1987 Targa no spark

[smokinrz]

My car stalled maybe four times intermittently at stop lights before it quit for good. The last time it quit was a little different in that i was driving and felt like fuel starvation. It did start one last time after sitting a few hours and I got it home a half block away where it died in the garage and has never started since.

The car would pull to redline during the stalling phase no problem and I was able to jump the fuel pump at the fuse junction and hear the fuel pump and it still would not start, so I don't think it is a fuel issue. Recent fuel filter plugs and wires.

Replaced the DME relay. No start.

Plugged in new CHT and ground it on the hood latch. No start.

Check for spark with spark plug lying on engine tin. No spark.

I checked voltage at the 8, 27, 25, & 26 terminals of the DME harness while cranking it over. No reading using my digital volt meter and grounding on the seat base. It was a little difficult to get my aligator clips in there but I'm sure I made connection with at least one of the terminals. O volts on any of them.

I then checked the Ohms on the reference and speed sensors at the motor. I'n not sure if I have the right setting on my ohm meter but for terminals 1&2 and 1&3 on both sensors I got a reading of 1. Again, I wasn't sure if I was using the right setting on my meter but for terminals 2&3 I got a reading of around 1060 on both sensors. Looking under the car I can see the insulation cracking on at least one of the sensors.

Ohm meter has settings for 2M, 200K, 20K, 2K, 200. Not sure which one to use.

I'm not sure where to go from here. I'm so tempted to call the tow truck. I keep telling myself that no matter how many parts I buy it will still be cheaper than taking it in and I will be more knowledgeable for it.

Where do I go from here? Coil? DME?

[bell]

i had a problem with starting when i reinstalled my 3.2 in my 85, it ended up being one of the flywheel sensors wasn't close enough to the flywheel.
maybe one of yours worked loose and is just a bit too far for it to pickup?

[rick-l]

Is it no spark or no spark and no fuel?

Noid light to see if the DME is pulsing the injectors?

[Por_sha911]

Ohms tells you that the sensor and its wires are good (over 1000). Set the meter on 2K.
There is an AC voltage test that will tell you if the sensors are gapped too far from the flywheel. Search is slow as molasses right at the moment. Let me know if you can't find it.

[MOMO3.2]

smokinrz:

First, I am sorry to hear about your predicament.

I faced the same challenge a few months back with my 1987 Carrera. I used Wayne's book, my Bentley, and help from this board to run a gaggle of tests. I came up with a blank.

It was frustrating because I had NO experience diagnosing electrical systems on a car. Therefore, I was not confident about my test results.

After guiding me through some basic test procedures online, Steve Wong offered to let me plug my ECM into his Carrera 3.2. His car would not start with my ECM, thus isolating my problem. Steve then checked the solder joints on the back of my EMC's circuit board and found a cracked joint (one that I missed on my own inspection). Steve re-soldered the joint, plugged my ECM back into his car and BINGO, it fired right up. My car has run perfect since.

My novice advice is as follows: After running the basic system checks, see if you can plug your ECM into another local Pelican's car. If it is your ECM, inspect all the solder joints for cracks and repair if necessary.

I would like to thank Steve Wong, again, for working patiently with me online and then making time in his busy schedule to diagnose and repair my ECM for nothing more than the satisfaction of knowing he helped a fellow enthusiast. Steve is a very intelligent, kind, and generous person.

Good luck.

Sincerely,

Mike

[The Turk]

The 87 Motronic turns off the fuel pump if the motor isn’t turning, it uses the same sensors as the ignition, if the sensors are too far away (most likely) or not working (unlikely) you will get no spark or gas.
See this thread:
No start, no spark?
Good Luck.

[smokinrz]

Thanks for all the replies everyone I can take the ECM out easy enough, but replacing those sensors looks a little intimidating with the motor in the car. I sure wish someone had a way to test the ECM. I believe there is Plelican that rebuilds thrm.

[MOMO3.2]

Someone from Dallas with a Carrera 3.2 needs to step up and let smokinrz plug his ECM into their car...

Mike

[Por_sha911]

Smokin: Before you start replacing stuff, test the sensors via Voltage AC. This will tell you if the sensor gap is wrong. Ask me how I know...

[rick-l]

Is it that tough to put a noid light on the injector?

FI pulses and no spark(at the coil) = DME problem (possibly cracked solder joints on DME)
No spark and no fuel = Look deeper.

[TroyGT]

No, very easy to stick a noid light on an injector. You can get a set at Advance Auto or Autozone... comes in a red plastic box pretty cheap. The kit has a noid for several different types of injection systems... including Bosche. It was the tool to end a long troubleshooting experience... See the 'Stranded 911' thread... it's huge and has lots of information from many smart pelicans.

