idle surging and rich help
03-07-2009, 10:05 AM
#16
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Hi.
I need help.
I have replaced the injectors with 8 new injectors.
Today i have tested the fuel pressure at the idle the pressure is 3,3 bar the same value of the Porsche 928 workshop manual. The value of the fuel pressure are correct at the idle and the fuel system mantains pressure when the engine stopped 3,8 bar.
This is the values of the emission test of my car at the idle the car that continues to have surging idle.
First test
CO 7,414 %vol
CO2 9,27 %vol
HC 488 PPMVOL
O2 1,26
LAMBDA 0,812
AFR 12,00
second test
CO 6,921 %vol
CO2 9,94 %vol
HC 446 PPMVOL
O2 0.72
LAMBDA 0,821
AFR 12,12
third test
CO 7,910 %vol
CO2 9,15 %vol
HC 518 PPMVOL
O2 0,94
LAMBDA 0,789
AFR 11,66
THANK YOU FOR YOUR HELP.
I need help.
I have replaced the injectors with 8 new injectors.
Today i have tested the fuel pressure at the idle the pressure is 3,3 bar the same value of the Porsche 928 workshop manual. The value of the fuel pressure are correct at the idle and the fuel system mantains pressure when the engine stopped 3,8 bar.
This is the values of the emission test of my car at the idle the car that continues to have surging idle.
First test
CO 7,414 %vol
CO2 9,27 %vol
HC 488 PPMVOL
O2 1,26
LAMBDA 0,812
AFR 12,00
second test
CO 6,921 %vol
CO2 9,94 %vol
HC 446 PPMVOL
O2 0.72
LAMBDA 0,821
AFR 12,12
third test
CO 7,910 %vol
CO2 9,15 %vol
HC 518 PPMVOL
O2 0,94
LAMBDA 0,789
AFR 11,66
THANK YOU FOR YOUR HELP.
03-14-2009, 01:54 PM
#18
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Hi people.
I have solved my idle problem and my rich exhaust condition.
8 new injectors cured the problem.
When i made the fuel pressure test the 8 new injectors had already been fitted but my exhaust chamber and my exhaust line werw still dirty for this reason the exhaust emission test was bad with high CO values. After an italian tune up the emission are goosd i think.
Whit air diverter valve of the air pump detached CO value is 0,1 lambda value is 1,000 AFM is 14,7.
Now however i have another problem i have when the engine is hot a notable ignition misfire only when the engine is hot and remains the problem of slightly high water temperature under the third white line not in the middle as my car had previously.
I have solved my idle problem and my rich exhaust condition.
8 new injectors cured the problem.
When i made the fuel pressure test the 8 new injectors had already been fitted but my exhaust chamber and my exhaust line werw still dirty for this reason the exhaust emission test was bad with high CO values. After an italian tune up the emission are goosd i think.
Whit air diverter valve of the air pump detached CO value is 0,1 lambda value is 1,000 AFM is 14,7.
Now however i have another problem i have when the engine is hot a notable ignition misfire only when the engine is hot and remains the problem of slightly high water temperature under the third white line not in the middle as my car had previously.
03-24-2009, 09:54 AM
#19
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Hi people 
I have solved my temperature problem.
The temperature gauge is out of calibration about 8 months ago the temperature gauge has decided that with the engine at normal temperatures would indicate the third white marks
When I bought my 928 about 4 years ago the temperature gauge had always indicated half way between the two white lines but now indicate the upper white line.
After changing 2 thermostats 1 radiator 1 fan switch 1 gauge temperature sensor on the thermostat body 1 expansion tank cap 1 expansion tank checked the operation of the flap and fan ECU controlled all temperatures of the engine with an infrared gun i have discovered that my temperature gauge is slightly mad slightly defective.
I discovered this with a fairly simple method i have attached my old gauge temperature sensor with the wiring of the gauge temperature sensor mounted on my engine plus a good ground on the engine i immersed the sensor in hot water i checked the temperature of the water with a thermometer and when the water was at about 90 C° (194 F°) my temperature gauge indicate the third white mark.
I think this is a common fault in many 928
I have solved my temperature problem.
The temperature gauge is out of calibration about 8 months ago the temperature gauge has decided that with the engine at normal temperatures would indicate the third white marks
When I bought my 928 about 4 years ago the temperature gauge had always indicated half way between the two white lines but now indicate the upper white line.
After changing 2 thermostats 1 radiator 1 fan switch 1 gauge temperature sensor on the thermostat body 1 expansion tank cap 1 expansion tank checked the operation of the flap and fan ECU controlled all temperatures of the engine with an infrared gun i have discovered that my temperature gauge is slightly mad slightly defective.
I discovered this with a fairly simple method i have attached my old gauge temperature sensor with the wiring of the gauge temperature sensor mounted on my engine plus a good ground on the engine i immersed the sensor in hot water i checked the temperature of the water with a thermometer and when the water was at about 90 C° (194 F°) my temperature gauge indicate the third white mark.
I think this is a common fault in many 928
