Rough idle and will not go over twenty mph?

Tiny
COWBOYHUTCH
  • MEMBER
  • 2007 JEEP CHEROKEE
  • 3.7L
  • 4WD
  • AUTOMATIC
  • 174,888 MILES
My vehicle her name is eagle is cut off, but it takes a few try’s to start but once started it does fine until it gets warm then it idles at 1,100 rpm's and won’t go over 20 mph. Had spark plugs changed a little less than a year ago. Had a transmission flush and transfer case replaced less than six months ago. Throws a eco code when idling rough.
Tuesday, January 29th, 2019 AT 8:48 PM

18 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi and thanks for using 2CarPros.

Is the check engine light staying on when the engine is running? If so, you need to scan the computer for diagnostic trouble codes. The ECO light you mentioned isn't related to a trouble code. Here is a link that shows how to scan a computer:

https://youtu.be/YV3TRZwer8k

This guide can help as well

https://www.2carpros.com/articles/engine-has-low-power-output

Now, once you do this, let me know the code. By having that, I will be better able to help diagnose the problem. Without the code, it becomes a guessing game. Honestly, it could be a fuel related issue, ignition, throttle actuator issue, engine vacuum or EVAP issue. The list goes on.

Let me know what you find.

Joe
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Wednesday, January 30th, 2019 AT 8:53 AM
Tiny
JEEPOWNERS
  • MEMBER
  • 1 POST
  • 2005 JEEP CHEROKEE
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 37,000 MILES
I do not dare to try passing in my "like new" Jeep. It accelerates like a slug. It always has since the first day I bought it new.

The one I test drove did not.

Here are the symptoms: I can press the gas pedal all the way down and the car does not accelerate. It eventually "kicks in" and then starts to acelerate. If I am moving at a higher speed, it is less noticeable - probably because there is momentum.

If the car is going up hill, the problem is more pronounced.

I've had it in several times. They just say they had it "on the computer" and everything is registering as it should.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Hesistating and lacking power

Check the exhaust system for restriction and the ignition timing if its advancing-could also be one of the following:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
PWALDROP61
  • MEMBER
  • 2 POSTS
  • 2004 JEEP CHEROKEE
I have changed water pump, thermostat, core, pack, #1 injector, spark plugs and raditor but the check light come on and when I give it gas it lose power. When stop it tremble and hesitate. The truck ran hot that is the reason for changing the things that I changed. I also change the hose from te radiator because it had a slit in it and cause the antifreeze to run out when I pulled over to see what was happening to cause the truck to over heat. It overheated when stuck in traffic. That was the reason I startedreplacing the water pump, thermostat, core pack, spark plugs, hose, and the #1 injector. Should I change all injector and see if that helps. I even used gas treatments several times.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check fuel pressure with a gauge and if service light on scan for codes. Auto parts rent gauges.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
PWALDROP61
  • MEMBER
  • 2 POSTS
What should the guage read for normal pressure? Could a bad valve cause the pressure to lose power when giving it gas? I want to check every option before committing to having a major job done and that's not the problem. Is there a way to check for a bad valve?
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
A bad valve in the engine? A compression check should do that. But it would also have a misfire if it were bad. Fuel pressure should be 44.2-54.2 with engine idling. Also scan for codes if service light is on auto parts do that for free.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
RECON1911
  • MEMBER
  • 1 POST
  • 2002 JEEP CHEROKEE
I have a 2002 Jeep Grand Cherokee, 6cyl, with 32,000 mi. The acceleration is poor, when you step on the gas to try and drop down the trans to a "passing gear", if it's still called that, it will not down shift. The plugs were replaced less than two months ago, and the check engine light is on. I checked the trans fluid, level appears to be OK. Some bubbles in the fluid though. I don't have an OBD reader, but may need on soon. Any ideas?
Thanks, Rich
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
DEMEARSJR
  • MECHANIC
  • 110 POSTS
Bubbles usually mean it's overfilled I believe.
Could be a transmission speed sensor.
I don't know if any of the other companies do it but stop by AutoZone. They'll check your code for free.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
HRHYMES
  • MEMBER
  • 1 POST
  • 2001 JEEP CHEROKEE
  • V8
  • 2WD
  • AUTOMATIC
  • 141,000 MILES
I have a 2001 Jeep Grand Cherokee Laredo V8. When I'm accelerating to climb a hill or simple to maintain my speed, my jeep randomly looses "power" and I'll have to feather tap the gas to get it to *****" back to life. It's almost like the gas flow stops or the gas peddle simply quits working. We've tested the fuel pressure during the spurts, and the gage doesn't move. It returns to the gear it was in immediately upon regaining "power" so it doesn't seem to be the transmission. We've replaced the cam sensor and are at a loss. What would cause this?
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Could be caused by one of the following below

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note:If it doesn't apply disregard it and keep testing.
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
JCHARD
  • MEMBER
  • 1 POST
  • 2001 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 141,000 MILES
Lost pulling power. 15 miles on the highway, no problem. Stopped at red light. Started to accelerate, lost pulling power, rpm's went up, no faster than 20mph
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Was the trans slipping?
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Saturday, August 1st, 2020 AT 12:49 PM (Merged)
Tiny
ANITAINFL
  • MEMBER
  • 2 POSTS
  • 2001 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 13,900 MILES
My 2001 Grand Cherokee recently ran hot, so after some investigation found that the fan is not kicking on to cool the engine. The fan and fan motor work (found this out by running power directly from that to the battery). But, when it has no 'help', it will not kick on on its own. The fan/fan motor is aparantly not getting power. So, how do I find out where the loss of power is? Thanks, Anita
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Saturday, August 1st, 2020 AT 12:50 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Next step is to check and test the radiator fan relay, also the engine temperature gauge switch or the coolant temperature sensor, fuse no. 10 15amp and fuse 5 40amp if all are okay-check the computer fan relay control circuit

See below


https://www.2carpros.com/forum/automotive_pictures/12900_fan_relay_15.jpg



Good Luck
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Saturday, August 1st, 2020 AT 12:50 PM (Merged)
Tiny
ANITAINFL
  • MEMBER
  • 2 POSTS
Thanks to your advice- and the advice from local parts store- it WAS in fact the radiator fan relay. After MUCH searching and dis-assembly we managed to find the relay mounted under the passenger side headlight housing. Needless to say, this has been relocated. Thanks for the great, timely, advice! -Anita-in-FL
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Saturday, August 1st, 2020 AT 12:50 PM (Merged)
Tiny
VIMTO69
  • MEMBER
  • 1 POST
  • 2000 JEEP CHEROKEE
  • 4 CYL
  • 2WD
  • MANUAL
  • 78,000 MILES
My 2.5td struggles to find bottom end power, I have already changed fuel filter new fuel injection pump but it is still the same, this problem only started after I changed the fuel filter the first time, please help
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Saturday, August 1st, 2020 AT 12:50 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Have you checked fuel pump pressure? Is the engine missing? Have you checked to make sure the catylatic converter isn't plugged?
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Saturday, August 1st, 2020 AT 12:50 PM (Merged)

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