My car had an engine light with several O2 Sensor Code responses. I was also idling very choppy and if idling for too long, then I would almost stall out or when i start to accelerate, the car not get much power.

Yesterday I cleaned the throttle body, replaced the IAC (which was ridden with carbon build up), and also replaced the TPS. The TPS looked different but I thought it was after market so just used it anyway.

The car was idling great, perfect actually, but gave it a test drive and it was horrible. Up and down with RPMs, wouldn't change gear, barely any power. Checked the OBD2 codes and there was no O2 sensor issues anymore, but a TPS voltage code.

So i took it out and put the old one in, and the idle was **** again, driving it was better, but same situation as above.

One thing is, I am not getting any engine light codes though, Granted, my O2 Sensor Codes might not have popped yet as I've only done about 10-15 miles since erasing the codes.

So my question is, if the new TPS (which must have been the incorrect one) made the idle better, but gave a TPS error code and ****ty drive, and my original TPS has no error code, but ****ty idle and good drive, is the TPS the issue? If so why no engine light code?

Also is there anything else that could possibly be causing this issue?

I'm desperately trying to get my Jeep back to life as I recently replaced the Power Steering Pump, Gear Box, Radiator, Tensioner, Serpentine Belt, IAC, AC Compressor (still trying to vac the lines on this though).

EDIT: Now I just drove the car to the store and it was puttering when changing gears, could this be TPS related, or is it most likely something else?

 

Yes. It definitely appears it could be related to a TPS issue with how you describe the s/s doesn't it?

Have you tested either sensor with a DVOM yet? It would be interesting if you were to see a difference between their voltage readings.

(edited to add):
I would be interested in the idle throttle closed readings between the two. Also, if the new one has a sketchy come-up in voltage as you opened the throttle.

The new sensor messes up the acceleration, but it improves the messy idle completely. The old sensor completely improves the messy acceleration, but you end up with a messy idle..? Then, they each solve the other ones problem?

It is common to have running issues sometimes even with a new aftermarket TPS sensor. So, I am not too suprised to hear it ran rough with the brand new aftermarket TPS. It is interesting the new aftermarket one may have a better low-end functionality, and/or voltage than the old TPS sensor ike that at idle...

 

No I have not. I have added an edit though with additional information too, but I will look into it. I am very sure that the first TPS was not the same.

 

Do you know how to test a TPS?

 

No I do not. or do I know what it should be reading.

The original TPS ran fine, but idled rough. The new TPS idled great but ran VERY rough, barely could switch gears. Also it wasn't the right shape and didn't fit the same. Now going back to the original TPS, the car is puttering when switching gears and acting sketchy when idling.

 

Why no engine light code?

A great question! I think the signs and symptoms of the system(s), and the complaint reported can sometimes help to solve a vehicle malfunction better than codes. Sometimes the codes are super helpful information. If you know why the code is being thrown? Sometimes, a code directs you right to the issue. Other times, it can fool you into thinking the wrong things. There is generally a sort of logic to how and why a vehicle throws a code though.

Sometimes, other systems that are not with any faults, they may signal as if they are malfunctioning, when they are only being influenced to function outside of their normal parameters because of a problem elsewhere, or they are detecting a problem elsewhere... Sometimes, there is no code. You end up just having to find the issues.

Either way, codes are only a piece of information to consider.

 

Your problem really sounds TPS related... The TPS is also directly involved with the transmission functioning. A bad TPS can mimick transmission problems, or express worse s/s while in gear, or switching gears.

You should test your TPS's. I would.. Closed idle throttle possition should be greater than 0.26V. Fully wide open throttle position should read around 4.5V. The come-up in voltage from closed to open throttle should be a smooth sweep in-line with whatever throttle position you are in as you slowly open the throttle.

I will post a TPS troubleshooting guide for you. In case you decide to want to try testing the TPS's.

 

Index

I. How to Test a Throttle Position Sensor

A. Is Your TPS Connected to Ground?

B. Is Your TPS Connected to Reference Voltage?

C. Is Your TPS Producing the Correct Signal Voltage?

I. How to Test a Throttle Position Sensor


The most common TPS test is to measure for resistance (ohms) or voltage at the various positions, including throttle plate closed, half open and fully open. We'll use voltage to test the TPS here.

1. Open the hood and remove the air cleaner assembly where it connects with the throttle body.

2. Inspect the throttle plate and the walls of the throttle body surrounding the throttle plate.

* If you see carbon buildup around the walls and under the throttle plate, spray some carburetor cleaner on a clean shop rag and wipe the buildup with it until the surface is completely clean. Carbon buildup can prevent the throttle plate from closing properly and moving freely.

