I have a 93 xj 4.0 stock motor but lifted with heavy body roll and it’s struggling with an occasional bad misfire. It drives good then suddenly misses then clears up then misses over like a ten minute drive especially after deceleration which is very strange I think. Some days it doesn’t miss and drives great.
My codes are 34 27 27 27 end code. Why are there 3 27’s? I used to only see one code 27 a few months ago.
Ive had an ignition tune up a year ago. I recently checked and double checked my injector connections and I’ve had mixed results. First time I checked the meter showed that two were under the correct voltage but the next week I checked and they read fine but there was still a misfire happening at idle on and off. A very slight miss nothing heavy. I don’t get how they checked out fine but still had a miss. I can hear each injector tick by holding a screwdriver to my ear against the injector but it was still running rough even though I can hear each injector tick.
I also get post ignition I think. While misfiring I’ll very rarely get a click or tick noise and feel my gas pedal tick or knock once. It’s never a bunch of ticks just a single one.

So my big questions are 1) could this be a vacuum line issue? 2) could this be a bad coil pack? Or ignition related problem? 3) could this be a bad fuel pump or tank issue? 4) this is the most important question of them all please answer this one. Would questions 1-3 have their own error codes if they were acting up? Like if it’s bad spark or no spark would a separate code read for that or a vacuum leak? 5) can I realistically narrow down my troubleshooting to only the injector circuit? Since I’m only getting codes 27? And why suddenly do I get 3 consecutive code 27s when I used to get just one?

Those are classic failing CkPS symptoms. It could be other things, too.


Dunno why there are three. Maybe 3 injectors are failing?


Could be a poor connection. Read this.

Do yourself a favor. Get one of these.


Yes, and it never hurts to do some leak hunting. It's not expensive.

A 93 with a coil pack? Not that I ever heard of. You should have a coil and distributor.

BTW, check the connection into the coil.

Yes and yes.

I don't know, but Cruiser might have that info or a list of codes on his site.

A 93 is OBD1, I think, so search for OBD1 info.