Jeep Driver Posted March 7, 2019 Share Posted March 7, 2019 1 minute ago, hakukamana said: Coolant temp switch on the block, operating temperature readings are correct, from cold start up to full operating temperature. I can monitor the temperature as the truck heats up after the thermostat opens runs about 187 at idle. What you are monitoring is what the ECU sees? You know that for a fact? Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 I am monitoring the data off the scanner, MT2500. Short of using a Lazer temp gun, which I have, how else would I verify temperature? Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 7, 2019 Share Posted March 7, 2019 2 minutes ago, hakukamana said: I am monitoring the data off the scanner, MT2500. Short of using a Lazer temp gun, which I have, how else would I verify temperature? What I'm wondering is if your temp sender is bad..........ECU sees cold temp, runs rich. (not the gauge sender......the other one) Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 The failures of the O2s we're open loop, Lean, not rich, and the voltages were way off, not swinging from low to high, it was like the heater fried, and then the rest of the sensor just went wacko. I just would not think (3) bad O2 sensors. But each one that failed, initially worked fine for a couple of days. Then just stopped working correctly. The latest one was installed today, and it's working Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 Isn't the CTS on the block and the temp sender in the head? I would think the scanner is monitoring the CTS and not the temp sender Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 7, 2019 Share Posted March 7, 2019 8 minutes ago, hakukamana said: Isn't the CTS on the block and the temp sender in the head? I would think the scanner is monitoring the CTS and not the temp sender This was my question to you. Which is it reading? Link to comment Share on other sites More sharing options...
JMO413 Posted March 7, 2019 Share Posted March 7, 2019 The scanner would read the CTS for the ECM. There one in the block. Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 Good question, I think I will have to look at some schematics and see what goes where? Link to comment Share on other sites More sharing options...
87MJTIM Posted March 7, 2019 Share Posted March 7, 2019 I am watching. I have an 87 4.0 with a 90 manual trans ECU. I also have Nickintime's REM to read the codes. I am having an issue with LTFT stuck at 154. That is running rich. I recently replaced the O2 sensor with a Bosch (replaced a NTK/NKG). The REM shows the O2 voltage jumping up and down from 1.xx to 4.xx, like it is supposed to do. The REM shows I am in CLSD loop, like it is should be. The STFT is constantly changing, BUT is continuously below 128, running lean. It mostly is showing double digits - 10 to 90. Sometimes it will drop to zero. If it stays there for 3 seconds, the ECU switches to OPEN loop (like is should). However, the LTFT NEVER changes! What can I do to fix/adjust the LTFT? Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 19 hours ago, Ωhm said: I'm not saying that, I'm wondering if it will. LTFT should trigger when STFT reaches one of its two limits (0 or 255). LTFT will then move lower or higher, allowing STFT (128) to start all over again. Thats the intent of STFT and LTFT. Now what I don't know is if RENIX will do this. I had a similar question to Ohm, LTFT is triggered by STFT hitting limits, then and only then would LTFT adjust itself depending on the triggered limit STFT hit? If you read the last sentence, thats the question, does the Renix ECU actually adjust the LTFT if the STFT hits a limit. I know as of this morning my LTFT is 128 rock solid no movement, the STFT is all over the place moving up and down in the 70's to the High 80's. But the scanner is showing voltage changes from lean to rich, it is running in closed loop, and the sensor appears to be operational at this point. Link to comment Share on other sites More sharing options...
JMO413 Posted March 7, 2019 Share Posted March 7, 2019 There scanner definitely reads the CTS in the block. I tested my theory today and unplugged the one in the intake with the scanner hooked up. It still reads a coolant temperature and the gauge doesn't register. Link to comment Share on other sites More sharing options...
Ωhm Posted March 7, 2019 Share Posted March 7, 2019 I too, would like to know more about this subject (STFT LTFT). I wonder if all ECU's are created equal. Does a 90 ECU offer more than say a 87 ECU, when it comes to Fuel Trim. 87MJTIM shows LTFT at 154 while other ECU's LTFT don't move and vehicle goes CLSD loop once STFT pegs one way or the other. Anyone else show LTFT movement? What year ECU? 87MFTIM does your LTFT value stay the same between KEY ON and KEY OFF cycles? If so, does that indicate Keep Alive Memory (KAM). 1 hour ago, 87MJTIM said: I am having an issue with LTFT stuck at 154. That is running rich. Doesn't 154 mean engine is running lean and LTFT is increasing INJ PW time? 1 hour ago, 87MJTIM said: The STFT is constantly changing, BUT is continuously below 128, running lean. Just the opposite here, doesn't below 128 mean engine is running rich and STFT is decreasing INJ PW time? Link to comment Share on other sites More sharing options...
87MJTIM Posted March 7, 2019 Share Posted March 7, 2019 29 minutes ago, Ωhm said: I too, would like to know more about this subject (STFT LTFT). I wonder if all ECU's are created equal. Does a 90 ECU offer more than say a 87 ECU, when it comes to Fuel Trim. 87MJTIM shows LTFT at 154 while other ECU's LTFT don't move and vehicle goes CLSD loop once STFT pegs one way or the other. Anyone else show LTFT movement? What year ECU? 87MFTIM does your LTFT value stay the same between KEY ON and KEY OFF cycles? If so, does that indicate Keep Alive Memory (KAM). Doesn't 154 mean engine is running lean and LTFT is increasing INJ PW time? Just the opposite here, doesn't below 128 mean engine is running rich and STFT is decreasing INJ PW time? My bad. I got rich and lean backwards. 154 LTFT is increasing the pulse width. My MPG has sucked! Link to comment Share on other sites More sharing options...
