M. E. Bye did pass the time by typing:

> Yup. Crank position sensor. Once I found it and removed it, I
> discovered that the wiring was badly burned at the mid point. I'm
> guessing that when the guy who put on a header replacing the bad
> exhaust manifold a couple years ago didn't bother about where the
> wiring from the connector to the sensor was routed.

Owtch.

You might be able to recover the sensor by splicing new wire but
that one is a bit tricky. Hopefully it didn't harm the computer.

--
DougW

 

In message <JxX2tWiP5BNp-pn2-LEdqnjqPzYNK@anon.none.net>, "Will Honea" wrote:

>On Thu, 9 Sep 2004 04:10:37 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> >Like I said, after 3 years and 60K miles with the thing I've just
>> >learned to release the clutch, tap the gas and live with that first
>> >stop at the bottom of the hill.
>>
>> That's probably the fix right there. Going downhill using the engine to slow
>> you down, the computer sees closed throttle but still a higher than normal idle
>> speed. That'll make the computer shove the IAC out all the way to try to get
>> the idle where it thinks it belongs. The computer has no idea the vehicle is
>> moving or that the clutch is engaged, so it doesn't know any better. Then you
>> disengage the clutch and the idle drops too much. Being that it's also cold
>> just adds to the problem, and it can't recover in time to keep from stalling.
>>
>> Today's computers are a little smarter and have more info to work with. :-)
>
>I've spent the last 40 years in and out of control system design -
>usually a lot more complex than a consumer fuel system - and pretty
>much decided that was the situation. That old Bendix computer is
>early 80's technology (damn, I hope I never have to replace it!), it's
>still in the open loop mode, and the moving parts are moving as slow
>as I do when cold. I figure that a lot of the responses are put
>out-of-band if conditions are even slightly abnormal for that old,
>slow, processor. I think they used the Motorola 6800 in there - speed
>demon it ain't.
>
>I got hold of the pinouts and signal descriptions at the computer plug
>a couple of years ago to build a breakout plug. I was (am) going to
>profile all the signals with my laptop just to see if I could clone
>the control system but got sidetracked before I got around to mashing
>the disk full of data.

About replacing that computer. I was shocked to find out we had one in stock
the other day. From the looks of the box though, I think it's just been sitting
around forever. I don't know if they're still available from DC or not.

I remember reading somewhere in an AMC manual once what processor they used.
Damned if I can remember what it said though. For what I do, it's not really
important. The box is either broke or it's not. :-)

You are correct about out of band conditions. They can do some strange stuff if
things don't look right to it.

 

In message <JxX2tWiP5BNp-pn2-LEdqnjqPzYNK@anon.none.net>, "Will Honea" wrote:

>On Thu, 9 Sep 2004 04:10:37 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> >Like I said, after 3 years and 60K miles with the thing I've just
>> >learned to release the clutch, tap the gas and live with that first
>> >stop at the bottom of the hill.
>>
>> That's probably the fix right there. Going downhill using the engine to slow
>> you down, the computer sees closed throttle but still a higher than normal idle
>> speed. That'll make the computer shove the IAC out all the way to try to get
>> the idle where it thinks it belongs. The computer has no idea the vehicle is
>> moving or that the clutch is engaged, so it doesn't know any better. Then you
>> disengage the clutch and the idle drops too much. Being that it's also cold
>> just adds to the problem, and it can't recover in time to keep from stalling.
>>
>> Today's computers are a little smarter and have more info to work with. :-)
>
>I've spent the last 40 years in and out of control system design -
>usually a lot more complex than a consumer fuel system - and pretty
>much decided that was the situation. That old Bendix computer is
>early 80's technology (damn, I hope I never have to replace it!), it's
>still in the open loop mode, and the moving parts are moving as slow
>as I do when cold. I figure that a lot of the responses are put
>out-of-band if conditions are even slightly abnormal for that old,
>slow, processor. I think they used the Motorola 6800 in there - speed
>demon it ain't.
>
>I got hold of the pinouts and signal descriptions at the computer plug
>a couple of years ago to build a breakout plug. I was (am) going to
>profile all the signals with my laptop just to see if I could clone
>the control system but got sidetracked before I got around to mashing
>the disk full of data.

