DME relay under the seat. You should notice a faint click when it switches the fuel pump on. The fuel pump comes on with the key in the START position regardless of whether the flywheel sensors see the flywheel rotating or not.

Once you confirm the fuel pump coming on during cranking (maybe you need an assistant with a test light) it is time to check for spark while cranking. For that get a used spark plug, unplug one spark plug wire and connect it to the spark plug. Ground it on the engine (don't hold it in your hand, just put it somewhere) and watch it while your assistant cranks. See if you have spark. If not it is either one of the sensors, the coil, the distributor, or the DME.

Ingo"

lastly, go to www.goolgle.com and type this in the search box:
site:Pelicanparts.com ischmitz "won't start"

old man neri

That would be my first step at well.

2002M3Drew

Some other things to check:

1. Check the ground strap to the chassis on the bottom of the car (rear) to see if it became disconnected somehow

2. Check the battery. My SC developed all kinds of weird symptoms two years ago, where I had power and then all of a sudden it all shut off - gauges, lights, ignition, everything. I dismissed the battery because it had been working and then just quit, but it turns out the battery had an internal short. The first thing I should have checked turned out to be the problem.

cal44

Superpilot, after I replaced $500.00 in parts it turned out to be the a twenty five year old Clifford alarm.
What rusnak said

superpilot27

Ok. Thanks for all your comments.

I took your advice and have narrowed it down.
Here is where we stand.
Car will crank but not start. It is getting fuel.

Cap and rotor removed and reinstalled-visual inspection shows both are good (brand new 8 months ago)
DME relay two methods test relay as good (brand new 8 months ago)
Ref and Speed sensors test good via Bentley manual ohm method (brand new 8 months ago)
Grounds: confirmed all ground points and straps visually and cleaned the DME ground point, trunk floor gnd point and fuse box gnd point (none needed it but I'm being as through as possible)
main issue:
no spark at plugs or coil. tested and
no power is getting to the coil (terminal 15).
I did not remove the DME/ECM for now. It is dry, car has been garaged, targa top is new refurb and I even keep desiccant next to DME to keep any moisture off. (this is a refurbished DME/ECM installed 8 months ago)
My guess is:
1. ignition switch is bad or
2. wire from ignition switch to coil is bad
3. wire from battery to ignition switch is bad
I'm going through the wiring diagram now, but does anyone know the wires to check or a method to rule out these 3 items?
any other ideas or experiences?

superpilot27

PS: car has no aftermarket alarms and is totaly stock. it has the factory alarm and I've never used it in the 10 years I've had the car

rusnak

Did you put a fuel pressure tester on the fuel rail to determine that it's got fuel? Use a very small screwdriver to remove the metal clip on one of the injectors, then remove the injector connector. Make sure you are getting 12v at the injectors.

It can be something as simple as corroded positve battery connector, which the 3.2 carreras are notorious for. The battery has to push 12.5v through to the injectors or they won't open. Its a good idea to clean all of your grounds, connections, and the connector for the dme relay and the dme brain contacts as well. Use a very small brass brush or some very light emery paper.

theiceman

i don't think it has anything to do with the ignition witch , just a hunch , start and ignition commands come from the DME. Pull it out and look it over , there is another recent thread on what to look for.

J. Brinkley

2. Check the battery, sounds silly, but if under 12.5 it won't start

Lorenfb

"no power is getting to the coil (terminal 15)."!!!!!!!!!!!!!!!!!!!!!

Now what can that be? Not many possibilities:

1. Maybe check the fuel pump?
"Did you put a fuel pressure tester on the fuel rail to determine that it's got fuel?" Maybe not!
2. Replace the DME relay? Maybe not!
3. Check the DME ECM sensors? Maybe not!
4. Replace the DME ECM?
"start and ignition commands come from the DME" Maybe not!
5. Buy new cap & rotor? Maybe not!

Terminal 15, now where does that come from?

rusnak

the reason I asked about the fuel pressure tester is that I think he might have jumper wired it at the dme relay socket, then thought that meant he was getting fuel.

I think the problem needs to be checked at the most basic upstream level, which is why I posted what I did.

Also, I posted a list of google search terms in another "no start" thread. Try those. There is one thread in which Ischmitz "Ingo" laid it all out in about a dozen logical things to check.