3. Locate the TPS mounted on the side of the throttle body. The TPS is a small plastic block with a three wire connector.


A. Is Your TPS Connected to Ground?
B. Is Your TPS Connected to Reference Voltage?

1. Now connect the black test lead from your DMM to the ground terminal on the TPS connector you just identified.

2. Turn the ignition key to the ON position, but don't start the engine.

3. Connect the red test lead to each of the other two terminals.

4. One of the terminals should read 5 volts, or pretty close to it. That terminal is providing the reference voltage to the TPS to produce the voltage signal. Make a note of the color of the wire connected to this terminal. The third wire corresponds to the signal voltage or signal wire.

* If you don't get 5 volts from any of the two terminals, there's a problem in the circuit you need to fix because there's no reference voltage going to the TPS. Check the circuit for bad terminals, loose, dirty or damage wires.

5. Turn the ignition key OFF.

6. Plug back in the electrical connector to the TPS.


C. Is Your TPS Producing the Correct Signal Voltage?

1. Now backprobe the signal and ground terminals on the TPS electrical connector. If necessary, use a couple of pins to backprobe the wires.

2. Connect the positive (red) test lead from your DMM to the signal wire and the black negative (black) test lead from your DMM to the ground wire.

3. Turn the ignition key ON but don't start the engine.

4. Make sure the throttle plate is fully closed.

5. Your DMM should read around 0.2 up to 1.5 Volts or close to it, depending on your particular model. If the readout on your meters shows only a zero, make sure you're at a low setting—usually at the 10 or 20 Volts setting. If your meter still reads zero, continue with this test anyway.

6. While watching the readout on your DMM, gradually open the throttle plate until is fully opened (or have an assistant gradually depress the gas pedal to the floor).

* Your DMM should read 5 volts or close to it when the throttle plate is fully opened.

* Also, make sure that the voltage increases smoothly as you gradually open the throttle plate.

* If you notice the voltage skipping or stuck at a certain voltage value, as you gradually open the throttle plate, your TPS is not working properly and you need to replace it.

* Also, if your TPS doesn't reach 5 volts, or close to it (up to 3.5V on some models), when the throttle plate is fully opened, replace the TPS.

7. Repeat step 6, only this time use the handle of a screwdriver to lightly tap on the position sensor as you open and close the throttle plate. If the voltage skips as you tap the sensor, replace it.



Note: TPS is directly involved with transmission shifting characteristics too...

 

I appreciate your help on this, I am literally on my way to getting a new TPS and to purchase a multimeter. Will let you know how it goes.

Does it make sense that after replacing IAC and Cleaning throttle body, but still having the old TPS, that that would worsen there performance of the TPS? Because this is worse than before I made any adjustments yesterday

 

I use a super cheap multimeter I got for free from Harbor FreFreight Tools store. If it works.. a cheap multimeter works well enough for an amateur.

It does make sense in a way. I see different reasons/scenarios for things. If there is an electrical current conduction problem in the sensor, its wiring, and/or in its circuitry.. by removing and cleaning your IAC and TB, you may have inadvertently moved the troubled faulting part of this circuitry around enough to make things worse.

Or, I also even think about how the cleaning was performed at the IAC and the TB. The sensors here all three of them do not like being exposed to harsh cleaning chemicals any at all.. If you accidentally sprayed them, or got even a little bit of the cleaner into the wrong electrical spots located here at the TB, its associated wiring and connectors, or any of these three sensors? Something like this could mess more up than what was wrong prior to you having performed this service.

The IAC stepper motor plunger valve is a sensitive component. When you clean it you need to be extra cautious, to be careful. It is possible to have messed this part up by cleaning it too vigorously. It doesn't sound like that happened to me though, because switching out your TPS sensors gives you a perfect idle again. If the IAC got messed up to cause a problem at your idle, it probably would not improve the idle like this in this way when you switch out the TPS's.

 

Also, to be certain about the o-ring located at the base of the IAC. Making sure you removed it before spraying and cleaning up the IAC? If not, it could be shot having dried up and gone bad from the cleaning process? I put lube on these whenever I am removing or replacing o-rings.

The TB gasket too.. To make sure it did not become misaligned, or if it was torn and compromised in any way when you were putting the TB back on, and tightening the bolts?

These are possibilities for why it may worsen after doing the TB and IAC maintinance.