About replacing that computer. I was shocked to find out we had one in stock
the other day. From the looks of the box though, I think it's just been sitting
around forever. I don't know if they're still available from DC or not.

I remember reading somewhere in an AMC manual once what processor they used.
Damned if I can remember what it said though. For what I do, it's not really
important. The box is either broke or it's not. :-)

You are correct about out of band conditions. They can do some strange stuff if
things don't look right to it.

 

In message <JxX2tWiP5BNp-pn2-LEdqnjqPzYNK@anon.none.net>, "Will Honea" wrote:

>On Thu, 9 Sep 2004 04:10:37 UTC bllsht <nospam@invaliddot.net> wrote:
>
>> >Like I said, after 3 years and 60K miles with the thing I've just
>> >learned to release the clutch, tap the gas and live with that first
>> >stop at the bottom of the hill.
>>
>> That's probably the fix right there. Going downhill using the engine to slow
>> you down, the computer sees closed throttle but still a higher than normal idle
>> speed. That'll make the computer shove the IAC out all the way to try to get
>> the idle where it thinks it belongs. The computer has no idea the vehicle is
>> moving or that the clutch is engaged, so it doesn't know any better. Then you
>> disengage the clutch and the idle drops too much. Being that it's also cold
>> just adds to the problem, and it can't recover in time to keep from stalling.
>>
>> Today's computers are a little smarter and have more info to work with. :-)
>
>I've spent the last 40 years in and out of control system design -
>usually a lot more complex than a consumer fuel system - and pretty
>much decided that was the situation. That old Bendix computer is
>early 80's technology (damn, I hope I never have to replace it!), it's
>still in the open loop mode, and the moving parts are moving as slow
>as I do when cold. I figure that a lot of the responses are put
>out-of-band if conditions are even slightly abnormal for that old,
>slow, processor. I think they used the Motorola 6800 in there - speed
>demon it ain't.
>
>I got hold of the pinouts and signal descriptions at the computer plug
>a couple of years ago to build a breakout plug. I was (am) going to
>profile all the signals with my laptop just to see if I could clone
>the control system but got sidetracked before I got around to mashing
>the disk full of data.

About replacing that computer. I was shocked to find out we had one in stock
the other day. From the looks of the box though, I think it's just been sitting
around forever. I don't know if they're still available from DC or not.

I remember reading somewhere in an AMC manual once what processor they used.
Damned if I can remember what it said though. For what I do, it's not really
important. The box is either broke or it's not. :-)

You are correct about out of band conditions. They can do some strange stuff if
things don't look right to it.

 

magicclaw@mac.com (Bob) wrote in message news:<47b769ae.0409090902.65ef29b9@posting.google. com>...
> Well, I don't know if this will help you any; I'm feeling lazy and not
> reading through all the responses you've already gotten to this.
> Anyway...
>
> I had similar problems, only I was getting two check engine fault
> codes. One said the MAP sensor reading was bad, the other said the TPS
> and MAP reading were inconsistent with each other.
>
> So, I replaced the MAP sensor. Problem solved...for half a day!
> Engine light came on--MAP code was gone, but the MAP/TPS disagreement
> reading was still there.
> So, I replaced the TPS. Problem solved--for good. That was 3 or 4
> months ago, and I haven't had a problem since, no matter the trip
> distance or the alititude (done some high pass trails in Ouray since
> then, too!).
>
> So, you might check the MAP sensor, too. I think I saw you mentioning
> some issues that you thought sounded like vacuum pressure, too--would
> the manifold absolute pressure sensor be applicable to that sort of
> diagnosis? (I'm asking, I don't know).
>
> Good luck.
>
> /Bob
>


I have a 98 TJ and I'm getting the same thing. check engine light and
bucking when taking off from first gear. It happens when it rains.
Moisture has something to do with it.

