88jeep1 Posted November 28, 2017 Share Posted November 28, 2017 88 mj 4.0 aw4 4x4. Did upgrade injectors new timing set, oil pan, rear main seal, water pump along Iac, Tps, coolant temp sensor, plugs,wires,cap,rotor, Upgrade factory computer to run renix system better. Also fuel pump is original to my knowledge with a new fuel filter if that helps at all. The truck has an eratic idle. It seems to respond well when I blip the throttle. What I notice is the engine comes back down after the rev back to an idle and it seems to drop sudden. Then it catches itself and picks back up in rpm. If I don't touch the pedal it sits and idles. Just isn't smooth has like a roughness to it or like a miss. Any help with this would be greatly appreciated! I will do my best to do the tests you guys suggest and report back. I just need someone that knows these alittle better that can help me out on this project of mine. Link to comment Share on other sites More sharing options...
Ωhm Posted November 28, 2017 Share Posted November 28, 2017 I'd start with cruiser tip #8 (TPS ) Renix TPS Adjustment Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 22 minutes ago, Ωhm said: I'd start with cruiser tip #8 (TPS ) Renix TPS Adjustment Thanks for answering. I will do this tomorrow and see what I come with. I also want to add I have an REM as well. If there's something on it I could tell you when it's plugged in let me know. Link to comment Share on other sites More sharing options...
Ωhm Posted November 28, 2017 Share Posted November 28, 2017 Make sure O2 sensor is switching and closed loop doesn't drop to open loop. Link to comment Share on other sites More sharing options...
cruiser54 Posted November 28, 2017 Share Posted November 28, 2017 Yes, use the REM. But, go to www.cruiser54.com and do Tips 1 through 5 anyway. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 28, 2017 Share Posted November 28, 2017 Does the Renix REM provide an air/fuel ratio display? Link to comment Share on other sites More sharing options...
cruiser54 Posted November 28, 2017 Share Posted November 28, 2017 15 minutes ago, HOrnbrod said: Does the Renix REM provide an air/fuel ratio display? No. But it shows short term and long term fuel trims and oxygen sensor activity, MAP voltage, engine vacuum etc. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 28, 2017 Share Posted November 28, 2017 2 minutes ago, cruiser54 said: No. But it shows short term and long term fuel trims and oxygen sensor activity, MAP voltage, engine vacuum etc. So no live A/F display? Link to comment Share on other sites More sharing options...
cruiser54 Posted November 28, 2017 Share Posted November 28, 2017 Not that I've seen. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 28, 2017 Share Posted November 28, 2017 Oh well, it can't have everything. I'd kill for a similar live monitoring display for an HO........... Link to comment Share on other sites More sharing options...
cruiser54 Posted November 28, 2017 Share Posted November 28, 2017 20 minutes ago, HOrnbrod said: Oh well, it can't have everything. I'd kill for a similar live monitoring display for an HO........... Especially one that was part of the dash clock........ I wish more guys here would get one. for the price of a coupla unneeded sensors, you can own one. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 12 hours ago, Ωhm said: I'd start with cruiser tip #8 (TPS ) Renix TPS Adjustment I did the flat 3 wire and got 4.87 b to a. I did the b to c and got .763. what is my desired number suppose to be? It says move the tps till I have my desired amount but doesn't tell me what I'm shooting for? Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 Also I will add I cleaned the c101 with crc electronics cleaner couple months back. Just to rid it of all that black tar crap. I actually did as many plug in the engine bay as I could see with the cleaner. Then let them air dry before I plugged them back in. Link to comment Share on other sites More sharing options...
