All o2 sensors are unplugged (do not fit) on my 99 Grand Cherokee...What will happen
05-16-2011, 06:58 PM
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All o2 sensors are unplugged (do not fit) on my 99 Grand Cherokee...What will happen
What will that mean for my jeep? I will try to make this as short as possible. Bought a 99 clean body GC Limited with a lifter tick.
It supposedly has an 03 engine and trans which I DO NOT BELIEVE ARE COMPATIBLE with a 1999!!!! If I look under car-part for an 03 engine there are 3 different V8 engines for that specific year and the previous owner said it has the high output vin J (from a 2003) and the original 99 engine is a 16T vin N....
But anyways...I bring to my mechanic (towed) after buying and he says the whole thing looks a mess like the guy didn't know what he was doing, and starting taking things apart....blue tape wrapped around different wires...
There were plugs missing, no AC lines, O2 sensors unplugged, a vacuum line disconnected...the whole 9 yards.
Anyways, to make a long story short the mechanic I used today said all o2 sensors are disconnected and are probably from an 03 engine so they do not plug in to my 99 (which has an 03 engine)....
What will this do to my Jeep?
I have 2 problems: 1 is a ticking from possibly the lifters and the 2nd big problem is that the jeep will die after about 4 miles....Turn the key and nothing!
Wait 40 minutes and then it will start again but the engine will be shaky...
I really like this jeep, clean body, nice interior leather, not really any electrical issues as far as radio or windows or power mirrors/seats....Just a real dumb*** that got under the hood and didn't know what he was doing...
It supposedly has an 03 engine and trans which I DO NOT BELIEVE ARE COMPATIBLE with a 1999!!!! If I look under car-part for an 03 engine there are 3 different V8 engines for that specific year and the previous owner said it has the high output vin J (from a 2003) and the original 99 engine is a 16T vin N....
But anyways...I bring to my mechanic (towed) after buying and he says the whole thing looks a mess like the guy didn't know what he was doing, and starting taking things apart....blue tape wrapped around different wires...
There were plugs missing, no AC lines, O2 sensors unplugged, a vacuum line disconnected...the whole 9 yards.
Anyways, to make a long story short the mechanic I used today said all o2 sensors are disconnected and are probably from an 03 engine so they do not plug in to my 99 (which has an 03 engine)....
What will this do to my Jeep?
I have 2 problems: 1 is a ticking from possibly the lifters and the 2nd big problem is that the jeep will die after about 4 miles....Turn the key and nothing!
Wait 40 minutes and then it will start again but the engine will be shaky...
I really like this jeep, clean body, nice interior leather, not really any electrical issues as far as radio or windows or power mirrors/seats....Just a real dumb*** that got under the hood and didn't know what he was doing...
Last edited by thegreatgate; 05-16-2011 at 07:14 PM.
05-17-2011, 01:51 PM
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44 views and 0 responses...I know it is a stupid question but I'm just trying to figure out how horrible is it to have all the o2 sensors unplugged and not fitting? I'm hoping that this small fix is what is causing my Jeep to cut off after a few miles and not turn over...Anyone?
05-17-2011, 02:19 PM
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Year: 1987
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Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
Having your O2 sensors unplugged means your ECM isn't getting any air/fuel mixture input to use to make setting corrections. The fact that it runs at all my guess is that it has some kind of a general setting as a backup. Without O2 sensor input, your Jeep will be sluggish especially when cold and it will get HORRIBLE gas mileage.
Did the PO get the ECM and engine wiring with the donor engine? The reason I ask is if I was going to get a newer donor engine for my XJ, I would get the engine and complete engine wiring harness with it. That way once you have power going to everything sensors shouldn't be an issue as none of them ever would have been disconnected from the ECM harness. And you know you have the right ECM and all the right sensors for the engine you have.
Since you were already left with a soup snadwich to try to get running. I would get the correct O2 sensor(s) for the 03 engine and cut off the connectors and hardwire them to the wiring that you believe to be your taped up O2 sensor wires.
