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Erratic Idle

4K views 8 replies 4 participants last post by  KHALED 
#1 ·
Need help .

My Exige won't ideal unless I stay on the throttle and it's very rough. Tried to drive around the block but it has no power , seems like it's running on 2-3 cylinders . There's a also a strong smell of fuel likely unburnt!
Pulled a P0601 code!

The problem occurred right after I span . Thought something might have snapped put of it's place but couldn't find anything apparent .

Need help please. What I should check for, where to look?

Thanks
 
#2 ·
That's a watchdog error. I think you mean you wrecked the car and then this popped up? If the battery came loose (scary easy - I have repaired fiberglass from where it happened to me) then it could be that you bricked the ECU. I'd call up a dealer and see if you need to mail in to have them reset it.
 
#3 ·
Check the thread below, post #31 was the solution for one guy here - inspect the intake camshaft position sensor. You're probably not sparking on 1 or more cylinders because of that code which would explain the rich and smelly exhaust.

Like cyow5 says, it's unclear what you mean by "The problem occurred right after I span ." ?

http://www.lotustalk.com/forums/f259/my-ecu-fried-no-spark-119654/
 
#4 ·
According to my reading of the ECU code the P0601 error is evaluated upon ECU power on, and is a checksum error. I find that the checksum (P0601) and watchdog (P0606) errors are mislabeled in parts of the Lotus service notes for the 2zz elise (the labels for different model years switch, so one is erroneous).

This CEL appears to be set when the ECU learning data is corrupted.

Here is my understanding (based on 2005 MY Elise ECU code): between power cycles the ECU stores the state of various counters, sensor offsets/drift, RAM parameters and the VIN in flash memory. When the data is saved a simple 32-bit checksum is calculated and saved along with it in order to check the fidelity of the saved data. When the ECU boots it loads the saved data from flash memory back into static RAM (to two locations- one a buffer that contains the data to be saved between power cycles and the other where the data is used and updated in runtime) and it re-calculates the checksum based on the loaded data. If the loaded checksum (calculated before saving the data to flash) and the currently calculated checksum do not match, then a flag is set that triggers the P0601 error to be saved.

I have heard many stories of people losing the stored VIN (and somehow not simultaneously getting the checksum error), but this is the first time I've heard a report of the checksum error.
 
#5 ·
Thank you all for your valuable input.

Let me explain a little bit more. I span, hit a curb and damaged my front left wheel and cracked my headlight lens. The battery didn't come loose.

Right now I have two codes P0601 & P0630
I haven't mentioned the P0630 in my initial thread since I thought it was irrelevant. I've had that code for many years for now, right from the first day of ownership when the car was brand new. I had the VIN reprogrammed by the dealer and the code cleared but it came back after disconnecting the battery for a long period. The dealer did worn me it would come back if the battery is disconnected for a long time.
 
#6 ·
Thanks for the additional info. Don't assume the ECU is bad just yet. See the thread I linked above.

The force from hitting the curb may have disrupted the cam position sensor or (more likely) its wire harness. When that sensor fails, it won't talk to the ECU and that can trigger a P0601.
 

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#9 ·
I finally had the time to get back to it.
Removed my oversized intercooler to check the sensors underneath it. They all looked fine.
However, I found an open vacuum lines on the throttle body. Kept looking for a hose or something to plug it in there but didn't find anything. Instead, found a plastic cap in the engine bay that fits the opening perfectly. Plugged it and the engine started right away strong and smooth.

Thank you all for your support.
 
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