1eliminator1 Posted January 16, 2012 Share Posted January 16, 2012 my 4.0 hasnt been acting right. i know the renix engines do their own things, but mine has been idling a little high. and when i slow down i can feel the engine fighting the brakes. sometimes when in neutral or park it will idle at about 1500 then drop to 1200 and go right back up and do this over and over. And if it is idling high, i tap the throttle and it goes down to about 800. I have been checking for vacuum leaks but no luck yet Link to comment Share on other sites More sharing options...
Pete M Posted January 16, 2012 Share Posted January 16, 2012 cleaned the throttle body and IAC yet? which technique are you using to find leaks? checked for leaks at the vacuum reservoir? in the 4wd lines? Link to comment Share on other sites More sharing options...
cruiser54 Posted January 17, 2012 Share Posted January 17, 2012 Check the "engine" side of your TPS using this, after cleaning the TB and IAC: RENIX TPS ADJUSTMENT Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up. IMPORTANT NOTE: Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. If you see more than 1 ohm of resistance some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed. MANUAL TRANSMISSION: RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body. This manual transmission vehicle TPS provides data input to the ECU. The manual transmission TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors.. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Adjust the TPS until you have achieved this percentage. If you can't achieve the correct output voltage replace the TPS and start over. AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three- wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES. However, the automatic TPS also has a square four-wire connector clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire connector side of the TPS. If you have ENGINE issues check the three-wire connector side of the TPS. For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced. Revised 11-28-2011 Link to comment Share on other sites More sharing options...
1eliminator1 Posted January 17, 2012 Author Share Posted January 17, 2012 I checked the 4wd lines. Been checking main lines on a basic diagram i found. And I bet the iac isnt helping, havent checked it yet Link to comment Share on other sites More sharing options...
Pete M Posted January 17, 2012 Share Posted January 17, 2012 how are you checking? propane? starter fluid? or just visual? Link to comment Share on other sites More sharing options...
1eliminator1 Posted January 17, 2012 Author Share Posted January 17, 2012 just visual Link to comment Share on other sites More sharing options...
Pete M Posted January 17, 2012 Share Posted January 17, 2012 try spraying a flammable liquid (such as a throttle body cleaner) around carefully. especially get the seam where the intake manifold meets the head. when the liquid gets sucked into a leak, the idle sped will change. you can also do it with an unlit propane torch. :thumbsup: Link to comment Share on other sites More sharing options...
1eliminator1 Posted January 18, 2012 Author Share Posted January 18, 2012 alright. thanks Link to comment Share on other sites More sharing options...
Pete M Posted January 18, 2012 Share Posted January 18, 2012 and clean the iac ports :thumbsup: Link to comment Share on other sites More sharing options...
1eliminator1 Posted January 18, 2012 Author Share Posted January 18, 2012 okay. :wrench: stupid carbon buildup Link to comment Share on other sites More sharing options...
kawaboy13 Posted January 20, 2012 Share Posted January 20, 2012 How do you make the adjustments? My truck has been dying when I push my clutch in. It's not at full warm up but it's not just when its cold anymore. Thanks! Link to comment Share on other sites More sharing options...
moparrr07 Posted February 2, 2012 Share Posted February 2, 2012 try fixing the broken throttle cable, its probably holding the blade open Link to comment Share on other sites More sharing options...
chastings Posted February 3, 2012 Share Posted February 3, 2012 Have you tried disconnecting the tps when its running? That could potentially eliminate some of the possible causes. Mine idled ridiculously fast (over 2000rpm). I checked for vacuum leaks with throttle-body cleaner, cleaned the grounds added an additional grounding strap to the engine, cleaned the C101 connector, cleaned the throttle-body, cleaned the iac and then tackled the tps. Turns out my tps was a little loose. Input voltage was 4.9, but the output was .02. I adjusted it to .86v tightened everything back up and it idles like a champ. I could have spent a fortune replacing sensors, but was very lucky... I only had to replenish my supply of throttle-body cleaner when it was all said and done. If you follow cruise54's post it'll steer you in the right direction. Good luck Link to comment Share on other sites More sharing options...
1eliminator1 Posted February 5, 2012 Author Share Posted February 5, 2012 yep. the clip at the end of my throttle cable decided to break in half and not let my throttle body completely close :dunno: i am relieved Link to comment Share on other sites More sharing options...
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