EPC light and 1200 idle
04-15-2018, 08:53 AM
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EPC light and 1200 idle
Hello all! This is my first forum thread here as I do need help as to I cannot find anything on google or other forum threads about my problem.
The last night coming home from a friends house my car would not turn on, and took 3 crank attempts at around 3-4 seconds each to finally turn on the car. I was starting to drive home very curious what was already wrong because I had just gotten a new battery 2 days prior (04/13/18) and I noticed within 10 seconds of driving my idle of around 900 normally was now 1200 and NOT going lower. My EPC light was on the whole time but I didn't see it as I somewhat tall but I noticed it half way home. There are and were no other lights to go with it. Not rough and don't have any weird squeaks coming from the car. Only at stopped it didn't stall or anything like I've read from other threads it just bounced around the 1100-1200 range.
My car is an Audi A4 3.0 V6 6spd manual Quattro: thank you for any help
P.S I do need a timing belt and oil change current mileage is 207,000
The last night coming home from a friends house my car would not turn on, and took 3 crank attempts at around 3-4 seconds each to finally turn on the car. I was starting to drive home very curious what was already wrong because I had just gotten a new battery 2 days prior (04/13/18) and I noticed within 10 seconds of driving my idle of around 900 normally was now 1200 and NOT going lower. My EPC light was on the whole time but I didn't see it as I somewhat tall but I noticed it half way home. There are and were no other lights to go with it. Not rough and don't have any weird squeaks coming from the car. Only at stopped it didn't stall or anything like I've read from other threads it just bounced around the 1100-1200 range.
My car is an Audi A4 3.0 V6 6spd manual Quattro: thank you for any help
P.S I do need a timing belt and oil change current mileage is 207,000
04-16-2018, 06:16 PM
#2
Did you put the battery in yourself or have someone do it? Something may have been damaged or unplugged in the process which could be causing the high idle. Maybe the air intake "tube" between the MAF and the intake manifold was partially knocked off its mounting or maybe the tube was punctured. Maybe a wire to the MAF or another sensor got unplugged.
You should scan the car with VCDS to see what codes its throwing.
You should scan the car with VCDS to see what codes its throwing.
04-18-2018, 09:37 AM
#4
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This sounds very similar to what my 3.0 did some months ago; high idle, EPC light, but also lower power. A restart would often correct that so the idle and power were normal.
The fault code that came up was for the crankshaft position sensor, also known as the CPS. I replaced that, but the problem wasn't really corrected, still occurred. One odd clue was that the EPC light, high idle, and lower power could be triggered by driving over a speed dot in the road. So when cleaning the CPS connector on the firewall didn't help, I opened the ECU box to disconnect and use electrical contact cleaner on all the connectors. While at it, I took out the transmission control module right under it to spray those contacts. And being that far into it, I removed the relays under the TCM to open them and check/clean the contacts. One relay, I believe was the fuel pump relay, had two sets of contacts- one for the fuel pump, and another smaller set for the ECU (I think). That smaller set was barely making contact when the relay's coil was powered. After flexing the brass arm for the movable small contact, and cleaning it, I have had no further problems like that at all. My explanation is that when going over a big enough bump in the street, the small contacts would bounce, interrupting power to the ECU briefly.
The fault code that came up was for the crankshaft position sensor, also known as the CPS. I replaced that, but the problem wasn't really corrected, still occurred. One odd clue was that the EPC light, high idle, and lower power could be triggered by driving over a speed dot in the road. So when cleaning the CPS connector on the firewall didn't help, I opened the ECU box to disconnect and use electrical contact cleaner on all the connectors. While at it, I took out the transmission control module right under it to spray those contacts. And being that far into it, I removed the relays under the TCM to open them and check/clean the contacts. One relay, I believe was the fuel pump relay, had two sets of contacts- one for the fuel pump, and another smaller set for the ECU (I think). That smaller set was barely making contact when the relay's coil was powered. After flexing the brass arm for the movable small contact, and cleaning it, I have had no further problems like that at all. My explanation is that when going over a big enough bump in the street, the small contacts would bounce, interrupting power to the ECU briefly.
04-23-2018, 06:41 PM
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This sounds very similar to what my 3.0 did some months ago; high idle, EPC light, but also lower power. A restart would often correct that so the idle and power were normal.
