I have a KA24E engine. On top of every injector is a small rubber boot, which I assume contains the electric components for the injector. Here is my problem.

I am having a rough idle, and some hesitation on acceleration. I have applied finger pressure to the top of the boot for each injector. When I apply finger pressure to the boots on 1 and 2, and push towards the passenger side, I can get the idle to smooth out or roughen up, depending on the current condition. Number 1 injector boot seems touchier than 2, but I don't get any change on 3 or 4. So, in conclusion, I am assuming that there might be an issue with these connections.

What is under these boots, and are they fixable, or would I need a whole wiring harness? Anyone have issues like this before?

Never heard of that problem...but...

Underneath the boot is the connector from the engine wiring harness to the injector. If you push on it, and it works, it could be a loose connection on either side (the harness, or the injector itself). Also, it is possible that by pushing on it, you are changing the angle of the spray pattern into the combustion chamber. This could effect idle with different carbon buildup areas on the back side of the intake valves.

I'm not sure what to tell you though, I've never heard of that problem. I would recommend taking it to a dealer so they can use a Consult to look over the engine sensors and so forth. Also, I'm going to move this thread to the Nissan Online Mechanic forum, as I think you will get better answers.

This condition is normal on injected cars and is caused by a lose or more likely a corrodied connection at those injectors. You can go to the local parts house and get new injector ends and replace them and clean the injector terminals on the injectors and you should be good to go. Check the injectors for fuel leakage around the connector socket or around the plastic top. Any fuel leaks and that injector or all will need to be replaced.

Newbie to the board and 240's, but, my wife's (new to us) 1990 240SX exhibits the same symptoms. Noticed a steady fuel leak around one of the injector tops, where the electrical boot meets the red gasket/plastic stuff on top of the injector. I noticed that if I rotated any of the other injectors I could really make that baby run like crap. A call to the local parts monger revealed that a new injector costs $109. Just for one! It seems like the kind of job you can start off replacing one and screwing up the remaining three in the process. Tell me it's not really that daunting. Perhaps someone around here does it several times a night in their sleep and can tell me all I need to know in several simple steps.

Thanks in advance for any takers.

I agree with the other folks about it possibly being a bad electrical connection. But, what about a vacuum leak? Maybe the seal where the injector meets the intake manifold is leaking vacuum, and when you push on the injector it seal up the leak? Just a thought.

It is not a difficult job to do and if 1 injector is leaking I would replace them all because the others are not far behind and if the injector nozzle is parcely clogged or restricted it can case a rough idle.