Rogue - you could be on to something. I just started the car with the pedal pressed about 80% started on first try, and ran smooth almost immediately....what does this tell me?

 

That there is too much fuel on-cranking.
That narrows it down some.

Possible reasons:

Leaking injector (unlikely)
Bad FPR or Dampener (would also cause running issues, so another unlikely in your case)
AFM is bad / going bad / not closing all the way.
AFM AIT sensor is bad (max fuel it could add is ~12%, I doubt enough to cause your issue)
DME coolant temp sensor is bad, or the wiring is bad (one or both of these is the most likely cause of your issue).

 

Clearly the solution here to to fit a Rogue Tuning MAF.

... and go over the coolant temp sensor/wiring. I hadn't thought about the wiring being bad.

[Edit- Just realised how snarky that sounded. Not intentional]

 

Ha - well that is a benefit of the MAF: no electro-mechanical hardware to wear-out, unlike the factory AFM...

The coolant temp sensor wiring happened to both my 944NA, and Sid's 951. With the logger we could see the issue immediately, which made diagnosis easy.

 

I have to think it is more the wiring, vice the sensor. The sensor is less than a year-old. How do I check/repair?

 

See the page here:

http://www.clarks-garage.com/shop-manual/elect-19.htm

 

As an update...I drove the car to work. Started up on first try with the accelerator pressed about 80%.
No rough idle after starting. Ran well to work, its a cooler morning today, and my car loves the cool weather. Ran strong.
I don't have much time this weekend, but hope to get a look at the coolant temp sensor and it's wiring.
Thanks everyone for your input. Will update as I check things, but right now I am ruling out fuel delivery, the FPR and leaky injectors. I don't think it is the speed and ref sensors either.

 

Pete, know it's a hectic weekend -- did you get any opportunity to check out the wiring?

 

I had exactly the same hard start problems a couple of timeswhen I ran the gas tank nearly empty and wasn't using the car much.

I never really pin-pointed the exact cause because both times the engine eventually started and went on to run perfectly after lots of coughing and spluttering and cutting out.

The only things that I changed was to clean the plugs,rotor arm and distributor and clean the injectors by flashing them with a PP3 9v battery as they seemed to be sticking .

My feeling is that it was due to sticky injectors or possibly water and debris getting into the fuel system from a empty gas tank.

Once the engine is running, injectors self-clean so the engine just runs better and better

 

Was feeling pretty good about being able to get the car to start, we had an 80's party to attend not too far from home so I thought it would be good to take the car there. We spent the night at the hotel where the party took place and the car was outside all night. When I tried to start it, the outside temp was well over 70 but there was a good bit of moisture in the air (windows were wet). I was incredibly hard to start, even with accelerator pressed. Almost gave up but it finally got going. Was getting "the look" from the wife, but once it was running it was solid. Frustrating.

 

Now it's not starting well with the pedal down. Confused.

 

Pete - trying to start it with pressing the pedal is only meant to be a test - not a method of normal use...

Find the problem and fix it. From what we've been able to diagnose it is most likely the coolant temp sensor or the immediate wiring. Both are an easy fix.

 

I understand it was just a test. Was just trying to confirm the problem. Last night, I tried to start, had problems, pulled the temp sensor connector, cleaned the contacts and reinstalled. Car fired right up.
But I think it had the right amount of fuel after trying to start.
Weird thing is, if I try and fail to start the car, then let it sit for a few minutes (10-15), it seems to start right off when I try again.

Rogue -- is there anything to be learned about the condition of the sensor by checking reistance across it's terminals? Right now, with the car parked the way it is, I cannot get to the DME.

 

Fixed...temp sensor connection or wiring. Unplugged, cleaned connector, starts on first try

 

excellent ! thats a nice cheap and easy fix

Good to have a solution for future researchers too!