The fault code that came up was for the crankshaft position sensor, also known as the CPS. I replaced that, but the problem wasn't really corrected, still occurred. One odd clue was that the EPC light, high idle, and lower power could be triggered by driving over a speed dot in the road. So when cleaning the CPS connector on the firewall didn't help, I opened the ECU box to disconnect and use electrical contact cleaner on all the connectors. While at it, I took out the transmission control module right under it to spray those contacts. And being that far into it, I removed the relays under the TCM to open them and check/clean the contacts. One relay, I believe was the fuel pump relay, had two sets of contacts- one for the fuel pump, and another smaller set for the ECU (I think). That smaller set was barely making contact when the relay's coil was powered. After flexing the brass arm for the movable small contact, and cleaning it, I have had no further problems like that at all. My explanation is that when going over a big enough bump in the street, the small contacts would bounce, interrupting power to the ECU briefly.
The fault code that came up was for the crankshaft position sensor, also known as the CPS. I replaced that, but the problem wasn't really corrected, still occurred. One odd clue was that the EPC light, high idle, and lower power could be triggered by driving over a speed dot in the road. So when cleaning the CPS connector on the firewall didn't help, I opened the ECU box to disconnect and use electrical contact cleaner on all the connectors. While at it, I took out the transmission control module right under it to spray those contacts. And being that far into it, I removed the relays under the TCM to open them and check/clean the contacts. One relay, I believe was the fuel pump relay, had two sets of contacts- one for the fuel pump, and another smaller set for the ECU (I think). That smaller set was barely making contact when the relay's coil was powered. After flexing the brass arm for the movable small contact, and cleaning it, I have had no further problems like that at all. My explanation is that when going over a big enough bump in the street, the small contacts would bounce, interrupting power to the ECU briefly.
04-23-2018, 06:43 PM
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04-23-2018, 06:47 PM
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Did you put the battery in yourself or have someone do it? Something may have been damaged or unplugged in the process which could be causing the high idle. Maybe the air intake "tube" between the MAF and the intake manifold was partially knocked off its mounting or maybe the tube was punctured. Maybe a wire to the MAF or another sensor got unplugged.
You should scan the car with VCDS to see what codes its throwing.
You should scan the car with VCDS to see what codes its throwing.
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04-23-2018, 07:23 PM
#8
My Bentley manual associates the P0322 code with the Engine Speed (RPM) Sensor G28. It says "The engine speed (RPM) sensor -G28- detects RPM and reference marks. The engine cannot be started without a signal from the engine speed (RPM) sensor -G28-. If the engine speed (RPM) sensor -G28- signal fails while the engine is running, the engine will stop immediately."
The symptoms of a failed G28 sensor listed in the manual don't match what you're seeing, but since P0322 is the only code you've got, I'd start by replacing the G28 sensor and see if that fixes your problem.
The symptoms of a failed G28 sensor listed in the manual don't match what you're seeing, but since P0322 is the only code you've got, I'd start by replacing the G28 sensor and see if that fixes your problem.
04-24-2018, 07:11 AM
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My Bentley manual associates the P0322 code with the Engine Speed (RPM) Sensor G28. It says "The engine speed (RPM) sensor -G28- detects RPM and reference marks. The engine cannot be started without a signal from the engine speed (RPM) sensor -G28-. If the engine speed (RPM) sensor -G28- signal fails while the engine is running, the engine will stop immediately."
The symptoms of a failed G28 sensor listed in the manual don't match what you're seeing, but since P0322 is the only code you've got, I'd start by replacing the G28 sensor and see if that fixes your problem.
The symptoms of a failed G28 sensor listed in the manual don't match what you're seeing, but since P0322 is the only code you've got, I'd start by replacing the G28 sensor and see if that fixes your problem.
04-24-2018, 10:24 AM
#10
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I stand corrected; the code was engine speed sensor G28, which I called the crankshaft position sensor. Anyway, I replaced that with a new Bosch part, but did not correct the fault. It was only after checking and tweeking the relay arm which was marginal, that the problem went away. My guess is that the ECU is always watching the G28 signal, counting ring gear teeth, and if anything interrupts that count, the ECU responds by logging a code and changing how the car runs. I think that the relay bounce due to the road shock caused the ECU to "think" that the G28 malfunctioned.