Could use some help troubleshooting a 3.2 no start
 

87 Targa - I know there are a thousand posts on this but I could really use some specific direction here.

A few days ago I was about 15 miles into a drive with the car running fine. I was coasting down a slight hill, braking for a stop sign and the engine died. I didn't notice any sputtering, just a sudden, total fail. When I tried to start it, the engine turned over but there was no sign of anything firing. I had the car flat-bedded home and have done the following:

-Replaced the DME relay with a new one that I tested a couple of years ago - still no start
-Checked for moisture in the dist cap - none
-Fuel pump fuse looks good
-I believe I hear the fuel pump buzzing under the frunk when the engine is cranked (something's running in there, I assume it's the fuel pump)
-Checked for spark by pulling a plug wire, putting a new plug in the connector, grounding the plug and cranking the engine. I'm seeing no spark. The only known good plug I have on hand is a new one for my lawn tractor -- would that make a difference?
-Checked voltage at the coil - I have 11.8 volts, which makes sense given all the cranking the battery has done over the past few days

Other info:
-About six months ago I replaced plugs, wires, dist cap and rotor
-About a week ago I got a new P-car, so the 87 got moved from the garage to the driveway. It may be pouting (it has been garaged for many years) or there could be moisture issues, critter issues (there is woods around the house) or I dunno what else from being outside

I have not checked the grounds at the transaxle or elsewhere - could that be it?

Other ideas?

Thanks very much

Ken

Flywheel sensors failed.

Measure the FW sensors: Disconnect the DME and use an Ohm meter for resistance and check both. They need to measure around 1000 Ohm. Then, crank with DME disconnected and measure AC voltage of both sensors. The speed sensor needs to produce about 1V - 2V AC and the reference sensor needs to show a small voltage of around 100mV AC. If not replace the sensors.

If the sensors check out it could be the DME itself. At that point you need a NOID light to see if you get fuel pulses and only spark is missing. That is a pretty solid indicator of a failed DME.

If you have someone close by to borrow a DME that is a very quick way to identify if it's root cause.

Best of luck,
Ingo

Thanks for the responses. I hope to have time tomorrow to test the sensors. And maybe the coil? (can't hurt).

I'll report back.

Ken

I agree it is most likely either the speed or reference sensor. They are identical sensors, so you can compare the resistance measurement form one with the measurements for the other as a reference. If one of them has failed I would suggest replacing both while you are in there. It is a Bosch sensor and there is an equivalent sensor sold for a BMW that is the same with the exception that the wire is slightly longer, but the BMW sensor is ½ the cost of the Porsche. The BMW part is Bosch 0-261-210-002, and can be purchased from our host here.

Could be the sensors, but before replacing them, I would, if possible, plug your DME (the box, not the relay) into another car and see whether (the other car) starts. Could be the solder joints on the ignition circuit failed, a common problem. This happened to me a couple of years ago, and I sent my DME to Sal (sarcellar[?] on this site and he resoldered it for a very reasonable price.

Good luck!

If the flywheel sensors on your 87 have never been replaced, it is time anyway. I would replace them as a mater of maintenance.

And trying your DME in some other 87 is a good thing to try, but not many people have a friendly 87 owner on hand.

I replaced both flywheel sensors and the CHT sensor two years ago in my ‘87 3.2. The wires were crispy and brittle from decades of cat heat. I suggest replacing all three as a matter of course.
PLEASE ALSO CONSIDER REPLACING THE RUBBER FUEL LINES. Mine were beyond serviceable but weren’t leaking.

I just want to close the loop here and let everybody know how this was resolved. Turns our HNichols was right -- the problem was the DME itself. A shop had it "refurbished" and I'm back in business. As GH85 suggested, I also replaced the flywheel sensors since they looked original and were getting a bit crispy, but they had not failed. Thanks again for all the great help. As always this board is exceptional.

just one thing BR- do not throw away the old sensors..save them

Ivan

Whatever for?

My last set of sensors had a intermittent fail. The car ran but like it was possessed. Aftee the new sensors, it ran perfect. I could check the ohms and they tested out as perfect. If I hit them with heat from my heat gun they went flaky. I can't imagine ever re-using old sensors when the new ones are not that expensive. I would only replace with new if going to the trouble of taking them out.

What use do you know of for old sensors?

Glen, it is obvious that was not his problem.......cracks on the surface of the cable does not mean anything but the price of the sensor means a lot.....plus it can be used as a tool in the future for testing....

have you seen the price lately?

I just replaced mine with sensors from Pelican, I found out later that the BMW version is about 1/2 the price.

i know about the MBW..;-)..still..no reason to throw them away if there is nothing wrong with them,.....

Ivan