Okay, n00b question for the late-model 4-liter(re) set.

I drove my car daily for months with no issues. The one day it simply didn't start. The starter works fine, but the engine will not fire. At all. I have determined that there is no current reaching the plugs, so it's down the ignition track I go.

The tow from my home to the only shop I currently have a trust relationship with (for an old jag, anyway) is pretty damn expensive, and the ignition system on this engine appears pretty easy to work on, so I am motivated to diagnose this myself.

Distributor (cap'n'rotor) > coil > spark control module > crank sensor; that's pretty much my checklist, right? Who are the usual suspects in a case like this, and what's the most practical way of testing these components?

My previous experience with ignition bugs like this has me betting on having to source a replacement spark control unit...

Thanks Heaps!

 

Just for the record, the failure turned out to be the cap and rotor.

I replaced the crankshaft sensor first, since that seems to be the usual suspect on an ignition failure, but no dice. It appears that wear on the plugs caused increased resistance at the cap, so all new plugs, cap, and rotor are now installed (plus a new sensor). Finally driving my car again today!

I didn't realize the cap could cause a binary failure like this, so at least I learned something from it.

 

Not being a "newer" car kind of guy.... But the 1st thing I would have done is plug a tester into the OBD2(I think) port. This might have told you the crank sensor was good as well as any other issues. I'm glad you found the problem and it wasn't too expensive.

Rob

 

There's not going to be an OBD2 port on a '93 Jag is there?

Is pulling OBD1 codes (besides the FF codes already reported to the dash) something that can done practically (without expensive/out-of-date tools)?

 

I was under the impression that OBD2 was implimented about 91ish but like I said, I am not a new car guy. I also phrased my statement wrong. I was more asking if it could have been done, not that it is what you should have done. My 90 is the newest car I've ever owned out of 60ish cars so I'm not too up to date on computer stuff.

 

No worries! These are open questions for the forum; I didn't intend to imply that I was strictly replying only to you, sorry about that.

I knew less that you regarding OBD2 before I got up this morning, but my morning google-fu exercise indicates that OBD2 wasn't broadly adopted until '96, although I found indications that Jaguar may have implemented it as early as '95 (ahead of the curve as usual).

I would love to be wrong; a working OBD2 connection with a bluetooth reader looks like a barrel of monkeys.