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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Been dealing with an odd issue for a few weeks now.
not sure if its related but it only happens when my temp gauge isnt reading (sometimes it will drop all the way for a few minutes until it goes back up to about 210, which has always been normal.)
if the jeep dies it wont start back up until i pull the wire off the ignition coil, turn it over until i see spark, then plug it back in fires right up. Always stalls when coming to a stop.
replaced ignition coil last week. New radiator(there was a leak)
i put the fuel pump in in march when i bought it.
only code that comes up is for my downstream o2 sensor (sensor 1 bank 2) but my Cat was cut off already when i bought it and it never caused any issues.
not sure what to do at this point without wasting money on it i plan on changing out the thermostat today (already have it just didnt replace it yet)
anyone else had a similar issue? Any help would be appreciated.
had a small vacuum leak up until yesterday due to the rubber plug coming off the bung on the side of the intake manifold (capped and fixed, much better idle but still stalls) [picture of said bung attatched below]
This O2 code is because of the oxygen sensor voltage. The voltage being seen and picked up here at the oxygen sensor is directly related to having a lack of, or either an excess of oxygen being sensed downstream of the catalytic converter. Ideally, the sensor should average as close to 0.45V at all times on a perfectly operating vehicle. That is never the case though. The voltage is always fluctuating based off what is going on with the fueling. If there is excess fuel in the system (rich running condition). Then, there will be an inverse relationship corresponding to the amount of oxygen existing in the exhaust as it comes out of the catalytic converter. Conversely, if there is a lack of fuel (lean running condition). Then, there will be an excess amount of oxygen being picked up as existing in the exhaust via the oxygen sensors. The oxygen sensors relay this information to the PCM by way of their voltages.
A high voltage of up to 0.9V by the oxygen sensor indicates a rich running condition. A low voltage down to 0.0V by the oxygen sensor is indicating there is a lean running condition occuring.
The oxygen sensor code P0138 gets tripped whenever the oxygen sensor voltage goes at or above 0.9V if it holds there at this higher than ussual voltage for greater than 10 consecutive seconds.
This all makes sense to say with some level of certainty that you should replace the engine coolant temperature sensor (ECT). The problems you are experiencing may very well completely resolve themselves afterwards.
Your ECT sensor is showing as faulty by way of seeing a misrepresented faulty low reading on your cluster engine temperature gauge. If the PCM thinks the engine temperature is low, then it may switch the system from how it should be normally running on a hot engine temperature, and go into an abnormally running open loop cold engine temperature setting instead.
The engine runs rich in the open loop cold engine temperature setting. An abnormally rich running engine has poor performance and this may cause it to stall.
Since you already know there is a fault going on somewhere with the engine temperature readings seen on your cluster gauge. It makes sense the stalling problem is potentially related to a fault with the ECT.
Even without having a known ECT fault like you do.. The ECT is still always one of the primary suspects to rule out whenever seeing a high voltage reading oxygen sensor code.
I understand you have done a new fuel pump. New parts fail. Can you check your fuel pressure with;
- Key On, Engine Off? Will the system hold pressure for 5-10 minutes with out too much bleed off.
- Fuel pressure at idle?
- Fuel pressure under load (Power Brake the engine, bring it up to about 1500 RPM's for a few seconds).
so if it stalls you have to unplug the coil and wait for spark. sounds like the coil is overheating. i know ya said it was replaced, but as mentioned before, new parts fail.
I understand you have done a new fuel pump. New parts fail. Can you check your fuel pressure with;
- Key On, Engine Off? Will the system hold pressure for 5-10 minutes with out too much bleed off.
- Fuel pressure at idle?
- Fuel pressure under load (Power Brake the engine, bring it up to about 1500 RPM's for a few seconds).
I havent checked the pressure officially, but the fuel pressure is ridiculous at the Schrader valve on my fuel rail. Shoots out like a fire hose right to the airbox. I know thats not an "accurate reading" but i will test officially later today. Im going to go ahead and replace the ECT as someone else said as well because my coolant temp is Bonkers when it stalls out but if its reading the thing runs like a Top. Ille keep you guys updated.
