Dickinson County Comanche Posted October 12 Share Posted October 12 Hello all, my Jeep has developed the interesting quirk of a very intermittent issue where the engine falls on its face while under very light throttle inputs. If I give it more gas, it’ll rev up no problem, or if I go back to idle it’ll idle fine. I deleted the EGR believing it was the problem however it has remained afterwards. TPS maybe? Link to comment Share on other sites More sharing options...
pizzaman09 Posted October 13 Share Posted October 13 Check to see if all of your header nuts are tight or even there. Sounds like a small vacuum leak to me. Link to comment Share on other sites More sharing options...
TurboedMJ Posted October 13 Share Posted October 13 Check fuel pressure Link to comment Share on other sites More sharing options...
M.T.Hands Posted October 14 Share Posted October 14 Man, off idle like that sounds like something "dirty" with the Idle circuit, I'm very new to this vehicle, but my 04 wrangler had a messed up TPS and it would not idle but definitely could be vacuum or fuel pressure related Link to comment Share on other sites More sharing options...
89 MJ Posted October 14 Share Posted October 14 Here’s Cruiser’s thread on adjusting the tps: And you might as well give the throttle body a good cleaning too: Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 On 10/13/2024 at 2:29 PM, TurboedMJ said: Check fuel pressure It’s not down on power, and when I floor it when it’s doing it the truck picks right back up, so I don’t think it’s fuel system related. Pump is only 2 years old. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 On 10/13/2024 at 9:23 PM, M.T.Hands said: Man, off idle like that sounds like something "dirty" with the Idle circuit, I'm very new to this vehicle, but my 04 wrangler had a messed up TPS and it would not idle but definitely could be vacuum or fuel pressure related My idle circuit isn’t working properly so I have it disconnected. It’s been that way for ~2 years now. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 O2S with slow response time. O2 is a maintenance item. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 12 minutes ago, Ωhm said: O2S with slow response time. O2 is a maintenance item. What’s it’s supposed to be like? I have a snap-on scan tool hooked to it right now looking it over. Oxygen sensor was also new 2 years ago, it’s an NTK unit. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 Pretty sure the Coolant temp sensor is no good. IMG_0299.MOV Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 13 minutes ago, Ωhm said: O2S with slow response time. O2 is a maintenance item. Seemed to react pretty snappy. Went from ~2.2V at idle/upon acceleration to ~4-5V upon decel Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 O2 (V) seems frozen at idle. Should switch rapidly between 0.5 and 4.5. Rapidly like at the speed of light. Coolant sensor is trashed, or wire is your problem. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 4 minutes ago, Ωhm said: O2 (V) seems frozen at idle. Should switch rapidly between 0.5 and 4.5. Rapidly like at the speed of light. Coolant sensor is trashed, or wire is your problem. It’s in open loop, if that makes any difference. Very rarely does it ever enter closed loop. Wires looked fine going to the sensor. It’s a pretty cheap old thing, so it’s probably that coolant sensor itself that’s bad. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 With that O2 and maybe that Coolant sensor, it can't go into Closed Loop. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 Check O2S heater circuit for continuity. Looking for ≈5-7 Ω's. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 3 minutes ago, Ωhm said: With that O2 and maybe that Coolant sensor, it can't go into Closed Loop. Even with it running ok it’s almost never entered closed loop. I almost wonder if the computer isn’t faulty a little bit. Ive used it fine without it entering closed loop but having the iac disconnected is a bit annoying when it’s cold. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 Sound to me like the ECU is doing what it's suppose to do. Open Loop. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 2 minutes ago, Ωhm said: Sound to me like the ECU is doing what it's supposed to do. Open Loop. Now that I’m thinking on it more, I think it’s that O2 sensor. I was trying to delete my EGR valve and when I removed it I dropped it (about 3-4”) so I almost wonder if that didn’t break it. I don’t believe I remember feeling the issue before then, so it makes the most sense to me now. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 Key OFF. Disconnect O2S. At the sensor measure ohms between C229_A and C229_B. Look for 5-7 ohms. If good, then signal side of sensor is bad because it's just not switching at idle. Link to comment Share on other sites More sharing options...
eaglescout526 Posted October 15 Share Posted October 15 Closed loop will let the engine run more efficiently and see your mileage improve. open loop is full of defaults for the engine to just run and drive vs what closed loop does. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 8 minutes ago, Ωhm said: Key OFF. Disconnect O2S. At the sensor measure ohms between C229_A and C229_B. Look for 5-7 ohms. If good, then signal side of sensor is bad because it's just not switching at idle. I am showing 0 (or near 0) ohms between A & B. About 4 between C and B. Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 Looks like O2S heater element (A-B) is shorted together internally. No heater. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 Great. Any leads as to where that would maybe be at? Link to comment Share on other sites More sharing options...
Ωhm Posted October 15 Share Posted October 15 It's internal to the O2S itself. Part of the O2S. Link to comment Share on other sites More sharing options...
Dickinson County Comanche Posted October 15 Author Share Posted October 15 That was on 1 minute ago, Ωhm said: It's internal to the O2S itself. Part of the O2S. Wait so am I checking the sensor’s connector or the trucks connector? I got 0 ohms at the trucks connector since it was the one that matched the diagram Link to comment Share on other sites More sharing options...
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