ExitWound

No other ideas eh? I dunno where to go from here either.

jpk

Have someone wiggle the connection on that refrence sensor while you crank it over.

apierce918

are you getting fuel? i saw it was mentioned to check, but didnt see if you confirmed whether or not you were.

If you are indeed getting spark, fuel, and compression then it should start, if not, then i would go back to that sensor

ExitWound

How do I tell if the injectors are firing? I can hear the fuel pump running and the fuel rail filling and cycling fuel if I bypass the DME. How do I verify that the injectors are firing though? And the wiggling of the sensor is a good idea.

Legoland951

Use the search function. I have typed the same response at least 10 times in the past. Use the noid light for injector pulse. Past write ups will give you complete diagnostic procedures.

Kburke

first things first oil is thicker at cooler temps and thinner at hotter temps. running 20/50 in the summer is great running it in the winter and the hydraulic lifter can stick and not oil will not move because the oil is already thick and now even thicker because of the cool temp. the best thing to do is to change to 10w 30 oil or 5w30 for the winter this will help for cooler temp since it can flow more easily in the cool temp.

ExitWound

11/20/08 Update

• Throttle position sensor operates perfectly, all three settings.
• Air flow meter voltage is operating perfectly, smooth as the door is open.

11/22/08 Update

• Noid light confirms all four injectors are getting a pulse as the engine is cranking.
• Ignition coil sending spark.
• All four plug wires are sparking.
• Fuel pressure at the rail is 38psi with the DME relay removed and jumped.
• Fuel pressure at the rail is 38psi with the DME relay installed.
• Fuel Pressure dampener and regulator have no fuel in the vacuum lines.
• Pulled the fuel rail. tips of the injectors are wet.
• Replaced the reference and speed sensors with ones that are known to work from another 86 944. No change.

The only thing I can see that might be an issue, other than what was posted above, is that the fuel pressure in the rail drops to zero after about 1 minute when the car is off. Shouldn't the rail retain the pressure for quite some time after? It's a new fuel pump, with new valve, new fuel pressure regulator, but the dampener was never replaced.

At this point, I believe I have fuel, spark, and air. The only possible causes are lack of proper timing due to the reference & speed sensors being old, and the quickly falling pressure from the fuel rail when the engine is off.

Any thoughts?

jpk

I can suggest one more thing... I'm assuming your battery is still good and you've either got it on a charger or have jumper cables. Hold the throttle to the floor - wide open, and crank it for 20-30 seconds.
If it kicks, coughs, sputters and starts running, keep the throttle to the floor. It should gradually pick up speed. Once it gets to 3500-4000 rpm, it should smooth out and run normally. If it does that, PM me and I'll tell you what's wrong.

ExitWound

I already have that test on tap for Sunday's work. I went through more than 1500 posts today, noting many including yours with this symptom.

I'll let you know!

ExitWound

For anyone interested, we think we have the problem narrowed down to the female side of the speed and reference sensors. I haven't yet replaced/fixed them, but they seem to be the cause of the intermittant no-start.

I have replaced the speed & reference sensors with new ones and the car still wouldn't start. A wiggle and rearrangement of them cured me though, and the car started immediately.

As for the low oil pressure, I put in the original OPRV this car came with and I now see 2bars at warm idle, 4.5/5bars at cold. It's better than it was, but see no real difference with a different OPRV. My finger is now pointing towards the oil pump, which during rebuild had seized innards, all rusted and stucklike. We had gotten them clean as best as possible and reassembled the pump. We're betting that the issue is there and not related to the OPRV or oil thickness. However, the 20W50 has at least let me drive the car properly, giving me 3bars during warm 2-4k rpm, and ~2bars idle. Until I can get an oil pump job done on it, this will have to suffice.

JohanvdWalt

YOU DID WHAT????
Lets rather talk about the weather, the flowers, birds ............ anything but cars.

ExitWound

You have to realize that the car came from someone else, with the engine all disassembled. Looks like he left the bucket of engine parts in the rain, or in the humidity of Georgia or something, and some of the parts got a little rusty. The oil pump gears were coated in rust. We took it all apart, removed all the rust, did a complete cleaning of the parts. It's not like we slapped it all back together in that shape!

theiceman

your main bearings could be shot resulting in low oil presure, but go with your plan. BTW the guys who say change the oil because it won't start are full of crap or are unqualified to comment. thicker oil MAY cause slower cranking and cold engine wear but will NOT cause your car not to fire. I use 20w50 in my 911 ( fair enough with larger bearing clearances ) and it is good to about -10C if you check the charts.

Having said all that though . if you have flooded your engine in trying to start it. ( as in ANY car ) you should change your oil as the fuel washes down the cylinder walls and dlilutes your oil .

just my 2c cad

Mike C.

So it was those pesky reference sensor connections after all...

whalebird

Year, make, model.
If early car twist fuses.
after cranking for a second. Go under the hood and check the schrader valve on the front of the fuel rail. You should get a shot of gas out of the fuel rail. It should be under pressure. take all the oligatory precautions for squirting fuel. If you do not get fuel check DME. You said you jumped it - how? Did you get the fuel pump to run?
oil is not the problem