Does the throttle not open at all, or is it opened all of the way already?
Me thinks the latter is the case.




"Glenn" <jeepthing66@hotmail.com> wrote in message
news:1191757548.916842.97010@50g2000hsm.googlegrou ps.com...
> Hi all, was trying to be a good brother today doing a major service
> and repairing the cracked exhaust manifold on my sisters 99XJ.
> Repairing the exhaust manifold obviously entails taking of the inlet
> manifold, unplugging all the wires, fuel line off the fuel rail etc.
> Everything went back together ok but when I fired it up, the engine
> raced to max revs instantly, pretty sure it would rev till blew up
> from the sound of it if I didn't switch it off. I can't understand how
> it could do this, particularly since the throttle butterfly does not
> open at all. I tried resetting the computer, no luck, I'm out of ideas
> at the moment other than towing it to the nearest Jeep dealer, Any
> idea's anyone???
>

 

STOP

He said that the throttle does not open. I think we have to make sure it is
not full open already before we go looking for leaks and other gremlins.

I happen to agree with the leak diagnosis, but since it is reported that the
throttle won't even open, I have to think the throttle is actually Full Open
already, and the fact that it doesn't budge needs to be addressed before we
start looking to gaskets and disconnected hoses.




"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4708ee41$0$22717$9a6e19ea@unlimited.newshosti ng.com...
> That usually means you forgot to hook up a vacuum line. You have an air
> leak into the intake someplace likely.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
> Glenn wrote:
>> Hi all, was trying to be a good brother today doing a major service
>> and repairing the cracked exhaust manifold on my sisters 99XJ.
>> Repairing the exhaust manifold obviously entails taking of the inlet
>> manifold, unplugging all the wires, fuel line off the fuel rail etc.
>> Everything went back together ok but when I fired it up, the engine
>> raced to max revs instantly, pretty sure it would rev till blew up
>> from the sound of it if I didn't switch it off. I can't understand how
>> it could do this, particularly since the throttle butterfly does not
>> open at all. I tried resetting the computer, no luck, I'm out of ideas
>> at the moment other than towing it to the nearest Jeep dealer, Any
>> idea's anyone???
>>

 

STOP

He said that the throttle does not open. I think we have to make sure it is
not full open already before we go looking for leaks and other gremlins.

I happen to agree with the leak diagnosis, but since it is reported that the
throttle won't even open, I have to think the throttle is actually Full Open
already, and the fact that it doesn't budge needs to be addressed before we
start looking to gaskets and disconnected hoses.




"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4708ee41$0$22717$9a6e19ea@unlimited.newshosti ng.com...
> That usually means you forgot to hook up a vacuum line. You have an air
> leak into the intake someplace likely.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
> Glenn wrote:
>> Hi all, was trying to be a good brother today doing a major service
>> and repairing the cracked exhaust manifold on my sisters 99XJ.
>> Repairing the exhaust manifold obviously entails taking of the inlet
>> manifold, unplugging all the wires, fuel line off the fuel rail etc.
>> Everything went back together ok but when I fired it up, the engine
>> raced to max revs instantly, pretty sure it would rev till blew up
>> from the sound of it if I didn't switch it off. I can't understand how
>> it could do this, particularly since the throttle butterfly does not
>> open at all. I tried resetting the computer, no luck, I'm out of ideas
>> at the moment other than towing it to the nearest Jeep dealer, Any
>> idea's anyone???
>>

 

STOP

He said that the throttle does not open. I think we have to make sure it is
not full open already before we go looking for leaks and other gremlins.

I happen to agree with the leak diagnosis, but since it is reported that the
throttle won't even open, I have to think the throttle is actually Full Open
already, and the fact that it doesn't budge needs to be addressed before we
start looking to gaskets and disconnected hoses.




