1989 Eliminator Posted June 26, 2014 Author Share Posted June 26, 2014 So what brand should I get for a new IAC. $70 autozone $140 Mopar Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 27, 2014 Author Share Posted June 27, 2014 Okay call me crazy. But why wouldnt this work... If i made a rod made out of metal or wood the same diameter of the iac hole, couldnt i just take the iac out but still connected and place the rod in the throttle body so i can manually adjust the amount of air. And since the iac is out i could then observe if its moving at all Link to comment Share on other sites More sharing options...
cruiser54 Posted June 27, 2014 Share Posted June 27, 2014 Okay so now i had the truck running and probed the o2 sensor wires and the voltage was varying from ~0.8V to ~4.5V. Good or bad? When i first start the truck though the rpms are okay and the o2 output is steady around 2V then slowly drops below 1V then starts to jump around in voltage. Good. How fast was it switching? Link to comment Share on other sites More sharing options...
sinkrun Posted June 27, 2014 Share Posted June 27, 2014 So what brand should I get for a new IAC. $70 autozone $140 Mopar Sensors from just about any parts store are JUNK anymore. Just replaced a 3 month old TPS from advance then tried a NAPA I swear it was the same sensor it came apart in my hand while installing it. I ordered a Mopar one from ebay $72.00 shipped my local dealer wanted $110.00. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 29, 2014 Author Share Posted June 29, 2014 So the that voltage difference is good? It was switching every second. Like its supposed to. I do not know what to check next. I'm at a stand still! Link to comment Share on other sites More sharing options...
cruiser54 Posted June 29, 2014 Share Posted June 29, 2014 So the that voltage difference is good? It was switching every second. Like its supposed to. I do not know what to check next. I'm at a stand still! What voltages? .1 to 4.9? Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 29, 2014 Author Share Posted June 29, 2014 Yes thats the voltages after the truck is warmed up a few minutes after startup. Link to comment Share on other sites More sharing options...
cruiser54 Posted June 29, 2014 Share Posted June 29, 2014 Yes thats the voltages after the truck is warmed up a few minutes after startup. Perfect. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted June 29, 2014 Author Share Posted June 29, 2014 Hm okay. I'm still stuck of what to check next Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 1, 2014 Author Share Posted July 1, 2014 Update on my progress. I ordered a new egr valve. Reason being is one time i took off the vacuum hose from the transducer to the egr valve and water came out. A bad egr could be causing my issue. So I'm trying this Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 2, 2014 Share Posted July 2, 2014 Can't the EGR just be eliminated and a blockoff plate installed in its place? Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 2, 2014 Author Share Posted July 2, 2014 Yeah... A plate and plug for the exhaust manifold. But its illegal technically. And I'm not sure how the truck would run without it. During acceleration and high rpms the ecu tells the egr solenoid to open which then opens the egr valve. And if its not there then I'm not sure what will happen. So i just ordered a new one Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 3, 2014 Author Share Posted July 3, 2014 The EGR will be in saturday but I did some more thread searching and found this one...: http://www.naxja.org/forum/showthread.php?t=905849&highlight=Renx+files&page=8 This is a very long thread but around page 8 is where he figured his problem out. He said it was his TPS but mine is new like his was and he said it was bad out of the box. I did the same ohm test as he did and my values concurred with his. So I at least know my TPS is okay. As far as if the TCU and ECU are getting those same readings is a different story. BTW...my truck recently has a new symptom of mis-shifting between 3th gear and 4th. The truck will be going around 45 mph and then not shift. The rpms will reach 2500 around 65 mph and when i step on the gas the truck shifts up and the rpms go down but only for a short span of time. ????????? :dunno: :wall: Link to comment Share on other sites More sharing options...
cruiser54 Posted July 3, 2014 Share Posted July 3, 2014 Ohms test on a TPS? Nah. RENIX TPS ADJUSTMENT Before attempting to adjust your TPS, there are two things that need to be done. 1) 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. 2) With the Key OFF, and using the positive (red) lead of your ohmmeter, set on the lowest scale, 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. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, 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. TPS ADJUSTMENT FOR ENGINE ISSUES Both RENIX manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. DO NOT UNPLUG THE CONNECTORS !! 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. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over. Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage. TPS ADJUSTMENT FOR AUTOMATIC TRANSMISSION ISSUES RENIX automatic transmission equipped XJs and MJs 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 outlined above—FOR ALL 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. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. First off, DO NOT UNPLUG THE CONNECTORS !! Key ON, measure voltage between "A" positive and "D" ground by back-probing the connector. 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. 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. The square 4 wire connector is just not used. Revised 12-15-2013 Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 3, 2014 Author Share Posted July 3, 2014 Yeah I also did that and everything checked out okay. But I did check the resistance of the ground on the transmission side of the TPS (4 prong connector) and it was well over 2000 ohms. So, I plan on just making my own ground straight to the engine block ground. This would work correct? Link to comment Share on other sites More sharing options...
cruiser54 Posted July 3, 2014 Share Posted July 3, 2014 That should ground to the engine dipstick tube stud..... Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 4, 2014 Author Share Posted July 4, 2014 Right. Thats what i was going to do directly. Because as of right now it comes from the TPS-across the firewall-then splices. But i didnt have enough time. I was doing continuity tests from the TPS connector to different wires to find the reason for the high resistance. I have my FSM electronic manual and ive been following that. I am making sure the TCU also has a good ground. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 4, 2014 Share Posted July 4, 2014 Excellent. If you read Post 1 in my tips, you can see how many critical things ground at that dipstick stud. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 4, 2014 Author Share Posted July 4, 2014 Yup! I totally know how important that is. I already made my own grounds for other sensors. Its just weird about that one ground with that high resistance. Ill have an update sunday. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 4, 2014 Share Posted July 4, 2014 You've read post 6 I take it? Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 4, 2014 Author Share Posted July 4, 2014 Yes I have. I checked all my sensors but when I checked the TPS i only did the ECU side. From the diagram in the manual the tps grounds to the dipstick/engine and a separate wire coming from the TCU (which is apart of one of the trans connectors) also grounds there. So my guess is that somewhere in the wire harness there is a broken wire or something. Link to comment Share on other sites More sharing options...
cruiser54 Posted July 4, 2014 Share Posted July 4, 2014 Done #10? Link to comment Share on other sites More sharing options...
jhickman Posted July 4, 2014 Share Posted July 4, 2014 This is a very informative topic and I've been following it with interest because I just bought an 88 but I don't know all of the acronyms that are being used. Is there somewhere on the site that lists the acronyms or could someone give a quick rundown of them.....I know TPS but I'm not sure of the TCU and ECU. Thanks. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 4, 2014 Author Share Posted July 4, 2014 Cruiser, I cleaned those plugs with contact cleaner and applied di-electric grease. Somewhere else in the wire is the issue. Jhickman, TCU is Transmission Control Unit. Sometimes people call it TCM which stands for Transmission control module. ECU is Engine Control Unit. It also can be called ECM. Link to comment Share on other sites More sharing options...
87MJTIM Posted July 4, 2014 Share Posted July 4, 2014 This is a very informative topic and I've been following it with interest because I just bought an 88 but I don't know all of the acronyms that are being used. Is there somewhere on the site that lists the acronyms or could someone give a quick rundown of them.....I know TPS but I'm not sure of the TCU and ECU. Thanks. Hope this helps! http://comancheclub.com/topic/12163-acronyms/ (July 2014 MJOM) Link to comment Share on other sites More sharing options...
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