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98xj 4.0L high idle question code question

rapom

NAXJA Forum User
Location
Northern OH
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Hopefully someone can help me here. I just did a exhaust manifold change last week. Everything has been running fine until a couple of days ago. I cleaned the throttle body with some throttle body cleaner a couple of days ago. Yesterday the engine seemed to stay reved between shifts. (5 speed manual) At stop lights the idle would stay at 1250 rpms. When I would shut the engine off it would be idling normally at about 700 to 900 rpm. But after I would start driving it would stay at 1250 rpm all the time even at stops. Then the check engine light comes on. I went to Autozone today and they checked it out. I got 2 codes. One was the fuel level senser which which doesn't have anything to do with the problem. The other was P1294 (Injector High Side Open- Bank 2/ Target Idle not reached) As usual Autozone didn't have a clue. So after thinking to myself I figured the code was refering to injector 2 having a loose connection. When I got home I unplugged the No. 2 fuel injector wiring and then plugged it in again. I then went for a test drive and noticed the ck eng. light was off. (I thought it had to be reset manually by a code tester for 98 cherokees) It seems to idle better now between shifts but still likes to stay above 1000 rpms until I come to a complete stop when it settles down to 900rpm. Did I just have a loose connection or could the injector be going bad? Could there be something that happened to one of the sensors on the throttle body (I did clean it before all this happened) that would wouldn't show up on the computer code? Any additional input would be appreciated. Thanks
 
The sensors in the throttle body are very sensitive to spray cleaners, most of the cleaners are NOT plastic friendly. If you just sprayed the heck out of to get it nice and shiny again you probably did in either the map and/or the tps. The best method to clean the TB is to remove it and dismount the sensors then clean it. The other way to do it on the engine is to have the engine running, thumb on the throttle, with the thin plastic tube on the can start spraying but keep the end of the tube away from the sensors. Good luck.
Oh, if you do need to replace the TPS those torx screws are locktited in there, much easier to break them loose on the workbench.
 
Thanks for the reply. I cleaned the throttle body with the engine running. I bought a good Napa branded cleaner that was suppost to be safe for sensors. Thanks for the tips though. I will make sure to clean it your way next time.
 
Found the problem (I think). I first checked for vaccum leaks by spraying throttle body cleaner around the throttle body while the engine was running. (If the idle changes while spraying you found the leak) Then I checked where the intake goes to the head. Bingo, the last 2 runners at the back of the engine were leaking. That must of been the reason that the code definition was talking about Bank 2 which are the last 3 injectors. (I still don't know what the leak had to do with the injectors unless they were trying to compensate for the extra air)
Anyway that is a real big relief to me. I was very surprised though because I really torqued down the intake. I guess I should have put some sealer between the intake and the gasket like I thought I should have done in the first place.
 
Just for reference, you should retorque the intake bolts after a heat cycle or two. The best sealer is Permatex CopperCote in the spray can.

Also, "sensor safe" refers to the problem with RTV silicone sealants that if used where they can outgas and get sucked through the engine, will kill the O2 sensors. It has nothing to do with the problem of getting it in the TPS. SensorSafe has become an over used marketing buzzword, kind of like " newl ow carb" for something that never had carbs in it to start with.
 
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