Kyleinreallife Posted November 10, 2017 Share Posted November 10, 2017 In preparation for a trip to Zion national Park, I'm finally around to addressing my stuttering idle and hard cold start. I have a 1987 4 x 4 base model. After removing, disassembling and inspectig my idle air control it would appear that it needs to be replaced as the motor is only working intermittently, unless anyone knows of any other solutions. I also opened up and cleaned out the throttlebody. After doing that and adjusting my throttle control sensor to have the output be 17% of the input, the truck is now running smoother but feels slightly under powered. The best way to describe it would it slightly stumbles through the beginning of each gear. Additional info: The actuation on the gas pedal cable itself feels nice and smooth, the issue feels more electronic in origin. Questions: Would resetting my ECM potentially help with this and if not should I adjust my idle control positive or negative and how much?Non Sequitur: Are there any interior component from a zj that will fit our mj's? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Marine1Texas Posted November 10, 2017 Share Posted November 10, 2017 the renix stores nothing. it resets every time your turn it off. not till the HO version did it store codes. things to check on renix 87 4.0 is vacuum lines, the ground wiring under hood, under dash, and driver tail light. Also check, clean or take out c101 junction box. c101 junction box can cause all kind of weird things with renix 4.0. I wired mine direct no more c101 box. make sure your fuel pressure is around 31 with vacuum hooked fuel regulator and 39 psi with it not hooked up. I upgraded my ecu to the 1989 ECU, it was a upgrade for sure. Link to comment Share on other sites More sharing options...
Kyleinreallife Posted November 10, 2017 Author Share Posted November 10, 2017 the renix stores nothing. it resets every time your turn it off. not till the HO version did it store codes. things to check on renix 87 4.0 is vacuum lines, the ground wiring under hood, under dash, and driver tail light. Also check, clean or take out c101 junction box. c101 junction box can cause all kind of weird things with renix 4.0. I wired mine direct no more c101 box. I have the 2.5, I already refreshed my grounds according to cruiser54s renix tips, however I couldn't find one behind the driver tail light assembly (will add pics later today). I cleaned the c101, didn't have time for the delete, will get around to it this weekend. So I should leave my TCS where it's at and look elsewhere?Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted November 10, 2017 Share Posted November 10, 2017 tire size can contribute to an underpowered feeling. or is this something that has happened since the new tires? Link to comment Share on other sites More sharing options...
Kyleinreallife Posted November 10, 2017 Author Share Posted November 10, 2017 tire size can contribute to an underpowered feeling. or is this something that has happened since the new tires? It's been the same tires as long as I've had it. The "soggy" feeling came after I adjusted the TCS in order to fix the stuttering idle. It began having an intermittent flooding issue. As I would be driving along, the power would cut in and out occasionally as if it was getting juuuuuuuuust too much fuel. I'd hit the pedal, flood the cylinders, burn off excess fuel and everything would return to normal for a bit. After some research, I adjusted the TCS which got rid of the idle stutter and the intermittent highways power loss but made the peda feel soggy, like it's still getting just a bit too much gas on the bottom end. Also, on start up and on the "soggy bottom" end of the power band, it smells a bit rich... Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Pete M Posted November 10, 2017 Share Posted November 10, 2017 done the renix tips from cruiser54 yet? (in the link in my sig) by TCS, do you mean the throttle position sensor? Link to comment Share on other sites More sharing options...
Kyleinreallife Posted November 10, 2017 Author Share Posted November 10, 2017 done the renix tips from cruiser54 yet? (in the link in my sig) by TCS, do you mean the throttle position sensor? Yes, as I was working through cruiser54s tips, I fixed the stutter but now it runs smoothly albeit a little rich, hence the issue I'm having at the bottom end And yes throttle position/control sensor87' 4x4 Sportruck Link to comment Share on other sites More sharing options...
Pete M Posted November 10, 2017 Share Posted November 10, 2017 how old is the o2 sensor? tested the map sensor? Link to comment Share on other sites More sharing options...
Kyleinreallife Posted November 10, 2017 Author Share Posted November 10, 2017 how old is the o2 sensor? tested the map sensor? I don't imagine any of the sensors have ever been replaced. I'm trying not to replace too many components right now because I plan on a 4.0 swap. How would I test those sensors? I can pull and clean them this weekend.87' 4x4 Sportruck Link to comment Share on other sites More sharing options...
Pete M Posted November 10, 2017 Share Posted November 10, 2017 should be the whole gamut here: http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm Link to comment Share on other sites More sharing options...
87MJTIM Posted November 10, 2017 Share Posted November 10, 2017 Check out "NickintimeFilms" on fakebook. He sells a Renix Engine Monitor (REM) that will help you diagnose sensor problems with the Renix. The REM's work for 2.5 and 4.0 and auto and manuals. Link to comment Share on other sites More sharing options...
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