Did the PO get the ECM and engine wiring with the donor engine? The reason I ask is if I was going to get a newer donor engine for my XJ, I would get the engine and complete engine wiring harness with it. That way once you have power going to everything sensors shouldn't be an issue as none of them ever would have been disconnected from the ECM harness. And you know you have the right ECM and all the right sensors for the engine you have.
Since you were already left with a soup snadwich to try to get running. I would get the correct O2 sensor(s) for the 03 engine and cut off the connectors and hardwire them to the wiring that you believe to be your taped up O2 sensor wires.
05-17-2011, 02:21 PM
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Year: 2004
Model: Grand Cherokee
Engine: 4.7L V8
That could cause it to run rich, or maybe not at all.
I'd say a bigger issue is whether you have the '99 PCM trying to control that '03 HO engine and its '03 sensors, (AIS, IAC, CTS, cam sensor, etc.), or have you changed the PCM to match the engine? I know even in the same year, the 4.7L HO calls for a different PCM than the standard 4.7L V8.
I'd say a bigger issue is whether you have the '99 PCM trying to control that '03 HO engine and its '03 sensors, (AIS, IAC, CTS, cam sensor, etc.), or have you changed the PCM to match the engine? I know even in the same year, the 4.7L HO calls for a different PCM than the standard 4.7L V8.
Last edited by ol"blue; 05-17-2011 at 02:25 PM.
05-17-2011, 02:33 PM
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Year: 1987
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Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
A good start would be to get some answers out of the Knotthead PO of your Jeep like:
1.) The exact year and engine he put in it (i.e. HO or non HO)
2.) Did he get the computer and wiring harness for the donor engine or did he just throw the engine and tranny in and try to hack and slash the original 99 engine computer wiring to the new 03 engine.
3.) Does he still have the old 99 engine and tranny so you could have access to usable pieces (i.e. you could get the original 99 AC pump, hoses and wiring and attach the pump to the new engine. everything else should just plug back in). That would be the easiest way to get the AC going.
4.) Ask him what the engine tick is in the new engine and if the tick was there when he swapped the motor in or what did he do to it to cause the tick. You might very well have another blown or close to blown engine in your Jeep to start with.
1.) The exact year and engine he put in it (i.e. HO or non HO)
2.) Did he get the computer and wiring harness for the donor engine or did he just throw the engine and tranny in and try to hack and slash the original 99 engine computer wiring to the new 03 engine.
3.) Does he still have the old 99 engine and tranny so you could have access to usable pieces (i.e. you could get the original 99 AC pump, hoses and wiring and attach the pump to the new engine. everything else should just plug back in). That would be the easiest way to get the AC going.
4.) Ask him what the engine tick is in the new engine and if the tick was there when he swapped the motor in or what did he do to it to cause the tick. You might very well have another blown or close to blown engine in your Jeep to start with.
05-17-2011, 02:40 PM
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I'm gonna post some pics in a new thread in a minute....Has a little water drip coming from the exhaust too which I talked to someone on the phone and they said it could be the beginnings of a bad head gasket.
Said that jeeps are notorious for bad fuel pumps, or possible bad cam or crank sensor and that could be what is causing it to cut off after a few mile drive.
Said that jeeps are notorious for bad fuel pumps, or possible bad cam or crank sensor and that could be what is causing it to cut off after a few mile drive.
05-17-2011, 04:51 PM
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Year: 1993
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There is no need to post any pictures until you answers all 5 of Bucks questions.
#1 First and for most, we MUST know about the PCM.
We can not help until you answer the questions.
Ron
#1 First and for most, we MUST know about the PCM.
We can not help until you answer the questions.
Ron
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05-17-2011, 05:10 PM
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Here are some of my answers but I have no idea about the PCM...Not even sure what that is, never heard of it ... Maybe tomorrow or Thursday I will drive/tow it to a shop that can fix the problem for $1200 but I know it will be much more than that...