Lorenfb

"Also, I posted a list of google search terms in another "no start" thread."

When troubleshooting, it's always best to start checking the most key and
simplest to check, i.e. the spark. Then work either forward or backward
from there. It does a disservice to those having a problem to "shotgun"
a problem and having them waste money and time evaluating unnecessry
parts. This is usually what happens with those "brain-dead" ones over on
the "dark side" including some who write books and claim comprehensive
Porsche knowledge.

There's no need to do a Google search, as the Rennlist forum has many
threads discussing this problem over and over again. A 911 3.2 is one
of the easiest 911s to troubleshoot.

rusnak

I'm 100% for not wasting money on parts. When I get some time I'll see if I can find the post that I was referring to. It would be awesome if you guys can evaluate it then. We should all have a checklist for the "no start" condition. If we all pitch in, it would become comprehensive and probably valuable.

The Google search function is valuable for searching multiple sites simultaneously.

For Example:
site:rennlist.com site:forums.pelicanparts.com "no start" +loren

or +ingo

or +911chips.com

This will produce the posts that these people have submitted, and you can choose to read what they have written.

rusnak

I'm not advocating Pelican Parts, or Ingo, or any one person or company. I do think that this Ischmitz person has posted the best 3.2 911 troubleshooting stuff that I've seen, so I think we can take some basic information off of his post and start a 3.2 911 "no start" thread.

Let's synthesize a single list that you can print out and put in your glovebox for those times when your 3.2 911 fails to start or won't run properly.

(1) First post:
I recommend a search and some reading - this has been covered in great detail at least two times in the last couple of days here.

In summary, you need to do a systematic diagnosis rather than throwing parts at it - the standard answer of "change the DME relay" or "replace the sensors" doesn't make any sense without proper investigation. Most of that can be done easily without any special tools. A 3.2 DME is not very complicated. Here is a quick list of checks:

- check if you have power to the DME with the ignition to ON (ICV vibrates with the key to ON) if not it could be the DME relay or factory alarm if present

- verify that your fuel pump comes on during cranking (test light on the correct fuse), if not it could be a bad pump, fuse, or DME relay

- check if you have spark (old plug connected to one spark plug wire while an assistant cranks the engine), if not it could be a bad DME, or one of the sensors, check the sensor resistance to be close to 1000 Ohm.

- check whether you get fuel injector signals (LED test light while an assitant cranks). If not same as above.


If you get one but not the other it is either something downstream (coil, rotor, cap) or the DME but NOT the sensors

Finally, for more advanced checks you need a fuel pressure gauge, an oscilloscope. The engine should start even with cylinder head temp sensor being bad, O2 sensor being bad, AFM being bad but run badly. My guess from experience is that if you have fuel but no spark you either have a bad coil or a bad DME. Hope that helps,

Ingo


(2) Secont post:

IF you can feel the ICV vibrating with the key to ON and you are positive that you get fuel smell after prolonged cranking at the exhaust you seem to have lost spark. This is not a sensor issue or a DME relay issue since a missing sensor or bad DME relay will prevent fuel AND spark.

Things to check are:
Cap, rotor, coil resistance http://forums.pelicanparts.com/showt...ight=coil+ohms.

If all checks out you might have a damaged DME box (the large silver box uinder the driver's seat). Turn your ignition to ON and feel if the coil gets very warm - a sure sign for a broken DME.

(3) Third Post:
Quote:
Originally Posted by dtw
Rick - I'm a relative newbie to DME. Am used to CIS and MFI (no expert on those either but I can usually troubleshoot a no-start). Where is the idle air control valve? Under what condition will it vibrate - ignition on, or do I need to be cranking.

The ICV is a silver cannister that sits on the intake in the center of the engine. It has about an inch and a half diameter and two rubber hoses and an electrical connector. It will vibrate as soon as the key is turned to ON (not cranking) and indicates that the computer in the DME is powered (good first stage of the DME relay). With that you can safely exclude the factory alarm or a catastrophic failure of the DME to be the root cause.

Then, once you crank the fuel pump and the O2 sensor will get powered. A test light on the right fuse will confirm that and give the DME relay a clean bill of health.

Next, if the DME receives proper signals from the speed and reference sensors it will produce fuel injector and spark signals. If one is missing while the other is present it is either something downstream (fuel pressure regulator, coil, rotor, cap) or the DME is bad. Sal has posted a nice tutorial to confirm the signals for coil and fuel injectors with an LED test light. Do a search - it was just the other day.

