CEL when over 80mph

[flipnoy213]

When i cruse over 80 mph or close to 4k rpm, i keep getting a Check Engine Light. When it comes on the car doesn't run as good. So when it comes up i would just shift to neutral and idle for about 5 sec and the car runs normal again but the CEL stays on. But when i go back to cruising over 80 the car would run like shit again. The scanner always shows these two codes:
P1500.....Alternator FR Terminal circuit.
P0300..... Multiple cylinder misfiring detected
I already tried changing my plug and gapping them properly and that didn't help. Also don't have a 6 bolt conv. You guy got any idea whats the problem?

 

[dave99gst]

maybe the voltage reg in the alt is on its way out ?

 

[92awddsm]

You will keep getting the misfire code with the 6 bolt swap until you get dsm link or a chipped eprom ecu. Im not a 2g owner but these are the things Ive heard. I was also told that you could disconnect the tps to prevent it but Im not sure.

 

[flipnoy213]

i dont have a 6 bolt con.

 

[92awddsm]

i dont have a 6 bolt con.

Sorry, I glanced and thought it said you did have a 6 bolt conv.

 

[flipnoy213]

maybe the voltage reg in the alt is on its way out ?

Is it replaceable or do i have to change the whole Alternator? and does that have anything to do with misfires? because both codes comes out at the same time.

 

[Boosted98gsx]

Do you have a reflased EPROM that shows knock w/ the check engine light?

Do me a favor and just step on the gas when you're not moving and see if the rpms will climb up all the way to 7k rpms.

 

[flipnoy213]

Do you have a reflased EPROM that shows knock w/ the check engine light?

Do me a favor and just step on the gas when you're not moving and see if the rpms will climb up all the way to 7k rpms.

Nope its not reflased and im pretty sure it will make it to 7k but ill find out tommrow

 

[flipnoy213]

just checked today and it does get to 7k

 

[Boosted98gsx]

k, i just had a suspicion that your car had DSMlink and that checkengine light was it's knock "flasher"

N/m then.

 

[flipnoy213]

here some data from Carchip software when CEL comes on

View / Vehicle Trouble Log / Record Problem 1
Overview
Time : 1/3/2005 2:43 PM
Vehicle : Eclipse
CarChip : J-3986-A
Trouble Code : P0300
Description : Random/Multiple Cylinder Misfire Detected
Comments :
Engine Status
Fuel Pressure (Gage) :
Intake Manifold Pressure (Absolute) :
Engine Coolant Temperature : 168.8 °F
Calculated Load Value : 21.2 %
Engine Speed : 3,848 RPM
Vehicle Speed : 89 MPH
Fuel Trim Status
Short-Term Fuel Trim (Bank 1) : 5.47 %
Short-Term Fuel Trim (Bank 2) :
Long-Term Fuel Trim (Bank 1) : 0.00 %
Long-Term Fuel Trim (Bank 2) :
Fuel System Status
Fuel System 1 Status :
Fuel System 2 Status : Closed loop; using oxygen sensor(s) as feedback for fuel control.

 

[92awddsm]

The only thing I see from the log is coolant temp seems to be low. It should be closer to 185-190 at full operating temp. I would try swapping a known good coolant temp sensor.

 

[flipnoy213]

Here another log when i got a CEL today. seems closer to op. temp
View / Vehicle Trouble Log / Record Problem 22
Overview
Time : 1/7/2005 5:15 PM
Vehicle : Eclipse
CarChip : J-3986-A
Trouble Code : P0300
Description : Random/Multiple Cylinder Misfire Detected
Comments :
Engine Status
Fuel Pressure (Gage) :
Intake Manifold Pressure (Absolute) :
Engine Coolant Temperature : 176.0 °F
Calculated Load Value : 27.5 %
Engine Speed : 3,824 RPM
Vehicle Speed : 73 MPH
Fuel Trim Status
Short-Term Fuel Trim (Bank 1) : -2.34 %
Short-Term Fuel Trim (Bank 2) :
Long-Term Fuel Trim (Bank 1) : 7.03 %
Long-Term Fuel Trim (Bank 2) :
Fuel System Status
Fuel System 1 Status :
Fuel System 2 Status : Closed loop; using oxygen sensor(s) as feedback for fuel control.

 

[flipnoy213]

is it possible its misfiring because the alternator drops the voltage low enough for a second or two were the ignition system cant function properly. Or maybe because i have no cat(as it mention something about that in the shop manual)?

 

[race my talon]

i am having the same problem i get the p0300 and p1500 codes all the time..cant semm to figure it out..i also have no cat

 

[flipnoy213]

man i still have the problem, i just give up i cant figure out how to fix it, i just stay under 80. I changed the spark plug, spark plug wires, cleaned the injectors, changed the coils, changed resistor pack, put my CAT back on, list goes on? Im thinking of changing my temp sensor soon.