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2002 Escalade, 1998 STS
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Discussion Starter #1
Hello Everyone,

I am new to this Forum and I need your HELP!!!!

I Have a 2002 Escalade 6.0 AWD. The issues I am having is that sometimes when ideling for about 3 mins it idles rought and around 200rpm and feels like its going to die but doesnt. The exhuast sounds more like a deep tone, then the service engine light turns on and then stops idleing rough...Also sometimes When im going around 55mph the truck starts feeling heavy and let its going to choke and i start losing speed evening though i am flooring it doesnt pick up speed. then after i would say half a mile then it starts picking up speed again like normal and that happens right after the engine light turns on....So it can go a day with the issue but then it comes back...I have cleaned the throttle body,checked the fuses and cleaned the MAF sensor and still having the same issue. You may ask why not hook up the computer and read the codes. The issue with that is that the previous owner swaped seats from a 04 escalade and they override something cause when they installed the seats the truck didnt want to turn on so i think that is why i hook up the computer to read the codes the computer tells me to turn the key which it is, so it isnt much help. ANY IDEAS or maybe someone has had the same issue please HELP me out!!! thanks everyone.
 

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2005 escalade
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89 Posts
I would look at two things, First fuel I would put a fuel guage on the motor and ck what the pressure is. (could be filter or pump) check when you are reving or take it for a drive put guage out the fback of hood. if you dont have a guage they a cheap. If that is not it then I would think your cat is plugged. The noise you are discribing is the motor is starving so if it is starving ---gas or air is the usual things.
 

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2005 escalade
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89 Posts
I agree but if he is on the gas throttle body should not stop the motor from red lining and bogging but idle issue would be a yes
 

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03 cadillac escalade
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11,902 Posts
osure said:
I agree but if he is on the gas throttle body should not stop the motor from red lining and bogging but idle issue would be a yes
You never know cause the drive by wire system can be picky if a sensor is bad or dirty it will cause a multitude of problems I know cause when my PCM failed it showed the tps at 98.9% even though I wasn't touching the pedal and the throttle body didn't respond to the pedal even after replacing the throttle body no fix so it ended up being the PCM
Just keep in mind that there three modules tied into the fuel pedal 1.the throttle body 2 the PCM 3. The throttle actuator control module and pedal sensor.
Also the throttle body has three sensors inside it.
 

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2002 Escalade, 1998 STS
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Discussion Starter #8
Well. I checked the fuel pressure and its normal.cleaned the throttle body and confirmed my MAF is good. The other two things that i have not gotten to yet is the PCM, which i really hope it is not that and the Catalytic Converter. Now I have noticed and please correct if i am wrong. The Catalytic Converter acts up when ever the car/truck is warmed up and i notice that when i first turn on the truck and let it idle it runs fine untill if i let it sit for 15mins and the engine is warm then it starts acting up. Do you guys think this could be it???
 

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03 cadillac escalade
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2002cadilade said:
Well. I checked the fuel pressure and its normal.cleaned the throttle body and confirmed my MAF is good. The other two things that i have not gotten to yet is the PCM, which i really hope it is not that and the Catalytic Converter. Now I have noticed and please correct if i am wrong. The Catalytic Converter acts up when ever the car/truck is warmed up and i notice that when i first turn on the truck and let it idle it runs fine untill if i let it sit for 15mins and the engine is warm then it starts acting up. Do you guys think this could be it???
If it was the catalytic converters it would set a few misfire codes in the PCM due to too much back pressure,
Sounds kinda like a o2 sensor given as to how you said it idles after 15mins, is the check engine light on or flashing?
 

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2002 Escalade, 1998 STS
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Discussion Starter #10
Yep, when i turn it on the light engine is not on so then i let it idle then it starts acting up and then the light turns on... so then i step on the gas and the exhaust back fires...
 

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03 cadillac escalade
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2002cadilade said:
Yep, when i turn it on the light engine is not on so then i let it idle then it starts acting up and then the light turns on... so then i step on the gas and the exhaust back fires...
Is it steady or flashing?
 

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03 cadillac escalade
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2002cadilade said:
It is Steady
Then there should be a code in the computer if you can go to auto zone and see what the code or codes are that will help me out a lot in pinpointing the source of the problem.
 

