This car has an erratic starting problem. Sometimes it starts fine and sometimes it takes a long time. It does not matter if the engine is hot or cold. After starting, the engine runs fine - no obvious problems. The check engine light is not on. I took it to a garage who told me that the problem was that the knock sensor wiring was chewed by a pack rat. OK, but I do not understand why a problem with the knock sensor would affect how the car starts. I thought that detected knocking from the engine would only adjust the spark timing. Also if there is a problem with the knock sensor shouldn't the check engine light be on?

Anybody know anything about this?

Also, does anybody know where the knock sensor is located?

Thanks in advance

 

Sounds like rubbish to me. The knock sensor is basically a microphone that picks up sounds at a certain frequency. In the eec-iv and early eec-v coding I've seen it's only used for spark control so I'd be surprised if Ford have changed it. In fact, during cranking the spark timing is fixed and I wouldn't be surprised if the knock routines weren't used.

 

Thats what I thought, but there's so much complexity now that I wondered if there might be some strange effect.

A major Ford garage performed the "diagnosis" and they wanted just under $1000 to replace it - I guess it must be buried deep in the engine.

 

You need to determine if you are losing fuelling or ignition, when it fails to start straight away.
Does it always prime in position 2 ?
Knock sensor will NOT do this.
tabetha

 

Hi Tabetha,

I do hear the whine from a (fuel?) pump when I turn on the engine evry time (position 2 is the ignotion key position before starting?) Is there a better test apart from hearing the whine that I can do?

 

The fuel pump will prime for about a second or so and then should shut off if you don't try to crank the engine. Using your ears to listen for the pump is fine

Did they put their diagnostic equipment on it and it came back clear with no saved errors?

 

The only report I received was that the knock sensor and/or wiring was damaged by pack rats. I think I will take it to a local parts store as see what error codes are stored - Maybe the garage stopped at the first error

 

Sorry, forgot to say that they did put test equipment on it. The work was "Diagnosis of EEC system and Ignition system, includes installing test equipment and component testing"

 

Try the diagnostic test before going down the 'costing you lots of money' road, it might reveal something.

Can you describe the starting problem? e.g. cranking but not firing

 

I have just checked the car with a scan tool and there are no stored codes. When I start the car the starter moter runs fine, If I just turn the ignition on without the start, I hear the fuel pump motor and I hear it switch off. When I start the engine, it turns overs rapidly but often does not start straight away - it can be more than 5 seconds before it starts. There does not seem to be any firing until it actually starts. Other times, it will start immediately. The poor starting does not seem related to anything. It can take a long time to start from cold, but it will also start straight away. If the engine has been running, and I turn off and then on again it will often be poor to start and also it might start straightaway. It starts poorly probably about half the times that I try to start the car

 

Sounds like it's going to be one of those hard to find faults Could be a intermittent contact of a wire or maybe the CPS playing up. I'd check to see whether its lack of spark or fuel giving the problem next.