Engine won't Idle
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Joined: Jan 2005
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From: Portland, Oregon
Engine won't Idle
after I stomped on it the car started running very rough and won't hold an idle. it is running rich, when I scanned it, it gave me 40 codes So I unplugged the battery and waited 30 seconds then I reset my cannon plugs. I also look for anything obvious too. still runds rough and wont idle the O2 Sensors are 23 years old.
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From: Cape Coral, Florida
So what are your 2 DTC’s ??…P0172/0175 ??…are you using a scan tool ??…if so look at your upstream O2 sensors and see if the millivoltage is reading low around 100 millivolts or so…if your downstreams are reading 700-900 millivolts your O2 sensor is “lying” and will need to be replaced…let us know what you see…a good upstream O2 will oscillate between 200-800 millivolts…what codes are you seeing ??…what “cannon” plugs did you reset ??
Last edited by C5 Diag; May 27, 2023 at 05:33 PM.
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Joined: Jan 2005
Posts: 62
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From: Portland, Oregon
I check for vacuum leaks and found none. I also found a line to the PVC at the connection point cracked I fixed. not much of a difference when running. So I disconnected the MAF sensor and it runs smoother and idles but still have all these codes.
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Joined: Jan 2005
Posts: 62
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From: Portland, Oregon
I reset the TPS, MAF, throttle body actuator. and the O2 sensors. now to my scan tool it is a Innova 5160RS. I should replace the O2 Senors since none of them have been changes since 1998
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Joined: Jan 2005
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From: Portland, Oregon
I am sorry about that
P0102,P0103,P0113,P0116,P0125,P0126,P013 1,P0132,P0134,P0134 and it goes on total is 40 codes flagged. I aleast got it to run and Idle by disconnecting my MAF cannon plug.
P0102,P0103,P0113,P0116,P0125,P0126,P013 1,P0132,P0134,P0134 and it goes on total is 40 codes flagged. I aleast got it to run and Idle by disconnecting my MAF cannon plug.
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From: Cape Coral, Florida
You have a lot of “circuit” codes which denotes something electrical…with key ON see if you have 12 volts on the pink wire (power feed for MAF)...this may be a power feed issue.
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From: Cape Coral, Florida
Do this….clear all the codes and then turn the key off for 10 seconds…start the car and see what codes come back…MAF and O2 heaters are on different circuits so I’m seeing what is common with what you have…look at your MAF, IAT and O2’s.
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From: Cape Coral, Florida
With the MAF unplugged see if you have 5 volts on the yellow wire key ON…if no 5 volts we may have to look at the PCM power….that 5 volts comes from the PCM.
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From: Cape Coral, Florida
Plug the MAF back in and if there is a MAF code set clear it and run the engine at idle…MAF should read about 6.0-6.2 grams/second….then do a snap acceleration and see that the grams/seconds increase…look at your O2 sensors and see if the upstream O2’s are oscillating between 200-800 millivolts…40 codes are strange.
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From: Cape Coral, Florida
With your scan tool looking at live data…how’s your battery ??…is it charging properly ??..this may be a bad battery…if battery voltage goes low during starting it can throw all kinds of codes !!…you may want to get your battery load tested.
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From: Cape Coral, Florida
The MAF in grams/second should read approximately the liter displacement of the engine and 6.0 to 6.2 is good…if you see 3.5 the MAF is under reporting and when you unplugged it and it ran better this may be a bad MAF…what do your fuel trims look like…short and long terms ??….if the upstream O2’s are stuck at .860 millivolts the PCM thinks it’s a rich condition and your fuel trims will be negative…those O2 should be oscillating between 200-800mv’s !!