Peace9

Recently bought my 90' 944 S2 and is having starting problems.
Initially thought the last owner didnt drive it much so it just needed to be driven more to fix the problem, but it hasn't shown improvement.

It sometimes starts fine and other times it doesn't start with out putting the gas pedal down, unless you keep trying it. After the start up it idles rough as well. Also when it starts up rough it shoots out some clear smoke out the exhaust smelling like fuel. However, once it steadys its idle and I start to drive everything appears to be fine, so I'm sorta confused.

So far I have ran 2 tanks of gas through with injector cleaner (thinking they were dirty) and have also put a new DME Relay in.

Any suggestions on where to look next?
Thanks

JakeS2

Broken ignitor module (located behind left driving light under bonnet) ? The symptoms match:
"It sometimes starts fine and other times it doesn't start with out putting the gas pedal down, unless you keep trying it. After the start up it idles rough as well"

Don't use injector cleaners!! Take them to somewhere to get cleaned.

Peace9

Ah ok will definately check it out, and see.
Thanks

Tom R.

check the plug to the DME. Take it off and blow some air on the connectors to make sure they are clean.

hamlin

Had the same problem when I purchased my 1989 944S2 13 years ago.

Very likely either the fuelf pressure regulator or the fuel pressure damper.

See the attached page from the Porsche parts list.

Part # 8 or part #9 will leak internally, and the tubing will carry the fuel thru to the bottom of the intake plenum and get sucked in when staring causing an over rich condition and hard starting.

I replaced both and the problem immediately went away and has never returned.

Good luck, Let us know.

David

Peace9

I originially thought that it might be the regulator or damper but sometimes the car starts fine after sitting (occasionally), which would mean the pressure would've already gone down. Did yours ever start normally with your condition?

hamlin

yes, the symptoms can be intermittent.

Peace9

Ok, so I'll probably just replace those two first and hope for the best.

Also do you happen to know if the 3.0 engine has two speed sensors, because I heard that they could cause problems so I checked and only saw one that looked pretty clean. But notice another hole below it with the exact same setup as if something was supposed to be there.

: Attached is a picture of the one I found and a little bit above the black wire with the white stripe would be the other hole

JakeS2

Yup, the 16V engines are a bit more advanced so they don't need the another sensor ; one is good enough.

Concerning the pic ; who knows where the vacuum line from parts '13' go ? Haven't seen a complete vacuum line diagram for the S2.

Peace9

Alright just wanted to make sure. Took out the other sensor and cleaned it (though not very dirty) and the car has been 2/2 on good starts. Could be just luck but will probably be replacing the fuel pressure regulator and damper if it starts the problem again.

Thanks for help
Will let you know

JakeS2

Good that it's running. Don't go exchanging parts just for fun. I changed all sensors, vacuum lines etc etc etc... and no luck. The problem was the broken MAF. Before changing FPR or damper, measure the fuel pressure on the delivery rail - if the problem surfaces again

Der Treiber

I've got a similar problem w/ my '90 S2. Starts every time when cold, but after running for > 30 minutes, then shut off warm, it will not restart. Occasionally, removing the gas cap will work for restart, so I thought there was some kind of fuel pressure issue. I purchased an FPR but I can't get the fuel rail cover off because the strut brace has it trapped in place. If I loosen the strut brace mounting nuts enough to wiggle out the fuel rail cover...will I mess up alignment/strut mounting, etc? Obviously not a suspension guru.

Looked around for a fuel pressure gauge just to verify this was the issue, but couldn't find anything w/ the right size adapter for less than $300 bucks, and don't have the metalworking tools to make the adapter mentioned over at Clark's Garage. Ideas?

Peace9

Update:

Just put in a new fuel pressure regulator and it seems to have made no change. Car still takes a little time to start, sometimes even a second or too for the speedometer needle to start to jump slightly. Then the rpms will rapidly change from around 1000 - 200ish untill it stables itself out and then runs like nothing is wrong.

Is it worth trying to put in a new damper as well since I'm beginning to think its not a fuel problem? or is it possibly a problem with a sensor?

Grandpa#3

You know it could be as simple as the fuel pump check valve. Its sole function is to keep fuel at the fuel rail for start up. It is located on the out flow side of the fuel pump.

Cheers,
Larry

Peace9

Update:

Sorry for not updating sooner, but just replaced my dampner two days ago and that seemed to the trick. The car now starts up well and idles fine right away.

All in all I replaced the following... (In this order)
Fuel Pressure Regulator (Same Bad Start)
Fuel Injectors (Same Bad Start)
Dampner (Started Up Fine!)

Might want to start with the dampner since this seemed to fix the problem, but it could've been a combination of the three. Hope this helps any one with the same problem.

Thanks to all those that helped!