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I have a 1997 Jetta 2.0l The car idles rough but smooths out

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I have a 1997 Jetta...
I have a 1997 Jetta 2.0l The car idles rough but smooths out when the rpm is raised. replaced rotor, distributor cap, plugs, plug wires. coil checks good. it is showing a P0102 and P0303
Submitted: 2 years ago.Category: VW
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Answered in 23 minutes by:
8/1/2015
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago
Wolfgang
Wolfgang, VW Master Technician
Category: VW
Satisfied Customers: 4,884
Experience: Senior VW Master Tech 15 yrs
Verified

Thanks for choosing Just Answer . I'm Wolfgang here to help!!
Below is my first answer or request for more information. If you do not understand it, or you need more information from me, or need me to go in more detail. Do not rate yet, just reply. Put yourself in my shoes, I can not see, smell, hear, feel or touch your car, nor do I know any history on it. So take into consideration I am doing my best based on what you tell me. Also understand fixing cars often requires sophisticated tools, that you may not own. So even if you can not do what is outlined in my answer, that does not mean my answer is wrong deserving to be rated negative.

can you tell me how did you verify that the coil is good please .

thanks

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Customer reply replied 2 years ago
I checked the coil resistance it is .7 I also checked the plug outer pins 12Vdc
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

please do this procedure . have the engine running and have a cup of water . while running splash the coil with water . does the vehicle run rough and even stall?

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Customer reply replied 2 years ago
No real change with water. stays idling rough. if I rev the rpm and take my foot off the gas the engine dies. if i ease off the gas it will stay running rough
Customer reply replied 2 years ago
only current code is P0102
Customer reply replied 2 years ago
When maf unplugged no change in rough idle
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

ok perform this step then door open , disconnect the battery both cables touch and hold for 10 minutes , ignition on then hook up positive cable then the negative cable . you will hear a beep and noises normal. start the car does the idle become better?

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Customer reply replied 2 years ago
Did it. Still rough. Check engine cleared and came back p0102. Only code shown
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

ok i do need your vin # ***** pull up factory info!!

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Customer reply replied 2 years ago
3vwxa81h7vm123987
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

ok on pin 3 when the car is running on the mass air flow sensor what is the voltage please?

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Customer reply replied 2 years ago
14 volts
Customer reply replied 2 years ago
All other pins 0v to neg terminal
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

ok disconnect the ecu then measure resistance of pin 1 to ground . then check the reistance of the same pin to ecu pin 1. then measure resistance pin 2 of the maf to pin 16 of the ecu and then pin 4 to pin 17

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Customer reply replied 2 years ago
Pin 1 to ground 0.5
Pin 1 to pin 1 plug open
Pin 2 maf to pin 16. 0.2
Pin 4 to pin 17. 0.2
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

just to make sure pin #1 at the ecu is a brown wire and pin #1 at the maf is brown /red wire . please double check the resistance on those 2 please

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Customer reply replied 2 years ago
Wire color is correct
Pin 1 Ecu harness to pin 1 maf sensor is 0.3
Customer reply replied 2 years ago
Replaced maf sensor. Runs better. But still rough at idle. Code p0102 cleared.
Customer reply replied 2 years ago
Car ran better for about 20 miles and now running really rough again like before
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

what scan tool are you using please . make and model

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Customer reply replied 2 years ago
Innova 3020b
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

can you get ecu sensor readings of what are the mixtures if it is running lean?

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Customer reply replied 2 years ago
Not on this tool
Customer reply replied 2 years ago
P0304 keeps showing and clearing
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

ok then you need to recheck the work make sure that the plug wire is on good and plug looks ok swap #3 and 4 plug and see if the misfire moves . if still on #4 then a compression check is needed to see if you have low compression or not

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Customer reply replied 2 years ago
The misfire code has cleared. But still rough idle. Compression checked good. Mechanic who checked compression thought it might be a fuel injector. Tried a new one no change. The car runs aliitle better when cold and gets worst as it warms up
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

when running rough what happens if you spray carb cleaner in the intake does it run better?

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Customer reply replied 2 years ago
It actually ran worst and died
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

there are readings needed to see what the ecu is seeing . and your scan tool is not right for the job. VAG com is needed to check these readings out . do you know some one that has vag com?

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Customer reply replied 2 years ago
I have a innova 1003f. Will that work
VW Mechanic: Wolfgang, VW Master Technician replied 2 years ago

i'm sorry but no.

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