"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4708ee41$0$22717$9a6e19ea@unlimited.newshosti ng.com...
> That usually means you forgot to hook up a vacuum line. You have an air
> leak into the intake someplace likely.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
> Glenn wrote:
>> Hi all, was trying to be a good brother today doing a major service
>> and repairing the cracked exhaust manifold on my sisters 99XJ.
>> Repairing the exhaust manifold obviously entails taking of the inlet
>> manifold, unplugging all the wires, fuel line off the fuel rail etc.
>> Everything went back together ok but when I fired it up, the engine
>> raced to max revs instantly, pretty sure it would rev till blew up
>> from the sound of it if I didn't switch it off. I can't understand how
>> it could do this, particularly since the throttle butterfly does not
>> open at all. I tried resetting the computer, no luck, I'm out of ideas
>> at the moment other than towing it to the nearest Jeep dealer, Any
>> idea's anyone???
>>

 

STOP

He said that the throttle does not open. I think we have to make sure it is
not full open already before we go looking for leaks and other gremlins.

I happen to agree with the leak diagnosis, but since it is reported that the
throttle won't even open, I have to think the throttle is actually Full Open
already, and the fact that it doesn't budge needs to be addressed before we
start looking to gaskets and disconnected hoses.




"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4708ee41$0$22717$9a6e19ea@unlimited.newshosti ng.com...
> That usually means you forgot to hook up a vacuum line. You have an air
> leak into the intake someplace likely.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
> Glenn wrote:
>> Hi all, was trying to be a good brother today doing a major service
>> and repairing the cracked exhaust manifold on my sisters 99XJ.
>> Repairing the exhaust manifold obviously entails taking of the inlet
>> manifold, unplugging all the wires, fuel line off the fuel rail etc.
>> Everything went back together ok but when I fired it up, the engine
>> raced to max revs instantly, pretty sure it would rev till blew up
>> from the sound of it if I didn't switch it off. I can't understand how
>> it could do this, particularly since the throttle butterfly does not
>> open at all. I tried resetting the computer, no luck, I'm out of ideas
>> at the moment other than towing it to the nearest Jeep dealer, Any
>> idea's anyone???
>>

 

"SnoMan" <admin@snoman.com> wrote in message
news:sevhg3lieru9ikg435jdfhb17hfgf1cqat@4ax.com...
> On Sun, 07 Oct 2007 10:36:26 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>>That usually means you forgot to hook up a vacuum line. You have an air
>>leak into the intake someplace likely.
>
>
> It is going to take more than a small vacum line to do that. Maybe the
> line forvacuum power brake booster could cause that but you have a
> major air/acuum leak somewhere and this is what you should look for.
> not a simple small line.
> -----------------

Think about this for a second. The Fuel Injector Timing is going to dictate
the fuel delivery, and if there is a drop of gas (as should exist in an idle
condition) but a flood of air, the result ought not be a racing engine. If
the engine was supposed to be at idle, and one disconnected vacuum ports and
left them open, the engine would stall, it would not run away. For it to run
away, it needs both gas and air. The throttle is full open, not full closed.

Since the engine is racing AND "the throttle butterfly does not open at
all," I suggest the trouble is that the throttle is already full open. This
would give lots of gas, instead of just a drip, to go along with all of the
extra air that would be needed for a runaway engine.

 

"SnoMan" <admin@snoman.com> wrote in message
news:sevhg3lieru9ikg435jdfhb17hfgf1cqat@4ax.com...
> On Sun, 07 Oct 2007 10:36:26 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>>That usually means you forgot to hook up a vacuum line. You have an air
>>leak into the intake someplace likely.
>
>
> It is going to take more than a small vacum line to do that. Maybe the
> line forvacuum power brake booster could cause that but you have a
> major air/acuum leak somewhere and this is what you should look for.
> not a simple small line.
> -----------------

Think about this for a second. The Fuel Injector Timing is going to dictate
the fuel delivery, and if there is a drop of gas (as should exist in an idle
condition) but a flood of air, the result ought not be a racing engine. If
the engine was supposed to be at idle, and one disconnected vacuum ports and
left them open, the engine would stall, it would not run away. For it to run
away, it needs both gas and air. The throttle is full open, not full closed.

