84 944 crank but no start

[yorkee]

I have a 84 944 it crank but no start.

In the beginning, it just happen once in a blue moon. In the last couple of months it happen more frequent and it takes more crank cycle to start it.

Now, it won't start at all. It crank, but no start.



So far, I have done the following:

tested all 4 plug and make sure they have spark (pull them out and make sure they get ground connection to body/engine when cranking)

Disable one of the first injector and try to start it, no luck.

The tech is bouncing.

Took out the vacuum hose from the FPR and there is no smell of gas.

I charge up the battery with a battery tender to make sure it has enough juice.

I tested the fuel pressure from the rail, its giving me 35psi when cranking.

I tried swapping several of the dme relay still no luck. (That shouldn’t matter since I have fuel pressure and spark?)

I turn the idle screw couple turns out.

What else I should try?

Thanks in advance...

[944 Ecology]

Do you have compression?

[yorkee]

Originally Posted by 944 Ecology

Do you have compression?

Very good point. It should compression have because it's driving normally couple days ago. That said I will compression test tonight. Thanks.

[uvachief]

Starter is dying is my guess. Your hard or cold start issues would progressively get worse. Cross reference sensors are a common culprit. If not them, try checking your grounds. They tend to get corroded and really gunked up over time. A bad ground will cause starting problems.

[yorkee]

Originally Posted by uvachief

Starter is dying is my guess. Your hard or cold start issues would progressively get worse. Cross reference sensors are a common culprit. If not them, try checking your grounds. They tend to get corroded and really gunked up over time. A bad ground will cause starting problems.

Thanks for the suggestions. Probably more stuff I can check

If the starter is dying, shouldn't it not crank at all? The starter is cranking when I turn the key. When the battery is charge up, it is cranking very strong....

As for the cross reference sensor, can we check by looking at the tech bounce?

I have only roughly check the battery ground... Maybe I should take a second look.

[wolfgang116]

Engine reference sensor connector was my problem when this happened on my 84 944. It would crank all day, but no start. Than, I'd hop under the hood, literally wiggle the connection on the back of the intake manifold... and boom! It would start on the next crank. Worth a shot, it was the bottom connector of the two.

Here's the Clarks Garage test: Speed and Reference Sensors - Checking, Replacement, and Adjustment

[yorkee]

So I did compression test on all 4 cylinder, front to back:
120psi
135psi
110psi
135psi

I also swap out the 3 months old spark with the original spark plug that was on the car one by one as I compression test each cylinder. Guess what… The car start after replacing the last one!

So much for the premium spark plug… (NGK Iridium BPR5EIX)

I still wonder… I have those plug in the car for the last couple months and it works fine. They all gap correctly. Why they fail now? Shouldn't they fail couple months ago?

I also wonder if it make any difference if I put a bit of antiseize on the plugs before I install…. the anti-seize shield the plug from connecting to the engine body… thoughts?

[944 Ecology]

Congratulatons on finding and fixing your problem.

As to spark plugs, I stay away from the platinum and iridium plugs on the 944 cars. I stick with Bosch Copper or Bosch Silver and have had no problems. The issue with the platinum and iridium plugs is that you cannot look at them and tell if they are worn out or not.