fiatslug87 Posted November 28, 2017 Share Posted November 28, 2017 38 minutes ago, 88jeep1 said: I did the flat 3 wire and got 4.87 b to a. I did the b to c and got .763. what is my desired number suppose to be? It says move the tps till I have my desired amount but doesn't tell me what I'm shooting for? from Cruiser's tips: 1-KEY ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage. 2-KEY ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage. 3-Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. So in your case 0.828 And what does this mean? "Upgrade factory computer to run renix system better." Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 4 minutes ago, fiatslug87 said: from Cruiser's tips: 1-KEY ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage. 2-KEY ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage. 3-Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. So in your case 0.828 Ok so I have 82 then the tps would be good right? I just did the coil terminals cleaned and sandpapered. Plugs cleaned on it. Also a while back the grounds were upgraded to 0 gauge head to firewall the dipstick grounds were cleaned and a bigger ground added to a bolt near the engine mount. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 Also when I got this truck the emissions container was missing as well. Could a vacuum/plug setup be missing from it not being on the firewall?? Like needing a signal to run better? I have one on my donor 88 stick mj I could install. What do you think on that? Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 When the rem is plugged in running it says just after start up 15tps, 13.6-14.1map, 15.4-15.7vac, 14-15ign, 586-619 rpm, 14.0battery volts, 0.70-(4.96 on occasion)vO2, says Lean ex, open lp. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 43 minutes ago, fiatslug87 said: from Cruiser's tips: 1-KEY ON, measure voltage from “A” positive to “B” ground by back-probing the connectors. Note the voltage reading–this is your REFERENCE voltage. 2-KEY ON, back-probe the connector at wires “B” and “C”. Measure the voltage. This is your OUTPUT voltage. 3-Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. So in your case 0.828 And what does this mean? "Upgrade factory computer to run renix system better." I put a newer ecu in was told it would open a few more HP's up and mellow the idle out even more. It's a bendix 428 out of a newer auto XJ. Link to comment Share on other sites More sharing options...
87MJTIM Posted November 28, 2017 Share Posted November 28, 2017 23 minutes ago, 88jeep1 said: When the rem is plugged in running it says just after start up 15tps, 13.6-14.1map, 15.4-15.7vac, 14-15ign, 586-619 rpm, 14.0battery volts, 0.70-(4.96 on occasion)vO2, says Lean ex, open lp. If the REM is telling you the engine is Lean and in Open Loop, then either your O2 sensor is bad or possibly the O2 heater relay is bad. Swap out relays in the box on the passenger side engine compartment. Recheck the REM for Lean/Open conditions. There are instructions on testing the O2 sensor as well. Use the meter to test that before swapping parts. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 28, 2017 Author Share Posted November 28, 2017 1 minute ago, 87MJTIM said: If the REM is telling you the engine is Lean and in Open Loop, then either your O2 sensor is bad or possibly the O2 heater relay is bad. Swap out relays in the box on the passenger side engine compartment. Recheck the REM for Lean/Open conditions. There are instructions on testing the O2 sensor as well. Use the meter to test that before swapping parts. I have to go to work now. I will try that tomorrow to see what I end up with. I had a cracked exhaust manifold. When I got another used one I never changed the O2 out. Just reused the one that was in it. Testing on that stuff tomorrow thanks! Link to comment Share on other sites More sharing options...
87MJTIM Posted November 28, 2017 Share Posted November 28, 2017 A cracked exhaust manifold would trigger the lean condition with the 2 sensor - too much air getting to the O2 after combustion. Link to comment Share on other sites More sharing options...
omega_rugal Posted November 29, 2017 Share Posted November 29, 2017 first, how many RPMs at idle? second, does it happen cold, hot or both? Link to comment Share on other sites More sharing options...
88jeep1 Posted November 29, 2017 Author Share Posted November 29, 2017 1 hour ago, omega_rugal said: first, how many RPMs at idle? second, does it happen cold, hot or both? The rpm fluctuates on the rem from about 586-619. When it's cold my oil pressure is about 80 on the cluster gauge after first start if that's even a good thing to go by. Seems to mellow out after it warms up more. It never quite goes away. The other thing I noticed if I rev it alittle not alot of rpms it almost seems like it's going to fall on its face trying to recoupe from being rev'd alittle. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 29, 2017 Author Share Posted November 29, 2017 5 hours ago, 87MJTIM said: A cracked exhaust manifold would trigger the lean condition with the 2 sensor - too much air getting to the O2 after combustion. I changed the cracked one out. I got another used one that was good tho it came with a used O2 sensor in it. I just through it back on the head with a new gasket and all bolts torqued. Link to comment Share on other sites More sharing options...
88jeep1 Posted November 29, 2017 Author Share Posted November 29, 2017 21 hours ago, 87MJTIM said: On 11/27/2017 at 11:04 PM, Ωhm said: Make sure O2 sensor is switching and closed loop doesn't drop to open loop. So I read somewhere about cleaning the I AT on the intake. I cleaned it and all of a sudden my lean/ open loop went to displaying closed and now lean/rich changing back and forth. I believe I have uncovered alittle of my problem. It went to closed loop almost immediately after cleaning the iat. Link to comment Share on other sites More sharing options...
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