This O2 code is because of the oxygen sensor voltage. The voltage being seen and picked up here at the oxygen sensor is directly related to having a lack of, or either an excess of oxygen being sensed downstream of the catalytic converter. Ideally, the sensor should average as close to 0.45V at all times on a perfectly operating vehicle. That is never the case though. The voltage is always fluctuating based off what is going on with the fueling. If there is excess fuel in the system (rich running condition). Then, there will be an inverse relationship corresponding to the amount of oxygen existing in the exhaust as it comes out of the catalytic converter. Conversely, if there is a lack of fuel (lean running condition). Then, there will be an excess amount of oxygen being picked up as existing in the exhaust via the oxygen sensors. The oxygen sensors relay this information to the PCM by way of their voltages.
A high voltage of up to 0.9V by the oxygen sensor indicates a rich running condition. A low voltage down to 0.0V by the oxygen sensor is indicating there is a lean running condition occuring.
The oxygen sensor code P0138 gets tripped whenever the oxygen sensor voltage goes at or above 0.9V if it holds there at this higher than ussual voltage for greater than 10 consecutive seconds.
This all makes sense to say with some level of certainty that you should replace the engine coolant temperature sensor (ECT). The problems you are experiencing may very well completely resolve themselves afterwards.
Your ECT sensor is showing as faulty by way of seeing a misrepresented faulty low reading on your cluster engine temperature gauge. If the PCM thinks the engine temperature is low, then it may switch the system from how it should be normally running on a hot engine temperature, and go into an abnormally running open loop cold engine temperature setting instead.
The engine runs rich in the open loop cold engine temperature setting. An abnormally rich running engine has poor performance and this may cause it to stall.
Since you already know there is a fault going on somewhere with the engine temperature readings seen on your cluster gauge. It makes sense the stalling problem is potentially related to a fault with the ECT.
Even without having a known ECT fault like you do.. The ECT is still always one of the primary suspects to rule out whenever seeing a high voltage reading oxygen sensor code.
just to make sure, my o2 sensor is non existent, as is the catalytic converter. Whoever had this thing before i got it about a year ago cut it off likely due to it being clogged. The wiring for the sensor is zip tied to a wire running over the exhaust. Ive ran my 94 GMC Jimmy No Cat No o2 sensor for years with no problem. Im going to replace the ECT and see how that goes considering its only a ~$20 part. Will update here if anything changes. With the ignition coil unplugging and plugging back in, its not that im waiting for spark, its more of a verify i have spark type deal but its odd that it starts right up afterwards. It did the same thing with the old one (pretty sure it was original the came on the car) ive noticed a large improvement in my spark as it is no longer weak coming right off the ignition coil. If the ECT Doesn't settle it should i start looking into the distributor/CKPS? Ive heard these can cause the same deal of trouble.
You know, it makes sense to replace the ECT because it is possibly showing as faulty by seeing incorrect readings on the temperature gauge.
However, it is starting to sound more correct to me about the coil how it was mentioned by dt750 for you in the post above, as a more likely reason for the stalling out issues. It makes sense that it sounds more like it is related to having poor, or no sparks. Especially, since I think you are saying that you do not have spark, and messing with the coil fixes it to make it start again to run.
I think replace the ECT whenever you get the chance. This very possibly may deliver an improved overall running condition.
But, for the stalling out problem.. I think this issue is probably more likely related to losing sparks. To fix the stalling issue it sounds like you may have to chase down the sparks pathway.
I would start simple though. By first looking into verifying the associated relays when it is stalled out and not starting for you. The ASD relay particularly at this point, since you are noticing a loss of sparks. Then, verify the fuel pump relay next. I always reccomend to use the windshield wipers relay as a control relay to swap them out if wanting to test them that way. It sounds like coil, or maybe CkPS crank sensor problem though.
(edited):
I was thinking to compare the activities of the upstream oxygen sensor to the downstream sensors in my above post. When the fact of the matter is, I have always been told the downstream oxygen sensors do not really play a vitally important role in how a vehicle runs. The downstream oxygen sensors are mostly there for environmental reasons based off what I've been told.. I never wanted to believe this honestly, and this fact did not really click with me at first until after I woke up and got some sleep..
Okay.. I am back to thinking the two are possibly more related than I thought - the spark and the ECT. Read this what I found out below, paying close attention to what they say about spark how it is correlated to the function of ECT. Since they are even actually calling it an Engine 'Master' Switch (this is obviously a very important component)., And, since you say the stalling out problem ussually always happens whenever the engine temperature gauge drops out...
