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

N_Halbert

Sounds like the DME relay but you have already replace it. Are there another conditions at the time of the hard starts? First thing in the morning. Cooler temperatures. Higher humidity? White smoke is usually associated with moisture in engine or antifreeze. Black with a too rich fuel condition.

It might be the AFM. If it is getting stuck and not reading correctly. The 944 has a barn door type AFM.

For some ideas and testing proceedures try www.clarks-garage.com under Garage Shop Manual.

aj986s

X2 on the Air Fuel Meter (its the box between the air filter and throttle body. If car is idling poorly, try tapping/rapping the AFM and see if the idle changes. If the barn door is sticking, its sending bad info to the computer. I've been able to resuscitate mine twice by spraying Mass Air Flow Sensor cleaner into it (I'm concerned that carb cleaner would be too harsh).

Peace9

As far as I can tell the conditions really don't play a part, like I said sometimes it starts really good and others it doesn't. All the days have been pretty much the same temperature, nothing extreme.

But will definately check out the AFM and see how that goes.

Will post results.

DANNiE

AGREED!

Peace9

Took a look at the AFM and the inside seems to be pretty clear. Pressed the barn door and it moves without any hesitation, so I don't think its sticking. The sensor could still be dirty so I'll check into that.

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, and then the rpms will rapidly change from around 1000 - 200ish.

Is it worth trying to put in a new damper as well? or is it possibly a problem with a sensor?

smlporsche

I have a spare AFM I just took of an '89 S2 w/ 62K on it if you're interested...

PM me if interested.

dan gl

so.....what was the problem ?

Nyx

I seem to have the same issue right now with my 90, S2. with 58K miles on it. Not to long ago I had my AFM open, and cleaned it out tracking down a pesky eventual grounding problem. But, now this is exactly as described above. No extreme conditions, both hot and cold. With the car warm, turned off and immediately turned on again, no catch. Foot to the floor, and turn it over and it will hesitatingly start.

Any further ideas? This has just happened since replacing my starter...

Peace9

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 (Still Bad Start)
Fuel Injectors (Still 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!

Nyx

Did the surging idle go away some times? Or was it always an issue, no matter if the car was cold / hot? Did you have power dips at lower RPM's? ...

I have recently had my AFM out, and cleaned it / tested .. AOK...
but now im having a hard start problem (even with the DME relay jumper'd)

My problem is that the car will run / idle fine right after you try hard to start it. And then, it will be a hesitant at lower RPM to get up and go... but not all the time. The temp is moderate out right now.

Any ideas?

Peace9

Some times the idle would be fine right after start up if the start up was good (rare) but once I replaced the dampner the hard start problem was fixed immediately and it fixed the idle too. You can try to replace the dampner if it is having a hard start, but any other specific problems the car encounters when either driving it or starting it?

Forexample, sometimes mine would take awhile to completely warm up, meaning if i slowed down and started to accelerate again the car would jerk like it was about to stall even though I was pushing the gas down (Problem fixed with dampner aswell)

Hope this helps.