low idle warm 90 jeep 4.0
03-19-2006, 06:42 PM
#61
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
The O2 sensors for the renix computer system that you should have in
your 90 are under recall. If it hasn't been done you can get it
replaced free still.
The renix system has no codes.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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)
HarryHydro wrote:
>
> Hi Guys:
> Thanks for the good info. It's been too cold and windy for me today
> to do too much, but I did tap into the O2 sensor and that seems pretty
> non-responsive. The voltage slowly drops from about .45 to .3 volts,
> motor still running and no engine lights. Shouldn't it be closer to
> .5V? Even with that, it seems to run fine after its ran a few minutes.
> Humm. Maybe that engine light is burnt out. Any quick ways to check
> for codes, with a laptop or something?
> Thanks!
> Harry
your 90 are under recall. If it hasn't been done you can get it
replaced free still.
The renix system has no codes.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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)
HarryHydro wrote:
>
> Hi Guys:
> Thanks for the good info. It's been too cold and windy for me today
> to do too much, but I did tap into the O2 sensor and that seems pretty
> non-responsive. The voltage slowly drops from about .45 to .3 volts,
> motor still running and no engine lights. Shouldn't it be closer to
> .5V? Even with that, it seems to run fine after its ran a few minutes.
> Humm. Maybe that engine light is burnt out. Any quick ways to check
> for codes, with a laptop or something?
> Thanks!
> Harry
03-19-2006, 08:37 PM
#62
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
I hate that!
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
03-19-2006, 08:37 PM
#63
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
I hate that!
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
03-19-2006, 08:37 PM
#64
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
I hate that!
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
03-19-2006, 08:37 PM
#65
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
I hate that!
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/
Mike Romain wrote:
>
> You are right, the letters got messed up in my head...
>
> Mike
03-19-2006, 09:46 PM
#66
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
In message <1142811109.772500.249000@i40g2000cwc.googlegroups .com>, "HarryHydro"
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
03-19-2006, 09:46 PM
#67
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
In message <1142811109.772500.249000@i40g2000cwc.googlegroups .com>, "HarryHydro"
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
03-19-2006, 09:46 PM
#68
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
In message <1142811109.772500.249000@i40g2000cwc.googlegroups .com>, "HarryHydro"
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
03-19-2006, 09:46 PM
#69
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
In message <1142811109.772500.249000@i40g2000cwc.googlegroups .com>, "HarryHydro"
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
wrote:
>Hi JD:
> I don't think I have a PCV valve, but I do have an EGR which I
>changed. I cleaned the throttle body valve not too long ago. The TPS
>is a couple of years old. At that same time I changed the MAP sensor.
>The Jeep runs fine and smooth axcept when it's hot-started for 2
>minutes or so.
>Something I've been suspecting:
>When it's warm, the alternator puts out lower voltage. I think the
>same time the fuel pump is pumping less pressure. Lowering RPM and
>voltage and even lower pressure. I've had a pressure gauge on the
>injection manifold. The pressure does drop, but the pressure regulator
>does seem to work also, I suppose with no feedback of the pressure, but
>just today I tested pulling the vacuum off this regulator, and the
>engine does speed up, even with the line plugged. I think the O2 sensor
>should quickly correct the rich mixture and lean it back out, but it
>didn't. While doing this I noticed little change in voltage coming from
>the O2 sensor.
>Harry
Maybe that's the problem. O2 voltage should always be changing between 0 and 5
volts.
Low fuel pressure would be more likely to cause problems under load, not at
idle.
03-20-2006, 11:31 AM
#70
Guest
Posts: n/a
Re: low idle warm 90 jeep 4.0
If the TPS and MAP sensors have been changed, and TB is clean, I agree:
next thing to look at is the O2 sensors and their connections.
On that EGR, just for laughs, disconnect it temporarily and see if the
problem goes away, esp. if it was an aftermarket unit. After failing a
smog check on the beater last year, I discovered that the problem was a
$90 Napa EGR that I had just replaced. The shop guys told me that all
aftermarket EGR's were pure junk, and after installing an OEM unit, it
passed famously. I had another shop re-diagnose and repair the thing
to insure an accurate diagnosis. No obvious symptoms like you
describe, but it's worth looking at.
next thing to look at is the O2 sensors and their connections.
On that EGR, just for laughs, disconnect it temporarily and see if the
problem goes away, esp. if it was an aftermarket unit. After failing a
smog check on the beater last year, I discovered that the problem was a
$90 Napa EGR that I had just replaced. The shop guys told me that all
aftermarket EGR's were pure junk, and after installing an OEM unit, it
passed famously. I had another shop re-diagnose and repair the thing
to insure an accurate diagnosis. No obvious symptoms like you
describe, but it's worth looking at.
