Breeze Posted June 10, 2007 Share Posted June 10, 2007 Hi guys! I haven't had a chance to introduce myself yet, but I need some help. I have an 88 MJ, 4.0L I6 engine. I seem to have a sensor (I think) on the left side,in the center, right above where the oil pan mounts to the engine. It looks like it has been broken off and we can't tell where it may have attached. m Does anyone know what the heck this thing is and/or does? Thanks! Link to comment Share on other sites More sharing options...
rockhardzj Posted June 10, 2007 Share Posted June 10, 2007 picture would help, if at all possible. Link to comment Share on other sites More sharing options...
Breeze Posted June 10, 2007 Author Share Posted June 10, 2007 sorry... Link to comment Share on other sites More sharing options...
Eagle Posted June 10, 2007 Share Posted June 10, 2007 That would be your knock sensor. Replacing it ASAP would be a good idea. Do you get a lot of PING when driving? I can't imagine how you can even drive it with no knock sensor, unless you keep the radio turned up so you don't hear the engine destroying itself. Link to comment Share on other sites More sharing options...
Breeze Posted June 10, 2007 Author Share Posted June 10, 2007 We haven't heard any pinging, knocking, rattling at all. But then, we haven't driven it for any longer than 10 min. We just got it about a month ago and have been busy modding it. Dude that gave it to us didn't mention anything about engine noise, and he would have as he's paranoid about noises after he blew the engine in his Cherokee. (We rebuilt it for him and he gave us MJ in trade). But, we'll definitely get that replaced! Thanks! Link to comment Share on other sites More sharing options...
Eagle Posted June 11, 2007 Share Posted June 11, 2007 Yeah, you need it. The Renix setup is such that the ignition defaults to full advance, and when that sensor "hears" the motor start to ping it retards the timing until it doesn't "hear" ping anymore. Some are more sensitive than others. The one in my '88 XJ is a replacement and I never hear anything from that. The one in my '88 MJ is (I think) the original. It is intact, but I can't put my foot in it going up any kind of a hill or I get constant, light pinging. Link to comment Share on other sites More sharing options...
Oizarod115 Posted June 11, 2007 Share Posted June 11, 2007 i've got two sensors here both on the drivers side of the block, presumably one is the knock sensor, the other?? EDIT: these pics are upside down sorry. stuffed the cam down in there sideways :oops: this is the 97 motor that was swapped in before my time so it could be anything. Link to comment Share on other sites More sharing options...
Breeze Posted June 11, 2007 Author Share Posted June 11, 2007 I'm assuming the bottom pic is the knock one? All of the pics I've seen for a replacement don't look like that. Is replacing this thing going to involve wiring as well? Link to comment Share on other sites More sharing options...
HOrnbrod Posted June 11, 2007 Share Posted June 11, 2007 i've got two sensors here both on the drivers side of the block, presumably one is the knock sensor, the other?? EDIT: these pics are upside down sorry. stuffed the cam down in there sideways this is the 97 motor that was swapped in before my time so it could be anything. I think that's the coolant temp sensor. BTW, knock sensors were a Renix thing; the 4.0L HO engines starting in 1991 did not have knock sensors. Here's a good site that tells more than you ever wanted to know about Renix sensors: http://tinyurl.com/2md8a5 Link to comment Share on other sites More sharing options...
87manche Posted June 11, 2007 Share Posted June 11, 2007 give that man a cookie. one is the knock sensor, the other is the coolant temp sensor that goes to the ECU. THe ECU and the guage have different senders, the one for the guage is in the top of the head, drivers side, at the firewall. Link to comment Share on other sites More sharing options...
Oizarod115 Posted June 12, 2007 Share Posted June 12, 2007 give that man a cookie. one is the knock sensor, the other is the coolant temp sensor that goes to the ECU. THe ECU and the guage have different senders, the one for the guage is in the top of the head, drivers side, at the firewall. that was our guess was it was the ECU temp sensor... my other sensor is actually at the thermostat housing ;) 97into89 thing. gets annoying sometimes. Link to comment Share on other sites More sharing options...
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