JMO413 Posted March 7, 2019 Share Posted March 7, 2019 LTFT only changes over time thus long term. STFT fluctuates until you reach operating temp thus short term. I can't find a positive answer on what way is rich and what way is lean. Everywhere I look has opposite answers. My STFT starts at 128 which I believe is default. From there as it warms up it drops to the 90's which makes sense my LTFT is 91. So am I rich or lean on LTFT? Link to comment Share on other sites More sharing options...
Ωhm Posted March 7, 2019 Share Posted March 7, 2019 It's confusing, yes. Number below 128 take fuel away (decreasing INJ PW time, O2S sees RICH engine). Number above 128 add fuel (increasing INJ PW time, O2S sees LEAN engine). In your case O2S sees RICH engine. Link to comment Share on other sites More sharing options...
Ωhm Posted March 7, 2019 Share Posted March 7, 2019 Yes, 128 is the starting point for both STFT and LTFT. Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 Is there a Renix fuel injection guru on the forum? I started the post to try an understand the reasons for my failures of O2 sensors. I don't think Renix ECU's had KAM, then it would be able to store data, ie codes? But the understanding of the relationship between STFT and LTFT as controlled by the ECU is interesting, but I have looked through all my manuals including the Renix FI, manual and nothing specific Link to comment Share on other sites More sharing options...
87MJTIM Posted March 7, 2019 Share Posted March 7, 2019 3 minutes ago, hakukamana said: Is there a Renix fuel injection guru on the forum? I started the post to try an understand the reasons for my failures of O2 sensors. I don't think Renix ECU's had KAM, then it would be able to store data, ie codes? But the understanding of the relationship between STFT and LTFT as controlled by the ECU is interesting, but I have looked through all my manuals including the Renix FI, manual and nothing specific See the attached link for the Renix Fuel Injection Manual. A handy booklet to have. http://alpinefurniturestore.com/JeepDocumentation/MJs/Jeep_Renix_Fuel_Injection_manual.pdf Link to comment Share on other sites More sharing options...
hakukamana Posted March 7, 2019 Author Share Posted March 7, 2019 Read the section Pulse Width Modification, what is ALFACL? What ever it is, its a correction factor that controls pulse width and can change based upon a number of external conditions. Link to comment Share on other sites More sharing options...
Ωhm Posted March 7, 2019 Share Posted March 7, 2019 My thinking/guess is ALFACL is STFT only. Link to comment Share on other sites More sharing options...
JMO413 Posted March 7, 2019 Share Posted March 7, 2019 If I'm reading this correctly 0 is ultimate rich and 255 is ultimate lean. This is a screen shot out of the Renix infection manual. So hopefully it right. On 2/26/2019 at 3:32 PM, WahooSteeler said: They had already replaced stock 1 holes with 4 hole units and were happy with them, but then recently went to the newer 12 hole units. They both seemed to feel the idle and throttle response improved again, much like it had when going from 1 to 4 hole. Others reported additional MPG gains............ Limey, after more research, apparently stock flow rate is 23.2/lb which is interesting considering that I had planned on the 746's based on many discussions here. 746's come to find out are rated at 20.2/lb. Also have seen a lot of info on people running 703's (23/lb) on Renix 4.0's because they have the same EV1 connectors. 99+ guys seem to mostly run 784's (24.4/lb), they have the EV6 connectors. I just want to make sure when I purchase "new" units, I've got the best ones suited for my stock Renix 4.0L and only have to swap them once. And if I'm reading this right mine is rich beacuse the 746 injectors are 20.2/lb and stock injectors are 23.2/lb? So the ECM is compensating? Sorry too high Jack your post. Just want to understand this fuel trim thing. Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 8, 2019 Share Posted March 8, 2019 35 minutes ago, JMO413 said: If I'm reading this correctly 0 is ultimate rich and 255 is ultimate lean. This is a screen shot out of the Renix infection manual. So hopefully it right. And if I'm reading this right mine is rich beacuse the 746 injectors are 20.2/lb and stock injectors are 23.2/lb? So the ECM is compensating? Sorry too high Jack your post. Just want to understand this fuel trim thing. Meaningless without known fuel pressure. Pressure effects actual fuel delivery at the injector. Link to comment Share on other sites More sharing options...
Ωhm Posted March 8, 2019 Share Posted March 8, 2019 42 minutes ago, JMO413 said: If I'm reading this correctly 0 is ultimate rich and 255 is ultimate lean. The terms RICH and LEAN here are what the O2S sees. Link to comment Share on other sites More sharing options...
JMO413 Posted March 8, 2019 Share Posted March 8, 2019 30 with vacuum 39 without. Just checked this and replaced the FPR. Link to comment Share on other sites More sharing options...
Ωhm Posted March 8, 2019 Share Posted March 8, 2019 4 minutes ago, JMO413 said: 30 with vacuum 39 without. True, but JD's question was "What pressure were they tested at to determine there flow rate (lbs)". Link to comment Share on other sites More sharing options...
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