Car recently had a Head changed. It has 170K was running great before. After inital start ran rough, fixed huge vaccum loss, then started having no start drama. At first after that engine would crank and fire but not catch. After much holding of the pedal down it caught and started. Ran rough first but smoothed out and after warmup it idled. But still seemed slightly rough. Checked codes and only one I could get was 1-2-3. Then could not get it to fire up. Checked spark and it had orange light shown at each plug (test light). Finally changed cam sensor and crank sensor with known good ones. Recharged battery and switched too new plugs. Could not clear the code, still will not start. Switched out plugs showed it had fuel. Have not checked fuel pressure but it pushes fuel out through valve. Still engine will not catch and fire up. Any ideas? Any help offered would be great. Mike

 

Car needs 5 things to start/run:

1. Fuel
2. Compression
3. Air
4. Timing
5. Spark

You'll need to go down the line and figure out what is missing. I know those 960 have those funny intake boots etc. on the manifold. Make sure all of them are tight and on good.

 

Code 123 is the coolant sensor. Maybe it is not sending the correct or an erroneous signal. It would not start possibly because it is sending a signal that is counter to what is really needed, such as warm engine when it is cold or cold engine when it really is hot.

There is only two sensors that are required for the engine to run.
RPM and throttle position. All of the others can be disconnected and the engine will run, maybe not smoothly or efficiently but it will run. Even with out the MAF. That limp home mode is in place mostly when a sensor stops sending a signal or the signal is lost, but if a sensor sends a flawed signal within set norms, there will be not check engine light and a non running or poorly running engine.

I would check all of your electrical connections, sometimes pins within a plug can slip out of position.

Is the throttle cable connected correctly, no tension on the throttle plate?
All major vacuum hoses in place, the brake booster.
The little hose connecting to the idle speed motor.

I did have an occurance once on doing a head gasket, where the ground lead that is on the driverside engine mount bracket was not re attached. The ground feeds the power stages, in my case the car started up, I let it run about 15 minutes, turned it off, went in the house to clean up, it would not start after that. Took some time but figured out that missing ground wire, it made some contact for the initial start and warm up, but moved away from what ever metal part it was touching on the second start.

DanR '94 964 387,000 miles (153,000 on the new engine)

 

Thanks for the input I was slowly whittling down the issues that work vs all that might stop it. Finally figured it out and got it started. One of the issues was the sensor- the other was some issues with the wiring. Checled everything with test light and after much checking finally got it up and running. Thanks again Mike