Thread: p1123 and p1125
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Old 03-05-2007, 03:25 PM   #8
MNBoxster
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Join Date: Sep 2005
Location: Minneapolis/St. Paul, Minnesota, USA
Posts: 3,308
Quote:
Originally Posted by NickCats
Jim,

Why do you think the EVO would throw up codes related to throttle position ?

Just wondering...

Thanks,

Nick
Hi,

@ Nick - There are lots of components which do not have their own CEL. For instance take a MAF - there is no OBDII or 'P' code which states "Bad MAF". This is because the sensor either isn't self-diagnosing, or for reasons of cost, memory space, or complicated code, the DME doesn't monitor the sensor's specific condition.

Consequently, many of the CELs report a variance to known or expected voltages or conditions. Therefore, you often need to do a little detective work figuring out which components affect such conditions and using experience (we all know how susceptible the MAF is to any screwing around), intuition and deduction, zero-in on the offending component, such as in this instance.

I say it was the Evo because when it was swapped, I suspect that it either jarred the MAF into failing, or let loose some dirt from the intake tubing and set off the MAF. A MAF malfunction could manifest itself into a condition resembling a throttle body issue - Revs not matching TPS (Throttle Position Sensor), or OČ Sensor data not matching expected Data (too rich/lean), etc.

This is why it isn't that unusual to see CELs when people add or disturb components which were otherwise working fine (or at least within acceptable tolerances).

I deduced that since dj reported the EVO swap, this was complicit in the issue. If he hadn't added the EVO, I suspect the car would have never thrown the code (of course, this is speculating)...

Happy Motoring!... Jim'99
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