Ingo
If the ICV doesn't vibrate you have no power to the DME. I am not terribly familiar with the battery hookup on a 3.2. In essence once you turn the key to ON (oil light comes on, etc) you provide power to the first stage of the DME relay. You should hear it click. When you put your hand on it while you turn the ignition to ON you can feel it switch. The DME relay in fact powers the DME. And once the DME has +12 V on pin 18 and pin 35 it will operate the ICV with an 80 Hz signal.

So when you put your hand onto the ICV and do not feel anything that is a sure sign you have missing power to the DME box (or a bad DME, unlikely but not impossible). What baffles me is that you say you smell fuel when you crank. I don't see how that is happening without the DME being energized.

Ingo

(4) Fourth Post:
When you have the no-start situation check if the DME is actually running. Simply switch the key to ON and check if the ICV vibrates. It's the silver can on the intake.

This is a very quick check to confirm that the DME gets power and actually runs.

Quote:
Originally Posted by crashr
Could the battery cause this type of behavior?

Could bad solder joints in the DME cause this type of behavior?

I was under the impression you swapped your DME into another car and it ran. Why are you still questioning the DME being faulty?


Your battery voltage is too low. You want at least 12.4 Volts. If you have 11.4 volts and start to crank I bet the voltage will drop below 10V and that will cause issues.

Ischmitz,

I checked the DME by swapping out my DME with one from a 1988 3.2 NA car. In fact I didn't really want to do this because the part numbers were different for the DME. I later realized that two pins are swapped between the years of 87 and 88. My DME DID work in the other car however I didn't want to harm the other car by trying to drive around and letting it warm up so I can't be certain thats what the problem was.

I have checked what I believe is the AFM (4 pin plug), when the key is at the on position I get 4.6-4.8V on the blue/green wire, which I believe I read somewhere was the test? I don't believe I checked it while I was cranking.

The voltage on the AFM connector is from an internal voltage regulator. The fact that it is present tells you the DME sees more than 6 or 7 volts on its supply pins while not cranking. Nothing else. The same is true when you feel the ICV vibrating: You know that the internal CPU is running and that the idle control output stages are fine.

However, once you crank your car a weak battery can quickly let its output drop below 8 volts. This is why Sal is recommending a load test at an auto parts store. Charge it overnight is also a very good idea in case it simply isnt't fully charged. The low battery voltage will first fail to open the injectors. This is why you need to know your system voltage (battery) while cranking.

BTW: Different DME's can be swapped even if part numbers don't match for the 3.2. The only thing you might notice is that a newer DME results in hunting idle on an older car. But that is an adjustment issue of the AFM air bypass and won't hurt anything. You can drive the test car with your DME and let it warm up. It won't hurt a thing in the new car. IF your DME was going to hurt the test car it would have happened instantly (burned injectors or ICV in case a driver stage in yours is short). The vert fact that the test car started tells you that wasn't the case.

I recommend letting your DME fully warm up in the test car to exclude any doubt that is has an issue.

Ingo

(5) Fifth Post:
The voltage on the AFM connector is from an internal voltage regulator. The fact that it is present tells you the DME sees more than 6 or 7 volts on its supply pins while not cranking. Nothing else. The same is true when you feel the ICV vibrating: You know that the internal CPU is running and that the idle control output stages are fine.

However, once you crank your car a weak battery can quickly let its output drop below 8 volts. This is why Sal is recommending a load test at an auto parts store. Charge it overnight is also a very good idea in case it simply isnt't fully charged. The low battery voltage will first fail to open the injectors. This is why you need to know your system voltage (battery) while cranking.

BTW: Different DME's can be swapped even if part numbers don't match for the 3.2. The only thing you might notice is that a newer DME results in hunting idle on an older car. But that is an adjustment issue of the AFM air bypass and won't hurt anything. You can drive the test car with your DME and let it warm up. It won't hurt a thing in the new car. IF your DME was going to hurt the test car it would have happened instantly (burned injectors or ICV in case a driver stage in yours is short). The vert fact that the test car started tells you that wasn't the case.

I recommend letting your DME fully warm up in the test car to exclude any doubt that is has an issue.

Ingo


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