Also, I've replaced both sensors without unbuckling anything. Not hard, just have to get the rear up and the driver's rear wheel off. Two hex heads hold each sensor and they are close to each other. Just DON'T loosen the brackets that hold them in place or you'll be facing nasty spacing/alignment headaches. Other than that tidbit, they are easy to replace in the car.

Test the coil... they are prone to fail for no apparent reason.

-Troy

[smokinrz]

Thanks guys, I will pick up a noid light by this weekend. It sure sounded expensive and complicated. I'm much more familar carb jets and distributor weights But I'm learning.

I will also check the sensors voltage AC.

One of the reasons I got this car was I figured it was one of the last hobby cars I could work on myself.

[The Turk]

You’re barking up the wrong tree… No spark, no fuel on a 87-89 tells you it’s something to do with the Motronic (not likely) or the sensors (very likely).
These tests can be done in 10 minutes with a multimeter and will tell you if the sensors are working.
You need to disconnect the connector on the Motronic under the drivers seat.
There’s a spring steel clip where the wires enter on one side of the plug, push it away from the plug with one hand while pulling on the same side of the plug with the other hand, the plug is hooked on the other end and needs to be pulled from the wire side first.
Once disconnected set your multimeter to 2K ohm, put the probes into the 25&26 connectors on the harness side, you should have around 1000 ohms, next check the 8&27, your first post said you had 1060 ohms on both, they’re good.
Now switch your multimeter to 20 DC volts, put the probes into the same connectors and crank the motor, you should have approximately 1.5 volts on the reference sensor (25&26) and 6 volts on the speed sensor (27&8), if you do the sensors are working and adjusted correctly, if you don’t they are either bad (not likely) or need adjustment (most likely).
Post your results.
Good Luck.

[smokinrz]

Thanks again for all the replies everyone, I have read each one repeatedly.

Troy, I followed your thread in real time in fear of something like that happening to me.

My noid light came in today, checked it in a dark garage and nothing happened. As soon as I get a helper I will check the sensors by the voltage method.

I ran across this bit of information in my search of the archives.

"if the DG is nonfunctional the engine will get spark but no signal to the injectors, and the tach does not flutter with the starter revs. With DG functioning and BG out the engine gets fuel but no spark."

Does this sound accurate?

I don't have spark or signal at the fuel injection harness and my tach flutters just a little.

Again, the car quit while going 30 mph just like it ran out of fuel. Then started right up four hours later, drove 100 yards to my garage and died again for good.

[TroyGT]

Your situation sounds familiar... I was xmas shopping and mine cut off exiting the parking lot. It restarted and I moved it a little.... then went dead again. Pushed it to the side and grinded on it for awhile. Nothing. Came back the next day w/tools... it cranked. Ran a few minutes... I backed it out and it went dead. Grinded on it some more... nothing. Had it towed. As soon as it was off the flatbed... cranked right up and ran for awhile. Next day, cranked and went dead... that's when all mine fun began.

-Troy

[ejr601_carrera]

I was wandering if you have checked your ignition coil yet? You stated no spark, I guess that would be a logical place to look in the troubleshooting process

[smokinrz]

I have the motronic out now. Can a Porsche dealer test these or is there some place that I can send it to be tested?

[450knotOffice]

The best thing you can do is find another Dallas Pelican who has a car with a Motronic and do a quick swap to see if your DME will fire up his or her car. If yes, yours is good. If no, yours is bad. That's the easiest and most foolproof test I can think of. If I were close by, I'd offer that myself.

I fired up another thread asking if anybody in your area would come by to try that out. Good luck to you.

[Por_sha911]

Scott is correct if the other car has the same year and NA vs Euro. I used the same method to determine the brain on my cruise was bad.

[Lorenfb]

"Check for spark with spark plug lying on engine tin. No spark."

Actually, one always starts checking for a spark at the coil wire,
i.e. removed from the distributor cap and placed about 10mm
from the fan housing. Then one uses a test light to check for
pulses at the coil, i.e. pulses and no spark indicates a bad coil.

"My noid light came in today, checked it in a dark garage and nothing happened."

Usually this AND no spark usually indicate a problem other than
the DME ECM. Although the DME relay was replaced, no mention
in the thread of actually checking for power on pins 1, 18, & 35
using a test light, right? Also remember, most 3.2s have an alarm
module which removes power to the DME ECM.

As was mentioned, the troubleshooting effort is about a 10 minute process.