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Posted

Every time I start my truck, once it goes into closed loop, the short term fuel trim immediately maxes out. It starts to stumble and almost stalls then recovers by going back to open loop. It does this two or three times before finally staying in closed loop. Sometimes it just stays in open loop the whole drive. I replaced my O2 sensor which fixed the problem but it failed after a week or so. I get terrible gas mileage so I would love to figure out why my O2 sensor failed so quickly...

Posted

You may want to purchase a Renix Engine Monitor (REM) from Nickintime on facebook.  https://www.facebook.com/search/top/?q=nickintimefilms

 

He sells these units that will give you real time info on how the engine is running.  One reading is the O2 sensor.  It may be operating correctly, but something else is causing it to run in open loop.

 

This is an issue I'm having.  My O2 bounces around a lot but mostly stays at or below 2.5.Yet, I'm running in open loop most of the time.

Posted
25 minutes ago, 87MJTIM said:

You may want to purchase a Renix Engine Monitor (REM) from Nickintime on facebook.  https://www.facebook.com/search/top/?q=nickintimefilms

 

He sells these units that will give you real time info on how the engine is running.  One reading is the O2 sensor.  It may be operating correctly, but something else is causing it to run in open loop.

 

This is an issue I'm having.  My O2 bounces around a lot but mostly stays at or below 2.5.Yet, I'm running in open loop most of the time.

I have an REM that’s how I can see it just dumps fuel when it goes into closed loop. Sometimes the o2 voltage doesn’t budge at all. 

Posted

Swap out the Oxygen Sensor Heater Relay with a known good one. No voltage to O2/O2 heater will simulate a lean condition. Something is telling the ECU your running lean. Also check for low fuel pressure, dirty injectors, both cause a lean condition.

Posted
7 minutes ago, Ωhm said:

Swap out the Oxygen Sensor Heater Relay with a known good one. No voltage to O2/O2 heater will simulate a lean condition. Something is telling the ECU your running lean. Also check for low fuel pressure, dirty injectors, both cause a lean condition.

Thanks I’ll mess around after work tomorrow to see if the relay is shot.

Posted

Just put in the new NTK sensor. On the first start up the truck went into closed loop with no problems! I’m going to monitor it closely going to and from work this week to see if it starts doing what the Bosch did. Thanks guys!

  • 1 year later...
Posted

Did the ntk o2 sensor work out okay? What was the part number?

On 5/19/2019 at 7:04 PM, saveevryjp1998 said:

This is an old thread. I believe Rock Auto sells the proper Renix NTK assuming your looking for an 88 4.0 it's

2112094181_Capture_2019-05-19-22-03-19.png.99dec4bda33501456d6100896e245dce.png

Old threads help with issue of today.

90 cherokee.

87-90 uae same parts.

Thanks for the info. It helps.

Posted

True true. My heep was stumbling like crazy and had two 02 sensor codes. Fond a thread from 8 years ago that pointed me in the right direction. I do t know if the older systems are the same but I merely had a blow 02 sensor fuse.  Saved me close t0 $150 for the time being. 

99PDCREV3_26_14.jpg

  • 8 months later...
Posted
On 10/1/2017 at 6:27 PM, Minuit said:

NTK aren't perfect either. Just had to replace mine after about 10,000 miles. It got stuck high.

I noticed the same thing, got two NTK 23553 with failure, one after a week or so, and the second now after  only 16000 km

Got a Bosch earlier not much better and one unbranded still same malfunction 

 

What was the original brand and type/number  for a O2 sensor in a 89 Comanche?

Looking for quality replacement

 

 

 

 

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