oleskool Posted December 27, 2021 Share Posted December 27, 2021 For 2 days in the morning I’ve gotten this symptom. It cranks up and misfires / runs rich. I’ve replaced CPS, MAP, IAC, TPS, all power wires and grounds. Cool and ignition module are new because they were failing when I bought the truck. I have not replaced cap rotor, cap or plug wires yet. I will pick them up today. This truck was in a barn for several years not running so I have went through most of this just refreshing everything. It runs great when it runs. The injectors are new and have been running great too. They are upgraded 4 hole injectors. Any other ideas of what would cause this. When I give it gas it’s obvious there is a serious lack of power and it has a super rich exhaust. TIA Link to comment Share on other sites More sharing options...
oleskool Posted December 27, 2021 Author Share Posted December 27, 2021 I’m starting to wondering if the new MAP is causing the issue. I’ll dig deeper into that this afternoon. I saved the old one just in case. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 28, 2021 Share Posted December 28, 2021 I'm with you. also, carefully inspect the hose/tubing from throttle body to MAP. A small crack will cause the MAP to think you have the gas pedal on the floor and make it run very rich. Link to comment Share on other sites More sharing options...
OldManComanche Posted December 28, 2021 Share Posted December 28, 2021 Is this the some problem you have had before? Are we plowing the same field we plowed before?? Link to comment Share on other sites More sharing options...
oleskool Posted December 28, 2021 Author Share Posted December 28, 2021 2 hours ago, OldManComanche said: Is this the some problem you have had before? Are we plowing the same field we plowed before?? Unfortunately no it’s not the same issue I had before. Validated the MAP and it’s correct. I had a MAP vac line leak that caused my original issue. Tried again this morning and got the same issue. Oddly enough after letting it sit for 30 minutes or so it cranks up. I swapped back in the old TPS sensor and calibrated it again. Runs fine now but we shall see. Link to comment Share on other sites More sharing options...
Ωhm Posted December 28, 2021 Share Posted December 28, 2021 Couple of could be's. Leaky Fuel Pressure Regulator (FPR). Check for fuel in vacuum line. Slow leak. O2S Heater circuit. O2S is a maintenance item. Replace ≈87.5kmiles. Link to comment Share on other sites More sharing options...
oleskool Posted December 30, 2021 Author Share Posted December 30, 2021 Ok. I’ve been dealing with this every morning. Once the truck cranks correctly it’s runs and drives fine all day. Just replaced cap, rotor, and plug wires. Still have the same issue. Went back through and re verified the TPS, CPS and IAC. All seem to be correct. Throttle body is clean and set to a 3 thou gap. Checked grounds again and all seems good. Fuel pump is good and working correctly. Injectors and fuel pressure regulator are brand new within the last 6 months. I did go through the entire fuel system because I had to anyway. The truck runs and drives great until this happens. Any other sensors I need to look into on this truck. This is the first renix I’ve owned. Link to comment Share on other sites More sharing options...
oleskool Posted December 30, 2021 Author Share Posted December 30, 2021 When it does finally crank correctly it runs perfect at 750RPM. You give it gas and it revs correctly etc. @cruiser54 I retested the grounds on the TPS harness. B terminal to ground on battery and get a consistent 2.9 ohms. It does not change with any type of wiggling wires etc. is this acceptable or do I need to dig back into grounds? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 30, 2021 Share Posted December 30, 2021 We're shooting for .5 ohms. Link to comment Share on other sites More sharing options...
oleskool Posted December 30, 2021 Author Share Posted December 30, 2021 27 minutes ago, cruiser54 said: We're shooting for .5 ohms. I figured. I’ve updated all grounds from your page. Just odd I don’t get any variations when moving the harness around. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 30, 2021 Share Posted December 30, 2021 That ground circuit terminates at the dipstick tube stud. Link to comment Share on other sites More sharing options...
oleskool Posted December 30, 2021 Author Share Posted December 30, 2021 12 minutes ago, cruiser54 said: That ground circuit terminates at the dipstick tube stud. It’s all brand new but I’ll go back through it and see what it does. Link to comment Share on other sites More sharing options...
oleskool Posted December 30, 2021 Author Share Posted December 30, 2021 59 minutes ago, cruiser54 said: That ground circuit terminates at the dipstick tube stud. Alright went back through and I think my measurement was off. I cleaned everything and get 1 ohm through the harness. Doesn’t move when moving the harness from the dipstick side or injector side. This is the reading I got when I originally installed the new ground and cleaned up everything. Is that better? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 31, 2021 Share Posted December 31, 2021 Sure is. Link to comment Share on other sites More sharing options...
