Alaska Cabrio

Hello,


Been reading thru a few threads that have similar issues, my 1990 S2 has been demonstrating.


Bought the car last March 2015, drove it across the USA and then shipped to Alaska. Car has 121, 938 miles on it.


When leaving Las Vegas and driving all night at low ambient temps, near 70 mph the car started acting like it had water in the gas; loss of power, engine stuttering. This lasted a couple of seconds then it ran fine. Happened several times, along a 30 mile stretch.


First remedy was to buy some heat and that seemed to help, rest of drive didn't have any issues again.


Then driving from Anchorage to my hometown, early April, major snow storm, going up a pass, it started doing it again. This time it would run fine, however at random intervals, it would stutter again for a couple of seconds then run fine again. Adding heat this time did not help.


Last year I put about 3500 miles on it. 99% of the time it ran great.1% of the time at random, it stutters for a few seconds then runs fine. When it stutters it acts like water in the fuel, or like someone is turning the ignition off and on really fast.


It sat all winter in a garage. I replaced fuel filter, oil filter, air filter and completely replaced brakes rotors/pads and installed new wheel bearings.


Today decided to drive it to work. Ran fine until turning into work parking lot. Began to stutter again, this time it would idle, really rough, no throttle response or engine power available. Just as I was getting ready to turn it off, it began to run normally.


Tonight on the way home it began to stutter, heard a backfire noise, and then it lost all power. Pulled over and found the #3 cylinder plug wire completely loose from the spark plug. Ok, put it back on and the car ran great for about 5-miles. Then it really decided it was done for the day, stuttering, giving it any throttle and the RPMs would increase but the engine sounds like it is running on 2-cylinders, no power available to drive anywhere.


Checked all the rubber intake hoses and connections for cracks in the rubber, tight connections, etc. Everything looks great.


This is my fourth 944 (2nd S2), all of the other 944's have not had any symptoms like this.


Reading here it looks like I will be looking at the DME sensor and at the fuel pressure regulator.


What else could be causing this stuttering?


Thanks for any help, suggestions you can provide.


Mike

djantlive

Could be bad coil, plug, vac leak, failed sensor, fuel pump. I would not drive it much until you fix it so you don't get stranded.

You should check plugs and coils next

AlphaOmegaPower

Start the car and wiggle the tps plug

V2Rocket

I'm thinking...plugs/wires/distributor/dizzy rotor are suspect.

Maybe worn out rotor, getting some condensation on it, or something.

Alaska Cabrio

Thank you everyone for your replies, looks like I have some work to do.


Friend helped get the car home last night, decided to check the plug that the lead came loose on.


It was almost completely out of the threads, threads were galled up and it looks like I'll need to heli-coil new threads before plug can be replaced.


Carfax showed a complete tune-up approx. 18,000 miles before I bought the car. Was thinking to completely add new tune-up parts next winter, now it looks like it'll be as soon as the parts can get here.


The condensation idea might be what is happening, only time car seems to have issues is when it is cold (left Las Vegas and it was hot during the day), or wet outside. Normal sunny days and it runs fine....


Was hoping to find a common problem area, however; it looks like I'll be ordering and replacing a few more items before summer gets here.


My biggest problem will be to find a decent mechanic locally that can work on it. No Porsche mechanics or shops here on the Kenai Peninsula.


This is my 4th 944 and second S2 Cab. Did my own maintenance on the others, looks like I'll be doing the same and learning about other areas as well.


Mike

Alaska Cabrio

Not sure what the tps plug is.


Mike

PaulD_944S2

Just as a routine question, have you checked the inside of the distributor cap?

Alaska Cabrio

The distributer looks fine, after reading about the DME over on Clark's garage, decided to take a look at it.


My DME has three cracked solder connections. Plan is to re-solder and then use it until a new one can get here.


Found a Bosch set of plugs that come with a complete plug harness, distributer cap and rotor. Decided to buy it and a new Fuel Pressure Regulator along with the new DME.


Mike

djantlive

Good luck and keep us posted!

Alaska Cabrio

Took the DME apart today. Boy what terrible soldering. Top electro-magnet switch had one cracked solder connection and three different very questionable connections.

After redoing 4 of the solder joints, think my problem is solved.

In the year that I've owned a second Cabrio, learned to live with the factory speed limiter always stopping from reving to high.

Actually what was happening was fuel starvation, it seems!

Took the car for a test ride today after the re-soldering job was done.

Car is totally different! Runs snappier and it doesn't "hit" any speed limiter type symptoms. Pulls strong now, just like my first Cabrio I used to have.

All this time I thought it was the factory speed limter installed according to the trunk options sticker.


First photo show questionable solder joints vs., a good one.


Second Photo shows closeup.


Last photo shows the color difference between proper look and what might have been overheated.


Mike

Alaska Cabrio

I do want to say Thank you to Clark's garage.


He mentions right up front that the DME soldering is a bunch of trouble! From what I saw he is 100% on this.


I'm ordering both an OEM KAM from ebay, also bought the euroasian one. Will see what it looks like and the brand new KAM.


Before I install the new DME it will have been inspected for such solder problems.


Might be a good idea to take a look at the other relays as well.


I read through several threads, almost everyone mentioned the DME relay..


Yes, they were 125% right in my case! Thank You!


Mike

Jon951

I'm going with solid state DME relays from ftech9.com. No moving parts and optional fuel pump activation prior to start.

Alaska Cabrio

Read about their product, seems interesting.


Mike

PaulD_944S2

If you are going to keep that repaired DME relay around, I would resolder ALL of the connections.

mel_t_vin

What option number are you referring to? M454?

If so, that "Automatic Speed Control" option refers to what most folks here call "Cruise Control", and not a soft limiter on engine speed.