cruiser54 Posted May 13, 2015 Share Posted May 13, 2015 PM me. Link to comment Share on other sites More sharing options...
88mjblue Posted June 6, 2015 Author Share Posted June 6, 2015 Some updates: - Re-tested oxygen sensor, heater is working supplying 13.8 V, and 5V to ECU - Tested for continuity from O2 sensor plug to ecu, all good. - tested coolant temp sensor, got 243 ohms at operating temp - coolant temp sensor continuity good back to ECU - air intake temp ohms correct, signal reaches ECU as well - air bleed torx screw adjustment did nothing - tps retested and still at 0.83 V Idle was fine before I removed throttle body and cleaned it out and adjusted butterfly stop screw, I must have done something during that job... Right now I'm tempted to adjust Bob's stop screw and get it back to normal, even if it's masking the real problem. Link to comment Share on other sites More sharing options...
88mjblue Posted June 6, 2015 Author Share Posted June 6, 2015 Oh, and I noticed the knock sensor had some frayed wires, would this affect anything? I couldn't figure out how to unplug it to test for continuity to ecu... Link to comment Share on other sites More sharing options...
cruiser54 Posted June 6, 2015 Share Posted June 6, 2015 Oh, and I noticed the knock sensor had some frayed wires, would this affect anything? I couldn't figure out how to unplug it to test for continuity to ecu... Possibly, but not probable. Revisit your TB adjustment. Link to comment Share on other sites More sharing options...
88mjblue Posted June 6, 2015 Author Share Posted June 6, 2015 Oh, and I noticed the knock sensor had some frayed wires, would this affect anything? I couldn't figure out how to unplug it to test for continuity to ecu... Possibly, but not probable. Revisit your TB adjustment. I plan to take TB off completely again and adjust that stop screw from scratch. I also had the thought that maybe the TB gasket was not seated properly. Is there a possibility of the butterfly being too closed? I mean as long as it is not digging into the metal, I adjusted it so it is resting on that screw, but it should be closed down as much as possible, right? Link to comment Share on other sites More sharing options...
cruiser54 Posted June 7, 2015 Share Posted June 7, 2015 Oh, and I noticed the knock sensor had some frayed wires, would this affect anything? I couldn't figure out how to unplug it to test for continuity to ecu... Possibly, but not probable. Revisit your TB adjustment. I plan to take TB off completely again and adjust that stop screw from scratch. I also had the thought that maybe the TB gasket was not seated properly. Is there a possibility of the butterfly being too closed? I mean as long as it is not digging into the metal, I adjusted it so it is resting on that screw, but it should be closed down as much as possible, right? Tip 14. Link to comment Share on other sites More sharing options...
88mjblue Posted June 27, 2015 Author Share Posted June 27, 2015 Readjusted throttle body according to tip #14, still the same. I did some other testing:- CPS test: 0.6 AC volts cracking, so all good there - EGR valve test: passes valve closing test, but did not see anything moving with valve opening test.. could this be my problem? Anybody have a picture/video of what EGR opening should look like? Link to comment Share on other sites More sharing options...
cruiser54 Posted June 27, 2015 Share Posted June 27, 2015 Link to comment Share on other sites More sharing options...
88mjblue Posted July 20, 2015 Author Share Posted July 20, 2015 What I did this weekend: - 746 injectors - intake/exhaust gasket - new exhaust manifold - New CTS and pigtail - new EGR - motor mounts Still idles the same, no change whatsoever... Don't know what to do now. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 21, 2015 Share Posted July 21, 2015 Check your fuel pressure with a gauge at idle. Should be 31 PSI with the vacuum hose connected and 39 when it's disconnected from the fuel pressure regulator. At idle, spray carb cleaner all over the MAP sensor to throttle body hose. What happens? Link to comment Share on other sites More sharing options...
88mjblue Posted July 21, 2015 Author Share Posted July 21, 2015 Check your fuel pressure with a gauge at idle. Should be 31 PSI with the vacuum hose connected and 39 when it's disconnected from the fuel pressure regulator. At idle, spray carb cleaner all over the MAP sensor to throttle body hose. What happens? OK, thanks for the direction. I was reading into this and feel it's about darn time I got one of those gauges... so I will order one and do that test when I get the gauge. I'll try the MAP sensor test, do I spray down the actual sensor itself up by the firewall? Or just the vacuum line? When I get to the 2-port rubber stopper at the throttle body, do I spray that down too? Link to comment Share on other sites More sharing options...
cruiser54 Posted July 21, 2015 Share Posted July 21, 2015 Check your fuel pressure with a gauge at idle. Should be 31 PSI with the vacuum hose connected and 39 when it's disconnected from the fuel pressure regulator. At idle, spray carb cleaner all over the MAP sensor to throttle body hose. What happens? OK, thanks for the direction. I was reading into this and feel it's about darn time I got one of those gauges... so I will order one and do that test when I get the gauge. I'll try the MAP sensor test, do I spray down the actual sensor itself up by the firewall? Or just the vacuum line? When I get to the 2-port rubber stopper at the throttle body, do I spray that down too? Concentrate on the line end to end, fittings and all. Link to comment Share on other sites More sharing options...
