cold running problem
 

Hi group:

I have a problem with my '89 L98, it does not run right untill the coolant
temp. gets up to about 150. Before it gets to this temp it stumbles and
idles low (sometimes dies) after it reaches temp. it runes fine. If it had
a carb I would think the auto choke was not working, the symptoms are very
like that condition. I have heard about closed/open loop transitions with
the on board engine management, could this be the problem? any diagnostic
ideas welcomed, I am wondering where to start to track the problem down.

TIA Dave G.

"Dave Gee" > wrote:

>Hi group:
>
>I have a problem with my '89 L98, it does not run right untill the coolant
>temp. gets up to about 150. Before it gets to this temp it stumbles and
>idles low (sometimes dies) after it reaches temp. it runes fine. If it had
>a carb I would think the auto choke was not working, the symptoms are very
>like that condition. I have heard about closed/open loop transitions with
>the on board engine management, could this be the problem? any diagnostic
>ideas welcomed, I am wondering where to start to track the problem down.
>
>TIA Dave G.
================================================== ===========
Hi Dave,

It sounds as if your coolant temperature sensor has gone out of
calibration. Have someone scan your computer data stream with the car off and
cold, and see if the temp sensor is giving the ECM readings as if the car was
already warmed up. If it's out of calibration, the ECM should catch it when you
start the car cold--it compares the coolant sensor readings and the intake air
temp readings--they should be within a couple of degrees of each other with a
cold engine. You didn't mention if the "service engine" light was lit or not--If
the ECM caught the difference in cold readings, it should illuminate the lamp.


RON
================================================== ======
Remove the ZZZ from my E-mail address to send me E-mail.

"Dave Gee" > wrote:

>Hi group:
>
>I have a problem with my '89 L98, it does not run right untill the coolant
>temp. gets up to about 150. Before it gets to this temp it stumbles and
>idles low (sometimes dies) after it reaches temp. it runes fine. If it had
>a carb I would think the auto choke was not working, the symptoms are very
>like that condition. I have heard about closed/open loop transitions with
>the on board engine management, could this be the problem? any diagnostic
>ideas welcomed, I am wondering where to start to track the problem down.
>
>TIA Dave G.
================================================== ===========
Hi Dave,

It sounds as if your coolant temperature sensor has gone out of
calibration. Have someone scan your computer data stream with the car off and
cold, and see if the temp sensor is giving the ECM readings as if the car was
already warmed up. If it's out of calibration, the ECM should catch it when you
start the car cold--it compares the coolant sensor readings and the intake air
temp readings--they should be within a couple of degrees of each other with a
cold engine. You didn't mention if the "service engine" light was lit or not--If
the ECM caught the difference in cold readings, it should illuminate the lamp.


RON
================================================== ======
Remove the ZZZ from my E-mail address to send me E-mail.

> Hi Dave,
>
> It sounds as if your coolant temperature sensor has gone out of
> calibration. Have someone scan your computer data stream with the car off
and
> cold, and see if the temp sensor is giving the ECM readings as if the car
was
> already warmed up. If it's out of calibration, the ECM should catch it
when you
> start the car cold--it compares the coolant sensor readings and the intake
air
> temp readings--they should be within a couple of degrees of each other
with a
> cold engine. You didn't mention if the "service engine" light was lit or
not--If
> the ECM caught the difference in cold readings, it should illuminate the
lamp.
>
>
> RON
> ================================================== ======
> Remove the ZZZ from my E-mail address to send me E-mail.

Thanks for the reply Ron:

No service engine lite, or other codes, I would be interested in being
able to get
the "data stream" information. I have a laptop or two and have done a bit
of programming.
Does anyone offer a data tap for these cars, with some diagnostic software?
I would be
interested in getting into this.

TIA
Dave G.

> Hi Dave,
>
> It sounds as if your coolant temperature sensor has gone out of
> calibration. Have someone scan your computer data stream with the car off
and
> cold, and see if the temp sensor is giving the ECM readings as if the car
was
> already warmed up. If it's out of calibration, the ECM should catch it
when you
> start the car cold--it compares the coolant sensor readings and the intake
air
> temp readings--they should be within a couple of degrees of each other
with a
> cold engine. You didn't mention if the "service engine" light was lit or
not--If
> the ECM caught the difference in cold readings, it should illuminate the
lamp.
>
>
> RON
> ================================================== ======
> Remove the ZZZ from my E-mail address to send me E-mail.

Thanks for the reply Ron:

No service engine lite, or other codes, I would be interested in being
able to get
the "data stream" information. I have a laptop or two and have done a bit
of programming.
Does anyone offer a data tap for these cars, with some diagnostic software?
I would be
interested in getting into this.

TIA
Dave G.

If the coolant sending unit is not the problem on the engine, then it is the fuel injectors.... you will need to inspect each one to verify that you have the proper ohms, otherwise you have leaky injectors and the motor is running rich. I had the same problem on mine, and ended up replacing all the injectors and o-rings. It ran perfect after that...... not a real email address so don't bother responding. If you have questions ask, and I will look for answer. Pick up a corvette book from AutoZone for about $12.00. It will tell you the ohms/voltage reading you should have when testing. The reason it stumbles is because it runs to rich, then it dies when it gets warm cause it floods out. Testing these will require that you pull the wires by removing the goofy clip, and then testing the injector. It is done without car running or on. Just testing injector resitance. If you have to remove them, it will require a new plunim manifold, and I would just replace all injectors and o-rings to ensure that the problem is solved with out screwing around with it again later down the road.... That way they are all the same lbs. of fuel being delivered and all in good shape. Later and good luck.


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If the coolant sending unit is not the problem on the engine, then it is the fuel injectors.... you will need to inspect each one to verify that you have the proper ohms, otherwise you have leaky injectors and the motor is running rich. I had the same problem on mine, and ended up replacing all the injectors and o-rings. It ran perfect after that...... not a real email address so don't bother responding. If you have questions ask, and I will look for answer. Pick up a corvette book from AutoZone for about $12.00. It will tell you the ohms/voltage reading you should have when testing. The reason it stumbles is because it runs to rich, then it dies when it gets warm cause it floods out. Testing these will require that you pull the wires by removing the goofy clip, and then testing the injector. It is done without car running or on. Just testing injector resitance. If you have to remove them, it will require a new plunim manifold, and I would just replace all injectors and o-rings to ensure that the problem is solved with out screwing around with it again later down the road.... That way they are all the same lbs. of fuel being delivered and all in good shape. Later and good luck.


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------= Binary Usenet downloading made easy =---------
-= Get GrabIt for free from http://www.shemes.com/ =-