2001 Grand CherokeeWorking on vehicle.Throwing a few codesRun smooth at stsrt up. Abo

[dlmrun2002]

Got a chance to disconnect all 4 o2 sensors at one time. Results are the same. Stumble comes in about a minute after start up.
Not sure where to look next.

dlm ny country
2001 Grand Cherokee Laredo 4.0 (((not so Grand right now )))
1987 YJ Wrangler.....sold !!!
1974 BMW 2002
1991 BMW 318is

 

[JPNinPA]

So its difficult to tell in the video because your revving above 1500rpm. And not constant. Or is it doing that on it's own? There are only a few seconds at 750 idle. Is the knocking/clicking the engine or something else? It tough to tell.could you get the sound clip from the engine bay?


JPNinPA
Using Jeepz.com app

 

[dlmrun2002]

Maybe this will help. Was able to record live data while Jeep was running with the misfire. Not sure what all they numbers mean but timing seems to be jumping all over the place, besides other parameters. Hope this helps getting things moving forward.

dlm ny country

 

[JPNinPA]

You could compare the short and long term trims cold vs warm.
You should see them +/-5 more like +/-2 your long term ones are 10 or better indicating you may have a vac leak. Or this may be due to your butterfly valve being open.
I see tout TPS is not zero. At idle it should be 0 and your idle fairly constant at 750 rpm. Your TPS is 15% and idle all over. Thus the bad running.
Is the valve open or did you mess with the TPS? It may be time for a new one. Did you clean the TB and IAC? There is a write up for it you should follow.

As far as the O2 sensors they are switching between the correct voltages but the second ones O2S1-2 and O2S2-2 should switch slower than the O2S1-1and O2S2-1 it may be my ability to follow the moving target but the 2s seemed faster than the 1s. Or I'm too tired. Just check it. Usually 2s are slower or the same. I never have seen them faster. I don't think you could mess up the wiring without some deliberate effort to get the 2s faster.

So I'd clean the TB and IAC. And check for vac leaks by spraining around with carb cleaner or WD40. When the rpm changes you hit a leak. Check at the TB, the injectors, each leg of the intake at the engine and the spark plugs. Then all vac connections. Look for dry rot or cracked broken lines.
Then reset the PCM by disconnecting the battery. Turn the key to on for 30 sec. Off then reattach the battery.
Warm it up again

Then I'd rescan.

http://www.jeepforum.com/forum/f9/cleaning-iac-throttle-body-write-up-dummies-1114849/

Regards,
JPNinPA

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[dlmrun2002]

Thanks JPA... Will give it a go and do the list of things you said. I actually want to get this Jeep running right and I'm gonna dump this car. Like I said this car was giving to me a year ago. I never wanted it from the get go but thought it would be worth keeping since my Subaru is at it's end. But now after much time, a little money, I'm ready to get this Jeep out of my life. Bit I WILL fix it first.

dlm ny country

 

[JPNinPA]

Did you ever check your fuel pressure? There is a Schrader valve on the fuel rail.
Locate the valve and remove the cap. Attach the fuel pressure gauge.


Once the fuel gauge had been attached, turn the ignition key to the "ON" position. The gauge should jump up to between 45 psi and 58 psi for most (DPI) direct port inject systems,

While the engine is running, the fuel pressure should drop about 5 psi, to 52 psi., (no less than 49psi) also try snapping the throttle, the fuel system pressure should jump up about 5 psi., this means the fuel pressure regulator is working properly. If the system fuel pressure does not respond inspect the vacuum feed line, if okay, the fuel pressure regulator has failed.

If the fuel pressure is low under load or while idling the fuel filter could be clogged, or the fuel pump has failed.

When complete shut the engine off. You could check leakdown. The pressure should stay high for 2 min or better.

Use a shop rag to catch the gas that leaks out when you detach the gauge. There may be a lot.


JPNinPA
Using Jeepz.com app

 

[JPNinPA]

Also any time you change sensors reset the PCM. This clears stored values.


JPNinPA
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[dlmrun2002]

Also any time you change sensors reset the PCM. This clears stored values.


