Injector mix-up?

lwm said:

I have a '96 xj and just dropped in a remanufactured 4.0 L. The engine started okay but the check engine light is on and it just doesn't have the power that I was hoping for. It idles smoothly but just seems to be a bit doggy, or slow to accelerate. I am having the check engine light evaluated and the engine emissions tested, which I assume will fix the problem. However, as I was thinking about what could be wrong, I recalled that during the install, I labeled or checked to make sure the injectors were tagged so that they could be returned to their original location. During the install some of the original tags were brittle and fell off (bummer...) and while I am 98% confident the injectors are installed in the right place, I was wondering if anyone knew if an engine would run with two of the injectors switched and if it ran, would it run so poorly that such a problem would be easily recognized. And finally, is there a way to identify which injector goes where. Lots of questions I know, but thanks in advance. LM

Click to expand...

All of the injectors are the same. Are you talking about having the connectors swapped?

You say it idles smooth so I would look at the distributor indexing.

Yes, I was worried about the connectors being swapped causing the injector to release fuel at the wrong time.

lwm said:

Yes, I was worried about the connectors being swapped causing the injector to release fuel at the wrong time.

Click to expand...

I peeked at a 95 FSM for the wire colors, not sure they're the same on a 96. They all have a common DarkBlue-OrangeStripe wire and the second wires are as follows.

Injector 1 is White-DarkBlue, goes to pin 16 at ECM
Injector 2 is Tan, goes to pin 15 at ECM
Injector 3 is Yellow-White, goes to pin 14 at ECM
Injector 4 is LightBlue-Brown, goes to pin 13 at ECM
Injector 5 is Pink-Black, goes to pin 38 at ECM
Injector 6 is LightGreen-Black , goes to pin 58 at ECM

I checked the color coding on the injectors and they match the above description except for #5 - grey and #6 - brown with blue stripe. Otherwise everything matches. Of course, the two I was worried about were #5 and #6.... I went back and checked the distributor and it looks correct according to the indexing hole on the central portion that rotates. I took it to the dealer for an emissions test and the check engine light. They flashed the PCM and replaced the oxygen sensor, but could not get the check engine light to stay off (???). Apparently, it's getting a fault on the distributor pickup. I had just replaced the distributor with a rebuilt from Napa. They did not replace it or even test it because apparently chrysler has those parts backordered. I have been going through distributors about every year for the past couple of years which is why I replaced it. I did swap the pickup with old one that I had. The emission test was fine and seems to be running fine. Don't know what I'll do about the engine light. They did not charge me much because they could get the light to go out. Thanks for your help.

lwm said:

I checked the color coding on the injectors and they match the above description except for #5 - grey and #6 - brown with blue stripe. Otherwise everything matches. Of course, the two I was worried about were #5 and #6.... .

Click to expand...

Odd that those two are different colors. The color scheme doesn't seem to have changed over the years. I looked at my 88 XJ, 93 ZJ, 95 YJ, 95 XJ and a 2000 XJ FSM and they had the same wire colors as well. Different ECU pins of course since the ECUs changed. Worst case I suppose you could pull the connector off the ECU and verify what pin is connected to which injector.

If the distributor sensor is bad, the engine controller can't tell what cycle the engine is on and makes a guess. Guessing wrong will make it run like crap, but it will generally run and set the check engine line.

Sounded like having a factory service manual is the way to go, so I purchased one. The color codes are as noted above: #5 - grey and #6 - brown with blue stripe. Don't know why Chrysler would have changed the colors, but must have. Thanks for the help.

How long were the injectors sitting ? I wonder if the fuel that was in them maybe dried up turned into varnish....