1991 944 Turbo Starting/Running Problems!

[JSHammond]

Evening all,

Any help with this problem would be appreciated.

Recently developed problems starting the 944 after we ran the fuel down to its reserves. Car cut out on the way to the petrol station. Obvious first step was to top up the tank, 10 litres from some jerry cans later and still no start. Checked the fuel pump was working using the wire loop in the DME socket trick, pump whirled up fine, also would of removed any air bubbles that might of formed. Still no start. Checked the spark plugs and they didn't seem to be sparking too well so changed all plugs, distributor cap, rotor arm and ignition coil (all were on to-do list anyway). Left the car for a couple of days, went back and it started up fine, sounded very smooth but cut out after about 2 minutes. Checked the fuel is reaching the fuel rail and thats fine, the engine is also turning over well but just not catching. Checked all appropriate plugs and sensors have clean connections. Went to start it again tonight and had it running nicely for 10 minutes until it cut out.

Heres what I think the problem might be: Because the fuel ran right down to its reserves some gunk may have entered the fuel filter. When the car sits unused for a few days the fuel has time to filter through to feed the engine, but when the engine runs for a decent period of time the fuel can't flow fast enough to feed the engine, hence it cutting out.

Does this sound reasonable?

Josh

 

[944 man]

I have run my Turbo to virtually empty twice in the last week with no ill effect.

When was the fuel pressure regulator last changed or at least checked? The FPR is the new 'DME relay'.

 

[JSHammond]

I haven't tried that yet. I will check it tomorrow.

Thanks Simon

 

[944 man]

Google Clark's Garage and youll find a routine for checking the FPR.

 

[JSHammond]

Still no start.

In addition to changing the bits and pieces mentioned in my first post we have also replaced the in-tank fuel filter, fuel filter, FPR, fuel damper and double checked all hose connections to ensure they are tight and not letting any air/liquid escape.

Just did a spark plug test and it turns out non of the plugs are sparking. Clarks garage points to some good checks to make to see why this is the case but can anyone on here suggest something that might take me straight to the heart of the problem and how to solve it?

Josh

 

[Frenchy]

Start with the coil, and then rotor arm and cap, sounds like my black car at the moment still no start, not been near it today. if still no joy check the resistance on the flywheel sensors, you need a multimeter,preferably a digital jobbie to check thet the resistance reading is in acceptable range around 600-1600 ohms if i remember, but check Clarkes garage website to be sure.
There is a good you tube video showing how to check them type "Porsche Flywheel sensors"
One of the sensors detects the cranking speed which in turn brings in the DME relay and the other is for TDC for the ECU.

 

[George Elliott]

I have run my Turbo to virtually empty twice in the last week with no ill effect.

...and I run mine to near empty every time without any problem. The tank is plastic and the system is high pressure permanently recirculating from the pump to the rail. A blockage is possible but its one in a million I think.

I'd guess the problem is electrical and Frenchy's advice is what I would do. There are many possible component changes, but a couple of simple odd one's I might suggest are change the Ignition coil, and change the battery. Both can give wierd failure symptoms like you have where it works one minute but shortly after it won't.

Good luck
George
944t

 

[Jaybobsdad]

Hi Guys,
Just joined so a fanfare would be great!!!
I took my 2.7 s1 for a shakedown spin after a Head gasket change a couple of nights ago. I knew I was low on fuel but thought a couple of miles would be ok. About 100 yds from home, it just stopped. It seemed like it was trying to start but wouldn't catch. Pushed it the rest of the way home which nearly killed me and went to bed convinced I'd ran out of juice. Drained the ride on mower the next morning and put some fuel in but still no joy. Seemed to be sparking and all injectors were squirting. Turned out to be the coil lead sparking onto the distributor cap screw. Sometimes it the simplest things that catch you out.

 

[JSHammond]

Thank you for all the replies, very useful info.

Having run through all the tests for checking everything is getting power we found that all was ok in that sense. Changed the battery as the one installed was some unbranded thing that wasn't holding any charge but this didn't solve our problem unfortunately. Spark plugs still not sparking.

We have disassembled the ECU and it looks like water has been finding its way onto the circuit board. The last time the car fired up and ran properly was before it was washed, after the wash the engine was fired up but cut out a few minutes later which makes us very suspicious that water has frazzled the ECU. The car is kept in the garage and hasn't been driven in the rain yet so the only time water has got on it was when it was washed for the first time.

Can anyone suggest a good ECU specialist that can test and possibly repair the unit?

