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PLukas 11-07-2018 11:59 PM

944 S2 3.0 start problem

this is my first post, so sorry if something is wrong.
Just bought my first Porsche in USA and shipped it back home to Lithuania (North Europe).
Its 944 S2, 3.0 engine, cabriolet, 1990. And of course - red :)

It was working fine. Drove with it around 700miles. And now I started having issues with starting a car.
Please see video, of what happens when trying to start a car:

First thought was that its battery fault. But its not. I changed battery to new one.
Then I tried other DME relay. Didn't help...
Then removed starter and brought it to shop that specializes in starter repairs. They replaced starters solenoid and cleaned gear shaft. There were some dirt, which prevented gear from sliding freely back and forth. Installed started back in the car, but issue was still there. Nothing changed.

Do you guy have any thoughts what it could be? What next I should look into?

ps. here is a link to a picture of my new baby :) )


DannoXYZ 11-08-2018 12:13 PM

Hello and Welcome!
VERY nice car!!! :)

Most likely sensor issue. MEASURE the following and compare to FSM specs:

- IAT sensor
- ECT sensor, combined with above, DME uses to determines cold-start enrichment +20-30% fuel
- crank & cam sensors, measure waveforms with oscilloscope and compare to FSM

Without measuring, problem part will NOT be found and you will be replacing A LOT of perfectly working parts with brand-new perfectly-working parts and NOTHING will change. You'll end up replacing 100s of parts and spend 1000s of Euros before you accidentally and luckily replace actual problem part without actually ever diagnosing problem.

944 Ecology 11-08-2018 12:56 PM

Bad connection between the battery and the starter. Maybe a bad ground wire between the battery and the engine.

thomasryan 11-08-2018 02:03 PM

from your video, the voltage is too low to engage any relay or the starter, so do check the grounds.

charge the battery overnight, or a fresh battery, and she will probably fire up. once started, check the alternator output. if its in the high 13's or above, you might have a parasitic draw.

note the height on the replacement battery if you purchase one.

PLukas 11-09-2018 04:26 AM

DannoXYZ, thanks, I'll try to measure those next week. Just one dumb question... What is FSM specs and where can I find them?

944 Ecology, thanks, I'll try to look into that.

thomasryan, thanks. I bought completely new battery just days ago. I know that there is something wrong, because battery gets drained in couple days. Short circuit or something like that.
After I filmed this short video, I hooked Porsche to other car with jumper cables. Battery gauge at the dashboard was showing 13,5. And it didn't solve the problem. So I am pretty sure its not battery.

Jfrahm 11-09-2018 06:03 AM

Strange. If it's not the battery/charging system it almost has to be the battery connections to the starter and/or ground.

If not, then the engine must be difficult to turn. Hydrolocking from a bad head gasket can cause this condition, it'd be a good idea to pull the plugs before trying to turn the engine over again.

If the engine does not have coolant in a cylnder, see is it easy to roll start, or to rotate the engine with a wrench on the crankshaft?

TibetanT 11-16-2018 02:03 PM

Hello PLucas:

First and foremost, "Welcome to the Pelican Forums and Porsche ownership!"

I am certainly no expert, however watching the video you made I did notice there is no respective Tachometer bounce when you are trying to start the car.
Check you Crank sensor with a Porsche shop, unless of course you have the correct tool such as an Oscilloscope.
Could be some thing simple such as the reference sensor.

This would be the sensor which sends a signal to the ECU/DME brain, as well as activating the DME relay. Not sure what it is actually called...I am new to the "944S" myself, so I am learning about the 16v cars and look forward to answers here.

Just a thought, and "Good Luck" with you diagnosis.

Nice car.SmileWavy

djnolan 11-16-2018 03:36 PM

Fully charge the battery so the voltage reads above 12.5V. Then try to start it noting if there is tach bounce.

Report back.

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