Continued issue when car hits 125 degrees

[LGAFF]

Still having this issue with the car, within about 3-4 minutes of startup, when the car hits 125 degrees, without fail....the car sputters, and misfires, the alt readings drop and flutters. Once the car hits 3K RPM the engine corrects and the problem never comes back until the next time the temp drops below 125.
*Replaced 02 Sensor
*Checked 02 grounds
*Replaced primary fuel pump relay
*tried a different chip
*tried a different ECM
*Changed the plugs
*Checked fuel pressure with car off primary and 2ndry(it still hauls *** so unlikely a fuel issue)

[mike100]

Do you think the coolant temp sensor is reporting accurately? check the plug for it too.

[LGAFF]

Yep its working, the coolant temp moves up and down as appropriate....there must be something that occurs at 125 degrees that is causing the issue....

For example the fuel pumps go back and forth at 167 degrees....I believe the 2ndry starts the car and transitions to the primary

Not sure whats going on....

[XfireZ51]

Originally Posted by LGAFF

Still having this issue with the car, within about 3-4 minutes of startup, when the car hits 125 degrees, without fail....the car sputters, and misfires, the alt readings drop and flutters. Once the car hits 3K RPM the engine corrects and the problem never comes back until the next time the temp drops below 125.
*Replaced 02 Sensor
*Checked 02 grounds
*Replaced primary fuel pump relay
*tried a different chip
*tried a different ECM
*Changed the plugs
*Checked fuel pressure with car off primary and 2ndry(it still hauls *** so unlikely a fuel issue)

125F is 51C which is when the motor goes closed loop. Very likely going lean.

[LGAFF]

Dom,

Is there something tied to the O2 sesnors in the ECM that could be bad, I tested the ground(middle white wire) and it was good

[LGAFF]

Going lean because of the 02?

A fuel injector is not going to get better, neither is a pump....unless its a relay...primary replaced...I would think if the engine transitions from the secondary to primary the issue would be the primary relay or pump

if it were the pump....it would not go away

the issue lasts 30 seconds then gone

[XfireZ51]

Originally Posted by LGAFF

Going lean because of the 02?

A fuel injector is not going to get better, neither is a pump....unless its a relay...primary replaced...I would think if the engine transitions from the secondary to primary the issue would be the primary relay or pump

if it were the pump....it would not go away

the issue lasts 30 seconds then gone

Yeah I know. It's none of those.

[LGAFF]

I am going to replace the extension harness....are these heated 02s on the 90?

[scottfab]

Originally Posted by LGAFF

Going lean because of the 02?

Maybe so. I had one that until I began recording data with a datalogger (diacom) I had no clue. It was "lazy". In your case it could be that the heating element is not getting up to temp before close loop is entered. Then eventually get there with exhaust temps.

[QUOTE=LGAFF;181550]A fuel injector is not going to get better, neither is a pump....unless its a relay...primary replaced...I would think if the engine transitions from the secondary to primary the issue would be the primary relay or pump

Pumps can and do fail intermittently. Since your symptoms are so repeatable probably not but....

Originally Posted by LGAFF

if it were the pump....it would not go away

It can in fact go away but not as a function of engine temp.

Originally Posted by LGAFF

the issue lasts 30 seconds then gone

Job for a datalogger and then time to study what happening as the close loop bit is set (close loop entered), focusing on which side maybe going lean. Does this symptom happen in full eng power and not? But anyway.... time for a data capture for the full warm up period.

[LGAFF]

So Dom, are you thinking its possibly not a "Physical" parts failure....but that the engine enters a state of ......wait for it......

"Camfusion"

I need to trademark that word