Since the engine is racing AND "the throttle butterfly does not open at
all," I suggest the trouble is that the throttle is already full open. This
would give lots of gas, instead of just a drip, to go along with all of the
extra air that would be needed for a runaway engine.

 

"SnoMan" <admin@snoman.com> wrote in message
news:sevhg3lieru9ikg435jdfhb17hfgf1cqat@4ax.com...
> On Sun, 07 Oct 2007 10:36:26 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>>That usually means you forgot to hook up a vacuum line. You have an air
>>leak into the intake someplace likely.
>
>
> It is going to take more than a small vacum line to do that. Maybe the
> line forvacuum power brake booster could cause that but you have a
> major air/acuum leak somewhere and this is what you should look for.
> not a simple small line.
> -----------------

Think about this for a second. The Fuel Injector Timing is going to dictate
the fuel delivery, and if there is a drop of gas (as should exist in an idle
condition) but a flood of air, the result ought not be a racing engine. If
the engine was supposed to be at idle, and one disconnected vacuum ports and
left them open, the engine would stall, it would not run away. For it to run
away, it needs both gas and air. The throttle is full open, not full closed.

Since the engine is racing AND "the throttle butterfly does not open at
all," I suggest the trouble is that the throttle is already full open. This
would give lots of gas, instead of just a drip, to go along with all of the
extra air that would be needed for a runaway engine.

 

"SnoMan" <admin@snoman.com> wrote in message
news:sevhg3lieru9ikg435jdfhb17hfgf1cqat@4ax.com...
> On Sun, 07 Oct 2007 10:36:26 -0400, Mike Romain <romainm@sympatico.ca>
> wrote:
>
>>That usually means you forgot to hook up a vacuum line. You have an air
>>leak into the intake someplace likely.
>
>
> It is going to take more than a small vacum line to do that. Maybe the
> line forvacuum power brake booster could cause that but you have a
> major air/acuum leak somewhere and this is what you should look for.
> not a simple small line.
> -----------------

Think about this for a second. The Fuel Injector Timing is going to dictate
the fuel delivery, and if there is a drop of gas (as should exist in an idle
condition) but a flood of air, the result ought not be a racing engine. If
the engine was supposed to be at idle, and one disconnected vacuum ports and
left them open, the engine would stall, it would not run away. For it to run
away, it needs both gas and air. The throttle is full open, not full closed.

Since the engine is racing AND "the throttle butterfly does not open at
all," I suggest the trouble is that the throttle is already full open. This
would give lots of gas, instead of just a drip, to go along with all of the
extra air that would be needed for a runaway engine.

 

I believe the OP was implying the throttle plate was 'not open at all'.
not that it 'couldn't' open at all.

Mike

Jeff Strickland wrote:
> STOP
>
> He said that the throttle does not open. I think we have to make sure it
> is not full open already before we go looking for leaks and other gremlins.
>
> I happen to agree with the leak diagnosis, but since it is reported that
> the throttle won't even open, I have to think the throttle is actually
> Full Open already, and the fact that it doesn't budge needs to be
> addressed before we start looking to gaskets and disconnected hoses.
>
>
>
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4708ee41$0$22717$9a6e19ea@unlimited.newshosti ng.com...
>> That usually means you forgot to hook up a vacuum line. You have an
>> air leak into the intake someplace likely.
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>> (More Off Road album links at bottom of the view page)
>>
>> Glenn wrote:
>>> Hi all, was trying to be a good brother today doing a major service
>>> and repairing the cracked exhaust manifold on my sisters 99XJ.
>>> Repairing the exhaust manifold obviously entails taking of the inlet
>>> manifold, unplugging all the wires, fuel line off the fuel rail etc.
>>> Everything went back together ok but when I fired it up, the engine
>>> raced to max revs instantly, pretty sure it would rev till blew up
>>> from the sound of it if I didn't switch it off. I can't understand how
>>> it could do this, particularly since the throttle butterfly does not
>>> open at all. I tried resetting the computer, no luck, I'm out of ideas
>>> at the moment other than towing it to the nearest Jeep dealer, Any
>>> idea's anyone???
>>>
>