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P0304 Problem

I

intravino

CEG'er
Joined
Sep 9, 2004
Messages
170
Location
Montreal
Hey Gang,


I got a P0304 with acceleration.

Changed Plugs.

Changed Wires.

Checked Coil, ok in specs.

I thought I had a problem with the IAT sensor because one wire was cut, I repaired it and I still have the problem.

I saw readings on the OBD2 software for Intake Air Temp and Coolant Temp, so it's not those sensors.

I saw a short term fuel trim at 99 % almost always.

Now I'm Stuck,


Please Help :)


Thanks for your time,


Intravino
 
Maybe the injector. Could be clogged or not working correctly. Sometime it will throw a code for the injector if it's open, or resistence has gone high, not in all cases. I've seen it were the injectors have a 11 ohm resistence and then you come to the bad one, with 20 ohms resistence the computer doesn't throw a injector code, but have a missfire on the cylinder because lack of fuel.
 
injector resistance test

injector resistance test

I did check the injector on cylinder 4 and I got a reading of 14 ohms but then I checked all four of them and I got the same reading of 14 ohms all the 3 others.

I did run ScanMaster for few minutes at idle and I got this log file:

min average max
Fuel System 1 closed loop - 2,00 2,00 2,00

04 - Calculated Load Value 27 % 26,27 28,44 30,98
05 - Engine Coolant Temperature 100 °C 98,00 99,00 100,00
06 - Short Term Fuel Trim - Bank 1 -0,8 % -4,69 -0,94 2,34
07 - Long Term Fuel Trim - Bank 1 9,4 % 9,38 10,16 10,94
0C - Engine RPM 879 rpm 843,50 878,72 910,00
0D - Vehicle Speed 0 km/h 0,00 0,00 0,00
0E - Ignition Timing Advance for #1 Cylinder 30 ° 25,00 27,40 29,50
0F - Intake Air Temperature 42 °C 39,00 40,50 42,00
10 - Air Flow Rate 2,17 g/s 2,17 2,20 2,25
11 - Absolute Throttle Position 16,5 % 16,47 16,47 16,47
14 - Bank 1 - Sensor 1
Oxygen Sensor Output Voltage 0,750 V 0,03 0,46 0,82
Short Term Fuel Trim -1,6 % -5,47 -0,61 4,69
15 - Bank 1 - Sensor 2
Oxygen Sensor Output Voltage 0,240 V 0,21 0,26 0,29
Short Term Fuel Trim 99,2 % 99,21 99,21 99,21
 
I replaced the Fuel filter, no difference.

I saw the long term film trim stuck at 16 %.

I noticed also when I pulled the # 14 fuse and started the car after that the car never started so maybe the fuel pressure is low.

I will purchase a gauge to check the fuel pressure.


Intravino
 
replace the coil pack. Most likely breaking down underload. If you want to test that you need a cheap spark gap tester, will stress the coil and more likely to show a miss than a inline spark light.
 
replace the coil pack. Most likely breaking down underload. If you want to test that you need a cheap spark gap tester, will stress the coil and more likely to show a miss than a inline spark light.
Click to expand...

I'm starting to think the same JD2, the coil is probably the problem.

I just made a compression test.:

1-190 psi
2-185 psi
3-190 psi
4-190 psi

I did also check fuel pressure, key on car off : 36 psi

Key on engine on: 31 PSI.

Hold Fuel system : 40 PSI after 5 minutes.

Fuel pressure regulator is fine also.

They only thing left is Injector, I did take out the connector at idle and you fell the engine running on 3 cylinders and the Coil even if I have the good values of resistances at off.

Thanks,

Intravino
 
THANKS jd2-98s!!!

It was the coil finally.

I tested it at static and the resistance of the primary and secondary was all in spec's but I should of suspected that electronics sometimes are good in static tests but could be still defective.

I replaced the coil with a new one ($ 55.00) and the car runs almost like new now.

Thank Again,

Intravino
 
I get now a P0171 code since I replaced the coil.

I did play with so many things on the car.

Replaced the Fuel Filter, Plugs, High Tension Wires.

I cleaner also the MAF, I hope I did not damaged it !!! I cleaned it with ISO Alcohol but I do see the reading on the OBD2 Scanner

Also, I had a misfire on cylinder 4 and I rand the car to do test on the road, I could of damaged the Oxygen sensor also.

Problems.
 
I will check the PCV tube.

I cleaned again the MAF, but this time with a good electronic contact cleaner, there was a bit of black stuff on it.

I drove the car for an hour and I did not see the Check Engine Light until 3 minutes from my house (it came on). bummer....
 
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