Wetherden944

Hi All...
Sorry to jump in as a new member asking for help - hopefully I can share some helpful items back going forward.
My beloved1989 944S2 cab is running very rough & very very rich - it has been a problem for a while after sitting mostly idle for a few months unloved after moving home.
So far after reading through forums & getting advice/help from a couple of mechanics I know (car is currently at one of their garages) the following items have been replaced but has made no difference & we are all a bit stuck...

• FPR
• Fuel Injectors
• Dist Cap & rotor arm
• TPS (old one was confirmed dead)
• Spark plugs
• MAF
• DME Temp sensor
• Lots of connections cleaned...

Symptoms are...

• Running very rough
• Thick dark smoke that smells like a petrol station
• Spark plugs getting fouled almost immediately - all look exactly the same
• Emissions off the scale!
• Very heavy fuel consumption

If anyone has any further ideas it would be greatly appreciated!

Wetherden944

Ah - looks like this thread from last week has a couple of items to check... https://rennlist.com/forums/924-931-...dme-check.html
FYI: Leads & coil were also replaced only last year...

Jfrahm

Usually this is extra fuel leaking into the vacuum system via the FPR or damper, or a leaking injector. Or a wonky DME temp sensor. You may have addressed some of these but maybe mistakes or confusion are in play.

Wetherden944

Thanks for responding Joel.
The FPR & fuel injectors have been replaced & checked.
All spark plugs are exactly the same - very black & wet with fuel.
When replacing the FPR there was no fuel (or smell of fuel) in the vac line that was attached, must admit not checked the others or the fuel dampers.

walfreyydo

Whats the fuel pressure...

Wetherden944

I don't have the details with me - car is at my friends garage, will ask...

T&T Racing

Suggest removing the J Boot and looking inside. Is there oil, if yes, replace AOS seals. Leaking AOS seals allows entailed air to extract oil vapor from crankcase and the oil vapor condenses in the J Boot, lower atmospheric pressure and the condensed molecules go into the engine and some drop out into the J Boot

Wetherden944

Thanks for the advice - much appreciated, I have passed it on for when my mate has a few cycles.

944 timbo

Oxygen sensor?

Wetherden944

Thankyou, but I'm 95% sure mine does not have one, non-CAT UK model - but will verify.

Jfrahm

Some have found the harness to a sensor to be frayed under the strain relief, and replacing the sensor does not address the issue. You might look at the values at the DME to see what it is seeing for water/air temp, AFM, etc.
It's also worth checking again for fuel getting into the vacuum system. A DME relay jumper is good for this so you can leave the engine off. With no leaks fund there you could try running with the fuel system vacuum lines disconnected but still watch to see if fuel pours out of one at some point. The condition might even clear up, an FPR or damper could be dry normally but leak under vacuum. If you have a hand operated vacuum pump you could try that too.
Maybe run short hoses from the FPR and damper vacuum ports to some empty bottles or something to be safer running with the vacuum lines disconnected.

Beyond that we could try to look at the duty cycle and Hz of the injector signal, many inexpensive DMMs can do this. Ideally we find someone who can give us a good basis for comparison but we might try to calculate what it should be at maybe idle and 3K RPM no-load and see if your values are way off or what. Knowing for sure that the fuel is commanded by the DME vs. leaking in somehow would be helpful.

944 timbo

With all that extra gas probably the best thing to do is give it more air so just hit the throttle! Seriously tthough, there is also a little switch inside the dme, three settings i think.

Wetherden944

Thanks for the pointers Joel - I have next week off work & have allocated a couple of days to go to my friends workshop to with his help hopefully getting Peter (yes - named!) running & through its UK MOT test. Had Peter for 17 years now & up until the lack of use (apart from the alarm issue) has been ultra reliable. Just want him back on the drive & putting a grin on my face!

Wetherden944

Thanks, will take a look. I do like the idea of the heavier right foot as well though :-)

Wetherden944

Ok - finally after many many months my car is running perfectly again.
On top of the original parts there were a number of other bits...

1. Failing coil - which was only 3 years old.
2. Duff new water temp sensor.
3. Idle control valve - bit gunged up, now cleaned & working perfectly.
4. MAF required a bit of a tweak.
5. This is the BIG one... The new fuel injectors which I purchased which were listed as being for an S2 were in fact for a Turbo (PN#280150803) - which supply more fuel, sourced a good used set of the correct type (PN#0280150811). Unfortunately these were purchased over a year ago - pretty certain the just sent the wrong ones - so can't send back.

Good news is that I now have a fully sorted car to enjoy once (if) the weather gets better...

1. Everything on the ignition system has been sorted all the way through.
2. Fuel system fully investigated / issues resolved.
3. All belts replaced.
4. Water pump done.
5. Idlers & seals all done.
6. Engine given a clean bill of health.

I also have now gathered a number of known good parts when they are needed - always a great thing to have :-)