I have a 1991 XJ limited with the 4.0

A few months ago is started running like crap after start-up. Once it idled for 5-10 min. it would run fine. this went on for two or three days. Then I replaced the cap and rotor. Woldn't run right after that. It would start but run as if the timing was off a tooth. I did a fuel pressure test at the rail and it was within spec. changed the fuel pump just in case and not change with pressure. took the pump back to the store. did a vac test on the vacuum pressure regulator and it was fine. used a can of carb cleaner and did a redneck vac leak test. fixed a ffew with no results. replaced plugs, wires, coil. still no change. pulled the dist. out to check for excess wear or broken roll pin at the drive gear. NOTHING. Put it all back together and towed it to a family friends shop where it started and ran fine. had them keep it over night and try it in the morning cold. still running like a champ. Ran good for 2-3 weeks them the same initial symptoms all over again. I then replaced the dist since that was the only thing I had touched the day I took it too the shop. Now it wont fire at all. It cranks with no spark. I pulled the battery cable to do a hard reset to see if that would help. Nope.... using a test light I probed the plug for the crank pos sensor and with the key in the run pos I get power to one of the plugs but while cranking I don't get power at either of the other two wires. As of right now it is giving me a 12, 54, and 55 code


Sorry thats a tone to read.

I have a feeling I'm dealing with a few problems. Just dont know if I missed a small step anywhere. I have been pulling my hair out trying to sort this out. Thanks for any help in advance!

MIKE T.

 

Code 12 just means that the battery has been unhooked and 55 is the end of the diagnostics. I'm on my phone and not near my book. If someone doesn't beat me to it, I'll look up the 54 and post it later.

 

As already mentioned, codes 12 and 55 are informational and are expected with what you've already done.

Concentrate on code 54. "No camshaft position sensor signal detected during engine rotation".

The cam sensor is located inside of your distributor and can be tested with a manual and a meter. I know the distributor is new, that does not mean that the cam sensor couldn't have failed prematurely; it happens way more than you think with new parts.

 

I know you cant always trust new parts. Sad that its that way but it is.

So with the code 54, i also know that the crank sensor and cam sensor are on the same 5 amp circuit. With this its not uncommon for you to get a code for one when its the other.

Can you walk me through how to test the cam sensor. Im a little electrically challenged.

Oh on top of everything else i did prior to it not running at all i also discovered a massive exhaust leak at the header collector that i fixed. I cleaned the mass air flow sensor and the tps. Along with the throttle body.

Sorry im all over the place with this. I have tried soo much with no success.

Thanks again for the help