oleskool Posted December 31, 2021 Author Share Posted December 31, 2021 2 hours ago, cruiser54 said: Sure is. I decided to dig deeper measuring at the IAC and MAP as well. To note I have not dug into the harness and removed ground crimps on this circuit. They all measured right at 1 ohm. No movement from any test point when moving wires. If I get the issue tomorrow morning I’ll remeasure the grounds to verify the reading stays consistent. Other than this I’m really not sure where to go. When I get the issue the truck cranks up almost instantly instead of the long crank time that’s normal with a renix. It also goes up to a little over 1k RPM instead of the right at 2k RPM when it’s starts correctly. Link to comment Share on other sites More sharing options...
oleskool Posted December 31, 2021 Author Share Posted December 31, 2021 Ok. I measured grounds this morning. It was 60 degrees with heavy fog. It’s been unseasonably warm and raining the past few days. I read 1.4 ohms from the grounds on the TPS MAP and Intake sensor. No movement when wiggling wires. Tried to crank the truck and it fired right up. I’m wondering if there is something happening here I haven’t noticed so I’ll check it for a few days to collect data. Hopefully I find a correlation to something. Lol. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 31, 2021 Share Posted December 31, 2021 Done tip 3? Link to comment Share on other sites More sharing options...
oleskool Posted December 31, 2021 Author Share Posted December 31, 2021 4 hours ago, cruiser54 said: Done tip 3? Yes sir. I’ve done most of your mods. The only connector I haven’t been to yet is the Computer. The only ground I haven’t touched is the dash ground. I haven’t spliced the blower motor ground yet either. Every connector I could get to has been cleaned, brushed and packed with dielectric grease. It’s a super odd issue. I’ve had to troubleshoot a lot of electrical with my CJs but this one is throwing me for a loop. The fact it runs great rain or shine except for mornings when it wants to throw this issue up confuses me. I would understand if it was a rain / humidity issue or cold etc. drove it in the rain all day yesterday just fine. No issues what do ever. I have not done step 6 yet. That’s next on the list just to eliminate grounding issues that are intermittent. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 31, 2021 Share Posted December 31, 2021 test the IAT with an ohmmeter when cold. Link to comment Share on other sites More sharing options...
oleskool Posted January 1, 2022 Author Share Posted January 1, 2022 3 hours ago, cruiser54 said: test the IAT with an ohmmeter when cold. Quick interpolation. Intake was roughly 90 degrees from driving it today. Here is what I got. Measured around 1980 ohms and that interpolates to 93 degrees. I’ll check it cold in the morning too. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 1, 2022 Share Posted January 1, 2022 excellent plan. You could test the CTS also. Link to comment Share on other sites More sharing options...
oleskool Posted January 1, 2022 Author Share Posted January 1, 2022 36 minutes ago, cruiser54 said: excellent plan. You could test the CTS also. I’ll check that too. I measured resistance again tonight while I was under the hood. I get 1.1 ohms. So a noticeable drop in resistance. I'm guessing I need to dig out the crimps on the ground wires and eliminate them. Link to comment Share on other sites More sharing options...
oleskool Posted January 1, 2022 Author Share Posted January 1, 2022 Checked the IAT again this morning. It was a brisk 70 degrees here in upstate SC I measured the IAT sensor and got 3401 ohms. According the the chart I should be at 3400 ohms. Since my issue is at start up after sitting all night I think this isn’t the culprit. I also measured the ground resistance this morning on the TPS and got .9 ohms. It’s muggy outside but it’s staying around a similar value. I haven’t read the percent error of my particular meter but it would be enough to fluctuate ~.15 ohms I’m guessing based on the calibrated units I have at work and their percent errors. after checking sensors and grounds I tried to crank the truck and it fired right up like normal. It rained last night as well so if moisture is the issue it should have showed it’s head again this morning I haven’t got to the CTS yet, headed out for a New Years Day lunch so my better half is trying to keep me clean lol. I’ll check it later today too. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 1, 2022 Share Posted January 1, 2022 Way to hang in there. Link to comment Share on other sites More sharing options...
pizzaman09 Posted January 3, 2022 Share Posted January 3, 2022 I recently ran into a similar sounding issue on a similar vintage map controlled Toyota engine. Are you sure you have the TPS sensor adjusted correctly? Said another way, clocked correctly relative to the throttle? Once I went through the alignment procedure on aforementioned Toyota, the super rich running condition went away and it ran perfectly. You may consider checking this or adjusting it just slightly towards the lean side just to see if that fixes it. Link to comment Share on other sites More sharing options...
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