JPNinPA
Using Jeepz.com app

All good info. Thanks JPN. Hopefully I'll get to look st it tonight.

dlm ny country

Sent from my SM-G900P using Jeepz.com mobile app

 

[JPNinPA]

BTW. Did some reading on trans codes

Change you transmission relay and it should do the trick I would try to unplug the relay, clean it and put it back first. If it wouldn't do it, get a new one


Regards,
JPNinPA

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[dlmrun2002]

Thanks .. Think I did an unplug of the relay in the power distribution block. Will look at it again. Many thanks..again


dlm ny country

 

[dlmrun2002]

Got a chance to clean throttle body, IAC and map(elbow) sensor today. Found a vac leak going to canister that hangs on brake booster. Fixed vac leak with fuel line since that is all I had. Stumble came back though. Idle is a bit lower probable because of vac leak fix. Swapped out transmission relay with ASD relay since that is all I could do. Transmission still threw code P0753 but got rid of P0743 and P1765. Any case I cleared codes again and the only codes I am getting are the P0753 code and the P0136 code which I believe is the the o2 sensor I replace with the bosch. Also did a live data review and the TPS was still at 15% with the car at idle. So perhaps with some luck if I get a new TPS, new transmission relay and throw in my old o2 sensor maybe I'll have nome luck. I will try running with the P0136 sensor disconnected to see if that changes anything.
The journey continues.

dlm ny country
2001 Grand Cherokee Laredo 4.0 (((not so Grand right now )))
1987 YJ Wrangler.....sold !!!
1974 BMW 2002
1991 BMW 318is

 

[JPNinPA]

Sounds like a plan. Just remember the old O2 was bad and throwing codes. Or/and this could be a leaky exhaust.

Remeber use only OEM sensors.



FWIW about every 30k you should clean the TB and IAC. It will keep things running smooth. Add a good battery post and opposite end of the grounds clean n shine and your good.


JPNinPA
Using Jeepz.com app

 

[JPNinPA]

One more question you did say you checked all the fuses correct?

JPNinPA
Using Jeepz.com app

 

[dlmrun2002]

Exhaust is clean and quiet. But the rear muffler is on short notice. Yeah NTK o2 sensors only. Ordered a TPS. Will pick up transmission relay. Take it from there. Many thanks JPN !!

dlm ny country
2001 Grand Cherokee Laredo 4.0 (((not so Grand right now )))
1987 YJ Wrangler.....sold !!!
1974 BMW 2002
1991 BMW 318is

 

[JPNinPA]

Mine leaked and i got the same code. It sounded like a tick. At one point it was barely noticeable and i had the code.


JPNinPA
Using Jeepz.com app

 

[JPNinPA]

BTW congrats on knocking off a few codes.


JPNinPA
Using Jeepz.com app

 

[JPNinPA]

Exhaust is clean and quiet. But the rear muffler is on short notice. Yeah NTK o2 sensors only. Ordered a TPS. Will pick up transmission relay. Take it from there. Many thanks JPN !!

dlm ny country
2001 Grand Cherokee Laredo 4.0 (((not so Grand right now )))
1987 YJ Wrangler.....sold !!!
1974 BMW 2002
1991 BMW 318is

OEM TPS?
https://www.rockauto.com/en/catalog...uel+&+air,throttle+position+sensor+(tps),5136



JPNinPA
Using Jeepz.com app

 

[dlmrun2002]

I checked the fuses in the engine power supply box. Haven't done a thorough check under the dash but that is a good call. I ordered from Rock Auto the STANDARD MOTOR PRODUCTS TH189T

 

[dlmrun2002]

Got a chance to install TPS and new relay. Results are the same. All my codes came back and my running data on the TPS went from 15% to 16.9-17.3%. Got a new code too on ABS Cluster ..I think it was code 14. Checked all fuses under dash. They all ohmed out with my fluke for continuity. Spray carb cleaner over vac hoses and such..no rev increase.I did notice on the live data (same as posted here) that the timing advance is jumping all over the place. I wasn't sure if that is right. Possible bad crank sensor?

still lost in obd 2 hell
dlm ny country
2001 Grand Cherokee Laredo 4.0 (((not so Grand right now )))
1987 YJ Wrangler.....sold !!!
1974 BMW 2002
1991 BMW 318is

 

[JPNinPA]

You reset the codes?
Wiped out the PCM stored data? Battery disconnect?
What was your fuel pressure reading?

Lined up the TPS following the below?

There is a small pin that sticks out from the throttle body that interfaces with the TPS, it is visible once the old TPS is removed. This pin sticks into the hourglass shaped area in the TPS. Once you have the TPS seated you will need to turn the TPS clockwise very slightly to get the pin to slip into the hourglass shaped area, when it does turn it back to line up with the screw holes.

Install the two new screws that came with the TPS and plug in the modular plug. Reconnected your battery and you should be good to go.

The new TPS plug looked like the old? Somewhere in 01 or 02 they changed mid year. Think it was 02.

If you wiggle the TPS wires does the bucking stop?





Regards,
JPNinPA

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