 

Lastly, I think this is an area of concern;

When you clean up an IAC on these Jeep throttle bodies.. The IAC has its own entirely seperate chambers, or housing. The IAC housing attaches to the throttle body by bolts with a special star shaped hollow working-point head. Most people do not bother to seperate and clean it up well here. Except, in here at the IAC housing is one of the worst spots for getting detrimental carbon build-up that effects the IAC and your idle performance. I think you said your TB was pretty nasty. Which makes me think inside of the IAC housing was/is just as bad too.. By attempting a cleaning without removing the housing, it is possible to actually push and block up the small passageway where the IAC pintle plunger goes through while in normal operation worse than it was prior to servicing it.

 

I am hopng this is not it as I have taken this apart too many times in the last few days lol.

Ok so I bought a new TPS, but couldn't get a multimeter (holiday limiting my options). So since it was so poor prior, I had to give this a chance. I replaced with a new TPS matching identical to the one already there this time. Disconnect the battery for 15 minutes after install and then hook it back up and give it a shot. Car idles great. Engine light code P0152 immediately comes on (please see prior post for another issue with error codes)... Car drives great. I drive it around for about 20 minutes (10 miles), no problem.....

Go into a store for 20 minutes, come out, start it up, start driving and I experience the same problem as earlier. Idle dropping and rising while at red lights, hesitation in accelerating and puttering when switching gears. This went on for about 2 months and then stopped and ran fine again. Don't know if it's going to keep happening though.

Is this the computer learning the TPS and all other changes, or am I just walking from one issues to the next?

 

I am a little confused regarding what all you just said? What exactly you have just done, and if it is running good now, or not? Or, if you were talking only about how it was running recently awhile back?

I apologize if you were/are referencing a past post about a code(s) issue with your O2 sensor(s), as I did not see it. The O2 sensor code may be an important aspect? I am unsure in a way about your TPS sensors themselves? You have had a few, always with issues.. It's possible and likely the individual TPS sensors all have faults with them, but... It is also possible for the TPS circuitry to have the problem. This is a reason why it is important to test all of the circuitry associated with different sensors, modules, etc when there is a suspected corruption occuring in a system or in its components. If getting good volatage readings.. signal voltage.. a ground voltage.. and a good sweeping voltage from the closed to wide open throttle, with appropriate approximate values of 0.26V - 0.75V (best is likely 0.5V) for a closed throttle, and values of 4.49V - 5V on your DVOM for a wide open throttle position? With the TPS sensor itself...

It would be good now to check for appropriate continuity and resistance readings here at the sensor. Also, the connectors on the sensor (the pins may go bad, with invisible corrosion, or be pushed out the back somewhat, or have a wiring issue inside of the connector itself that is slightly removed from where it needs to be causing problems), and check readings in the wiring leading from the PCM and/or the wiring harness that leads to the TPS. Resistance & Voltage.

With the O2 sensor code.. These have a built in heater to get them to operating temperature at the O2 sensor for them to work correctly. The code you have says it detects a high voltage reading at the O2 sensor. The PCM knows when to see, and not to see high voltage at the oxygen sensors. The O2 sensors use most of the current to power up their heater element. So, the PCM expects to see minimal voltage from here when they are functioning correctly heating themselves up... If the PCM does not see any voltage here though (it is supposed to be low, but not zero voltage), it will throw this code. On the other end of the spectrum, the PCM will throw this code if the voltage it sees at the O2 sensor is too high. It is supposed to be very low while heating itself during normal operation how it pulls current, passing electrons over a wire.

If the O2 sensor code is saying there is a problem here, it can cause issues with how the Jeep runs.. Being too lean or fuel rich, with the air:fueling mixture. Poor idle, misfiring cylinders, and bad running conditions of the engine.

 

Here is my original post before I realized I had a TPS issue. https://www.cherokeeforum.com/f5/200...9/#post3570728

Sorry for the confusion as I will try to be more clear this time.

Yesterday after realizing the New TPS i bought was not the right one, i put my original back in. After driving it for a little while everything seemed OK driving wise, but the idle was still not great. This morning however I realized I was having trouble with the following:

• Spikes and drops in idle at red lights
• Not Accelerating properly, having to press peddle to the floor almost to get it to go
• Surges
• Puttering when trying to switch gears.

At that point I decided to make my new post which is the thread we are in now. After speaking with you I was able to get a new TPS but could not get a MultiMeter.

After installation, i unplugged my battery for 15 minutes as I saw that somewhere. Tested the car in idle and it was smooth, however my engine light came back on (it had been cleared since last night around 18 hours prior. The engine light message was P0152.

I test drove the car after putting in this new TPS that i just bought hours ago and everything was running PERFECT. I drove for around 20 minutes and 10 minutes and was going very smoothly. I stopped at a store for 20 minutes and when i came out things changed. When pulling out the parking lot I was noticing symptoms similar to this morning, when i created this post. The symptoms this time only lasted about 2-3 minutes, but I am nervous it will happen again.