88mjblue Posted August 23, 2015 Author Share Posted August 23, 2015 Back with another update: - Sprayed down the MAP sensor tube to throttle body with carb cleaner and nothing happened. Was something supposed to happen? - I got a fuel pressure gauge, hooked it up to the Schrader valve test port, and got the usual numbers of 39 psi with fuel pressure regulator disconnected, and 31 psi with fuel pressure regulator connected. Link to comment Share on other sites More sharing options...
88mjblue Posted August 23, 2015 Author Share Posted August 23, 2015 Also did vacuum gauge test: ~12-14 in. Hg fluctuating (I'm at 5,500 feet elevation by the way) Take a look: https://www.youtube.com/watch?v=X94xAatEpWo https://www.youtube.com/watch?v=PmZNMzPtFsw Link to comment Share on other sites More sharing options...
88mjblue Posted August 24, 2015 Author Share Posted August 24, 2015 Anybody have any insight on this idle issue? If I'm reading the vacuum gauge test correctly, it tells me I have an issue with ignition, so I'm going to re-examine the plugs, wires, cap, rotor. Do distributor or ignition coil fall into this? And, could this possible ignition problem be causing my low idle? I did another test with vacuum lines: I pulled out the rear (closer to firewall) CCV tube and idle goes up, then adjusts back to low idle. I plug it back in, idle drops down very low, almost stalls, but I believe it's the IAC that then steps in to correct this and brings the idle back up (to the low idle) Link to comment Share on other sites More sharing options...
metrictonner Posted August 26, 2015 Share Posted August 26, 2015 Have you tried idle with the throttle body airbox inlet disconnected? When was the last time you changed your air filter? Is your crankcase breather (front valve cover tube dumping into airbox) pumping out mucho smoke? Check your Idle speed stepper motor (what RENIX calls it, appropriate in this instance). Is it stuck? Throttle body need cleaning? Since the ISS seems to be working at cold idle but not hot it just may be a corroded old connector or a bad motor. Check all your connectors? Link to comment Share on other sites More sharing options...
88mjblue Posted August 28, 2015 Author Share Posted August 28, 2015 Throttle body is very clean, air filter is recently new. IAC has been replaced (no change), but I will check its electrical connector because I don't think I have checked that yet. But it seems to be working (just at a lower level) since it is able to make adjustments for vacuum leaks when I plug and unplug a vacuum line. What will disconnecting the throttle body airbox inlet prove? Link to comment Share on other sites More sharing options...
88mjblue Posted October 10, 2015 Author Share Posted October 10, 2015 Well, I've just about given up here trying to solve this low idle problem. I have scheduled an appointment with a mechanic (gasp!) to take a look and get another opinion. They have a Snap-On tool with the Jeep/Eagle diagnostic connector and I am hoping that viewing some live data will shed some light onto what's happening when the idle drops. Has anybody done this before? I know some people have gotten the old Snap-on MT-2500 (aka "the brick"). What should I be looking for, and what exactly can be read from this primitive Renix computer? Link to comment Share on other sites More sharing options...
88mjblue Posted October 10, 2015 Author Share Posted October 10, 2015 I checked out some used MT25000's on eBay, and for just a little bit more than what I will have to pay to have a mechanic use their fancy newer snap-on computer station I could buy my own. Does anybody own one of these, and know which adapter cable and/or cartridge to get? Link to comment Share on other sites More sharing options...
cruiser54 Posted October 10, 2015 Share Posted October 10, 2015 Many folks have one and they're great. Make sure you have the Jeep/Eagle adapter that will plug into the 2 diagnostic plugs on the passenger fender. Link to comment Share on other sites More sharing options...
88mjblue Posted October 10, 2015 Author Share Posted October 10, 2015 Found a good deal on a MT2500 on eBay for $70, got adapter for $10 and cartridge for $30. I cancelled my repair shop appointment, hopefully I can solve this myself! I will report back once it arrives and I can plug it in and see what's up. In the meantime, I did some more troubleshooting on the idle thing. I found out that unplugging the IAC at 750 rpm keeps the idle right there - a short term solution for my idle problem. Does this help pinpoint my problem? Or eliminate any other sensors/things? (As a recap, I have previously replaced the IAC with a new one, and no change) Link to comment Share on other sites More sharing options...
JMO413 Posted March 8, 2019 Share Posted March 8, 2019 Did you ever get this resolved? Link to comment Share on other sites More sharing options...
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