I say change the ECT out to try and resolve your problem;
(Copy and pasted):
HOW THE COOLANT SENSOR AFFECTS ENGINE OPERATION
Input from the coolant sensor may be used by the PCM for any or all of the following control functions:
* Start up fuel enrichment on fuel injected engines. When the PCM receives a cold signal from the coolant sensor, it increases injector pulse width (on time) to create a richer fuel mixture. This improves idle quality and prevents hesitation while the cold engine is warming up. As the engine approaches normal operating temperature, the PCM leans out the fuel mixture to reduce emissions and fuel consumption. A faulty coolant sensor that always reads cold may cause the fuel control system to run rich, pollute and waste fuel. A coolant sensor that always reads hot may cause cold driveability problems such as stalling, hesitation and rough idle.
* Spark advance and retard. Spark advance is often limited for emission purposes until the engine reaches normal operating temperature. This also affects engine performance and fuel economy.
* Exhaust gas recirculation (EGR) during warm-up. The PCM will not allow the EGR valve to open until the engine has warmed up to improve driveability. If EGR is allowed while the engine is still cold, it may cause a rough idle, stalling and/or hesitation.
* Evaporative emissions control canister purge. Fuel vapors stored in the charcoal canister are not purged until the engine is warm to prevent driveability problems.
* Open/closed loop feedback control of the air/fuel mixture. The PCM may ignore the oxygen sensor rich/lean feedback signal until the coolant reaches a certain temperature. While the engine is cold, the PCM will remain in "open loop" and keep the fuel mixture rich to improve idle quality and cold driveability. If the PCM fails to go into "closed loop" once the engine is warm, the fuel mixture will be too rich causing the engine to pollute and waste gas. This condition may also lead to spark plug fouling.
* Idle speed during warm-up. The PCM will usually increase idle speed when a cold engine is first started to prevent stalling and improve idle quality.
* Transmission torque converter clutch lockup during warm-up. The PCM may not lockup up the torque converter until the engine has warmed up to improve cold driveability.
* Operation of the electric cooling fan. The PCM will cycle the cooling fan on and off to regulate engine cooling using input from the coolant sensor. This job is extremely important to prevent engine overheating. Note: On some vehicles, a separate coolant sensor or fan switch may be used for the cooling fan circuit only.
(End copy and paste)
(edited to add):
Do you see how many times the reference words stall, stalled, and the stalling out were made by the experts...
Im going to go buy it tomorrow when i get off of work (The ECT that is) and swap out my stat while im in there. Appreciate you guys getting back to me so quickly as id completely looked over The ECT being an issue simply because i didnt make the connection.
Well, good news and bad news. Good news is i just did a fresh oil change and oh boy was she mighty dirty.
Bad news, Replaced the ECT and torqued it just a hair too tight. Nice inch or so crack in the Stat housing now. The metal seems pretty terrible to me but its a repairable one none the less. Will update if stalling subsides.
[Edit:] just replaced the entire housing, new thermostat, and ECT on new housing. Warmed up slower than i remember, but the motor is more responsive as far as i can tell, but i also changed the oil. Heat blew fine idled well. Havent had a stall in a few days but if it doesn't happen then im sitting pretty.
Last edited by Jacob Gourley; 11-30-2019 at 09:21 PM.
What kind of thetmostat? The old ones with the hole are an all or nothing type. The newer ones with the V slowly releases the coolant as they open. They are just different designs. Neither is really all that much better than the other. This could be why though you notice the difference in how the engine temperature increases a little differently is all..
What kind of thetmostat? The old ones with the hole are an all or nothing type. The newer ones with the V slowly releases the coolant as they open. They are just different designs. Neither is really all that much better than the other. This could be why though you notice the difference in how the engine temperature increases a little differently is all..
i guess none of it really mattered. Lady made a left turn while i was in the middle of an intersection yesterday ended up smacking the rear passenger of her civic. All cosmetic though. Her cars not pretty. We'll see what they want to pay for i guess.
well I guess that's one way to fix it...lol, sorry about your jeep, if they total it it might be worth buying back if you can get it cheap enough, got plenty off good parts if ya buy another one
11-27-2019, 11:27 AM
Stalling 99 XJ 4.0L stock