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2002 Escalade, 1998 STS
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Discussion Starter #14
OK will do, found out the previous owner changed the seats to from an 05 and messed something up with the computer so when i put the code reader it say there is no connection. I dont know if they must have cut some wires or somthing. i am going to have to get a hold of the guy who did it to find out what the hell he did. I think he bypassed something because first when they put the 05 seats the truck didnt want to turn on so he did some wire crap and was able to make it turn on....but now when you hook up anything to get the codes it reads that there is no connection.
 

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2005 escalade
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do you know anyone that does exhaust work if so take it to them they can punch a small hole to relieve pressure. if it is the cat it should start running better then all you have to do is spot weld the hole afterward. I found this is the easiest way to check for most people. ( I still think it is cat)
 

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2002 Escalade, 1998 STS
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Discussion Starter #16
Ok thanks, i am going to try that. At this point ill try anything!!! I just want to get my baby running again...For some reason i really also think it is going to be the Cat. But i guess we will wait and see!!
 

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2002 Escalade, 1998 STS
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Discussion Starter #17
Hello guys,

I havent been able to work on the escalade yet. I think at this point I really need to find out why any code reader is not reading my computer. Now my Front Cig. Ligther does not work. i was looking at another thread and it stated that they share the same power circuit. The fuse located under the hood is not blown. Did you guys have any diagram of this or maybe can point me in the correct direction in where to first start testing for wires or if there is another fuse i should check.
 

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03 cadillac escalade
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2002cadilade said:
Hello guys,

I havent been able to work on the escalade yet. I think at this point I really need to find out why any code reader is not reading my computer. Now my Front Cig. Ligther does not work. i was looking at another thread and it stated that they share the same power circuit. The fuse located under the hood is not blown. Did you guys have any diagram of this or maybe can point me in the correct direction in where to first start testing for wires or if there is another fuse i should check.
There are a few other fuses that might have something to do with I am not to where I can get to my owner's manuel but I will look when I get home to see if there is another fuse.
 

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2004 Escalade EXT
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2 Posts
One problem you need to figure out first before going through any other steps is to figure out why you cannot connect an OBD II code reader or scan tool through the OBD connector.
Check ALL fuses, not just the ones you think are powering the unit. Electrical has a way of finding a path where you least expect it to.

As far as your seats being changed, they have nothing to do with the Powertrain Control Module, they are on a seperate system controled by the seat memory module. Even if they were spliced in, unless the other owner spliced into the PCM harness for power, these systems have nothing to do with each other.

Now, you hopefully will find the problem causing no connection to register, and once you do, will be able to post a code on here that allows a lot easier diagnostics. Once you have determined that all fuses are ok, then look at any ground connections to the body of the vehicle, make sure they are clean and free of corrosion.

If your PCM is not accessible through the scan port, then you may have a lot of other issues. You may have corrosion inside of the PCM itself causing issues. From what you describe, both at idle, and while at a cruising speed is that the vehicle is going into closed loop, and one of the sensors is sending an intermitant signal, or your MAF is beginning to fail.

You did not describe how you were able to test the MAF, and if it is intermittant, then it may only happen for a split second, and unless you are recording the data through a full scan tool, and not a code reader you probably would not see it
 

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03 cadillac escalade
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TheCamel said:
One problem you need to figure out first before going through any other steps is to figure out why you cannot connect an OBD II code reader or scan tool through the OBD connector.
Check ALL fuses, not just the ones you think are powering the unit. Electrical has a way of finding a path where you least expect it to.

As far as your seats being changed, they have nothing to do with the Powertrain Control Module, they are on a seperate system controled by the seat memory module. Even if they were spliced in, unless the other owner spliced into the PCM harness for power, these systems have nothing to do with each other.

Now, you hopefully will find the problem causing no connection to register, and once you do, will be able to post a code on here that allows a lot easier diagnostics. Once you have determined that all fuses are ok, then look at any ground connections to the body of the vehicle, make sure they are clean and free of corrosion.

If your PCM is not accessible through the scan port, then you may have a lot of other issues. You may have corrosion inside of the PCM itself causing issues. From what you describe, both at idle, and while at a cruising speed is that the vehicle is going into closed loop, and one of the sensors is sending an intermitant signal, or your MAF is beginning to fail.

You did not describe how you were able to test the MAF, and if it is intermittant, then it may only happen for a split second, and unless you are recording the data through a full scan tool, and not a code reader you probably would not see it
I agree with you on a most of it but the ability to read live data depends on the scan tool I know cause mine can read live data.
 
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