My mechanic suggested changing the spark plug wires. Any comments?
> >

 

magicclaw@mac.com (Bob) wrote in message news:<47b769ae.0409090902.65ef29b9@posting.google. com>...
> Well, I don't know if this will help you any; I'm feeling lazy and not
> reading through all the responses you've already gotten to this.
> Anyway...
>
> I had similar problems, only I was getting two check engine fault
> codes. One said the MAP sensor reading was bad, the other said the TPS
> and MAP reading were inconsistent with each other.
>
> So, I replaced the MAP sensor. Problem solved...for half a day!
> Engine light came on--MAP code was gone, but the MAP/TPS disagreement
> reading was still there.
> So, I replaced the TPS. Problem solved--for good. That was 3 or 4
> months ago, and I haven't had a problem since, no matter the trip
> distance or the alititude (done some high pass trails in Ouray since
> then, too!).
>
> So, you might check the MAP sensor, too. I think I saw you mentioning
> some issues that you thought sounded like vacuum pressure, too--would
> the manifold absolute pressure sensor be applicable to that sort of
> diagnosis? (I'm asking, I don't know).
>
> Good luck.
>
> /Bob
>


I have a 98 TJ and I'm getting the same thing. check engine light and
bucking when taking off from first gear. It happens when it rains.
Moisture has something to do with it.

My mechanic suggested changing the spark plug wires. Any comments?
> >

 

magicclaw@mac.com (Bob) wrote in message news:<47b769ae.0409090902.65ef29b9@posting.google. com>...
> Well, I don't know if this will help you any; I'm feeling lazy and not
> reading through all the responses you've already gotten to this.
> Anyway...
>
> I had similar problems, only I was getting two check engine fault
> codes. One said the MAP sensor reading was bad, the other said the TPS
> and MAP reading were inconsistent with each other.
>
> So, I replaced the MAP sensor. Problem solved...for half a day!
> Engine light came on--MAP code was gone, but the MAP/TPS disagreement
> reading was still there.
> So, I replaced the TPS. Problem solved--for good. That was 3 or 4
> months ago, and I haven't had a problem since, no matter the trip
> distance or the alititude (done some high pass trails in Ouray since
> then, too!).
>
> So, you might check the MAP sensor, too. I think I saw you mentioning
> some issues that you thought sounded like vacuum pressure, too--would
> the manifold absolute pressure sensor be applicable to that sort of
> diagnosis? (I'm asking, I don't know).
>
> Good luck.
>
> /Bob
>


I have a 98 TJ and I'm getting the same thing. check engine light and
bucking when taking off from first gear. It happens when it rains.
Moisture has something to do with it.

My mechanic suggested changing the spark plug wires. Any comments?
> >

 

> My mechanic suggested changing the spark plug wires. Any comments?
> > >

I know I'm a newbie to theis NG, but I think I'm a fair shadetree mechanic.
In my opinion the best way to check plug wires is to takle the vehicle to a
dark area or garage and with the engine running to spray the wires down with
water bottle. If you see sparks replace the wires.

Hope the low tech helps,

Eric Shade

 

> My mechanic suggested changing the spark plug wires. Any comments?
> > >

I know I'm a newbie to theis NG, but I think I'm a fair shadetree mechanic.
In my opinion the best way to check plug wires is to takle the vehicle to a
dark area or garage and with the engine running to spray the wires down with
water bottle. If you see sparks replace the wires.

Hope the low tech helps,

Eric Shade

 

> My mechanic suggested changing the spark plug wires. Any comments?
> > >

I know I'm a newbie to theis NG, but I think I'm a fair shadetree mechanic.
In my opinion the best way to check plug wires is to takle the vehicle to a
dark area or garage and with the engine running to spray the wires down with
water bottle. If you see sparks replace the wires.

Hope the low tech helps,

Eric Shade