I'm losing power??

[natasha0021]

I have an 01 jeep grand cherokee . it will idle all day long with no problem. I can go down the road while slowly acceleration, but when I try and step on it I'll will bog, sputter, and sometimes stall, although it starts right back up. All sensors have been changed. I'm just looking to see if anyone out there has had and fixed this problem, because I love my jeep and thinking its something simple, but I'm no where near a mechanic.

 

[TerryMason]

Is the check engine light on, and is it giving any engine codes?

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[greg92jeepxj]

Agree with Terry Mason regarding the check engine light and trouble codes. Are there any codes now and more importantly , were there any before parts / sensors were replaced ? Not to second guess who did the diagnostics but where all the sensors bad ? Just finding it odd . First order of business is for a scan tool to check if all sensors are reading in range to,confirm the PCM is working right regardless that the engine starts and idles . It actually sounds like like the pcm is not advancing spark to the ignition. But to be fair , the fuel system needs to be checked for correct pressure as well. The condition of the injectors are probably alright if a clean idle and easy start is noted but may need checking if need be. Hoping the parts installed are a good brand. Guessing the symptoms are the same before and after parts swap ? Im thinking a cam sensor may be key to this but the scan tool will need to confirm .

 

[natasha0021]

No lights are on. I'm not very mechanically inclined, so I'm not sure about codes, haven't hooked it up to a computer.

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[drewbuddy]

Agree with the weirdness of all sensors being replaced, reasons for this? And agree with fuel system check, pump, filter, pressure. No CEL, but would check for codes any way. I have had this happen to me in a car I used to have, and a similar thing in a buddies jeep which I own now(except for stall). It ended up just needing new spark plugs and wires and fixed the issue. That being said, spark plugs, spark plug wires and coil need to be checked for proper operation as well and fuel pump, filter change(if it has been awhile, longer than 2 yrs I would just change it, issues or not). I think a cam sensor should trip a code, and considering you said All sensors were replaced,worth checking into though. Question to eliminate something stupid like a bulb, does the engine light illuminate when you turn ignition on? And did this issue arise soon after your senors were replaced or had work done to it?

 

[greg92jeepxj]

Realizing you are not near a mechanic , let's focus on getting any DTC's ( diagnostic trouble codes) if you are unable to get to an auto parts store such as autozone , pep boys , advance auto or what have you to ask for free help with their code reader , you can get the trouble codes yourself , providing any exist. Turn the ignition key on and off three times and leave it one after the third time . This should work . If not , repeat and go to the fourth cycle and leave the key on . When key is turned off , the PCM ( powertrain control module ) will reset. Whe key is left on at last cycle , you should see where the odometer is a code or codes which may begin with a "P". This means it's a powertrain related code. Write down the code or codes and please post back. If you want to research what the codes mean , you may search the code directly online. The explanation may or may not make sense to you since it may be too technical , but your welcome to try. What we need to know is of the pcm is capable of reading the sensors correctly and storing DTC ' s as the first way to determine if the PCM is working correctly. Obviously , more diagnostics is needed to determine if pcm works right but this is a first step and will help to disclose the obvious of its condition. There should absolutely be a dtc(s) since there is obviously a driveability problem. Agree with drewbuddy that a cam sensor would most DEFINATELY set a DTC of faulty. There are more than one sensor that can cause this present condition ; a map sensor , oxygen sensor , throttle position sensor , etc. But let's focus on obtaining dtc's if you can. A cam sensor is a big ticket item but a map sensor is equal in symptoms . Let's not put all our faith in just a sensor or which one , guessing causes is to change parts because we thought it may have been that. Things like 5 volt reference from any sensor are meaningful to,determine the PCM is functioning to,that capacity but proper diagnostics always need to be followed through to,find the cause and any other possible problem that may contribute. Hoping you may perform getting the codes (if any) or someone can help you too. Please,post your findings . Wishing best of luck . Greg

 

[drewbuddy]

Yes #1 you need obd 2 reader or have a garage check for codes( here it's like 50$) To check a lot of these things (sensors) you would need a voltmeter. I have a manual with proper values if needed. The swapping parts on a guess is a costly way to go with no guarantee. I avoided sensors because was said they were changed and the PCM should give a code as well. I am interested in the story behind sensor swaps though. And was it really all!? I'm assuming you paid someone to do this? If it was a professional job, maybe I would take it somewhere else to have codes pulled.

 

[natasha0021]

I changed the fuel filter because I was told there might not be enough gas going through the engine and it still does it, but after I changed the filter a code came up, a code for the map sensor. Do u think that will fix it?

 

[natasha0021]

I have changed everything that I have thot of that would cause it to not have the power that it needs. I found that if I pump e gas she goes better, and will not bog out ( as bad anyways). Idk what else I can do. The map sensor is probably my last resort

 

[greg92jeepxj]

Changing a fuel filter is never a bad thing , more people should do , I'm probably overdue . Reading back over posts in this thread , you've posted all sensors were changed . Assuming that would mean the MAP sensor as well , it time to find out if the MAP sensor is functioning properly. Also not knowing what diagnostic equiptment you own , a multimeter would be helpful for many tests bt let's try something simple. Remove the MAP sensor and with a flashlight look down the vacuum port to see if it's clear and if any dirt is present. If need be you can clean out any dirt but caution against being forceful . You LIGHTLY. Insert a q-tip to see if any dirt deposits come out just as a probe since this could possibly interfering with the internal diaphragm affecting operation . I've never personally sprayed cleaner into this port having never found it necessary but if cleaning is necessary I would wet a q-tip with mass air flow cleaner and wipe it out. Again , be careful not to apply pressure to the internal diaphram as it can be ruptured or at least separated and the sensor become useless. Let's try to refrain from this cleaning and only apply as a last resort. Try this : with the sensor in one hand ( wearing rubber gloves and protective goggles ) cover the vacuum port with your thumb and spray an electrical cleaner into the electrical contacts and the electrical harness connector as well. Let these connections completely dry before reassembly . Start the engine to see if the MIL ( malfunction indicator lamp , or check engine ) lamp lights. We are hoping this improves if not cures the driveability problem. A MAP sensor is an important part of the PCM's eyes and ears that lets it know you are accelerating and gives real measurement of load placed on engine in terms of vacuum read so it can more accurately increase adjust fuel trim and spark advance. Other sensors help out as well but we'll leave lecture for another time. Your jeep currently won't accelerate well and since the code is logged regarding the MAP sensor , let's try to fix that. Funny that your able to somewhat accelerate better since the filter change . Since the engine idles well , I'm not currently faulting injectors . Let's not entertain a TPS ( throttle position sensor) either since no code is present and I still would like to know if you own a multimeter since it can be useful and may be called upon yet. Let's refrain from spending $$ until we see results. Let us know what you find. Thank you for your membership at jeepz.com . We will try our best . Just sorry we have to make you do all the work . I will say one thing however , as you've stated earlier , it usually is something simple. Let's take it methodically and step by step. I do believe in process of elimination when the obvious isn't yet found.

 

[drewbuddy]

Agreed. Can only check one thing at a time. I would do what greg92jeepxj suggested with the MAP. Good place to start. I'm sure we are full of Ideas. And can help walk you through it. And I have the manual for spec/values. We all started somewhere . We all have different experiences and at some point, a busted up ride. :deadhorse:
I'm still hung up on the idea of bad spark plugs though, or wires

 

[natasha0021]

I would like to thank all of you for the help. I am going to unhook the map sensor and clean it out, I'm hoping that's what it is. I will def. Let u guys know..I wish there was an email Greg to better talk with you..