Josh

 

[944 man]

ORIGINAL: Jaybobsdad

Hi Guys,
Just joined so a fanfare would be great!!!
I took my 2.7 s1 for a shakedown spin after a Head gasket change a couple of nights ago. I knew I was low on fuel but thought a couple of miles would be ok. About 100 yds from home, it just stopped. It seemed like it was trying to start but wouldn't catch. Pushed it the rest of the way home which nearly killed me and went to bed convinced I'd ran out of juice. Drained the ride on mower the next morning and put some fuel in but still no joy. Seemed to be sparking and all injectors were squirting. Turned out to be the coil lead sparking onto the distributor cap screw. Sometimes it the simplest things that catch you out.

It might help you to learn that a 2.7l car is a series two, not a series one and that the S in S2 stands for Super. It wasn't that Super though, so Porsche tried again with the S2 which was far better.

Series one 944s have a 924 type dashboard and series two cars have the later oval type dashboard.

 

[Jaybobsdad]

ahhhhh. I see. I thought the s2 was the better looking 3.0. I like mine enough until I need a 2.7 specific part. Couldn't get a s2 within my budget, but thanks for pissing on my fire, Lol!!!. Better brush up on the old marque knowledge before I get myself in trouble. Only had it a couple of months.

 

[ChasR]

Fear not newbie, Simon merely enjoys getting the information right so as to avoid unnecessary confusion in post made attempting to find a solution.

As for your 2.7 part issue I feel your pain with my daily, a Mongdeo 3.0 V6 of things! ATM off the road for such a reason.

 

[zcacogp]

Getting back on topic ....

ORIGINAL: JSHammond

Can anyone suggest a good ECU specialist that can test and possibly repair the unit?

Given the age of the car I'd have thought you'd do better to find another ECU for diagnosis. Is the ECU specific to the 2.7 or is it shared with the 2.5? Can someone on here with a similar unit help out by lending him theirs for the purposes of diagnosing it?


Oli.

 

[JSHammond]

Well this problem has got the better of us, we have decided to get it collected and looked at by a specialist.

We have explored every possible test we are capable of doing at home and replaced many parts with no joy. Cant spend many more weekends in the garage making no progress, theres no enjoyment in doing that.

Items replaced:

Coil, dist cap, rotor arm, spark plugs, speed sensor, TDC sensor, FPR, FPD, in tank fuel filter, main fuel filter, DME relay, battery, A/C compressor and belts.

Items tested:

DME ECU (no faults), alarm unit bypass, 3 way bypass of DME, 12v DC at DME terminal 30, 12v DC at DME terminal 86, 12v DC on coil, 12v DC on injector plugs. No spark showing on plug lead with a tester attached.

Josh

 

[Monkeythree]

Clutching at straws here but other potential possibilities I can think of:

Engine earth connection?
Ignition amplifier module?
Aftermarket immobiliser?

 

[944 man]

Has anyone suggest the b*stard plug at the back of the engine which randomly comes loose?

 

[Frenchy]

What plug is this Simon as you also know having starting problems also ?

 

[peanut]

ORIGINAL: JSHammond

Well this problem has got the better of us, we have decided to get it collected and looked at by a specialist.

We have explored every possible test we are capable of doing at home and replaced many parts with no joy. Cant spend many more weekends in the garage making no progress, theres no enjoyment in doing that.

Items replaced:

Coil, dist cap, rotor arm, spark plugs, speed sensor, TDC sensor, FPR, FPD, in tank fuel filter, main fuel filter, DME relay, battery, A/C compressor and belts.

Items tested:

DME ECU (no faults), alarm unit bypass, 3 way bypass of DME, 12v DC at DME terminal 30, 12v DC at DME terminal 86, 12v DC on coil, 12v DC on injector plugs. No spark showing on plug lead with a tester attached.

Josh

josh the spark is provided by the ignition amplifier which is pulsed by the ECU.
There is a test proceedure for the ignition amplifier on clarkes garage.

If the IA checks out ok and the fuel pump and injectors are working ok it may be the ECU earth point has a bad connection.

The ECU earths everything (DME, injectors, Ignition amplifier etc ) internally .
The earthing point for the ECU is alongside the fuserelay box under the dash .I think it is MPl and MP11 from memory where all the brown earth wires come together.

If the ECU hasn't got a good earth then it won't ground the second coil on the DME relay or the ignition amplifier

 

[JSHammond]

Got the 944 towed to the guys at GT One.

They found the KLR unit to be faulty. Sourced a used one so hopefully she will be up and running soon.

Josh

 

[Frenchy]

I posted this question on here reagrds a KLR unit being the fault of the non starting issue that i have, no replies, one to have a go at, hopefully this is my problem as i have been through everything else.
I would like to know what part the KLR plays in starting and running ?