A good start would be to get some answers out of the Knotthead PO of your Jeep like:
1.) The exact year and engine he put in it (i.e. HO or non HO)
2003 HO
2.) Did he get the computer and wiring harness for the donor engine or did he just throw the engine and tranny in and try to hack and slash the original 99 engine computer wiring to the new 03 engine.
To me it looks like it was pieced together but the wiring harness is from an 03...I inquired about the harness at a dealership and they said my part number is from an 03
3.) Does he still have the old 99 engine and tranny so you could have access to usable pieces (i.e. you could get the original 99 AC pump, hoses and wiring and attach the pump to the new engine. everything else should just plug back in). That would be the easiest way to get the AC going.
No
4.) Ask him what the engine tick is in the new engine and if the tick was there when he swapped the motor in or what did he do to it to cause the tick. You might very well have another blown or close to blown engine in your Jeep to start with.
He said it was a ticking in the valve...I don't think he swapped the motor...He said it was bought with an 03 motor and transmission.
1.) The exact year and engine he put in it (i.e. HO or non HO)
2003 HO
2.) Did he get the computer and wiring harness for the donor engine or did he just throw the engine and tranny in and try to hack and slash the original 99 engine computer wiring to the new 03 engine.
To me it looks like it was pieced together but the wiring harness is from an 03...I inquired about the harness at a dealership and they said my part number is from an 03
3.) Does he still have the old 99 engine and tranny so you could have access to usable pieces (i.e. you could get the original 99 AC pump, hoses and wiring and attach the pump to the new engine. everything else should just plug back in). That would be the easiest way to get the AC going.
No
4.) Ask him what the engine tick is in the new engine and if the tick was there when he swapped the motor in or what did he do to it to cause the tick. You might very well have another blown or close to blown engine in your Jeep to start with.
He said it was a ticking in the valve...I don't think he swapped the motor...He said it was bought with an 03 motor and transmission.
05-17-2011, 05:15 PM
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Year: 2004
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Engine: 4.7L V8
Powertrain Control Module.
Go on here and scroll down for an explanation of each Modules functions and location. >http://www.wjjeeps.com/modules.htm
Click on image to enlarge.
Go on here and scroll down for an explanation of each Modules functions and location. >http://www.wjjeeps.com/modules.htm
Click on image to enlarge.
05-17-2011, 06:04 PM
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
simple answer unless you got it for free take it back they did make other ones that will be in just if not better shape and will have no issues jm2cw...
05-18-2011, 03:44 AM
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The PCM will read the HEGO sensors as "failed" - and respond accordingly.
1) It's going to throw a "hard code" - CEL and all.
2) It will fail over into "rich mode" - running about 12.8:1. Your fuel economy will decrease, you may lose some performance, but you'll still run. 12.8:1 isn't anywhere near the Rich Burn Limit, isn't so much to cause cylinder washdown, and shouldn't cause sooting.
I wouldn't run like that for very long - the rich exhaust will overheat the catalyst beds, and can kill your converters in short order (burn them out from overheating.) But, you can run it for a little bit and you shouldn't get permanent damage from it. I wouldn't go more than a couple of days, tops. (If you didn't have a cat, you wouldn't damage anything. But, cats are required on vehicles that came with them...)
1) It's going to throw a "hard code" - CEL and all.
2) It will fail over into "rich mode" - running about 12.8:1. Your fuel economy will decrease, you may lose some performance, but you'll still run. 12.8:1 isn't anywhere near the Rich Burn Limit, isn't so much to cause cylinder washdown, and shouldn't cause sooting.
I wouldn't run like that for very long - the rich exhaust will overheat the catalyst beds, and can kill your converters in short order (burn them out from overheating.) But, you can run it for a little bit and you shouldn't get permanent damage from it. I wouldn't go more than a couple of days, tops. (If you didn't have a cat, you wouldn't damage anything. But, cats are required on vehicles that came with them...)
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