Moffat007 Posted February 23, 2019 Share Posted February 23, 2019 Hey people, I’ve been struggling to get my 89 2.5 Comanche to run. She starts and idle well , but as soon as I step on the gas peddle she halts. The moment I let go of the gas she goes back to normal idling. I’ve replaced the CPS, Ignition Module, vacuum hoses and still no change - it’s sounds like she’s smothered either too much gas or to little gas. I’m ready to give up . Please help ! Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 Can this be a Electrical issue, like a grounding issue ? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 23, 2019 Share Posted February 23, 2019 O2 and MAP. Could be TPS also. You can watch the injector run, what's happening when you give it throttle? Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 I forgot to mention, it only happens like 5 mins after starting- as if something warms up and stops working .... if I drive immediately after start it doesn’t happen and I can get full RPMs . Then all of a sudden it would not let me touch the gasSent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 TPS is functional from what I can tellSent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 When MAP is unplugged, she’ll start but then immediately shuts off. When plugged in . She’ll idle forever BUTSent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 Injector is brand new Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
eaglescout526 Posted February 23, 2019 Share Posted February 23, 2019 Has the O2 been replaced or tested? Sounds like it runs fine in open loop but when it warms up and goes into closed loop, it sounds like it does not want to do what it should. Has the fuel pump ever been replaced or tested as well? Link to comment Share on other sites More sharing options...
Ωhm Posted February 23, 2019 Share Posted February 23, 2019 One test on O2 is to disconnect O2 sensor and on the O2 sensor side measure ohms between pin_A and pin_C. Your looking for ≈6ohms. This would be the O2 heater element. Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 Thanks for that I’ll give that a try. To answer the other question- pump is new Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 Do I test the sensor while idling or just with ignition on ?Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted February 23, 2019 Share Posted February 23, 2019 Static test. No Key ON, No engine running. Your're just testing the component (O2 sensor only). Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 23, 2019 Share Posted February 23, 2019 Temp sensor, the one in the intake. Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 23, 2019 Author Share Posted February 23, 2019 ... O2 sensor A and C...Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Ωhm Posted February 23, 2019 Share Posted February 23, 2019 I'm using the 88 electrical manual and I now notice different wiring between 2.5L and 4.0L for the O2 sensor. Try looking for the 6 ohms between pin_A and pin_B. Any one else notice this different wiring before? Link to comment Share on other sites More sharing options...
Eagle Posted February 24, 2019 Share Posted February 24, 2019 8 hours ago, Ωhm said: I'm using the 88 electrical manual and I now notice different wiring between 2.5L and 4.0L for the O2 sensor. Try looking for the 6 ohms between pin_A and pin_B. Any one else notice this different wiring before? Yes. My fuzzy recollection is that the 2.5L oxygen sensor doesn't have a heater. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 24, 2019 Share Posted February 24, 2019 If that ground on the firewall under the 15mm heaDED BOLT IS NOT BARE METAL CONTACT, AND/OR GHE STRAP IS NOT MAKING CONTACT AT THE HEAD, YOU WILL HAVE FITS WITH THE 2.5. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 24, 2019 Share Posted February 24, 2019 I have the strap at the head to chassis. I have a 4g ground to the dipstick and a 4g ground to the back of the alt, tied to a ground post at the chassis straight from the battery. You may find that redundant but I have no more fits. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 24, 2019 Share Posted February 24, 2019 17 hours ago, Moffat007 said: I forgot to mention, it only happens like 5 mins after starting- as if something warms up and stops working .... if I drive immediately after start it doesn’t happen and I can get full RPMs . Then all of a sudden it would not let me touch the gas Sent from my iPhone using Tapatalk Besides the grounds............ My guess from afar- O2 or Temp sensor. Link to comment Share on other sites More sharing options...
Moffat007 Posted February 24, 2019 Author Share Posted February 24, 2019 Thank you guys ! I’m installing the new O2 toady Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 24, 2019 Author Share Posted February 24, 2019 Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Moffat007 Posted February 24, 2019 Author Share Posted February 24, 2019 So the O2 sensor did not fix the problem. I’m down to the fuel pump and fuel regular. I did ground the fuel pump properly per the directions in another topic post. I will check and secure the wiring going into the tank to the pump. ( pump is new...) I’ll also be adding additional grounds per the above mentioned tip. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 24, 2019 Share Posted February 24, 2019 Just now, Moffat007 said: So the O2 sensor did not fix the problem. I’m down to the fuel pump and fuel regular. I did ground the fuel pump properly per the directions in another topic post. I will check and secure the wiring going into the tank to the pump. ( pump is new...) Sent from my iPhone using Tapatalk I'll repeat myself- Look at the injector as you give it throttle........what is happening? Temp sensor is critical. Link to comment Share on other sites More sharing options...
Moffat007 Posted February 24, 2019 Author Share Posted February 24, 2019 Ok got it - can you please guide me to the temp sensor? Is it the one on top or on the side of the manifold? Link to comment Share on other sites More sharing options...
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