What's the Best service manual for a 200 Ford Ranger?

Though I would have answered "the Factory Service Manual" previously - I now have one (on CD) and it's cryptic and almost unusable. I also have the Haynes manual. Also not good.

Trying to troubleshoot a cold starting issue that I think is timing-related.

Where can I find a good explanation about what sensor does what and how to test them?

Added (1). What is the "Best" service manual for a 2000 Ford Ranger?

Geez - can't edit the original question. It's a 2000 - not a 200…

The factory service manual would be the best since it has factory info that dealer techs use for specific model/years but can be difficult to comprehend without some study. Other manuals like Chilton or Haynes often have info for a wider range of model years and are often not as precise or detailed. But they also offer other general repair guides that go into detail as to what various sensors do… Proper testing though may not be in those guides. Some sites like TheRangerStation.com do have some good articles too and member forums and geared to mainly Ranger/Bronco issues.

Why do you suspect a timing issue? Most cold start issues are due to a bad coolant temp sensor (ECT) or clogged/ defective Idle Air Control valve (IAC) or weak fuel pressure, etc. And some such issues may not trip a trouble code/CEL if the ECT sensor data is within acceptable parameters… Just wrong for the actual conditions of a cold engine. A clogged/faulty IAC also has no feedback loop to the PCM. A cold engine needs a slightly richer fuel mixture which the PCM may not be providing in injector pulses if the ECT reads as a warm engine. Or a clogged IAC may not allow proper airflow into the engine at closed throttle/starting. If the fuel system can't hold proper pressure due to an internal leak/leaky injector/check valve, that can cause starting issues as well.

Try turning the key on without starting… You should hear the fuel pump in the tank run briefly and then shutoff… Turn off key and repeat that on/off process a couple times to build up fuel pressure… Then try starting as usual. If it starts better, then you may have a weak fuel pressure issue… Weak pump, clogged filter, bad pressure regulator, etc… Parts stores rent fuel pressure testers and testing process/specs found in manuals or online sites.

For a lot of issues I have stopped using a service manual and go to YouTube. While sometimes the person goes the hard way about the problem at least it helps me often to see the physical location of the part. One of the interesting ones was a guy who traced back his starting issue to the hot lead to the starter. He cut the end off of a perfectly good connecter at the battery so he would not need a crimp too to use the hot lead that had a crimp connection on it for the ECM. Oh well!